Systematic Review ARTICLE
The Yo-Yo Intermittent Tests: A Systematic Review and Structured Compendium of Test Results
- 1Institute of Sports Medicine, Molecular Genetics of Cardiovascular Disease, University Hospital Muenster, Muenster, Germany
- 2Institute of Biostatistics and Clinical Research, University of Muenster, Muenster, Germany
Background: Although Yo-Yo intermittent tests are frequently used in a variety of sports and research studies to determine physical fitness, no structured reference exists for comparison and rating of test results. This systematic review of the most common Yo-Yo tests aimed to provide reference values for test results by statistical aggregation of published data.
Methods: A systematic literature search for articles published until August 2017 was performed in MEDLINE, Web of Science, SPORTDiscus and Google Scholar. Original reports on healthy females and males ≥16 years were eligible for the analysis. Sub-maximal test versions and the Yo-Yo Intermittent Recovery Level 1 Children's test (YYIR1C) were not included.
Results: 248 studies with 9,440 participants were included in the structured analysis. The Yo-Yo test types most frequently used were the Yo-Yo Intermittent Recovery Level 1 (YYIR1, 57.7%), the Yo-Yo Intermittent Recovery Level 2 (YYIR2, 28.0%), the Yo-Yo Intermittent Endurance Level 2 (YYIE2, 11.4%), and the Yo-Yo Intermittent Endurance Level 1 (YYIE1, 2.9%) test. For each separate test, reference values (global means and percentiles) for sports at different levels and both genders were calculated.
Conclusions: Our analysis provides evidence that Yo-Yo intermittent tests reference values differ with respect to the type and level of sport performed.The presented results may be used by practitioners, trainers and athletes to rate Yo-Yo intermittent test performance levels and monitor training effects.
Since the introduction of the Yo-Yo Intermittent (YYI) test as a field test method in the 1990s, an evolution of the Yo-Yo test family has occurred (Bangsbo, 1994; Krustrup et al., 2003; Bangsbo et al., 2008). Today, Yo-Yo test variants are extensively used to assess physical fitness in different sports and populations.
In comparison to standard laboratory testing, field test methods have been developed to bring exercise testing to a more realistic setting with the additional practical benefit to determine exercise capacity also in groups (Krustrup et al., 2003). Modern wearable devices such as heart rate (HR)/ECG monitors, 3D gyroscopes and spirometers provide additional options for these testing methods. The majority of field tests are performed as exhaustive running tests measuring total distance covered, maximal test duration or maximal speed as easy-to-access outcome parameters. While continuous running tests (Balke, 1963; Léger and Boucher, 1980; Ramsbottom et al., 1987) such as the Cooper test (Cooper, 1968) are typically performed on 200 or 400 m tracks, multi-stage shuttle-run tests consist of repeated short distance runs (Léger and Lambert, 1982; Krustrup et al., 2003; Da Silva et al., 2011). In this regard, shuttle-run tests also include an agility component immanent to sports that involve intermittent exercise such as soccer or basketball (Bangsbo et al., 2008).
The Yo-Yo Intermittent Recovery (YYIR) test has been developed based on the maximal multistage 20-m shuttle-run test (20-MST) (Bangsbo et al., 2008) introduced by Léger and Lambert (Léger and Lambert, 1982) and was modified by an active recovery period by Bangsbo (Bangsbo et al., 2008). The main objective of the YYIR test was to measure the ability to repeatedly perform intense exercise including the potential to rapidly recover from such exercise (Krustrup et al., 2003). During the YYIR test, participants perform repeated 2 × 20-m runs at progressively increasing speed, intermitted by 10-s periods of active recovery (2 × 5 m) (Bangsbo et al., 2008). The test is performed until total exhaustion of the participant is reached (i.e., as maximal performance test). The pace is controlled by an automated acoustic device, indicating start, turn and finish but it is mandatory that the test is supervised by experienced personnel. YYIR performance is defined as the maximal distance covered (m) which is achieved when a participants has failed twice to reach the finishing line in time or discontinuous the test due to perceived exhaustion. The YYIR test can be performed at two different levels, designated as Yo-Yo Intermittent Recovery Level 1 (YYIR1) test and Yo-Yo Intermittent Recovery Level 2 (YYIR2) test. In detail, the YYIR1 test starts at a lower speed level (Castagna et al., 2006b) with 4 running bouts at 10–13 km·h−1 (0–160 m) followed by 7 runs at 13.5–14 km·h−1 (160–440 m), proceeding with stepwise 0.5 km·h−1 speed increments after every 8 running bouts until exhaustion (Krustrup et al., 2003). By contrast, the YYIR2 test starts at a higher speed level and two initial runs of 13 and 15 km·h−1, respectively, followed by two runs at 16 km·h−1, three runs at 16.5 km·h−1, 4 runs at 17.0 km·h−1, proceeding with stepwise 0.5 km·h−1 speed increments after every 8 running bouts until exhaustion (Krustrup et al., 2006; Bangsbo et al., 2008). Based on this difference, the YYIR1 test has been suggested as a method primarily to test endurance capacity, whereas the YYIR2 test was introduced to determine the ability to repeatedly perform intense exercise with a high anaerobic energy contribution (Bangsbo et al., 2008). Two additional common test modifications exist for the determination of endurance capacity, the Yo-Yo Intermittent Endurance Level 1 (YYIE1) test (starting at 8 km·h−1) (Castagna et al., 2006a) and the Yo-Yo Intermittent Endurance Level 2 (YYIE2) test (starting at 11.5 km·h−1) (Bradley et al., 2014). In both YYIE tests, the active recovery period is shortened to 5 s (2 × 2.5 m) and the stepwise increase is reduced from 0.5 to 0.25 km·h−1 (Reilly et al., 2000).
Despite the intensive use of Yo-Yo tests in athletic training, sports sciences and sports medicine, a comprehensive summary of test results is missing from the literature. The aim of this systematic review and analysis was to establish a structured list of reference values for the most common Yo-Yo tests to be used in practical and scientific applications. The current study will therefore provide a basis to interpret physical performance of healthy individuals ranging from sedentary and recreationally active subjects to amateur and elite athletes. In combination with known values for test reproducibility, the generated data will also help to interpret the individual response to specific training interventions.
Study Design and Participants Eligibility Criteria
Any original article reporting on performance testing using either of the four Yo-Yo test variants including the YYIR1, YYIR2, YYIE1, and YYIE2 test was considered for the analysis. Sub-maximal test versions, the Yo-Yo Intermittent Recovery Level 1 Children's test (YYIR1C) (Ahler et al., 2012; Bendiksen et al., 2013) or other test modifications were not included in the analysis. The original multistage 20-MST (Léger and Lambert, 1982) without recovery periods, which has occasionally been described as “Yo-Yo test” was not included in this analysis. Only reports on healthy humans (n ≥ 5) with no disability were eligible. Data on participants ≥16 years of age were included based on the analysis of age-related Yo-Yo test performance variation by Deprez et al. (2012, 2014, 2015b). Articles had to be original research (not a review, book [chapter] or conference abstract) and be written in English. Gray literature, including theses, reference lists or websites were not included. Articles were excluded if (1) they were not available as full-text (after an attempt to contact the corresponding author), (2) did not report original performance test results (i.e., reporting percent changes, etc.), (3) presented performance data only in figures, (4) reported test results in any other format than maximal distance (m), time (min), speed (m·s−1) or stages, or if (5) the type of test performed was not clearly defined. Articles were also excluded if the number of tested subjects or test performance mean or standard deviation (SD)/standard error of the mean (SEM) were missing or not clearly reported in the full-text. The eligibility criteria were selected also in accordance with the quality assessment (see below). This study is part of a larger project on the use of YYI tests to determine exercise capacity in adults and children and as tool to measure effects in randomized controlled trails (RCTs). A specific review protocol will be available upon request.
Search Strategy and Data Sources
A systematic search of the literature was conducted (CP) using PubMed (MEDLINE database), SPORTDiscus with Full Text, Google Scholar and Web of Science for all records published until August 2017. Databases were searched using the following key words: “Yo-Yo intermittent test” or “Yo-Yo intermittent” or “Yo-Yo intermittent recovery test” or “Yo-Yo intermittent recovery” or “Yo-Yo intermittent endurance test” or “Yo-Yo intermittent endurance” or “YYIR1” or “YYIR2” or “YYIR” or “YYIE1” or “YYIE2” or “YYIE” or “Yo-Yo IR” or “Yo-Yo IE” or “Yo-Yo IR1” or “Yo-Yo IE1” or “Yo-Yo IR2” or “Yo-Yo IE2” or “Yo-Yo test” or “YoYo test.” Manual searches were also performed using references from identified articles. Two authors (BS and CP) performed full-text screening on potential relevant reports. The individual steps of report identification, screening and processing are documented according to the PRISMA flow-chart (Figure 1) (Moher et al., 2009) with modifications. Search results and fulfillment of eligibility criteria were discussed if unclear (BS and CP) until consensus was achieved and upon disagreement, a third person was consulted to determine inclusion.
Study Selection and Data Extraction
Data were extracted by two reviewers (BS and CP) and tables were created including information on first author, year of publication, information on description of participants (total number, anthropometric data, competition level), type of sport, test type and performance data. If articles reported on test results of different age groups, separate data on participants ≥16 years of age were extracted if possible. In case of reporting on general intra- and inter-seasonal Yo-Yo test performance changes, the best test data were extracted. Inter-seasonal changes were analyzed separately as stated below (Bangsbo et al., 2008). In case of redundant data reported in separate publications, only data from the earlier report were extracted. If both females and males or different types of sports were tested in combination and could not be extracted separately, the test results were not included in the analysis and results were reported in online Supplementary Tables 1–4.
Individuals were classified as top-elite (international professional level, where indicated), elite (professional level), sub-elite (national level), amateur (non-professional, regional level), recreational or inactive based on the author's description. Studies presenting data on combined levels were analyzed and reported using the respective level combination as identifier. In case of imprecise, uncommon, unclear/ conflicting or missing descriptions of test participants, full-texts were screened by two reviewers (BS and CP) for additional information including club or union associations, training patterns or other information. Classification by a nearest-neighbor approach according to the documented performance data was performed when no useful information on participants could be identified. Player position-specific data were extracted separately if available. If performance data were reported in investigations involving any type of experimental condition with hypothesized effect on test performance, only pre-intervention data were extracted if available or data of (untreated) control groups were used. If intra-seasonal changes were reported, all data were extracted and the highest reported test result was included in the main analysis.
The methodological quality of the studies was assessed using the critical appraisal tool established by Brink and Louw (2012). The tool consists of 13 items assessing the quality of a study. The individual items can be scored as “yes,” “no,” or “not applicable.” For our analysis, we determined (in accordance with the above mentioned inclusion criteria) that the following items (8 out of 13) had to be scored “yes”: a detailed description of the subject sample was available, the qualification or competence of rater(s) performing the test was clarified, the reference standard was explained, the stability of the variable beaning measured was taken into account, the execution of the test was described in sufficient detail to permit replication, the execution of the reference standard was described in sufficient detail, withdrawals from the study were explained, the statistical methods were appropriate. Studies were rated by two reviewers (BS and CP). Disagreements were resolved by discussion if necessary. The researchers were not blinded to study authors, results or publication journal.
Statistical Data Analyses
Data for Yo-Yo test performance was analyzed as maximal distance (m). Maximal test duration (min), speed (m·s−1) or stages were recalculated for comparison. SD was calculated from SEM using the equation where n is the number of subjects. For each category (i.e., for each combination of sport, sex, and level) a global mean and global SD were calculated based on the reported means and SDs of the individual studies (or study subgroups) within this category. This was done assuming that the individuals from each study within the same category belong to the same population and that their test results were drawn from the same normal distribution. Each global mean was calculated as weighted mean of the individual reported means, with weights built by the number of subjects per study. Each global SD was calculated using the formula described in online Supplementary File 1. Finally, the global mean and global SD were translated into normal quantiles/ percentiles (20, 40, 60, 80%) for each category. Furthermore, separate forest plots were created for each category showing the individual mean and 95% confidence interval of each study as well as the calculated global mean and global SD. The I2 statistic was calculated for each category to quantify the heterogeneity within the respective individual study results (Higgins and Thompson, 2002). All forest plots including I2 statistics are available in the online repository.
Study Selection and Characteristics
The process of study identification, selection and final inclusion is presented in Figure 1. During the screening stage, 677 records were removed for not meeting the inclusion criteria of which 86 studies reported only on children and adolescents <16 years of age (Figure 1). Of 445 full-text articles assessed for eligibility, 264 studies were included in the qualitative synthesis. Each individual included study (or sub-study) with information on author, subgroup or performance level, sex, mean age and test results is presented in online Supplementary Tables 1–4, sorted by the test performed (including 16 studies reporting on combined sex or sports). Of these, 248 studies were included in the quantitative synthesis to obtain a global mean and SD for each category, i.e., for each combination of type of sport, performance level and sex. Global means for the YYIR1 test are presented in Figure 2, for the YYIR2 test in Figure 3, for the YYIE2 test in Figure 4 and for the YYIE1 test in Figure 5.
Figure 2. Yo-Yo Intermittent Recovery Level 1 (YYIR1) test results. RS, Rugby sevens; GF, Gaelic football.
Figure 3. Yo-Yo Intermittent Recovery Level 2 (YYIR2) test results. RS, Rugby sevens; GF, Gaelic football.
Results by Yo-Yo Test-Type
For the computation of YYIR1 test global means, SDs and quantiles (Figure 2), 239 studies or subgroups with a total of 4,726 participants (median of reported age means = 21.1, inter quartile range [IQR] of reported age means = 17.8–24.5 years) were used (Krustrup and Bangsbo, 2001; Krustrup et al., 2003; Mohr et al., 2003, 2010, 2016; Weston et al., 2004; Castagna et al., 2005, 2006b, 2008; Atkins, 2006; Thomas et al., 2006; Rampinini et al., 2007, 2008, 2010; Mujika et al., 2009; Ben Abdelkrim et al., 2010; Chaouachi et al., 2010; Dupont et al., 2010; Veale et al., 2010; Wong et al., 2010; Buchheit et al., 2011; Chtourou et al., 2011; Chuman et al., 2011; Cobley et al., 2011; Markovic and Mikulic, 2011; Matthys et al., 2011; Roberts et al., 2011; Spencer et al., 2011; Ueda et al., 2011; Alemdaroglu et al., 2012; Boullosa et al., 2012, 2013a,b; Cihan et al., 2012; Cone et al., 2012; Deprez et al., 2012, 2014, 2015a,b; Heaney, 2012; Ingebrigtsen et al., 2012, 2014; Lim, 2012; Scanlan et al., 2012, 2014; Shalfawi et al., 2012, 2013; Teplan et al., 2012a,b, 2013; Vernillo et al., 2012; Berdejo-del-Fresno and González-Ravé, 2013; Cullen et al., 2013; Faude et al., 2013; Higham et al., 2013; Idrizovic and Raickovic, 2013; Manzi et al., 2013; Oliveira et al., 2013; Román-Quintana et al., 2013; Wylie et al., 2013; Yuki et al., 2013; Casamichana et al., 2014, 2015; Clarke et al., 2014; Fabregat-Andres et al., 2014; Fanchini et al., 2014, 2015a,b; Hammouda et al., 2014; Hermassi et al., 2014, 2015, 2016; Idrizovic, 2014; Karavelioglu, 2014; Martínez-Lagunas and Hartmann, 2014; Michalsik et al., 2014; Mohr and Krustrup, 2014; Raman et al., 2014; Rollo et al., 2014; Santone et al., 2014; Soares-Caldeira et al., 2014; Till et al., 2014, 2015, 2016, 2017; Afyon et al., 2015; Attene et al., 2015; Campos-Vazquez et al., 2015a,b; Campos Vázquez et al., 2017; Darrall-Jones et al., 2015, 2016; Hasegawa and Kuzuhara, 2015; Iacono et al., 2015; Johnston et al., 2015; Köklü et al., 2015; Krustrup and Mohr, 2015; Lopez-Segovia et al., 2015; Macpherson and Weston, 2015; Mohr, 2015; Moss et al., 2015; Nakamura et al., 2015, 2016; Noon et al., 2015; Shultz et al., 2015; Abad et al., 2016; Bizati, 2016; Bruce and Moule, 2016; Castillo et al., 2016, 2017; Coratella et al., 2016; Eaton et al., 2016; Flatt and Esco, 2016; Furlan et al., 2016; Jones et al., 2016; Karsten et al., 2016; Kilding et al., 2016; Lockie et al., 2016d; Matzenbacher et al., 2016; McIntosh et al., 2016; Nyberg et al., 2016; Pareja-Blanco et al., 2016, 2017; Purkhús et al., 2016; Rabbani and Buchheit, 2016; Roe and Malone, 2016; Sánchez-Sánchez et al., 2016; Sant'anna and de Souza Castro, 2016; Schwesig et al., 2016; Sharpe and Macias, 2016; Smith et al., 2016; Taylor et al., 2016; Vescovi, 2016; Aloui et al., 2017; Aoki et al., 2017; Bonato et al., 2017; Dinardi et al., 2017; Dixon et al., 2017; Ferioli et al., 2017; Hamlin et al., 2017; Henrique Borges et al., 2017; Kavaliauskas et al., 2017; Malone et al., 2017; Nyakayiru et al., 2017; Risso et al., 2017; Rowat et al., 2017; Schmitz et al., 2017; Sparks et al., 2017; Veness et al., 2017).
Computation of YYIR2 test global means, SDs and quantiles (Figure 3) involved 116 studies/subgroups reporting on 2,478 participants (median age = 23.2 years, IQR = 20.7–26.0 years) (Young et al., 2005; De Souza et al., 2006; Krustrup et al., 2006; Thomas et al., 2006; Mohr et al., 2007, 2016; Iaia et al., 2008, 2015, 2017; Morton et al., 2009; Rampinini et al., 2010; Rebelo et al., 2010; Thomassen et al., 2010; Christensen et al., 2011; Chuman et al., 2011; Mooney et al., 2011, 2013a,b; Roberts et al., 2011; Ueda et al., 2011; Gunnarsson et al., 2012; Ingebrigtsen et al., 2012, 2013, 2014; Nakamura et al., 2012; Saunders et al., 2012; Wells et al., 2012, 2014; Bassini et al., 2013; Buchheit et al., 2013; McGawley and Andersson, 2013; Mohr and Krustrup, 2013, 2014, 2016; Owen et al., 2013; Pivovarniček et al., 2013; Yuki et al., 2013; Fanchini et al., 2014; Karavelioglu et al., 2014; Lollo et al., 2014; Miloski et al., 2014; Nunes et al., 2014; Sampaio et al., 2014; Skovgaard et al., 2014; Brocherie et al., 2015a,b; Cholewa et al., 2015; Coelho et al., 2015; Gatterer et al., 2015; Hogarth et al., 2015a,b; Jamurtas et al., 2015; Krustrup and Mohr, 2015; Leme et al., 2015; Mara et al., 2015; Matta et al., 2015; McLean et al., 2015; Michalsik et al., 2015; Mohr, 2015; Rogan, 2015; Stein et al., 2015; Boer and Van Aswegen, 2016; Bouaziz et al., 2016; Chan et al., 2016; Inness et al., 2016; Joo, 2016; Kilit and Arslan, 2016; Lockie et al., 2016a,b,c,d; Nogueira et al., 2016; Purkhús et al., 2016; Stevens et al., 2016; Veugelers et al., 2016; Kelly and Collins, 2017).
Computation of YYIE2 test global means, SDs and quantiles (Figure 4) included 48 studies/subgroups and 1,466 participants (median age = 23.0 years, IQR = 18.3–26.0 years) (Aziz et al., 2005; Rampinini et al., 2007; Bangsbo et al., 2010; Brito et al., 2010; Krustrup et al., 2010a,b,c, 2015; Randers et al., 2010, 2013; Ascensão et al., 2011; Bradley et al., 2011, 2013, 2014; Rebelo et al., 2011, 2013; Silva et al., 2011, 2013; Gibson et al., 2013; Dixon, 2014; Massuça et al., 2014; Massuca et al., 2015; Matta et al., 2014; Póvoas et al., 2014; Kvorning et al., 2017).
Computation of YYIE1 test global means, SDs and quantiles (Figure 5) involved 12 studies/subgroups reporting on 770 participants (median age = 21.3 years, IQR = 18.8–44.3 years) (Metaxas et al., 2005; Castagna et al., 2006a; Lategan et al., 2011; Rowan et al., 2012; Deliceoglu, 2013; Mohr et al., 2014; Akashi et al., 2015; Fløtum et al., 2016; Julian et al., 2017; Krustrup et al., 2017; Seidelin et al., 2017).
Results by Player Position
Player position data was available for 727 subjects (males and females) who performed the YYIR1 test including soccer, Gaelic football, rugby and netball (online Supplementary Figure 1). For the YYIR2 test, position data of 70 subjects (all male) was available for soccer, handball and Gaelic football (online Supplementary Figure 2). For the YYIE2, player position data of 341 individuals (all male) was analyzed for soccer and handball (online Supplementary Figure 3). No player position data was available for the YYIE1 test.
Intra-seasonal Test Results
To analyse the effects of intra-seasonal differences in YYIR test results, data of male soccer players who had performed either the YYIR1 (307 individual data points available, online Supplementary Figure 4) or YYIR2 (847 individual data points available, online Supplementary Figure 5) at a minimum of two different occasions during a single season were extracted. For other test types, sports or females, data were insufficient for an intra-seasonal analysis.
Risk of Bias
The quality of the included studies was assessed using the critical appraisal tool by Brink and Louw (2012), which does not incorporate a quality score and the impact of each item needs to be considered individually. Since the presented analysis was a study of one-point test result examination, the following 5 items were found not applicable: testing of interrater reliability and blinding of raters to the test results, blinding of raters to their own prior findings, variation of the order of examination, evaluation of time period between reference standard and index test, and independence of reference standard and index test. All other items were scored with “yes” by definition of the inclusion criteria. Other criteria for the assessment of bias, such us blinding of test participants or raters to the test results were unfeasible for this type of test.
Summary of Main Findings
This systematic review synthesized YYI test results of 248 studies comprising performance data of 9,440 participants. A statistical aggregation of published data resulted in reference lists showing global means, SDs and quantiles for the four most common YYI test variants structured by sport, performance level and sex. Data on sedentary and recreationally active females and males were also included in the analysis.
Some limitations for the presented analysis may exist. First, a high level of heterogeneity was noted in some subgroups, most likely based on the different demands that exist between different national leagues, etc. Inter-study differences including different participant characterization and description as well as definitions and nomenclature may have affected the classification process. Second, and besides methodological quality assessment of the selected studies, selection bias within individual studies may have occurred. For the presentation of Yo-Yo test results selection bias could occur in terms of test termination (i.e., the test is not stopped at the earliest time point violating the test requirements) or data partitioning and reporting of data subsets (i.e., reporting on best test results). Reporting and publication bias may have affected the present analysis since some data/ studies may have remained unreported or were not published because of unexpected/ contradictory, negative or not significant test results. Furthermore, the record search was limited to studies published in English and inclusion of data reported in other languages may have altered the results of subgroups with smaller sample sizes. The necessary pooling and transformation of data may also have affected the presented results to some extent.
The most frequently used YYI test to determine physical fitness in individuals ≥16 years of age was the YYIR1 test (57.7%), followed by the YYIR2 test (28.0%), the YYIE2 test (11.4%), and the YYIE1 test (2.9%). As the YYI test was originally proposed to test aerobic performance of soccer players, the largest dataset of test results was available for female and male soccer players (and referees) followed by different other types of sports marked by high intermittent exercise such as basketball, handball, rugby etc. Our study also documented that YYI variants have been used in other sports including futsal, cross-country skiing, endurance running, recreational team sports and a number of other activities on different levels. With respect to the documented test results and overall tests analyzed in this study, it can be generally stated that men performed better than women, elite athletes performed better than sub-elite or amateur athletes and higher test performance was seen for intermittent sports, which is in line with an earlier analysis by Bangsbo et al. (2008). However, individual performance from athletes of other sports with a high aerobic component such as cross-country skiing was also documented at high levels. Overall, the data also provide evidence that even within the category of sports marked by high intermittent exercise, differences in YYI test results can be detected, which might reflect the multifactorial nature in sports and the need for specific reference values. We have also noted that in individual cases, athletes or teams at lower competitive levels may reach high or very high test performance values, documenting outstanding physical performance. For example, our analysis on YYIE2 test results revealed that sub-elite soccer players may reach test results comparable to top-elite players. In addition, our analysis documented that physical fitness of recreationally active but also inactive subjects can be tested by either of the four Yo-Yo variants.
Position and Seasonal Data
Since different demands exist for the individual positions in team sports, we also generated position-specific global means, SDs and quantiles for each test where available. We only detected slight differences between outfield players in general, most likely reflecting the need for high endurance capacity of the entire team for dynamic and successful competition which is achieved by team-specific rather than player position-specific training. During the data extraction and evaluation we noticed that most studies explicitly excluded goalkeepers from their analysis. Our analysis on available data revealed that goalkeepers tended to lower performance over the analyzed test types and sports (soccer, gaelic football, and handball) and their performance should thus indeed be evaluated separately from the outfield players. This example illustrates that individual training modalities such as specific goalkeeper training which besides aerobic and sprint training includes a considerable amount of reflex training, ball stopping, etc. are reflected by YYI test performance.
Intra-seasonal changes were limited to an analysis of male soccer players in the YYIR1 and YYIR2 test as sufficient data for females, other sports or test types was not available. The analysis suggested that players' YYIR test results tend to be generally lower when assessed during preseason and increase with regular seasonal training as would be expected (Bangsbo et al., 2008). However, this data should be interpreted with care as scheduled seasonal testing routines enable participants (players and coaches) to control their test performance toward increasing results to indicate adequate training response.
The YYIR test was initially introduced to measure the ability to repeatedly perform intense exercise including the potential to rapidly recover from such exercise with a particular focus on intermittent sports such as soccer or basketball (Krustrup et al., 2003; Bangsbo et al., 2008). Thus, the validity can be tested by comparison of YYIR test performance and performance during actual competitive games. For the YYIR1 test, the reported significant correlation with high-intensity running (>15 km·h−1) during a soccer match was r = 0.71 (n = 18, elite soccer players) (Krustrup et al., 2003) and the correlation with high-intensity activity and total distance covered during a soccer match was r = 0.77 and r = 0.65, respectively (n = 19, young soccer players, age ~14 years) (Castagna et al., 2009). For the YYIR2 test, the correlation with the time above 85% of HRmax during a soccer match was r = 0.71 (n = 18, young soccer players, age ~14 years), the correlation with high-speed running (>14.4 km·h−1) during small-sided game was r = 0.70 (n = 113, soccer players, age range ~17–24 years) (Stevens et al., 2016), the correlation with load·min−1 during football matches was r = 0.77 (n = 20, elite football players, age ~22 years) (Mooney et al., 2013b) and the correlation with high-speed running (>15 km·h−1) during football matches was r ≥ 0.62 (n = 15, elite football players, age ~22 years) (Mooney et al., 2013a). For the YYIE2 test, the reported correlation with high-intensity running (≥19.8 km·h−1) during professional soccer matches was r = 0.54 (n = 22, Premier League soccer players, age ~26 years) and r = 0.64 (n = 21, Championship soccer players, age ~25 years) (Bradley et al., 2013). The observed correlations between the different YYI tests and match performance parameters can thus be rated as moderate to strong.
In addition, Yo-Yo test variants have been suggested to determine aerobic performance capacity and thus to estimate maximal oxygen uptake (VO2max). For the YYIR1 test, the reported significant correlation with VO2max determined in a laboratory setting was r = 0.71 (n = 15, elite soccer players) (Krustrup et al., 2003). This finding was confirmed by a report on the significant correlation of YYIR1 test performance and laboratory VO2max in recreationally active subjects (r = 0.87, n = 19) (Thomas et al., 2006). Castagna et al. (2006b), however, did not detect a significant correlation between YYIR1 test performance and laboratory VO2max (r = 0.46, n = 24, amateur soccer players, age ~25 years). For the YYIE2 test, the same group reported a significant correlation with laboratory VO2max at r = 0.75 (n = 24, amateur soccer players, age ~25 years) (Castagna et al., 2006b). For the YYIR2 test, Thomas et al. (2006) reported no significant correlation between test performance and laboratory VO2max (r = 0.43, n = 19, recreationally active men). For the YYIE1 test, correlation with laboratory VO2max was r = 0.63 (n = 62, young soccer players, age ~14 years) (Wong et al., 2011) and r = 0.65 (n = 18, youth soccer players, age ~16 years) (Castagna et al., 2006a). The latter study, however, also measured VO2max directly during the YYIE1 and reported that VO2max was not significantly associated with the distance covered during the test (r = 0.53). Interestingly, they also noted that maximal respiratory variables determined in the laboratory setting and YYIE1 test were not significantly different (Castagna et al., 2006a). The authors concluded that YYIE1 performance does not exclusively depend on maximal aerobic power. With respect to these results, future studies on the YYI tests are needed and should involve wearable spirometry devices to gain better insight into the cardio-respiratory responses during the different tests.
It has been suggested that changes in athletes' performance in response to different training strategies may be monitored by the YYI test (Krustrup et al., 2006). To this respect, the level of test reproducibility is important and has been analyzed in a number of different populations during the past two decades. For the YYIR1, the reported coefficients of variation (CV) were 4.9% (n = 13) (Krustrup et al., 2003), 7.3% (n = 24, young soccer players) (Fanchini et al., 2014), 8.1% (n = 28) (Bangsbo et al., 2008) and 8.7% (n = 16, recreationally active men) (Thomas et al., 2006). For the YYIR2, the CVs ranged from 7.1% (n = 24, young soccer players) (Fanchini et al., 2014) to 9.6% (n = 29, normally trained male subjects and elite soccer players) (Krustrup et al., 2006), 10.4% (n = 53) (Bangsbo et al., 2008) and 12.7% (n = 17, recreationally active men) (Thomas et al., 2006). For the YYIE1, CV of 5.7% was observed in young soccer players (age ~14, n = 51) (Wong et al., 2011) and for the YYIE2, CV of 4.5% was observed in domestic female soccer players (n = 27) (Bradley et al., 2014). With respect to age (and potentially training experience in intermittent sports) as a major confounding factor for test reproducibility, Póvoas et al. reported on Yo-Yo tests in schoolboys (9–16 years) and observed that the CV decreased with increasing age from 11.1 to 8.5% (Póvoas et al., 2016). Deprez and colleagues reported that the CV for the YYIR1 decreased with increasing age from 17.3 to 7.9% in 78 sub- and non-elite soccer players (age-range 11.3–17.2 years) (Deprez et al., 2014). It is therefore important to note that smaller effects on physical fitness might not be detectable using either of the YYI test variants in any population. With respect to practical implications this would translate into certain minimal detectable changes as follows. Exemplified, for male sub-elite soccer players tested by the YYIR1 test (global mean distance = 1,891 m) and application of the lowest CV (4.9%) the estimated minimal change indicating a suggestive meaningful improvement would be >92 m and thus ≥5 full 20-m shuttles. The application of an estimated mean over the available reported CVs of ~7.3% for the same group would results in an estimated minimal change indicating a likely meaningful improvement of >138 m and thus ≥7 full 20-m YYIR1 test shuttles. For the YYIR2 test (lowest reported CV = 7.1%) and male sub-elite soccer players, the estimated minimal change indicating a suggestive meaningful improvement would be >134 m and thus ≥ 7 full 20-m shuttles. The application of an estimated mean over the available reported CVs of ~9.9% for the same group would results in an estimated minimal change indicating a likely meaningful improvement of >187 m and thus ≥10 full 20-m YYIR1 test shuttles. This might also have consequences for YYI test-based analysis of interventional programs in the field of primary prevention of diseases and underlines the need for controlled trials with adequate group sizes.
Potential Test Limitations and Practical Instructions
Per definition, the YYIR1/2 and YYIE1/2 test are designed as maximal performance tests (Krustrup et al., 2003; Bangsbo et al., 2008). It is thus an essential requirement that the tested participant is willing to perform until total exhaustion. If the participant resists to this concept, for example to achieve underestimation of the training status at the beginning of a training season or to prevent from exhaustive exercise during match preparations, the test result will be of limited value. It is thus important that participants are highly motivated and are familiar with the general concept of the test and its application. Participants also need to understand the test settings and rules including the criteria of termination (i.e., failure to reach the finishing line within time, etc.), which can best be realized by familiarization with the test. To achieve maximal performance, motivation of the participant including verbal encouragement during the test as well as (competitive) group settings might be helpful. With respect to the latter aspect, it is not only mandatory that the test is supervised by experienced personnel but it should be a general standard that the test is supervised and documented by at least two raters. This will allow for the prevention of errors in general such as documentation errors or test procedure errors (i.e., failure of the participant to cover the full running/ recovery distance) and will also limit the effect of observer errors including failure of timely test termination (which will lead to overestimation of the result). Moreover, we suggest that raters which document test results are blinded to the findings of other raters and interrater reliability is reported (Brink and Louw, 2012) together with other important test parameters (including location, number of supervisors/ assistants, group size, etc.). Finally, modern devices such as wearable HR monitors, 3D gyroscopes and (in track) timing gates might further increase the value of Yo-Yo test variants.
The most frequently used Yo-Yo intermittent test to determine physical fitness in individuals ≥16 years of age was the YYIR1 test (57.7%), followed by the YYIR2 test (28.0%), the YYIE2 test (11.4%) and the YYIE1 test (2.9%). Our analysis provides evidence that YYI tests reference values differ depending on gender as well as type and level of sport performed. In general, higher test performance was seen for intermittent sports but YYI test variants may also be used to determine physical fitness in other sports as well as recreationally active and inactive subjects. The presented results may be used by practitioners, trainers and athletes to rate Yo-Yo intermittent test performance and monitor training effects. With regard to varying reproducibility values, caution is warranted when using YYI tests to determine performance changes in response to different training strategies.
BS, S-MB, AF, MB, and CP contributed to the conception and design of the study. CP performed the systematic search. CP and BS screened records and edited the data. BS, MB, CP, and KK performed the data analysis. BS and CP wrote the manuscript. All authors contributed to the drafting and revision of the manuscript. All authors approved the final version of the manuscript.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
We thank Franziska Breulmann for reviewing the extracted data after entry into the databases.
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fphys.2018.00870/full#supplementary-material
Abad, C. C. C., Pereira, L. A., Kobal, R., Kitamura, K., Cruz, I. F., Loturco, I., et al. (2016). Heart rate and heart rate variability of Yo-Yo IR1 and simulated match in young female basketball athletes: a comparative study. Int. J. Perform. Anal. Sport 16, 776–791. doi: 10.1080/24748668.2016.11868927
Afyon, Y. A., Mulazimoglu, O., Hazar, K., Çelikbilek, S., Erdogdu, M., and Tokul, E. (2015). The effect of six-week period small-sided game training on the aerobic endurance performance among elite professional soccer players. J. Educ. Sociol. 6, 93–96. doi: 10.7813/jes.2015/6-2/21
Ahler, T., Bendiksen, M., Krustrup, P., and Wedderkopp, N. (2012). Aerobic fitness testing in 6- to 9-year-old children: reliability and validity of a modified Yo-Yo IR1 test and the Andersen test. Eur. J. Appl. Physiol. 112, 871–876. doi: 10.1007/s00421-011-2039-4
Akashi, K., Tanaka, M., Tanaka, H., and Higaki, Y. (2015). Effects of body contact during incremental and intermittent exercise on running power in handball players. Int. J. Sport Health Sci. 13, 102–110. doi: 10.5432/ijshs.201527
Alemdaroglu, U., Dündar, U., Köklü, Y, and Aşci, A. (2012). Evaluation of aerobic capacity in soccer players: comparison of field and laboratory tests. Biol. Sport. 29, 157–161. doi: 10.5604/20831862.990468
Aloui, A., Driss, T., Baklouti, H., Jaafar, H., Hammouda, O., Chamari, K., et al. (2017). Repeated-sprint training in the fasted state during Ramadan: morning or evening training? J. Sports Med. Phys. Fitness. 58, 990–997. doi: 10.23736/S0022-4707.17.07090-6
Aoki, M. S., Ronda, L. T., Marcelino, P. R., Drago, G., Carling, C., Bradley, P. S., et al. (2017). Monitoring training loads in professional basketball players engaged in a periodized training program. J. Strength Cond. Res. 31, 348–358. doi: 10.1519/JSC.0000000000001507
Ascensão, A., Leite, M., Rebelo, A. N., Magalhäes, S., and Magalhäes, J. (2011). Effects of cold water immersion on the recovery of physical performance and muscle damage following a one-off soccer match. J. Sports Sci. 29, 217–225. doi: 10.1080/02640414.2010.526132
Attene, G., Laffaye, G., Chaouachi, A., Pizzolato, F., Migliaccio, G. M., and Padulo, J. (2015). Repeated sprint ability in young basketball players: one vs. two changes of direction (Part 2). J. Sports Sci. 33, 1553–1563. doi: 10.1080/02640414.2014.996182
Bangsbo, J., Iaia, F. M., and Krustrup, P. (2008). The Yo-Yo intermittent recovery test: a useful tool for evaluation of physical performance in intermittent sports. Sports Med. 38, 37–51. doi: 10.2165/00007256-200838010-00004
Bangsbo, J., Nielsen, J. J., Mohr, M., Randers, M. B., Krustrup, B. R., Brito, J., et al. (2010). Performance enhancements and muscular adaptations of a 16-week recreational football intervention for untrained women. Scand. J. Med. Sci. Sports. 20, 24–30. doi: 10.1111/j.1600-0838.2009.01050.x
Bassini, A., Magalhães-Neto, A. M., Sweet, E., Bottino, A., Veiga, C., Tozzi, M. B., et al. (2013). Caffeine decreases systemic urea in elite soccer players during intermittent exercise. Med. Sci. Sports Exerc. 45, 683–690. doi: 10.1249/MSS.0b013e3182797637
Ben Abdelkrim, N., Chaouachi, A., Chamari, K., Chtara, M., and Castagna, C. (2010). Positional role and competitive-level differences in elite-level men's basketball players. J. Strength Cond. Res. 24, 1346–1355. doi: 10.1519/JSC.0b013e3181cf7510
Bendiksen, M., Ahler, T., Clausen, H., Wedderkopp, N., and Krustrup, P. (2013). The use of Yo-Yo intermittent recovery level 1 and Andersen testing for fitness and maximal heart rate assessments of 6- to 10-year-old school children. J. Strength Cond. Res. 27, 1583–1590. doi: 10.1519/JSC.0b013e318270fd0b
Boer, P. H., and Van Aswegen, M. (2016). Effect of combined versus repeated sprint training on physical parameters in sub-elite football players in south africa. J. Phys. Educ. Sport 16, 964–971. doi: 10.7752/jpes.2016.03152
Bonato, M., Agnello, L., Galasso, L., Montaruli, A., Roveda, E., Merati, G., et al. (2017). Acute modification of cardiac autonomic function of high-intensity interval training in collegiate male soccer players with different chronotype: a cross-over study. J. Sports Sci. Med. 16, 286–294.
Bouaziz, T., Makni, E., Passelergue, P., Tabka, Z., Lac, G., Moalla, W., et al. (2016). Multifactorial monitoring of training load in elite rugby sevens players: cortisol/cortisone ratio as a valid tool of training load monitoring. Biol. Sport 33, 231–239. doi: 10.5604/20831862.1201812
Boullosa, D. A., Abreu, L., Nakamura, F. Y., Muñoz, V. E., Dominguez, E., and Leicht, A. S. (2013a). Cardiac autonomic adaptations in elite Spanish soccer players during preseason. Int. J. Sports Physiol. Perform 8, 400–409. doi: 10.1123/ijspp.8.4.400
Boullosa, D. A., Abreu, L., Tuimil, J. L., and Leicht, A. S. (2012). Impact of a soccer match on the cardiac autonomic control of referees. Eur. J. Appl. Physiol. 112, 2233–2242. doi: 10.1007/s00421-011-2202-y
Boullosa, D. A., Tonello, L., Ramos, I., Silva Ade, O., Simoes, H. G., and Nakamura, F. Y. (2013b). Relationship between aerobic capacity and Yo-Yo IR1 performance in Brazilian professional futsal players. Asian J. Sports Med. 4, 230–234.
Bradley, P. S., Bendiksen, M., Dellal, A., Mohr, M., Wilkie, A., Datson, N., et al. (2014). The application of the Yo-Yo intermittent endurance level 2 test to elite female soccer populations. Scand. J. Med. Sci. Sports 24, 43–54. doi: 10.1111/j.1600-0838.2012.01483.x
Bradley, P. S., Carling, C., Gomez Diaz, A., Hood, P., Barnes, C., Ade, J., et al. (2013). Match performance and physical capacity of players in the top three competitive standards of English professional soccer. Hum. Mov. Sci. 32, 808–821. doi: 10.1016/j.humov.2013.06.002
Bradley, P. S., Mohr, M., Bendiksen, M., Randers, M. B., Flindt, M., Barnes, C., et al. (2011). Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer. Eur. J. Appl. Physiol. 111, 969–978. doi: 10.1007/s00421-010-1721-2
Brito, J., Fernandes, L., Seabra, A., and Rebelo, A. (2010). Factors influencing the performance of young football players in the yo-yo intermittent endurance test (Level 2). 2, 51–53. doi: 10.2478/v10101-010-0012-z
Brocherie, F., Millet, G. P., Hauser, A., Steiner, T., Rysman, J., Wehrlin, J. P., et al. (2015a). “Live high-train low and high” hypoxic training improves team-sport performance. Med. Sci. Sports Exerc. 47, 2140–2149. doi: 10.1249/MSS.0000000000000630
Brocherie, F., Millet, G. P., Hauser, A., Steiner, T., Wehrlin, J. P., Rysman, J., et al. (2015b). Association of hematological variables with team-sport specific fitness performance. PLoS ONE 10:e0144446. doi: 10.1371/journal.pone.0144446
Buchheit, M., Racinais, S., Bilsborough, J., Hocking, J., Mendez-Villanueva, A., Bourdon, P. C., et al. (2013). Adding heat to the live-high train-low altitude model: a practical insight from professional football. Br. J. Sports Med. 47, i59–i69. doi: 10.1136/bjsports-2013-092559
Buchheit, M., Voss, S. C., Nybo, L., Mohr, M., and Racinais, S. (2011). Physiological and performance adaptations to an in-season soccer camp in the heat: associations with heart rate and heart rate variability. Scand. J. Med. Sci. Sports 21, e477–e485. doi: 10.1111/j.1600-0838.2011.01378.x
Campos Vázquez, M. Á., Casamichana Gómez, D., Suárez Arrones, L., González Jurado, J. A., Toscano Bendala, F. J., and León Prados, J. A. (2017). Medium-sided games in soccer: physical and heart rate demands throughout successive working periods. J. Hum. Sport Exerc. 12, 129–141. doi: 10.14198/jhse.2017.121.11
Campos-Vazquez, M. A., Mendez-Villanueva, A., Gonzalez-Jurado, J. A., Leon-Prados, J. A., Santalla, A., and Suarez-Arrones, L. (2015a). Relationships between rating-of-perceived-exertion- and heart-rate-derived internal training load in professional soccer players: a comparison of on-field integrated training sessions. Int. J. Sports Physiol. Perform. 10, 587–592. doi: 10.1123/ijspp.2014-0294
Campos-Vazquez, M. A., Romero-Boza, S., Toscano-Bendala, F. J., Leon-Prados, J. A., Suarez-Arrones, L. J., and Gonzalez-Jurado, J. A. (2015b). Comparison of the effect of repeated-sprint training combined with two different methods of strength training on young soccer players. J. Strength Cond. Res. 29, 744–751. doi: 10.1519/JSC.0000000000000700
Casamichana, D., Román-Quintana, J. S., Castellano, J., and Calleja-González, J. (2015). Influence of the type of marking and the number of players on physiological and physical demands during sided games in soccer. J. Hum. Kinet. 47, 259–268. doi: 10.1515/hukin-2015-0081
Casamichana, D., Suarez-Arrones, L., Castellano, J., and Román-Quintana, J. S. (2014). Effect of number of touches and exercise duration on the kinematic profile and heart rate response during small-sided games in soccer. J. Hum. Kinet. 41, 113–123. doi: 10.2478/hukin-2014-0039
Castagna, C., Abt, G., and D'Ottavio, S. (2005). Competitive-level differences in Yo-Yo intermittent recovery and twelve minute run test performance in soccer referees. J. Strength Cond. Res. 19, 805–809. doi: 10.1519/R-14473.1
Castagna, C., Impellizzeri, F., Cecchini, E., Rampinini, E., and Alvarez, J. C. (2009). Effects of intermittent-endurance fitness on match performance in young male soccer players. J. Strength Cond. Res. 23, 1954–1959. doi: 10.1519/JSC.0b013e3181b7f743
Castagna, C., Impellizzeri, F. M., Belardinelli, R., Abt, G., Coutts, A., Chamari, K., et al. (2006a). Cardiorespiratory responses to Yo-yo Intermittent Endurance Test in nonelite youth soccer players. J. Strength Cond. Res. 20, 326–330. doi: 10.1519/R-17144.1
Castagna, C., Impellizzeri, F. M., Chamari, K., Carlomagno, D., and Rampinini, E. (2006b). Aerobic fitness and yo-yo continuous and intermittent tests performances in soccer players: a correlation study. J. Strength Cond. Res. 20, 320–325. doi: 10.1519/R-18065.1
Castagna, C., Impellizzeri, F. M., Rampinini, E., D'Ottavio, S., and Manzi, V. (2008). The Yo-Yo intermittent recovery test in basketball players. J. Sci. Med. Sport 11, 202–208. doi: 10.1016/j.jsams.2007.02.013
Castillo, D., Cámara, J., Castagna, C., and Yanci, J. (2017). Effects of the off-season period on field and assistant soccer referees ‘physical performance. J. Hum. Kinet. 56, 159–166. doi: 10.1515/hukin-2017-0033
Chan, H. C., Fong, D. T., Lee, J. W., Yau, Q. K., Yung, P. S., and Chan, K. (2016). Power and endurance in Hong Kong professional football players. Asia Pac. J. Sports Med. Arthrosc. Rehabil. Technol. 5, 1–5. doi: 10.1016/j.asmart.2016.05.001
Chaouachi, A., Manzi, V., Wong del, P., Chaalali, A., Laurencelle, L., Chamari, K., et al. (2010). Intermittent endurance and repeated sprint ability in soccer players. J. Strength Cond. Res. 24, 2663–2669. doi: 10.1519/JSC.0b013e3181e347f4
Cholewa, J. M., Grannis, D. J., Jaffe, D. A., GuimarÃ£es-Ferreira, L., Matthews, T. D., and Paolone, V. J. (2015). The effects of sodium bicarbonate supplementation on asoccer specific conditioning test in division III soccer players. J. Trainol. 4, 19–24. doi: 10.17338/trainology.4.1_19
Christensen, P. M., Krustrup, P., Gunnarsson, T. P., Kiilerich, K., Nybo, L., and Bangsbo, J. (2011). VO2 kinetics and performance in soccer players after intense training and inactivity. Med. Sci. Sports Exerc. 43, 1716–1724. doi: 10.1249/MSS.0b013e318211c01a
Chtourou, H., Hammouda, O., Souissi, H., Chamari, K., Chaouachi, A., and Souissi, N. (2011). The effect of ramadan fasting on physical performances, mood state and perceived exertion in young footballers. Asian J. Sports Med. 2, 177–185. doi: 10.5812/asjsm.34757
Chuman, K., Hoshikawa, Y., Iida, T., and Nishijima, T. (2011). Relationships between Yo-Yo intermittent recovery tests and development of aerobic and anaerobic fitness in U-13 and U-17 soccer players. Int. J. Sport Health Sci. 9, 91–97. doi: 10.5432/ijshs.201110
Cihan, H., Can, I., and Seyis, M. (2012). Comparison of recovering times and aerobic capacity according to playing positions of elite football players. / elit futbolcularin oyun pozisyonlarina göre aerobik kapasite ve toparlanma sürelerinin karsilastirilmasi. J. Phys. Educ. Sports Sci. / Beden Egitimi ve Spor Bilimleri Dergisi. 6, 1–8.
Clarke, A. C., Presland, J., Rattray, B., and Pyne, D. B. (2014). Critical velocity as a measure of aerobic fitness in women's rugby sevens. J. Sci. Med. Sport 17, 144–148. doi: 10.1016/j.jsams.2013.03.008
Cobley, J. N., McGlory, C., Morton, J. P., and Close, G. L. (2011). N-Acetylcysteine's attenuation of fatigue after repeated bouts of intermittent exercise: practical implications for tournament situations. Int. J. Sport Nutr. Exerc. Metab. 21, 451–461. doi: 10.1123/ijsnem.21.6.451
Coelho, D. B., Pimenta, E. M., da Paixão, R. C., Morandi, R. F., Becker, L. K., Júnior, J., et al. (2015). Analysis of chronic physiological demand of an annual soccer season. / Análise da demanda fisiológica crônica de uma temporada anual de futebol. Braz. J. Kineanthropometry Hum. Perform. 17, 400–408. doi: 10.5007/1980-0037.2015v17n4p400
Cone, J. R., Berry, N. T., Goldfarb, A. H., Henson, R. A., Schmitz, R. J., Wideman, L., et al. (2012). Effects of an individualized soccer match simulation on vertical stiffness and impedance. J. Strength Cond. Res. 26, 2027–2036. doi: 10.1519/JSC.0b013e31823a4076
Coratella, G., Beato, M., and Schena, F. (2016). The specificity of the Loughborough Intermittent Shuttle Test for recreational soccer players is independent of their intermittent running ability. Res. Sports Med. 24, 363–374. doi: 10.1080/15438627.2016.1222279
Cullen, B. D., Cregg, C. J., Kelly, D. T., Hughes, S. M., Daly, P. G., and Moyna, N. M. (2013). Fitness profiling of elite level adolescent Gaelic football players. J. Strength Cond. Res. 27, 2096–2103. doi: 10.1519/JSC.0b013e318277fce2
Darrall-Jones, J. D., Jones, B., and Till, K. (2015). Anthropometric and physical profiles of english academy rugby union players. J. Strength Cond. Res. 29, 2086–2096. doi: 10.1519/JSC.0000000000000872
Darrall-Jones, J. D., Jones, B., and Till, K. (2016). Anthropometric, sprint, and high-intensity running profiles of english academy rugby union players by position. J. Strength Cond. Res. 30, 1348–1358. doi: 10.1519/JSC.0000000000001234
Da Silva, J. F., Guglielmo, L. G., Carminatti, L. J., De Oliveira, F. R., Dittrich, N., and Paton, C. D. (2011). Validity and reliability of a new field test (Carminatti's test) for soccer players compared with laboratory-based measures. J. Sports Sci. 29, 1621–1628. doi: 10.1080/02640414.2011.609179
Deprez, D., Coutts, A. J., Lenoir, M., Fransen, J., Pion, J., Philippaerts, R., et al. (2014). Reliability and validity of the Yo-Yo intermittent recovery test level 1 in young soccer players. J. Sports Sci. 32, 903–910. doi: 10.1080/02640414.2013.876088
Deprez, D., Fransen, J., Boone, J., Lenoir, M., Philippaerts, R., and Vaeyens, R. (2015a). Characteristics of high-level youth soccer players: variation by playing position. J. Sports Sci. 33, 243–254. doi: 10.1080/02640414.2014.934707
Deprez, D., Fransen, J., Lenoir, M., Philippaerts, R., and Vaeyens, R. (2015b). The Yo-Yo intermittent recovery test level 1 is reliable in young high-level soccer players. Biol. Sport 32, 65–70. doi: 10.5604/20831862.1127284
De Souza, J., Gomes, A. C., Leme, L., and Da Silva, S. G. (2006). Changes in metabolic and motor performance variables induced by training in handball players. Rev. Bras. Med. Esporte 12, 118e−122e. doi: 10.1590/S1517-86922006000300004
Dinardi, R. R., Andrade, C. R., and Ibiapina, C. (2017). Effect of the airmax® internal nasal dilator on peak nasal inspiratory flow, aerobic capacity, and rating of perceived exertion in healthy rugby players. J. Exerc. Physiol. Online 20, 92–101.
Dixon, H., Baker, C. E., Baker, J. S., Dewhurst, S., and Hayes, L. D. (2017). Sodium bicarbonate ingestion improves Yo-Yo intermittent recovery test 1 performance: a randomized crossover trial. Nutr. Diet. Suppl. 9, 23–27. doi: 10.2147/NDS.S131947
Dupont, G., Defontaine, M., Bosquet, L., Blondel, N., Moalla, W., and Berthoin, S. (2010). Yo-Yo intermittent recovery test versus the Universite de Montreal Track Test: relation with a high-intensity intermittent exercise. J. Sci. Med. Sport 13, 146–150. doi: 10.1016/j.jsams.2008.10.007
Eaton, T. R., Potter, A., Billaut, F., Panchuk, D., Pyne, D. B., Gore, C. J., et al. (2016). A combination of amino acids and caffeine enhances sprint running capacity in a hot, hypoxic environment. Int. J. Sport Nutr. Exerc. Metab. 26, 33–45. doi: 10.1123/ijsnem.2015-0108
Fabregat-Andres, O., Munoz-Macho, A., Adell-Beltran, G., Ibanez-Catala, X., Macia, A., and Facila, L. (2014). Evaluation of a new shirt-based electrocardiogram device for cardiac screening in soccer players: comparative study with treadmill ergospirometry. Cardiol. Res. 5, 101–107. doi: 10.14740/cr333w
Fanchini, M., Castagna, C., Coutts, A. J., Schena, F., McCall, A., and Impellizzeri, F. M. (2014). Are the Yo-Yo intermittent recovery test levels 1 and 2 both useful? Reliability, responsiveness and interchangeability in young soccer players. J. Sports Sci 32, 1950–1957. doi: 10.1080/02640414.2014.969295
Fanchini, M., Ghielmetti, R., Coutts, A. J., Schena, F., and Impellizzeri, F. M. (2015a). Effect of training-session intensity distribution on session rating of perceived exertion in soccer players. Int. J. Sports Physiol. Perform. 10, 426–430. doi: 10.1123/ijspp.2014-0244
Fanchini, M., Schena, F., Castagna, C., Petruolo, A., Combi, F., McCall, A., et al. (2015b). External responsiveness of the Yo-Yo IR Test Level 1 in high-level male soccer players. Int. J. Sports Med. 36, 735–741. doi: 10.1055/s-0035-1547223
Faude, O., Roth, R., Di Giovine, D., Zahner, L., and Donath, L. (2013). Combined strength and power training in high-level amateur football during the competitive season: a randomised-controlled trial. J. Sports Sci. 31, 1460–1467. doi: 10.1080/02640414.2013.796065
Ferioli, D., Bosio, A., La Torre, A., Carlomagno, D., Connolly, D. R., and Rampinini, E. (2017). Different training loads partially influence physiological responses to preparation period in basketball. J. Strength Cond. Res. 32, 790–797. doi: 10.1519/JSC.0000000000001823
Flatt, A. A., and Esco, M. R. (2016). Evaluating individual training adaptation with smartphone-derived heart rate variability in a collegiate female soccer team. J. Strength Cond. Res. 30, 378–385. doi: 10.1519/JSC.0000000000001095
Fløtum, L. A., Ottesen, L. S., Krustrup, P., and Mohr, M. (2016). Evaluating a nationwide recreational football intervention: recruitment, attendance, adherence, exercise intensity, and health effects. Biomed Res. Int. 2016:7231545 doi: 10.1155/2016/7231545
Furlan, N., Waldron, M., Osborne, M., and Gray, A. J. (2016). Ecological Validity and Reliability of the Rugby Sevens Simulation Protocol. Int. J. Sports Physiol. Perform. 11, 749–755. doi: 10.1123/ijspp.2015-0487
Gatterer, H., Klarod, K., Heinrich, D., Schlemmer, P., Dilitz, S., and Burtscher, M. (2015). Effects of a 12-day maximal shuttle-run shock microcycle in hypoxia on soccer specific performance and oxidative stress. Appl. Physiol. Nutr. Metab. 40, 842–845. doi: 10.1139/apnm-2014-0479
Gibson, N., Currie, J., Johnston, R., and Hill, J. (2013). Relationship between measures of aerobic fitness, speed and repeated sprint ability in full and part time youth soccer players. J. Sports Med. Phys. Fitness 53, 9–16.
Gunnarsson, T. P., Christensen, P. M., Holse, K., Christiansen, D., and Bangsbo, J. (2012). Effect of additional speed endurance training on performance and muscle adaptations. Med. Sci. Sports Exerc. 44, 1942–1948. doi: 10.1249/MSS.0b013e31825ca446
Hamlin, M. J., Olsen, P. D., Marshall, H. C., Lizamore, C. A., and Elliot, C. A. (2017). Hypoxic repeat sprint training improves rugby player's repeated sprint but not endurance performance. Front. Physiol. 8:24. doi: 10.3389/fphys.2017.00024
Hammouda, O., Chtourou, H., Aloui, A., Mejri, M. A., Chahed, H., Miled, A., et al. (2014). Does Ramadan fasting affect the diurnal variations in metabolic responses and total antioxidant capacity during exercise in young soccer players? 10, 97–104. doi: 10.1007/s11332-014-0179-8
Henrique Borges, P., Rechenchosky, L., Paulo Deprá, P, Vaz Ronque, E. R., Juan Greco, P., Menezes Menegassi, V., et al. (2017). Impact of aerobic power, strength of lower limbs and speed on technical skills in young soccer players. J. Exerc. Physiol. Online 20, 221–230.
Hermassi, S., Aouadi, R., Khalifa, R., van den Tillaar, R., Shephard, R. J., and Chelly, M. S. (2015). Relationships between the yo-yo intermittent recovery test and anaerobic performance tests in adolescent handball players. J. Hum. Kinet. 45, 197–205. doi: 10.1515/hukin-2015-0020
Hermassi, S., Gabbett, T. J., Spencer, M., Khalifa, R., Chelly, M. S., and Chamari, K. (2014). Relationship between explosive performance measurements of the lower limb and repeated shuttle-sprint ability in elite adolescent handball players. Int. J. Sports Sci. Coach. 9, 1191–1204. doi: 10.1260/1747-9518.104.22.1681
Hermassi, S., Ingebrigtsen, J., Schwesig, R., Fieseler, G., Delank, K. S., Chamari, K., et al. (2016). Effects of in-season short-term aerobic and high-intensity interval training program on repeated sprint ability and jump performance in handball players. J. Sports Med. Phys. Fitness 58, 50–56. doi: 10.23736/S0022-4707.16.06770-0
Higham, D. G., Pyne, D. B., Anson, J. M., and Eddy, A. (2013). Physiological, anthropometric, and performance characteristics of rugby sevens players. Int. J. Sports Physiol. Perform. 8, 19–27. doi: 10.1123/ijspp.8.1.19
Hogarth, L. W., Burkett, B. J., and McKean, M. R. (2015a). Activity profiles and physiological responses of representative tag football players in relation to playing position and physical fitness. PLoS ONE 10:e0144554. doi: 10.1371/journal.pone.0144554
Hogarth, W. L., Burkett, J. B., and McKean, R. M. (2015b). The relationship between physical capacity and match running performance in men's tag football. Int. J. Perform. Anal. Sport 15, 147–158. doi: 10.1080/24748668.2015.11868783
Iacono, A. D., Eliakim, A., and Meckel, Y. (2015). Improving fitness of elite handball players: small-sided games vs. high-intensity intermittent training. J. Strength Cond. Res. 29, 835–843. doi: 10.1519/JSC.0000000000000686
Iaia, F. M., Fiorenza, M., Larghi, L., Alberti, G., Millet, G. P., and Girard, O. (2017). Short- or long-rest intervals during repeated-sprint training in soccer? PLoS ONE 12:e0171462. doi: 10.1371/journal.pone.0171462
Iaia, F. M., Fiorenza, M., Perri, E., Alberti, G., Millet, G. P., and Bangsbo, J. (2015). The effect of two speed endurance training regimes on performance of soccer players. PLoS ONE 10:e0138096. doi: 10.1371/journal.pone.0138096
Iaia, F. M., Thomassen, M., Kolding, H., Gunnarsson, T., Wendell, J., Rostgaard, T., et al. (2008). Reduced volume but increased training intensity elevates muscle Na+-K+ pump alpha1-subunit and NHE1 expression as well as short-term work capacity in humans. Am. J. Physiol. Regul. Integr. Comp. Physiol. 294, R966–R974. doi: 10.1152/ajpregu.00666.2007
Ingebrigtsen, J., Bendiksen, M., Randers, M. B., Castagna, C., Krustrup, P., and Holtermann, A. (2012). Yo-Yo IR2 testing of elite and sub-elite soccer players: performance, heart rate response and correlations to other interval tests. J. Sports Sci. 30, 1337–1345. doi: 10.1080/02640414.2012.711484
Ingebrigtsen, J., Brochmann, M., Castagna, C., Bradley, P. S., Ade, J., Krustrup, P., et al. (2014). Relationships between field performance tests in high-level soccer players. J. Strength Cond. Res. 28, 942–949. doi: 10.1519/JSC.0b013e3182a1f861
Ingebrigtsen, J., Shalfawi, S. A., Tønnessen, E., Krustrup, P., and Holtermann, A. (2013). Performance effects of 6 weeks of aerobic production training in junior elite soccer players. J. Strength Cond. Res. 27, 1861–1867. doi: 10.1519/JSC.0b013e31827647bd
Inness, M. W. H., Billaut, F., and Aughey, R. J. (2016). Team-sport athletes' improvement of performance on the yo-yo intermittent recovery test level 2, but not of time-trial performance, with intermittent hypoxic training. Int. J. Sports Physiol. Perform. 11, 15–21. doi: 10.1123/ijspp.2014-0246
Jamurtas, A. Z., Douroudos, I. I., Deli, C. K., Draganidis, D., Chatzinikolaou, A., Mohr, M., et al. (2015). Iron status markers are only transiently affected by a football game. J. Sports Sci. 33, 2088–2099. doi: 10.1080/02640414.2015.1064154
Johnston, R. D., Gabbett, T. J., and Jenkins, D. G. (2015). Influence of playing standard and physical fitness on activity profiles and post-match fatigue during intensified junior rugby league competition. Sports Med. Open 1:18. doi: 10.1186/s40798-015-0015-y
Jones, B., Emmonds, S., Hind, K., Nicholson, G., Rutherford, Z., and Till, K. (2016). Physical qualities of international female rugby league players by playing position. J. Strength Cond. Res. 30, 1333–1340. doi: 10.1519/JSC.0000000000001225
Julian, R., Hecksteden, A., Fullagar, H. H., and Meyer, T. (2017). The effects of menstrual cycle phase on physical performance in female soccer players. PLoS ONE 12:e0173951. doi: 10.1371/journal.pone.0173951
Karavelioglu, M. B. (2014). Detection of the effects of sodium bicarbonate supplement on blood lactate and heart rate values of female futsal players before and after Yo-Yo/1 test. Anthropologist 18, 745–749. doi: 10.1080/09720073.2014.11891605
Karavelioglu, M. B., Harmanci, H., and Ünveren, A. (2014). Pulse rate before and after Yo-Yo 2 test at young footbalers and deciding changes at some blood parameters. Int. J. Inform. Technol. Bus. Manag. 29, 49–54.
Karsten, B., Larumbe-Zabala, E., Kandemir, G., Hazir, T., Klose, A., and Naclerio, F. (2016). The effects of a 6-week strength training on critical velocity, anaerobic running distance, 30-M sprint and Yo-Yo intermittent running test performances in male soccer players. PLoS ONE 11:e0151448. doi: 10.1371/journal.pone.0151448
Kavaliauskas, M., Kilvington, R., and Babraj, J. (2017). Effects of in-season uphill sprinting on physical characteristics in semi-professional soccer players. J. Sports Med. Phys. Fitness 57, 165–170. doi: 10.23736/S0022-4707.16.06066-7
Kelly, R. A., and Collins, K. (2017). The seasonal variations in anthropometric and performance characteristics of elite inter county Gaelic football players. J. Strength Cond. Res. doi: 10.1519/JSC.0000000000001861. [Epub ahead of print].
Kilding, A. E., Dobson, B. P., and Ikeda, E. (2016). Effects of acutely intermittent hypoxic exposure on running economy and physical performance in basketball players. J. Strength Cond. Res. 30, 2033–2042. doi: 10.1519/JSC.0000000000001301
Kilit, B., and Arslan, E. (2016). Laboratory and field-based assessment of maximal aerobic and anaerobic power in professional tennis players. Int. J. of Sports Sci. 6, 153–158. doi: 10.5923/j.sports.20160604.04
Köklü, Y., Sert Ö, O., Alemdaroglu, U., and Arslan, Y. (2015). Comparison of the physiological responses and time-motion characteristics of young soccer players in small-sided games: the effect of goalkeeper. J. Strength Cond. Res. 29, 964–971. doi: 10.1519/JSC.0b013e3182a744a1
Krustrup, P., and Bangsbo, J. (2001). Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training. J. Sports Sci. 19, 881–891. doi: 10.1080/026404101753113831
Krustrup, P., Bradley, P. S., Christensen, J. F., Castagna, C., Jackman, S., Connolly, L., et al. (2015). The Yo-Yo IE2 test: physiological response for untrained men versus trained soccer players. Med. Sci. Sports Exerc. 47, 100–108. doi: 10.1249/MSS.0000000000000377
Krustrup, P., Christensen, J. F., Randers, M. B., Pedersen, H., Sundstrup, E., Jakobsen, M. D., et al. (2010a). Muscle adaptations and performance enhancements of soccer training for untrained men. Eur. J. Appl. Physiol. 108, 1247–1258. doi: 10.1007/s00421-009-1319-8
Krustrup, P., Hansen, P. R., Andersen, L. J., Jakobsen, M. D., Sundstrup, E., Randers, M. B., et al. (2010b). Long-term musculoskeletal and cardiac health effects of recreational football and running for premenopausal women. Scand. J. Med. Sci. Sports 20, 58–71. doi: 10.1111/j.1600-0838.2010.01111.x
Krustrup, P., Mohr, M., Amstrup, T., Rysgaard, T., Johansen, J., Steensberg, A., et al. (2003). The yo-yo intermittent recovery test: physiological response, reliability, and validity. Med. Sci. Sports Exerc. 35, 697–705. doi: 10.1249/01.MSS.0000058441.94520.32
Krustrup, P., Mohr, M., Nybo, L., Jensen, J. M., Nielsen, J. J., and Bangsbo, J. (2006). The Yo-Yo IR2 test: physiological response, reliability, and application to elite soccer. Med. Sci. Sports Exerc. 38, 1666–1673. doi: 10.1249/01.mss.0000227538.20799.08
Krustrup, P., Skoradal, M. B., Randers, M. B., Weihe, P., Uth, J., Mortensen, J., et al. (2017). Broad-spectrum health improvements with one year of soccer training in inactive mildly hypertensive middle-aged women. Scand. J. Med. Sci. Sports 27, 1893–1901. doi: 10.1111/sms.12829
Kvorning, T., Hansen, M. R. B., and Jensen, K. (2017). Strength and conditioning training by the danish national handball team before an olympic tournament. J. Strength Cond. Res. 31, 1759–1765. doi: 10.1519/JSC.0000000000001927
Leme, L. C., Oliveira, R. S., de, P. R., Nakamura, F. Y., Milanez, V. F., and Leicht, A. (2015). The influence of a weekend with passive rest on the psychological and autonomic recovery in professional male handball players. Kinesiology 47, 108–114.
Lim, B. H. (2012). Influence of the “Off the Street, On the Ball” Midnight Football Program on physical fitness, self-esteem and quality of life in youth-at-risk. Malays. J. Sports Sci. Recreation 8, 16–31.
Lockie, R. G., Davis, D. L., Birmingham-Babauta, S. A., Beiley, M. D., Hurley, J. M., Stage, A. A., et al. (2016a). Physiological characteristics of incoming freshmen field players in a men's division i collegiate soccer team. Sports 4:34. doi: 10.3390/sports4020034
Lockie, R. G., Jalilvand, F., Moreno, M. R., Orjalo, A. J., Risso, F. G., and Nimphius, S. (2016b). Yo-Yo intermittent recovery test level 2 and its relationship to other typical soccer field tests in female collegiate soccer players. J. Strength Cond. Res. 31, 2667–2677. doi: 10.1519/JSC.0000000000001734
Lockie, R. G., Stage, A. A., Stokes, J. J., Orjalo, A. J., Davis, D. L., Giuliano, D. V., et al. (2016c). Relationships and predictive capabilities of jump assessments to soccer-specific field test performance in division i collegiate players. Sports 4:56. doi: 10.3390/sports4040056
Lockie, R. G., Stecyk, S. D., Mock, S. A., Crelling, J. B., Lockwood, J. R., and Jalilvand, F. (2016d). A cross-sectional analysis of the characteristics of division i collegiate female soccer field players across year of eligibility. J. Aust. Strength Cond. 24, 6–15.
Lollo, P. C. B., Amaya-Farfan, J., Faria, I. C., Salgado, J. V. V., Chacon-Mikahil, M. P. T., Cruz, A. G., et al. (2014). Hydrolysed whey protein reduces muscle damage markers in Brazilian elite soccer players compared with whey protein and maltodextrin. A twelve-week in-championship intervention. Int. Dairy J. 34, 19–24. doi: 10.1016/j.idairyj.2013.07.001
Lopez-Segovia, M., Pareja-Blanco, F., Jimenez-Reyes, P., and Gonzalez-Badillo, J. J. (2015). Determinant factors of repeat sprint sequences in young soccer players. Int. J. Sports Med. 36, 130–136. doi: 10.1055/s-0034-1385880
Macpherson, T. W., and Weston, M. (2015). The effect of low-volume sprint interval training on the development and subsequent maintenance of aerobic fitness in soccer players. Int. J. Sports Physiol. Perform. 10, 332–338. doi: 10.1123/ijspp.2014-0075
Malone, S., Hughes, B., and Collins, K. (2017). The effect of training load distribution on aerobic fitness measures in hurling players. J. Strength Cond. Res. doi: 10.1519/JSC.0000000000002004. [Epub ahead of print].
Manzi, V., Bovenzi, A., Franco Impellizzeri, M., Carminati, I., and Castagna, C. (2013). Individual training-load and aerobic-fitness variables in premiership soccer players during the precompetitive season. J. Strength Cond. Res. 27, 631–636. doi: 10.1519/JSC.0b013e31825dbd81
Mara, J. K., Thompson, K. G., Pumpa, K. L., and Ball, N. B. (2015). Periodization and physical performance in elite female soccer players. Int. J. Sports Physiol. Perform. 10, 664–669. doi: 10.1123/ijspp.2014-0345
Markovic, G., and Mikulic, P. (2011). Discriminative ability of the Yo-Yo intermittent recovery test (level 1) in prospective young soccer players. J. Strength Cond. Res. 25, 2931–2934. doi: 10.1519/JSC.0b013e318207ed8c
Martínez-Lagunas, V., and Hartmann, U. (2014). Validity of the Yo-Yo Intermittent Recovery Test Level 1 for direct measurement or indirect estimation of maximal oxygen uptake in female soccer players. Int. J. Sports Physiol. Perform. 9, 825–831. doi: 10.1123/ijspp.2013-0313
Massuca, L., Branco, B., Miarka, B., and Fragoso, I. (2015). Physical fitness attributes of team-handball players are related to playing position and performance level. Asian J. Sports Med. 6:e24712. doi: 10.5812/asjsm.24712
Matta, M., Figueiredo, A., Garcia, E., and Seabra, A. (2014). Morphological, maturational, functional and technical profile of young brazilian soccer players. Rev. Bras. Cineantropom. Desempenho Hum. 16, 277–286. doi: 10.5007/1980-0037.2014v16n3p277
Matta, M. O., Figueiredo, A. J., Silami Garcia, E., Zacaron Wernek, F., and Seabra, A. (2015). Relative age effect on anthropometry, biological maturation and performance of young soccer players. / Efeito da idade relativa na antropometria, maturação biológica e desempenho em jovens futebolistas. Braz. J. Kineanthropometry Hum. Perform. 17, 257–268. doi: 10.5007/1980-0037.2015v17n3p257
Matthys, S. P. J., Vaeyens, R., Vandendriessche, J., Vandorpe, B., Pion, J., Coutts, A. J., et al. (2011). A multidisciplinary identification model for youth handball. Eur. J. Sport Sci. 11, 355–363. doi: 10.1080/17461391.2010.523850
Matzenbacher, F., Pasquarelli, B. N., Rabelo, F. N., Dourado, A. C., Durigan, J. Z., Rossi, H. G., et al. (2016). Adaptations in the physical capacities of u-18 futsal athletes during a competitive season. Rev. Bras. Cineantropom. Desempenho Hum. 18, 51–61. doi: 10.5007/1980-0037.2016v18n1p50
McIntosh, N. D., Love, T. D., Haszard, J., Osborne, H., and Black, K. E. (2016). beta-hydroxy beta-methylbutyrate (HMB) supplementation effects on body mass and performance in elite male rugby union players. J. Strength Cond. Res. 32, 19–26. doi: 10.1519/JSC.0000000000001695.
McLean, B. D., Tofari, P. J., Gore, C. J., and Kemp, J. G. (2015). Changes in running performance after four weeks of interval hypoxic training in australian footballers: a single-blind placebo-controlled study. J. Strength Cond. Res. 29, 3206–3215. doi: 10.1519/JSC.0000000000000984
Metaxas, T. I., Koutlianos, N. A., Kouidi, E. J., and Deligiannis, A. P. (2005). Comparative study of field and laboratory tests for the evaluation of aerobic capacity in soccer players. J. Strength Cond. Res. 19, 79–84. doi: 10.1519/14713.1
Miloski, B., Moreira, A., Andrade, F. C., Freitas, V. H., Pecanha, T., Nogueira, R. A., et al. (2014). Do physical fitness measures influence internal training load responses in high-level futsal players? J. Sports Med. Phys. Fitness 54, 588–594.
Moher, D., Liberati, A., Tetzlaff, J., and Altman, D. G., and PRISMA Group (2009). Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 339:b2535. doi: 10.1136/bmj.b2535
Mohr, M. (2015). Effect of sodium bicarbonate ingestion on measures of football performance - with reference to the impact of training status. Fróð*skaparrit - Faroese Sci. J. 62, 102–122. doi: 10.18602/fsj.v62i0.30
Mohr, M., Krustrup, P., and Bangsbo, J. (2003). Match performance of high-standard soccer players with special reference to development of fatigue. J. Sports Sci. 21, 519–528. doi: 10.1080/0264041031000071182
Mohr, M., Krustrup, P., Nielsen, J. J., Nybo, L., Rasmussen, M. K., Juel, C., et al. (2007). Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development. Am. J. Physiol. Regul. Integr. Comp. Physiol. 292, R1594–R1602. doi: 10.1152/ajpregu.00251.2006
Mohr, M., Lindenskov, A., Holm, P. M., Nielsen, H. P., Mortensen, J., Weihe, P., et al. (2014). Football training improves cardiovascular health profile in sedentary, premenopausal hypertensive women. Scand. J. Med. Sci. Sports 24, 36–42. doi: 10.1111/sms.12278
Mohr, M., Mujika, I., Santisteban, J., Randers, M. B., Bischoff, R., Solano, R., et al. (2010). Examination of fatigue development in elite soccer in a hot environment: a multi-experimental approach. Scand. J. Med. Sci. Sports 20, 125–132. doi: 10.1111/j.1600-0838.2010.01217.x
Mohr, M., Thomassen, M., Girard, O., Racinais, S., and Nybo, L. (2016). Muscle variables of importance for physiological performance in competitive football. Eur. J. Appl. Physiol. 116, 251–262. doi: 10.1007/s00421-015-3274-x
Mooney, M., Cormack, S., O'Brien, B., and Coutts, A. J. (2013a). Do physical capacity and interchange rest periods influence match exercise-intensity profile in Australian football? Int. J. Sports Physiol. Perform. 8, 165–172. doi: 10.1123/ijspp.8.2.165
Mooney, M. G., Cormack, S., O'brien, B. J., Morgan, W. M., and McGuigan, M. (2013b). Impact of neuromuscular fatigue on match exercise intensity and performance in elite Australian football. J. Strength Cond. Res. 27, 166–173. doi: 10.1519/JSC.0b013e3182514683
Mooney, M., O'Brien, B., Cormack, S., Coutts, A., Berry, J., and Young, W. (2011). The relationship between physical capacity and match performance in elite Australian football: a mediation approach. J. Sci. Med. Sport 14, 447–452. doi: 10.1016/j.jsams.2011.03.010
Morton, J. P., Croft, L., Bartlett, J. D., Maclaren, D. P., Reilly, T., Evans, L., et al. (2009). Reduced carbohydrate availability does not modulate training-induced heat shock protein adaptations but does upregulate oxidative enzyme activity in human skeletal muscle. J. Appl. Physiol. 106, 1513–1521. doi: 10.1152/japplphysiol.00003.2009
Moss, S. L., McWhannell, N., Michalsik, L. B., and Twist, C. (2015). Anthropometric and physical performance characteristics of top-elite, elite and non-elite youth female team handball players. J. Sports Sci. 33, 1780–1789. doi: 10.1080/02640414.2015.1012099
Nakamura, D., Suzuki, T., Yasumatsu, M., and Akimoto, T. (2012). Moderate running and plyometric training during off-season did not show a significant difference on soccer-related high-intensity performances compared with no-training controls. J. Strength Cond. Res. 26, 3392–3397. doi: 10.1519/JSC.0b013e3182474356
Nakamura, F. Y., Flatt, A. A., Pereira, L. A., Ramirez-Campillo, R., Loturco, I., and Esco, M. R. (2015). Ultra-short-term heart rate variability is sensitive to training effects in team sports players. J. Sports Sci. Med. 14, 602–605.
Nakamura, F. Y., Pereira, L. A., Cal Abad, C. C., Kobal, R., Kitamura, K., Roschel, H., et al. (2016). Differences in physical performance between U-20 and senior top-level Brazilian futsal players. J. Sports Med. Phys. Fitness 56, 1289–1297.
Nogueira, F. C. d. A., de Freitas, V. H., Nogueira, R. A., Miloski, B., Werneck, F. Z., and Bara-Filho, M. G. (2016). Improvement of physical performance, hormonal profile, recovery-stress balance and increase of muscle damage in a specific futsal pre-season planning. Rev. Andaluza Med. del Deporte 11, 63–68. doi: 10.1016/j.ramd.2015.11.008
Noon, M. R., James, R. S., Clarke, N. D., Akubat, I., and Thake, C. D. (2015). Perceptions of well-being and physical performance in English elite youth footballers across a season. J. Sports Sci. 33, 2106–2115. doi: 10.1080/02640414.2015.1081393
Nunes, J. A., Moreira, A., Crewther, B. T., Nosaka, K., Viveiros, L., and Aoki, M. S. (2014). Monitoring training load, recovery-stress state, immune-endocrine responses, and physical performance in elite female basketball players during a periodized training program. J. Strength Cond. Res. 28, 2973–2980. doi: 10.1519/JSC.0000000000000499
Nyakayiru, J., Jonvik, K. L., Trommelen, J., Pinckaers, P. J., Senden, J. M., van Loon, L. J., et al. (2017). Beetroot juice supplementation improves high-intensity intermittent type exercise performance in trained soccer players. Nutrients 9:E314 doi: 10.3390/nu9030314
Nyberg, M., Fiorenza, M., Lund, A., Christensen, M., Romer, T., Piil, P., et al. (2016). Adaptations to speed endurance training in highly trained soccer players. Med. Sci. Sports Exerc. 48, 1355–1364. doi: 10.1249/MSS.0000000000000900
Oliveira, R. S., Leicht, A. S., Bishop, D., Barbero-Álvarez, J. C., and Nakamura, F. Y. (2013). Seasonal changes in physical performance and heart rate variability in high level futsal players. Int. J. Sports Med.. 34, 424–430. doi: 10.1055/s-0032-1323720
Pareja-Blanco, F., Sanchez-Medina, L., Suarez-Arrones, L., and Gonzalez-Badillo, J. J. (2017). Effects of Velocity Loss During Resistance Training on Performance in Professional Soccer players. Int. J. Sports Physiol. Perform. 12, 512–519. doi: 10.1123/ijspp.2016-0170
Pareja-Blanco, F., Suarez-Arrones, L., Rodríguez-Rosell, D., López-Segovia, M., Jimenez-Reyes, P., Bachero-Mena, B., et al. (2016). Evolution of determinant factors of repeated sprint ability. J. Hum. Kinet. 54, 115–126. doi: 10.1515/hukin-2016-0040
Pivovarniček, P., Pupiš, M., Tonhauserová, Z., and Tokárová, M. (2013). Level of sprint and jump abilities and intermittent endurance of elite young soccer players at different positions. SportLogia 9, 109–117. doi: 10.5550/sgia.130902.en.006P
Póvoas, S. C., Ascensao, A. A., Magalhaes, J., Seabra, A. F., Krustrup, P., Soares, J. M., et al. (2014). Analysis of fatigue development during elite male handball matches. J. Strength Cond. Res. 28, 2640–2648. doi: 10.1519/JSC.0000000000000424
Póvoas, S. C., Castagna, C., da Costa Soares, J. M., Silva, P., Coelho-E-Silva, M. J., Matos, F., et al. (2016). Reliability and construct validity of yo-yo tests in untrained and soccer-trained schoolgirls aged 9-16. Pediatr. Exerc. Sci. 28, 321–330. doi: 10.1123/pes.2015-0212
Purkhús, E., Krustrup, P., and Mohr, M. (2016). High-Intensity Training improves exercise performance in elite women volleyball players during a competitive season. J. Strength Cond. Res. 30, 3066–3072. doi: 10.1519/JSC.0000000000001408
Raman, A., Macdermid, P. W., Mündel, T., Mann, M., and Stannard, S. R. (2014). The effects of carbohydrate loading 48 hours before a simulated squash match. Int. J. Sport Nutr. Exerc. Metab. 24, 157–165. doi: 10.1123/ijsnem.2013-0108
Rampinini, E., Impellizzeri, F. M., Castagna, C., Abt, G., Chamari, K., Sassi, A., et al. (2007). Factors influencing physiological responses to small-sided soccer games. J. Sports Sci. 25, 659–666. doi: 10.1080/02640410600811858
Rampinini, E., Impellizzeri, F. M., Castagna, C., Azzalin, A., Ferrari Bravo, D., and Wisloff, U. (2008). Effect of match-related fatigue on short-passing ability in young soccer players. Med. Sci. Sports Exerc. 40, 934–942. doi: 10.1249/MSS.0b013e3181666eb8
Rampinini, E., Sassi, A., Azzalin, A., Castagna, C., Menaspa, P., Carlomagno, D., et al. (2010). Physiological determinants of Yo-Yo intermittent recovery tests in male soccer players. Eur. J. Appl. Physiol. 108, 401–409. doi: 10.1007/s00421-009-1221-4
Randers, M. B., Andersen, L. J., Orntoft, C., Bendiksen, M., Johansen, L., Horton, J., et al. (2013). Cardiovascular health profile of elite female football players compared to untrained controls before and after short-term football training. J. Sports Sci. 31, 1421–1431. doi: 10.1080/02640414.2013.792950
Randers, M. B., Nielsen, J. J., Krustrup, B. R., Sundstrup, E., Jakobsen, M. D., Nybo, L., et al. (2010). Positive performance and health effects of a football training program over 12 weeks can be maintained over a 1-year period with reduced training frequency. Scand. J. Med. Sci. Sports 20, 80–89. doi: 10.1111/j.1600-0838.2010.01091.x
Rebelo, A., Brito, J., Maia, J., Coelho-e-Silva, M. J., Figueiredo, A. J., Bangsbo, J., et al. (2013). Anthropometric characteristics, physical fitness and technical performance of under-19 soccer players by competitive level and field position. Int. J. Sports Med.. 34, 312–317. doi: 10.1055/s-0032-1323729
Rebelo, A. N., Ascensão, A. A., Magalhães, J. F., Bischoff, R., Bendiksen, M., and Krustrup, P. (2011). Elite futsal refereeing: activity profile and physiological demands. J. Strength Cond. Res. 25, 980–987. doi: 10.1519/JSC.0b013e3181a392ed
Risso, F. G., Jalilvand, F., Orjalo, A. J., Moreno, M. R., Davis, D. L., Birmingham-Babauta, S. A., et al. (2017). Physiological characteristics of projected starters and non-starters in the field positions from a division I women's soccer team. Int. J. Exerc. Sci. 10, 568–579.
Roberts, L. A., Beattie, K., Close, G. L., and Morton, J. P. (2011). Vitamin C consumption does not impair training-induced improvements in exercise performance. Int. J. Sports Physiol. Perform. 6, 58–69. doi: 10.1123/ijspp.6.1.58
Roe, M., and Malone, S. (2016). Yo-Yo intermittent recovery test performance in subelite gaelic football players from under thirteen to senior age groups. J. Strength Cond. Res. 30, 3187–3193. doi: 10.1519/JSC.0000000000001417
Rogan, S. (2015). Comparison of Two Kinds of Endurance Training Programs on the Effects of the Ability to Recover in Amateur Soccer Players. Asian J. Sports Med. 6:e22585. doi: 10.5812/asjsm.6(2)2015.22585
Rollo, I., Impellizzeri, F. M., Zago, M., and Iaia, F. M. (2014). Effects of 1 versus 2 games a week on physical and subjective scores of subelite soccer players. Int. J. Sports Physiol. Perform. 9, 425–431. doi: 10.1123/ijspp.2013-0288
Román-Quintana, J. S., Casamichana, D., Castellano, J., Calleja-González, J., Jukic, I., and Ostojic, S. M. (2013). The influence of ball-touches number on physical and physiological demands of large-sided games. / utjecaj broja dodira s loptom na fizicke i fiziološke zahtjeve velikih pomocnih nogometnih igara. Kinesiology 45, 171–178.
Rowan, A. E., Kueffner, T. E., and Stavrianeas, S. (2012). Short duration high-intensity interval training improves aerobic conditioning of female college soccer players. Int. J. Exerc. Sci. 5, 232–238.
Rowat, O., Fenner, J., and Unnithan, V. (2017). Technical and physical determinants of soccer match-play performance in elite youth soccer players. J. Sports Med. Phys. Fitness 57, 369–379. doi: 10.23736/S0022-4707.16.06093-X
Sánchez-Sánchez, J., Garcia-Unanue, J., Felipe, J. L., Jimenez-Reyes, P., Viejo-Romero, D., Gomez-Lopez, M., et al. (2016). Physical and physiological responses of amateur football players on third-generation artificial turf systems during simulated game situations. J. Strength Cond. Res. 30, 3165–3177. doi: 10.1519/JSC.0000000000001415
Sant'anna, R. T., and de Souza Castro, F. A. (2016). Aerobic power and field test results of amateur 15-a-side rugby union players. J. Sports Med. Phys. Fitness 57, 1605–1612. doi: 10.23736/S0022-4707.16.06574-9
Santone, C., Dinallo, V., Paci, M., D'Ottavio, S., Barbato, G., and Bernardini, S. (2014). Saliva metabolomics by NMR for the evaluation of sport performance. J. Pharm. Biomed. Anal. 88, 441–446. doi: 10.1016/j.jpba.2013.09.021
Saunders, B., Sunderland, C., Harris, R. C., and Sale, C. (2012). beta-alanine supplementation improves YoYo intermittent recovery test performance. J. Int. Soc. Sports Nutr. 9:39. doi: 10.1186/1550-2783-9-39
Scanlan, A. T., Dascombe, B. J., and Reaburn, P. R. (2012). The construct and longitudinal validity of the basketball exercise simulation test. J. Strength Cond. Res. 26, 523–530. doi: 10.1519/JSC.0b013e318220dfc0
Scanlan, A. T., Dascombe, B. J., and Reaburn, P. R. J. (2014). Development of the Basketball Exercise Simulation Test: A match-specific basketball fitness test. Journal of Human Sport & Exercise. 9, 700–712. doi: 10.14198/jhse.2014.93.03
Schmitz, B., Klose, A., Schelleckes, K., Jekat, C. M., Kruger, M., and Brand, S. M. (2017). Yo-Yo IR1 vs incremental continuous running test for prediction of 3000 m performance. J. Sports Med. Phys. Fitness 57, 1391–1398.
Schwesig, R., Hermassi, S., Hoffmeyer, B., Irlenbusch, L., Fieseler, G., Noack, F., et al. (2016). Relationship between the handball-specific complex-test and intermittent field test performance in elite professional handball players. J. Sports Med. Phys. Fitness. 58, 778–784. doi: 10.23736/S0022-4707.17.07373-X
Seidelin, K., Nyberg, M., Piil, P., Jorgensen, N. R., Hellsten, Y., and Bangsbo, J. (2017). Adaptations with intermittent exercise training in post- and premenopausal women. Med. Sci. Sports Exerc. 49, 96–105. doi: 10.1249/MSS.0000000000001071
Shalfawi, S. A. I., Ingebrigtsen, J., Dillern, T., Tønnessen, E., Delp, T. K., and Enoksen, E. (2012). The Effect of 40 M repeated sprint training on physical performance in young elite male soccer players. Serbian J. Sports Sci. 6, 111–116.
Shalfawi, S. A. I., Young, M., Tønnessen, E., Haugen, T. A., and Enoksen, E. (2013). The effect of repeated agility training vs. repeated sprint training on elite female soccer players' physical perfeomance. Kinesiol. Slovenica 19, 29–42.
Shovlin, A., Roe, M., Malone, S., and Collins, K. (2017). The positional anthropometric and performance profile of elite gaelic football players. J. Strength Cond. Res. doi: 10.1519/JSC.0000000000002071. [Epub ahead of print].
Shultz, S. J., Schmitz, R. J., Cone, J. R., Henson, R. A., Montgomery, M. M., Pye, M. L., et al. (2015). Changes in fatigue, multiplanar knee laxity, and landing biomechanics during intermittent exercise. J. Athl. Train. 50, 486–497. doi: 10.4085/1062-6050-49.5.08
Silva, J. R., Magalhães, J., Ascensão, A., Seabra, A. F., and Rebelo, A. N. (2013). Training status and match activity of professional soccer players throughout a season. J. Strength Cond. Res. 27, 20–30. doi: 10.1519/JSC.0b013e31824e1946
Silva, J. R., Magalhães, J. F., Ascensão, A. A., Oliveira, E. M., Seabra, A. F., and Rebelo, A. N. (2011). Individual match playing time during the season affects fitness-related parameters of male professional soccer players. J. Strength Cond. Res. 25, 2729–2739. doi: 10.1519/JSC.0b013e31820da078
Skovgaard, C., Christensen, P. M., Larsen, S., Andersen, T. R., Thomassen, M., and Bangsbo, J. (2014). Concurrent speed endurance and resistance training improves performance, running economy, and muscle NHE1 in moderately trained runners. J. Appl. Physiol. 117, 1097–1109. doi: 10.1152/japplphysiol.01226.2013
Smith, M. R., Coutts, A. J., Merlini, M., Deprez, D., Lenoir, M., and Marcora, S. M. (2016). Mental fatigue impairs soccer-specific physical and technical performance. Med. Sci. Sports Exerc. 48, 267–276. doi: 10.1249/MSS.0000000000000762
Soares-Caldeira, L. F., de Souza, E. A., de Freitas, V. H., de Moraes, S. M., Leicht, A. S., and Nakamura, F. Y. (2014). Effects of additional repeated sprint training during preseason on performance, heart rate variability, and stress symptoms in futsal players: a randomized controlled trial. J. Strength Cond. Res. 28, 2815–2826. doi: 10.1519/JSC.0000000000000461
Sparks, M., Coetzee, B., and Gabbett, T. J. (2017). Internal and external match loads of university-level soccer players: a comparison between methods. J. Strength Cond Res. 31, 1072–1077. doi: 10.1519/JSC.0000000000001560
Stein, J. G., Gabbett, T. J., Townshend, A. D., and Dawson, B. T. (2015). Physical qualities and activity profiles of sub-elite and recreational Australian football players. J. Sci. Med. Sport 18, 742–747. doi: 10.1016/j.jsams.2014.10.008
Stevens, T. G., De Ruiter, C. J., Beek, P. J., and Savelsbergh, G. J. (2016). Validity and reliability of 6-a-side small-sided game locomotor performance in assessing physical fitness in football playersJ. Sports Sci. 34, 527–534. doi: 10.1080/02640414.2015.1116709
Taylor, J. M., Macpherson, T. W., McLaren, S. J., Spears, I., and Weston, M. (2016). Two weeks of repeated-sprint training in soccer: to turn or not to turn? Int. J. Sports Physiol. Perform. 11, 998–1004. doi: 10.1123/ijspp.2015-0608
Teplan, J., Mal, ý,T., Zahálka, F., Hrásk,ý, P, Kaplan, A., Hanus, M., et al. (2012a). The level of aerobic capacity in elite youth soccer players and its comparison in two age categories. J. Phys. Educ. Sport 12, 129–134.
Teplan, J., Malý, T., Zahálka, F., Hráský, P., Malá, L., and Heller, J. (2012b). The level and differences of aerobic capacity in three different young soccer teams in the U17 category. Sport Sci. 5, 43–48.
Teplan, J., Malý, T., Zahálka, F., and Malá, L. (2013). Values of speed and aerobic capacity parameters as indicators of physical fitness in U18 and U19 soccer teams at the beginning of the pre-season period. Sport Sci. 6, 87–94.
Thomassen, M., Christensen, P. M., Gunnarsson, T. P., Nybo, L., and Bangsbo, J. (2010). Effect of 2-wk intensified training and inactivity on muscle Na+-K+ pump expression, phospholemman (FXYD1) phosphorylation, and performance in soccer players. J. Appl. Physiol. 108, 898–905. doi: 10.1152/japplphysiol.01015.2009
Till, K., Darrall-Jones, J., Weakley, J. J., Roe, G. A., and Jones, B. L. (2017). The Influence of Training Age on the Annual Development of Physical Qualities Within Academy Rugby League Players. J. Strength Cond Res. 31, 2110–2118. doi: 10.1519/JSC.0000000000001546
Till, K., Jones, B., Darrall-Jones, J., Emmonds, S., and Cooke, C. (2015). Longitudinal development of anthropometric and physical characteristics within academy rugby league players. J. Strength Cond Res. 29, 1713–1722. doi: 10.1519/JSC.0000000000000792
Till, K., Jones, B., Emmonds, S., Tester, E., Fahey, J., and Cooke, C. (2014). Seasonal changes in anthropometric and physical characteristics within English academy rugby league players. J. Strength Cond Res. 28, 2689–2696. doi: 10.1519/JSC.0000000000000457
Till, K., Jones, B., and Geeson-Brown, T. (2016). Do physical qualities influence the attainment of professional status within elite 16-19 year old rugby league players? J. Sci. Med. Sport 19, 585–589. doi: 10.1016/j.jsams.2015.07.001
Ueda, S., Yamanaka, A., Yoshikawa, T., Katsura, Y., Usui, T., Orita, K., et al. (2011). Differences in physiological characterization between yo-yo intermittent recovery test level 1 and level 2 in Japanese college soccer players. 9, 33–38.
Veale, J. P., Pearce, A. J., and Carlson, J. S. (2010). The Yo-Yo intermittent recovery test (level 1) to discriminate elite junior australian football players. J. Sci. Med. Sport. 13, 329–331. doi: 10.1016/j.jsams.2009.03.006
Veness, D., Patterson, S. D., Jeffries, O., and Waldron, M. (2017). The effects of mental fatigue on cricket-relevant performance among elite players. J. Sports Sci. 35, 2461–2467. doi: 10.1080/02640414.2016.1273540
Vernillo, G., Silvestri, A., and La Torre, A. (2012). The yo-yo intermittent recovery test in junior basketball players according to performance level and age group. J. Strength Cond Res. 26, 2490–2494. doi: 10.1519/JSC.0b013e31823f2878
Vescovi, J. D. (2016). Locomotor, Heart-Rate, and Metabolic Power Characteristics of Youth Women's Field Hockey: Female Athletes in Motion (FAiM) StudyRes. Q. Exerc. Sport 87, 68–77. doi: 10.1080/02701367.2015.1124972
Veugelers, K. R., Naughton, G. A., Duncan, C. S., Burgess, D. J., and Graham, S. R. (2016). Validity and Reliability of a Submaximal Intermittent Running Test in Elite Australian Football Players. J. Strength Cond Res. 30, 3347–3353. doi: 10.1519/JSC.0000000000001441
Wells, C., Edwards, A., Fysh, M., and Drust, B. (2014). Effects of high-intensity running training on soccer-specific fitness in professional male players. Appl. Physiol. Nutr. Metab. 39, 763–769. doi: 10.1139/apnm-2013-0199
Wells, C. M., Edwards, A. M., Winter, E. M., Fysh, M. L., and Drust, B. (2012). Sport-specific fitness testing differentiates professional from amateur soccer players where VO2max and VO2 kinetics do not. J. Sports Med. Phys. Fitness 52, 245–254.
Weston, M., Helsen, W., MacMahon, C., and Kirkendall, D. (2004). The impact of specific high-intensity training sessions on football referees' fitness levels. Am. J. Sports Med. 32, 54S–61S. doi: 10.1177/0363546503261421
Wong, P., Chaouachi, A., Castagna, C., Lau, P. W. C., Chamari, K., and Wisløff, U. (2011). Validity of the Yo-Yo intermittent endurance test in young soccer players. Eur. J. Sport Sci. 11, 309–315. doi: 10.1080/17461391.2010.521579
Wong, P. L., Chaouachi, A., Chamari, K., Dellal, A., and Wisloff, U. (2010). Effect of preseason concurrent muscular strength and high-intensity interval training in professional soccer players. J. Strength Cond Res. 24, 653–660. doi: 10.1519/JSC.0b013e3181aa36a2
Wylie, L. J., Mohr, M., Krustrup, P., Jackman, S. R., Ermiotadis, G., Kelly, J., et al. (2013). Dietary nitrate supplementation improves team sport-specific intense intermittent exercise performanceEur. J. Appl. Physiol. 113, 1673–1684.
Young, W. B., Newton, R. U., Doyle, T. L., Chapman, D., Cormack, S., Stewart, G., et al. (2005). Physiological and anthropometric characteristics of starters and non-starters and playing positions in elite Australian Rules Football: a case study. J. Sci. Med. Sport 8, 333–345. doi: 10.1016/S1440-2440(05)80044-1
Keywords: Yo-Yo IR, Yo-Yo IE, Yo-Yo test, performance testing, field test, physical fitness, exercise capacity
Citation: Schmitz B, Pfeifer C, Kreitz K, Borowski M, Faldum A and Brand S-M (2018) The Yo-Yo Intermittent Tests: A Systematic Review and Structured Compendium of Test Results. Front. Physiol. 9:870. doi: 10.3389/fphys.2018.00870
Received: 20 December 2017; Accepted: 18 June 2018;
Published: 05 July 2018.
Edited by:Gary Iwamoto, University of Illinois at Urbana-Champaign, United States
Reviewed by:Giovanni Messina, University of Foggia, Italy
Filipe Manuel Clemente, Polytechnic Institute of Viana do Castelo, Portugal
Waseem Iqbal, Armed Forces Institute of Rehabilitation Medicine (AFIRM), Pakistan
Copyright © 2018 Schmitz, Pfeifer, Kreitz, Borowski, Faldum and Brand. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Boris Schmitz, email@example.com
†These authors have contributed equally to this work.