Overview of The Journal of Physiology Special Issue on the ‘Biomedical basis of elite performance’

Perhaps no area of physiological research piques the interest of the general public more than the study of why elite athletes can achieve remarkable performances in a wide variety of sports. Not only is this interest driven by the public enthusiasm for sports, but people also look to the field of exercise physiology for guidance on sports nutrition and how to improve one's health and personal fitness levels. Important to the field of physiology, the study of elite sport performance provides unique insights into the capabilities of the respiratory, cardiovascular and muscular systems.

While the study of elite performance in humans dates back more than 100 years, the importance of genetics to elite performance has been appreciated since the beginning of horse racing where it has long been appreciated that genetics plays a major role in determining equine running performance. During the past several decades, numerous studies have examined almost every aspect of the factors that contribute to elite sports performance in humans. Nonetheless, many of the factors that form the physiological basis of elite performance remain unknown, and research continues to elucidate these unknown factors.

Given that scientific interest in the field of the biomedical basis of elite performance has grown markedly during the past three decades, the Biomedical Basis of Elite Performance (BBEP) conference was established in 2012 by The Physiological Society to accompany the London Olympics. This successful conference was organized to highlight research related to human and exercise physiology and related disciplines. The success of that first meeting was followed 4 years later (2016) with a second BBEP meeting. It is the goal of this special issue of The Journal of Physiology to highlight several of the presentations that arose out of this second BBEP meeting, dealing with research progress in several important areas of this field. This special issue opens with five original research manuscripts, followed by three letters (and one reply) that deal with aspects of three of these research studies. Finally, this special issue ends with nine state‐of‐the‐art reviews from experts in different areas of elite performance research. A brief overview of these original research manuscripts and the topical reviews follows.

This special issue begins with a study that highlights a nutritional aspect of elite performance: the role of diet in human endurance performance. Burke et al. (2017) demonstrate that a low‐carbohydrate high‐fat diet negated performance benefits in elite endurance athletes, in part due to reduced exercise economy (despite a significant improvement in peak aerobic capacity). Another metabolic study by Gejl et al. (2017) demonstrates that the depletion of spatially distinct glycogen compartments differs during supra‐maximal exercise and that the depletion changes with repeated exercise and is fibre type dependent. Heat stress in hot environments in female athletes is examined in the study of Lei et al. (2017) who show that menstrual cycle phase does not appear to affect exercise performance in the heat in well‐trained women, but humidity impairs performance, probably due to reduced evaporative power. Nielsen et al. (2017) explore the role of mitochondria inner membrane surface in elite performance, and demonstrate that endurance trained athletes have increased mitochondrial cristae density. They establish that there is a positive correlation between this and whole body oxygen uptake and muscle fibre's mitochondrial content, and that elevated mitochondrial cristae density is a regulatory mechanism for increasing metabolic power in human skeletal muscle.

The invited reviews in this special issue deal with numerous aspects of the biomedical basis of elite performance. A fitting start to these reviews is the paper from Edwards (2017), which serves as a primer to introduce the interested reader to systems biology. The history, definition, practice, opportunities and challenges of systems biology is presented, with a particular emphasis on a topic of special interest to exercise physiologists: metabolism.

Following this primer on metabolic systems biology, Evans et al. (2017) review studies dealing with the manner in which optimizing training and performance through nutritional strategies is central to supporting elite performance, much of which has focused on manipulating the relative intake of carbohydrate and fat and their contributions as fuels for energy provision during exercise. This review focuses primarily on the physiology of ketone bodies during and after exercise and in response to training, with a specific interest in studies that explore the physiological basis for exogenous ketone supplementation for maximizing elite performance in athletes.

Staying along the theme of nutrition, metabolism and elite performance, the review from Wilkinson et al. (2017) examines exercise studies dealing with the application of substrate‐specific stable isotope tracers. These methods, which have been used for more than 80 years, provide exquisite insight into amino acid, fatty acid and carbohydrate metabolic regulation (i.e. incorporation, flux, oxidation, and in a tissue‐specific and whole‐body fashion) in response to acute and chronic exercise. In particular, this review focuses on the most recent work that uses alternative stable isotope tracer techniques (deuterium oxide: D₂O or heavy water) that overcome previous limitations of isotope work. This review provides insight into the role of stable isotope tracers, from substrate‐specific to novel D₂O approaches, in facilitating metabolic factors that determine elite performance.

The next reviews focus on training protocols that maximize elite performance. For example, it has long been known that specificity is a core principle of exercise training to promote the desired adaptations for maximizing elite performance. The molecular profiles that generate the adaptive response to different exercise modes have undergone intense scientific scrutiny. Coffey & Hawley (2017) provide a timely review that examines studies of the molecular responses in skeletal muscle that provide evidence for an interference effect with concurrent training of resistance and endurance exercise, within the context of the specificity of training adaptation. They review the studies that show that divergent exercise can induce similar signalling and gene expression profiles in skeletal muscle, although it remains currently unclear as to how the molecular response is modified with training status.

It is widely agreed that exercise‐induced muscle fatigue involves several interacting factors and depends on type of exercise and fitness level of the individual. The review from Hostrup & Bangsbo (2017) highlights studies that have focused on the mechanisms underlying fatigue development and limitations for performance after high intensity exercise training. For example, intense exercise causes major ionic perturbations that have been shown to be strong factors in the development of fatigue during this exercise programme. This review has a particular focus on the effect of very high intensity training, and discusses potential mechanisms underlying enhancements in performance induced by this type of training in already well‐trained individuals, with a special emphasis on ion handling in skeletal muscle. This review is a must‐read for both the expert and novice investigator interested in studying training and high intensity‐induced muscle fatigue.

Continuing with the theme of research devoted to the examination of the training response in determining elite performance, MacInnis & Gibala (2017) consider the role of exercise intensity in mediating physiological adaptations to training, with a focus on the capacity for aerobic energy metabolism. They discuss the manner in which exercise intensity is an important mediator of mitochondrial adaptations, but they suggest that there remains insufficient data to determine the responsiveness of mitochondrial adaptations to changes in the duration or frequency of interval training.

The next review by Sarzynski et al. (2017) examines the burgeoning new field of research that studies the training response effect on genomic and transcriptomic predictors of endurance exercise. The authors focus on measurements of cardiorespiratory fitness, traits that have a wide‐ranging impact on elite performance indicators. Gains in fitness indicators demonstrate large inter‐individual variation, even in response to standardized exercise training programmes. This important new field of research uses bioinformatics exploration based on thousands of variants to investigate pathways and systems instead of single variants and genes, and the results are summarized in this review.

Moving into a different field of research, the review of Lazarus & Harridge (2017) focuses on the timely topic of the health benefits that are found in the study of the ageing elite athlete. Master athletes have been proposed as being a biological model in which an understanding of the physiology of the healthy and inherent human ageing process can be derived. These authors review studies of ageing athletes that put forward the important concept that a given threshold of physical activity is needed to age optimally and to maximize the ‘healthspan’, or the healthy years one has in a lifetime. Without question, this review will be important reading for those interested in the effect of exercise on healthy ageing.

Last, but certainly not least, in our list of reviews is the manuscript from Joyner (2017) that examines sex differences in elite endurance performance. This review summarizes factors associated primarily with the physiological determinants that result in differences in elite performance between men and women, but also touches on some historical and sociological factors relevant to the overall topic. The literature suggests that the main physiological factor responsible for the 10–12% slower times in women compared to men at the elite level are probably due to sex differences in ${\dot{V}}_{{\mathrm{O}}_2\max }$.

This special issue of The Journal of Physiology will be an invaluable resource for researchers worldwide who are interested in the biomedical basis of elite performance. The contributing authors to this special edition are leaders in their respective areas of research and each of these reports provides depth and insight into their respective topics. Notably, each of these original studies and reviews highlights important gaps in our knowledge that remain to be filled. It is hoped that identifying these key unanswered questions will serve as a stimulus for future research.

Additional information

Competing interests

None declared.