This blog post represents an ever-growing list of pertinent, up-to-date reviews relating to exercise physiology with brief descriptions. This blog covers a large scope (from applied to molecular physiology) so if you know what topic you're interested in hit ctrl-f or command-f for faster searching. If you have a review that you like and isn't on the list, let me know in the comments!
On Periodization
Abstract: Sports periodization has traditionally focused on the exercise aspect of athletic preparation, while neglecting the integration of other elements that can impact an athlete’s readiness for peak competition performances. Integrated periodization allows the coordinated inclusion of multiple training components best suited for a given training phase into an athlete’s program. The aim of this article is to review the available evidence underpinning integrated periodization, focusing on exercise training, recovery, nutrition, psychological skills, and skill acquisition as key factors by which athletic preparation can be periodized.
Various methods of exercise training periodization can contribute to performance enhancement in a variety of elite individual and team sports, such as soccer.
Recovery interventions should be periodized (ie, withheld or emphasized) to influence acute and chronic training adaptation and performance.
Nutrient intake and timing in relation to exercise and as part of the periodization of an athlete’s training and competition calendar can also promote physiological adaptations and performance capacity.
Psychological skills are a central component of athletic performance, and their periodization should cater to each athlete’s individual needs and the needs of the team.
Skill acquisition can also be integrated into an athlete’s periodized training program to make a significant contribution to competition performance.
Article deep dive (coming soon)
On Hypertrophy
Abstract: Skeletal muscle hypertrophy can be induced by hormones and growth factors acting directly as positive regulators of muscle growth or indirectly by neutralizing negative regulators, and by mechanical signals mediating the effect of resistance exercise. Muscle growth during hypertrophy is controlled at the translational level, through the stimulation of protein synthesis, and at the transcriptional level, through the activation of ribosomal RNAs and muscle-specific genes. mTORC1 has a central role in the regulation of both protein synthesis and ribosomal biogenesis. Several transcription factors and co-activators, including MEF2, SRF, PGC-14, and YAP promote the growth of the myofibers. Satellite cell proliferation and fusion is involved in some but not all muscle hypertrophy models.
Article deep dive (coming soon)
On Exercise Physiology
Abstract: Exercise represents a major challenge to whole-body homeostasis provoking widespread perturbations in numerous cells, tissues, and organs that are caused by or are a response to the increased metabolic activity of contracting skeletal muscles. To meet this challenge, multiple integrated and often redundant responses operate to blunt the homeostatic threats generated by exercise induced increases in muscle energy and oxygen demand. The application of molecular techniques to exercise biology has provided greater understanding of the multiplicity and complexity of cellular networks involved in exercise responses, and recent discoveries offer perspectives on the mechanisms by which muscle ‘‘communicates’’ with other organs and mediates the beneficial effects of exercise on health and performance.
Article deep dive (coming soon)
On Endurance Performance
Abstract: In the exercising human, maximal oxygen uptake (V̇O2max) is limited by the ability of the cardiorespiratory system to deliver oxygen to the exercising muscles. This is shown by three major lines of evidence: 1) when oxygen delivery is altered (by blood doping, hypoxia, or beta-blockade), V̇O2max changes accordingly; 2) the increase in V̇O2max with training results primarily from an increase in maximal cardiac output (not an increase in the a-v̄ O2 difference); and 3) when a small muscle mass is overperfused during exercise, it has an extremely high capacity for consuming oxygen. Thus, O2 delivery, not skeletal muscle O2 extraction, is viewed as the primary limiting factor for V̇O2max in exercising humans. Metabolic adaptations in skeletal muscle are, however, critical for improving submaximal endurance performance. Endurance training causes an increase in mitochondrial enzyme activities, which improves performance by enhancing fat oxidation and decreasing lactic acid accumulation at a given V̇O2. V̇O2max is an important variable that sets the upper limit for endurance performance (an athlete cannot operate above 100% V̇O2max. for extended periods). Running economy and fractional utilization of V̇O2max also affect endurance performance. The speed at lactate threshold (LT) integrates all three of these variables and is the best physiological predictor of distance running performance.
Article deep dive (coming soon)
Abstract: Maximal oxygen uptake (VO2max) is a physiological characteristic bounded by the parametric limits of the Fick equation: stroke volume × heart rate × arterio-venous oxygen difference. ‘Classical’ views of VO2max emphasize its critical dependence on oxygen transport to working skeletal muscle, and recent data are show convincingly that such limits must and do exist. ‘Contemporary’ investigations aim to elucidate the mechanisms underlying peripheral muscle fatigue. Systemic fatigue could be due to energetic supply/demand mismatch mediated through local metabolites at the skeletal muscle level. Elite endurance athletes have a high VO2max due primarily to a high cardiac output from a large compliant cardiac chamber. This large capacity for LV filling and ejection allows preservation of blood pressure during extraordinary rates of muscle blood flow and oxygen transport which support high rates of sustained oxidative metabolism.
Article deep dive (coming soon)
Abstract: Efforts to understand human physiology through the study of champion athletes and record performances have been ongoing for about a century. For endurance sports three main factors – maximal oxygen consumption, fatigue threshold and efficiency (i.e. the oxygen cost to generate a give running speed or cycling power output) – appear to play key roles in endurance performance. VO2max and fatigue threshold interact to determine the ‘performance VO2‘ which is the oxygen consumption that can be sustained for a given period of time. Efficiency interacts with the performance to establish the speed or power that can be generated at this oxygen consumption. This review focuses on what is currently known about how these factors interact, their utility as predictors of elite performance, and areas where there is relatively less information to guide current thinking.
Article deep dive (coming soon)
Abstract: Traditional exercise physiology dogma presents endurance capacity as a biological construct primarily determined through a combination of one’s maximal rate of whole-body oxygen consumption (VO2max), measure(s) of performance or fatigue threshold(s), and efficiency during exercise. Although all collective assumptions implicit in this traditional tenet have never been empirically verified directly, the aggregate literature examining human integrative physiology supports this premise. A slightly divergent interpretation of the relationship between these exact biological characteristics and endurance performance advocates that optimal endurance performance requires a robust and efficient capacity to transfer and utilize oxygen from the environment to mitochondria in working skeletal muscle. The aim of the current thesis is to empirically validate both postulates regarding the predictive physiology of competitive endurance performance.
Article deep dive (coming soon)
Abstract: In endurance sports, whole-body measurements such as the maximal oxygen consumption, lactate threshold, and efficiency/economy play a key role in performance. Although these determinants are known to interact, it has also been demonstrated that athletes rarely excel in all three. The leading question is how athletes reach exceptional values in one or all of these determinants to optimize their endurance performance, and how such performance can be explained by (combinations of) underlying physiological determinants. In this review:
Identifying key physiological determinants at the macroscopic (whole-body) and the microscopic level (muscle tissue, i.e., muscle fiber oxidative capacity, oxygen supply, muscle fiber size, and fiber type).
How these physiological determinants can be improved by training and what potential physiological challenges endurance athletes may face when trying to maximize their performance.
Optimal characteristics for endurance performance include type-I fibers with a high mitochondrial oxidative capacity with high capillarization and myoglobin concentrations to accommodate the required oxygen flux during endurance performance.
Article deep dive (coming soon)
The ‘Critical Power’ Concept: Applications to Sports Performance with a Focus on Intermittent High-Intensity Exercise - Jones and Vanhatalo 2017
Abstract: The curvilinear relationship between power output and the time for it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship ‘levels off’ at a ‘critical power’ (CP) that separates sustainable from non-sustainable power outputs. The amount of work that can be done during exercise above CP (W' ) is constant but may be utilized at different rates depending on the proximity of the exercise power output to CP. Traditionally, this two-parameter CP model has been employed to provide insights into physiological responses, fatigue mechanisms, and performance capacity during continuous constant power output exercise in discrete exercise intensity domains. However, many team sports (e.g., basketball, football, hockey, rugby) involve frequent changes in exercise intensity and, even in endurance sports (e.g., cycling, running), intensity may vary considerably with environmental/course conditions and pacing strategy. This has led to the development of a new CP model for intermittent exercise which has important applications in the real-time monitoring of athlete fatigue progression in endurance and team sports, which may inform tactics and influence pacing strategy.
Article deep dive (coming soon)
On the Cardiovascular Response to Exercise
Abstract: A number of mechanisms govern the rapid and precise changes in blood flow which occur in skeletal muscle with alterations in metabolic demand. Such mechanisms include sympathetic activity, functional sympatholysis, conducted vasodilation, flow mediated dilation, and compounds which stimulate formation of endothelium derived vasodilators. Compounds identified to be of importance in vasodilation include nitric oxide, prostacyclin, potassium, and nucleotides. In this review, the authors briefly describe some of the basic mechanisms and present selected contemporary contributions to the field. The main focus is on basic regulation of exercise hyperemia but aspects of training, age and sex have also been included.
Article deep dive (coming soon)
On the Nutrition for Performance
Abstract: Ingestion of carbohydrates should be based on duration (and intensity) of exercise. Studies have shown that during exercise lasting approximately 1 h in duration, a mouth rinse or small amounts of carbohydrate can result in a performance benefit. A single carbohydrate source can be oxidized at rates up to approximately 60 g/h and this is the recommendation for exercise that is more prolonged (2–3 h). For ultra-endurance events, the recommendation is higher at approximately 90 g/h. Carbohydrate ingested at such high ingestion rates must be a multiple transportable carbohydrates to allow high oxidation rates and prevent the accumulation of carbohydrate in the intestine. The source of the carbohydrate may be a liquid, semisolid, or solid, and the recommendations may need to be adjusted downward when the absolute exercise intensity is low and thus carbohydrate oxidation rates are also low. Carbohydrate intake advice is independent of body weight as well as training status but needs to be personalized by coaches and athletes to what is tolerable.
Article deep dive (coming soon)