OPINION article

Front. Sports Act. Living, 14 April 2025

Sec. Elite Sports and Performance Enhancement

Volume 7 - 2025 | https://doi.org/10.3389/fspor.2025.1571498

Do heart rates of elite marathon runners exhibit room for drift? Implications for durability

  • 1The National Coalition of Independent Scholars, Brattleboro, VT, United States
  • 2College of Education, Psychology and Human Studies, Aoyama Gakuin University, Tokyo, Japan

1 Introduction

Recent advances in marathon research have suggested that factors beyond the three classic physiological variables—maximal oxygen uptake (VO2max), fractional utilization of VO2max, and running economy—such as pacing and drafting strategies, environmental conditions, neoteric footwear, and physiological resilience, significantly influence race performance (1). In particular, Jones explained that endurance exercise performance is not solely a function of a runner's physiological status at the start line, but is also related to the runner's fatigue resistance or resilience to changes in the aforementioned indices during the race itself (1). Fatigue resistance and resilience are also expressed in terms of durability. Durability is defined as an individual's ability to resist and delay the decline in certain physiological parameters, both in terms of magnitude and time of onset, during prolonged exercise (2).

Regardless of the formal definition of “durability” (2), some studies have been conducted from a durability-like perspective in marathon races (39). Notably, in real marathon races, previous research has utilized the runner's heart rate (HR) and running speed to evaluate this concept. HR is a valid indicator of a runner's internal load (10), and deviations therein relative to the external load (running speed) serve as a practical measure for assessing durability during a race (4). For instance, if cardiovascular (CV) drift, i.e., when HR increases despite a constant running speed, occurs early in a marathon, it can be interpreted as a sign of low durability (1, 4, 11). Additionally, heat stress can exacerbate CV drift by increasing CV strain, with factors such as ambient and core body temperatures, hydration status, and exercise duration also playing a role (12).

This opinion paper summarizes previous research on runners' durability during marathons and highlights the necessity for durability studies, particularly at the international level to world-class marathon runners.

2 Durability from recreational to national runners

As previously noted, durability during a marathon has been assessed based on the relationship between HR and running speed, which is commonly referred to as the cardiac cost (3) or internal-to-external workload ratio (4). Among these two measures, cardiac cost, defined as HR divided by the running speed, serves as a potential index for CV drift (3, 5). Shimazu et al. investigated the relationship between cardiac cost and marathon performance in 14 male university student runners (finish times ranging from 2:28 to 4:49) (5). A notable strength of this study was the use of an incremental treadmill test prior to the race to assess physiological performance, specifically the first ventilatory threshold running speed. They found significant correlations between changes in cardiac cost in later race segments (0–5 km vs. 25–30, 30–35, and 35–40 km) and relative performance, which was defined as the average marathon race speed relative to the first ventilatory threshold running speed (r = −0.672, −0.671, and −0.661, respectively). This result suggests that excessive CV drift has a negative impact on relative performance. Another interesting study, conducted by Billat et al., examined 280 recreational runners (finish times ranging from 2:30 to 3:40) and observed that nearly 80% experienced a decline in running speed during marathons (6). Notably, HR began to increase around the halfway point of the race, preceding a noticeable decrease in running speed, which became apparent at approximately 26 km. More recently, Smyth et al. analyzed the internal-to-external workload ratio (essentially the same metric as the cardiac cost) in 82,303 runners (mean finish time: 3:46) (4). Two noteworthy findings were obtained from this large-scale study: first, the onset of decoupling was observed at an average distance of approximately 25 km; second, the relative marathon performance was significantly associated with both the magnitude and the onset of decoupling. The decoupling onset occurred at 33.4 and 19.1 km in the low (high performance) and high (low performance) decoupling groups, respectively.

Furthermore, maintaining an essentially even running pace is crucial for achieving superior marathon performance. Ideally, HR should peak near the finish line as the race concludes. A previous study involving 50 New York City Marathon participants (average finish time: 2:54) demonstrated that runners whose HR did not increase or decrease in the later stages of the race tended to exhibit a decline in running speed (7). In addition, although the finish time itself is not at the international level or world-class in standard athletes, some case studies have shown that an HR pattern characterized by peaking near the finish line is associated with superior performance in well-trained runners (8, 9). Specifically, these studies included a national-level female runner and a visually impaired marathoner, both of whom set personal bests during their respective races, including a world record at the time, which was considered world-class within the context of parasports.

Based on these findings, sustaining a stable HR at the target race pace, particularly up to the 25-km mark (approximately 60% of the marathon distance), appears to be a key strategy for achieving optimal performance in recreational as well as national-level runners.

3 Determining factors of durability

Before discussing the durability of elite marathons, we will attempt to explain the factors that determine durability. According to the abovementioned study by Shimazu et al. (5), runners with higher relative performance (higher durability) had a better running economy, as measured by oxygen cost, than did those with lower relative performance. Although the energy derived from oxygen can vary slightly depending on the relative contributions of carbohydrates and fats, oxygen cost is closely related to energy expenditure because runners generate energy based on oxygen consumption (13). Moreover, a recent study showed that runners with superior running economy predominantly retain slow muscle fibers, which have superior fatigue resistance (14). Considering the advantages of a superior running economy, it is reasonable to hypothesize that it partially contributes to high durability.

Another possible factor in durability is carbohydrate (CHO) availability. Clark et al. demonstrated that CHO supplementation (60 g/h) during a 2-h heavy intensity cycling exercise preserved critical power, as compared to supplementation with placebo (15). This preservation may be associated with higher muscle glycogen levels, elevated CHO oxidation rates, and stable blood glucose levels (15). Although running and cycling differ in their specific demands, CHO availability plays a key role in endurance performance in both sports (16). Therefore, during marathon running, CHO availability is considered a potential factor influencing runners' durability.

Other potential factors include resistance to muscle damage and autonomic nervous system responses (17), all of which may be interrelated. However, the extent to which each of these factors contributes to durability, and whether their relative importance differs according to sex or performance level, remain insufficiently understood.

4 Durability from international level to world-class runners

While numerous studies have evaluated durability during marathon races in recreational and national-level runners (39), data from international level to world-class runners—those running within 2:09 for men or 2:19 for women (18, 19)—remain scarce, leaving many scientific questions unanswered. Current evidence indicates that, before the widespread adoption of advanced footwear technology, a male athlete who held the half-marathon world record (0:58:23) for a prolonged period exhibited remarkably high maximal oxygen uptake (83 ml/kg/min) and superior running economy (oxygen cost: 150 ml/kg/km) (20). Despite these superior physiological attributes, his marathon performance (2:08:46) fell short of being classified as world-class (≤2:03:00). This discrepancy underscores the likelihood that additional non-classical variables, with durability as a representative example, contribute significantly to marathon performance.

Traditionally, the relative intensity of marathons is closely aligned with the first metabolic threshold (first ventilatory or lactate threshold), regardless of runner level (21). However, this assumption does not fully capture the nuanced relationship between exercise duration and intensity. Jones and Vanhatalo showed that the relative intensity of 12 male world-class marathon runners (finish times ranging from 2:03 to 2:08) was higher than the first metabolic threshold, which corresponded to 96% of the critical speed (equivalent to the second metabolic threshold) (22).

When considering durability or decoupling among world-class runners, the data pertaining to the HR of a pacemaker that supported the former world-record holder Eliud Kipchoge during his record-breaking marathon (2:01:09) presents intriguing information (23). The pacemaker, who maintained a world-record pace shortly after the 20-km mark, appeared to operate at near-peak HR from the early stages of the race. These data were likely derived from wrist-based photoplethysmography (PPG) and did not provide clear information about the pacemaker's potential maximum HR, while the report has not undergone a formal scientific peer-review process; thus, this information should be interpreted cautiously because of potential validity concerns. Nevertheless, this case highlights an exceptionally high relative intensity in these runners as compared to runners at recreational and national levels. Notably, decoupling becomes particularly pronounced in recreational to national runners during the finishing time of international and world-class runners, highlighting an intriguing disparity in durability.

Recreational and national-level runners typically run the early stages of a marathon race at <90% of their maximal HR (5), suggesting that they retain their reserve capacity, which allows for HR drift in the later stages of the race. In contrast, international and world-class runners run with little to no reserves from an early stage of the race. Consequently, if decoupling occurs in these runners, we suggest that it primarily results from a decrease in external load (running speed) rather than from internal limitations (Figure 1).

Figure 1
www.frontiersin.org

Figure 1. Summary of this opinion paper. (A) Hierarchical structure of marathon runners based on performance level, adapted from Burke et al. (18) and McKay et al. (19) using the world records at the time of writing as a reference. (B) Hypothetical heart rate and running speed during a marathon race in top-tier (elite) marathon runners. (C) Typically observed heart rate and running speed during a marathon race in recreational to national marathon runners.

5 Discussion

Durability is a critical factor influencing marathon performance; however, it remains largely unexplored, particularly among international to world-class runners. The physiological demands of marathon running differ significantly between international to world-class runners and recreational to national-level runners (18). While competitive cycling has provided extensive insights into international and world-class athletes (24), comparable data are lacking for marathon running, leaving a significant gap in our understanding of the unique physiological demands faced by international to world-class runners. Recent advancements in wearable technology, such as PPG-based devices, offer practical tools for assessing HR during prolonged, high-intensity exercise and could enable new investigations in this area. As a preliminary step, future research may benefit from investigating male runners with finish times between 2:10 and 2:20 and female runners between 2:20 and 2:30. This approach is expected to enable a larger sample size and contribute to a more detailed investigation of unexplored aspects of durability during a race, particularly considering the lack of such data at this level before examining elite runners. Moreover, while the influence of sex differences is not addressed in this preliminary phase, findings from these male runner data may offer valuable insights into the durability of female international level to world-class runners.

Alternatively, a comprehensive research approach—incorporating field-based observations, controlled laboratory trials, case studies, and cross-sectional evaluations across different performance levels—could provide a more thorough understanding of the physiological factors influencing durability in marathon running.

However, without direct data from international and world-class marathon runners, the interplay among durability, decoupling, and marathon performance cannot be fully understood. Therefore, studies conducted under racing conditions involving international and world-class runners should be prioritized. Such research would not only address the existing knowledge gap, but can also provide actionable insights into optimizing performance strategies for top-tier marathoners.

Author contributions

FT: Conceptualization, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing. AA: Investigation, Visualization, Writing – review & editing.

Funding

The author(s) declare that no financial support was received for the research and/or publication of this article.

Acknowledgments

We would like to thank Editage (http://www.editage.jp) for English language editing.

Conflict of interest

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.

Generative AI statement

The authors declare that generative AI was used in the creation of this manuscript. Specifically, during the preparation of this work, the authors used ChatGPT and Claude to enhance readability, language, and grammar of parts of this paper. After using the tools, the authors reviewed and edited the content as needed and took full responsibility for the final publication.

Publisher's note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

1. Jones AM. The fourth dimension: physiological resilience as an independent determinant of endurance exercise performance. J Physiol. (2024) 602:4113–28. doi: 10.1113/JP284205

PubMed Abstract | Crossref Full Text | Google Scholar

2. Maunder E, Seiler S, Mildenhall MJ, Kilding AE, Plews DJ. The importance of ‘durability’ in the physiological profiling of endurance athletes. Sports Med. (2021) 51:1619–28. doi: 10.1007/s40279-021-01459-0

PubMed Abstract | Crossref Full Text | Google Scholar

3. Billat VL, Mille-Hamard L, Meyer Y, Wesfreid E. Detection of changes in the fractal scaling of heart rate and speed in a marathon race. Physica A. (2009) 388:3798–808. doi: 10.1016/j.physa.2009.05.029

Crossref Full Text | Google Scholar

4. Smyth B, Maunder E, Meyler S, Hunter B, Muniz-Pumares D. Decoupling of internal and external workload during a marathon: an analysis of durability in 82,303 recreational runners. Sports Med. (2022) 52:2283–95. doi: 10.1007/s40279-022-01680-5

PubMed Abstract | Crossref Full Text | Google Scholar

5. Shimazu W, Takayama F, Tanji F, Nabekura Y. Relationship between cardiovascular drift and performance in marathon running. Int J Sport Health Sci. (2020) 18:197–206. doi: 10.5432/ijshs.202036

Crossref Full Text | Google Scholar

6. Billat VL, Palacin F, Correa M, Pycke JR. Pacing strategy affects the sub-elite marathoner’s cardiac drift and performance. Front Psychol. (2020) 10:3026. doi: 10.3389/fpsyg.2019.03026

PubMed Abstract | Crossref Full Text | Google Scholar

7. Best A, Braun B. Using a novel data resource to explore heart rate during mountain and road running. Physiol Rep. (2017) 5:e13256. doi: 10.14814/phy2.13256

PubMed Abstract | Crossref Full Text | Google Scholar

8. Takayama F. Assessment of blood glucose responses in a female national-level marathon runner using continuous glucose monitoring during a real-world marathon race. BioMed. (2023) 3:387–91. doi: 10.3390/biomed3030031

Crossref Full Text | Google Scholar

9. Takayama F. Heart rate response during visually impaired women’s marathon world record breaking race. Sports Perform Sci Rep. (2022) 162:1–3.

Google Scholar

10. Impellizzeri FM, Marcora SM, Coutts AJ. Internal and external training load: 15 years on. Int J Sports Physiol Perform. (2019) 14:270–3. doi: 10.1123/ijspp.2018-0935

PubMed Abstract | Crossref Full Text | Google Scholar

11. Jones AM, Kirby BS. Physiological resilience: what is it and how might it be trained? Scand J Med Sci Sports. (2025) 35:e70032. doi: 10.1111/sms.70032

PubMed Abstract | Crossref Full Text | Google Scholar

12. Wingo JE, Ganio MS, Cureton KJ. Cardiovascular drift during heat stress: implications for exercise prescription. Exerc Sport Sci Rev. (2012) 40:88–94. doi: 10.1097/JES.0b013e31824c43af

PubMed Abstract | Crossref Full Text | Google Scholar

13. Péronnet F, Massicotte D. Table of nonprotein respiratory quotient: an update. Can J Sport Sci. (1991) 16:23–9.

Google Scholar

14. Swinnen W, Lievens E, Hoogkamer W, De Groote F, Derave W, Vanwanseele B. Inter-individual variability in muscle fiber-type distribution affects running economy but not running gait at submaximal running speeds. Scand J Med Sci Sports. (2024) 34:e14748. doi: 10.1111/sms.14748

PubMed Abstract | Crossref Full Text | Google Scholar

15. Clark IE, Vanhatalo A, Thompson C, Joseph C, Black MI, Blackwell JR, et al. Dynamics of the power-duration relationship during prolonged endurance exercise and influence of carbohydrate ingestion. J Appl Physiol. (2019) 127:726–36. doi: 10.1152/japplphysiol.00207.2019

PubMed Abstract | Crossref Full Text | Google Scholar

16. Hawley JA, Leckey JJ. Carbohydrate dependence during prolonged, intense endurance exercise. Sports Med. (2015) 45:S5–S12. doi: 10.1007/s40279-015-0400-1

PubMed Abstract | Crossref Full Text | Google Scholar

17. Nuuttila OP, Laatikainen-Raussi V, Vohlakari K, Laatikainen-Raussi I, Ihalainen JK. Durability in recreational runners: effects of 90-min low-intensity exercise on the running speed at the lactate threshold. Eur J Appl Physiol. (2025) 125:697–705. doi: 10.1007/s00421-024-05631-y

PubMed Abstract | Crossref Full Text | Google Scholar

18. Burke LM, Whitfield J, Hawley JA. The race within a race: together on the marathon starting line but miles apart in the experience. Free Radic Biol Med. (2024) 227:367–78. doi: 10.1016/j.freeradbiomed.2024.10.277

PubMed Abstract | Crossref Full Text | Google Scholar

19. McKay AKA, Stellingwerff T, Smith ES, Martin DT, Mujika I, Goosey-Tolfrey VL, et al. Defining training and performance caliber: a participant classification framework. Int J Sports Physiol Perform. (2022) 17:317–31. doi: 10.1123/ijspp.2021-0451

PubMed Abstract | Crossref Full Text | Google Scholar

20. Lucia A, Oliván J, Bravo J, Gonzalez-Freire M, Foster C. The key to top-level endurance running performance: a unique example. Br J Sports Med. (2008) 42:172–4. doi: 10.1136/bjsm.2007.040725

PubMed Abstract | Crossref Full Text | Google Scholar

21. Farrell PA, Wilmore JH, Coyle EF, Billing JE, Costill DL. Plasma lactate accumulation and distance running performance. Med Sci Sports. (1979) 11:338–44.530025

PubMed Abstract | Google Scholar

22. Jones AM, Vanhatalo A. The ‘critical power’ concept: applications to sports performance with a focus on intermittent high-intensity exercise. Sports Med. (2017) 47:65–78. doi: 10.1007/s40279-017-0688-0

PubMed Abstract | Crossref Full Text | Google Scholar

23. COROS. Kipchoge’s World Record: Inside the Numbers (2022). Available online at: https://coroscom.wpcomstaging.com/world-record/ (accessed January 12, 2025).

Google Scholar

24. Mateo-March M, Valenzuela PL, Muriel X, Gandia-Soriano A, Zabala M, Lucia A, et al. The record power profile of male professional cyclists: fatigue matters. Int J Sports Physiol Perform. (2022) 17:926–31. doi: 10.1123/ijspp.2021-0403

PubMed Abstract | Crossref Full Text | Google Scholar

Keywords: cardiovascular drift, durability, elite athletes, fatigue resistance, running economy

Citation: Takayama F and Aoyagi A (2025) Do heart rates of elite marathon runners exhibit room for drift? Implications for durability. Front. Sports Act. Living 7:1571498. doi: 10.3389/fspor.2025.1571498

Received: 5 February 2025; Accepted: 31 March 2025;
Published: 14 April 2025.

Edited by:

Rodrigo Zacca, University of Porto, Portugal

Reviewed by:

Beat Knechtle, University of Zurich, Switzerland
David Bruce Pyne, University of Canberra, Australia

Copyright: © 2025 Takayama and Aoyagi. 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: Fuminori Takayama, ZnVtaW5vcmkudGFrYXlhbWFAbmNpcy5vcmc=

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.