Editorial: Comprehensive Evaluation of Various Training Protocols for Youth: Effects on Body Composition, Hemodynamics, and Motor Performance

Cristian Alvarez^1*Jarosław Domaradzki²

• ¹Andres Bello University, Santiago, Chile
• ²Wroclaw University of Health and Sport Sciences, Wrocław, Poland

2 Faculty of Physical Education and Sport, Wroclaw University of Health and Sport Sciences, Wroclaw, Poland Cardiometabolic health including arterial hypertension (1) and diabetes (2) have experienced a worrying increase in several countries and different exercise training modalities including moderate-intensity continuous (MICT), high-intensity interval (HIIT), resistance (RT) and concurrent training (CT) are widely recommended as preventive and treatment tool (3)(4)(5). In both young (i.e., children and adolescents at school environments) and adults' populations there is a need for increasing the exercise evidence for treating these abnormalities, but also when the performance is high, other specific exercise strategies are useful to optimize the performance. By the present special issue, we aimed to summarize current exercise strategies on youth and adults under cardiometabolic risk or performance optimization.The PEER-HEART study, studied (n=307) adolescents to test whether two 8-week of traditional HIIT and a plyometric HIIT (HIPT) in physical education classes. Both groups significantly reduced total body fat % and systolic (SBP)/diastolic (DBP) blood pressure, while increasing maximum oxygen uptake (VO2max). The authors conclude that brief HIIT or HIPT sessions are feasible for improving cardiovascular health in adolescents. Jovanović et al., A 12-week school-based Tabata HIIT warm-up (2×/week, 4-min bouts) replaced standard physical education class warm-ups for (n=30) Serbian boys (16 y), with 30 controls. Shuttle-run distance and estimated VO2max increased in both groups, but improvements were ~1.4 fold larger with HIIT. HIIT additionally boosted standing long jump and countermovement jump performance and right handgrip strength (HGS) versus control. Authors conclude that brief Tabata HIIT is an efficient to enhance cardiorespiratory fitness and lower limb power in adolescent boys. Sun et al., An 8-week randomized trial assigned (n=18) sedentary, normal weight Chinese adolescents to thrice-weekly HIIT, MICT or control. Both exercise modalities similarly reduce body fat mass and visceral fat area versus baseline. Only HIIT lowered waist-to-hip ratio and elicited marked falls in SBP (-6) and DBP (-11 mmHg) as well as triglycerides (-30 %). The authors conclude that short, school-friendly HIIT is a more effective and time-efficient prescription than volume-matched MICT for reducing adiposity and cardiometabolic risk in sedentary youth.Min-Seong Ha., A 16-week after-school combined exercise program (sports games plus MICT and RT) enrolled (n=33) Korean boys (11-12 y) with (n=16) and without obesity (n=17). In the obesity group body fat percentage was reduced from 37.6 % to 29.1 % and muscle mass increased ~31 %. C-peptide and resistin fell markedly (-1.6 and -3.0 ng mL⁻¹), while insulin growth factor (IGF-1) and growth hormone increased ~20 % to 25 %, and thus, C-peptide and IGF-1 as mechanistic markers of training responsiveness in adolescent boys with obesity. Nowak et al., A cross-sectional analysis of (n=495) male academy footballers (12-16 y) produced normative percentile charts for speed, endurance and power tests. Running times over 5 m, 10 m and 30 m, standing long-jump distance, and maximal aerobic speed (MAS) from the 30-15 intermittent fitness test were recorded during 2018-2022 training blocks. The sharpest gains appeared between ages 13-14: sprint times improved by 0.087-0.215 s (5-10 m) and 0.438-0.719 s (30 m), long-jump length rose 31-48 cm, and MAS increased 0.3-0.6 m s⁻¹. Percentile grids (P3-P97) allow coaches to benchmark individual progress and detect outliers in development trajectories. These charts provide a practical tool for tailoring youth-soccer conditioning, optimizing load, and mitigating injury risk throughout adolescence. Amare et al., conducted a randomized 8-week trial assigned (n=24) inactive, overweight/obese Ethiopian men (~49 y) to MICT, RT or CT. All groups lowered fasting blood glucose, insulin resistance, SBP/DBP, and waist-to-hip ratio versus baseline. RT and CT produced larger fasting glucose declines than MICT, and insulin resistance was reduced with RT compared with MICT. SBP dropped most in CT and RT. The exercise modality explained up to 57 % of the variance summarizing that short-term RT or CT are effective exercise modalities for cardiometabolic risk reduction in overweight and obese middle-aged men.strategies Feige et al., examined (n=11) elite fin swimmers (children <17 y and adults 17-29 y) during dynamic apnea dives of 25-100 m. Transcutaneous pulse oximetry and heart-rate monitoring during repeated pool dives showed a stereotypical diving response-bradycardia during immersion followed by tachycardic rebound at surfacing. Longer apnea duration, rather than swim speed, produced the greatest falls in oxygen saturation, whereas higher speeds chiefly intensified cardiovascular workload. The authors conclude that real-life dynamic apnea evokes age-dependent cardiorespiratory stress and provide benchmark data to guide training and risk assessment in pediatric and adult divers. Wu et al., studied (n=90) male college athletes that completed 7 days of moderate-intensity training and were randomized to true transcranial pulse current stimulation (tPCS) or control. Daily 20-min tPCS at 1.5 mA was delivered immediately post-exercise, fatigue was reported by subjective fatigue scale (RPE), functional near-infrared spectroscopy (fNIRS) cerebral oxygenation, and blood biomarkers. Compared with controls, the tPCS group reported lower RPE scores and showed smaller post exercise drops in oxygenated hemoglobin concentration (Oxy Hb) and rises in deoxyhemoglobin concentration (HHb), total hemoglobin concentration (HbTot) and hemoglobin concentration difference (HbDiff). Authors conclude that brief daily tPCS is an effective, non invasive countermeasure against the accumulation of exercise induced fatigue by preserving central neural function. Zhuan et al., applied a randomized crossover study testing whether adding three blood-flow-restriction (BFR) modes (continuous low, intermittent medium, and intermittent high-to high-intensity [75 % 1RM]) squat sessions boost lower limb and core muscle activation. Twelve RT college men performed 3 sets of 8 deep squats under each BFR condition and a no-BFR control while electromyography, thigh circumference and RPE were recorded. All BFR modes elevated vastus lateralis and vastus medialis maximum voluntary contraction during the first 2 sets versus control. Authors conclude that continuous low-pressure BFR offers the most stable posterior-thigh engagement, while intermittent high-pressure BFR optimizes spinal-extensor activation and perceived exertion, making both viable add-ons to heavy squat training.Taken together, all these studies strengthen the concept that different exercise training modalities such as MICT, HIIT, RT, CT or other variations of these, increase the cardiorespiratory fitness and modify positively the body composition in young populations in school environments, dynamic apnea reduce the diving risk, tPCS is effective to decrease the exercise-induced fatigue, and low-pressure BFR improve the heavy squat training performance.• There is a pressing need to explore inter-individual variability in exercise response and identify predictors of responsiveness in the context of responders and non-responders to the exercise stimuli. • Future work should compare different durations, intensities, and modalities of training in diverse populations to identify the optimal dose for effective response in various morphological and physiological features. • Long-term follow-ups are needed to assess whether effects observed in postintervention measurements translate into adult health benefits in long-time periods. • Personalized and context-specific interventions (e.g. biological, social-economic etc.) are needed to study the various condition diversity and its effect.