Dr. Martin Gibala is a professor and chair of the Department of Kinesiology at McMaster University in Hamilton, Canada. He studies the beneficial effects of exercise at the molecular to whole-body level in both healthy individuals and people with chronic diseases. Gibala’s research on the physiological adaptations to interval training has attracted immense scientific attention and worldwide media coverage. He is the author of a bestselling book on the topic, The One-Minute Workout: Science Shows a Way to Get Fit That’s Smarter, Faster, Shorter.
Freelap Friday Five with Dr. Martin Gibala
Freelap USA: A lot of confusion exists with the lactate response, as some coaches feel that changes in pH are meaningless, while others feel a rise in lactate is an anabolic trigger. To help coaches who are not strong in physiology, how can they understand fatigue better with regard to the lactate response?
Dr. Martin Gibala: Lactate is often (mis)characterized as a metabolic waste-product that accumulates under conditions of hypoxia or reduced oxygen availability and is linked to fatigue. The reality is that lactate is an important metabolite that plays a central role in the coordination of whole-body metabolism. During exercise, for example, lactate produced in skeletal muscle can be released into the bloodstream and circulate to other tissues such as the heart and liver, which can take up the lactate and use it as a source of energy. (As an aside and with respect to terminology, within the physiological pH range of muscle and blood, ~99% of “lactic acid” is dissociated into lactate ions [La–] and protons [H+].)
Lactate can also serve as a signaling molecule muscle and influence the expression of certain genes, although the significance for exercise-mediated adaptations in human skeletal muscle is unclear. The precise role of cellular hypoxia in lactate production is controversial; while the accumulation of blood lactate during exercise is associated with the capacity for whole-body oxygen delivery, lactate can also be produced in skeletal muscle under fully aerobic conditions. This is because other factors such as fiber type, enzyme concentration and activity, and circulating hormones also affect lactate metabolism.While lactate accumulation may play a role in athlete fatigue, it is not likely the primary cause. Click To Tweet
Fatigue is a complex phenomenon with numerous potential causes that range from reduced central nervous system activity to inhibition of the proteins that interact to produce muscle contraction. Certainly, high levels of lactate can reduce the amount of force generated by muscle fibers; however, while lactate accumulation may play a role in the fatigue experienced by athletes in certain circumstances, it is unlikely to be the sole or even primary cause.
Freelap USA: Mitochondrial adaptations are difficult to measure outside the lab. When coaches use low-intensity training to balance out their high-intensity training to rest joints and muscles, what can be done outside of interval training? Is aerobic conditioning for team sports dead or are there ways to further improve an athlete’s conditioning outside repeated sprints? Is traditional steady training of any value to athletes or is it just a waste of time?
Dr. Martin Gibala: The precise role of exercise intensity, duration, and volume in mediating mitochondrial adaptations to exercise is unclear, no doubt in part owing to individual variability in training responsiveness. There is evidence that exercising under conditions of reduced carbohydrate availability can augment mitochondrial adaptations even in highly trained individuals. This does not mean that athletes should routinely restrict carbohydrates; rather, periodic sessions commenced with reduced muscle glycogen content may be an effective strategy to augment training adaptations by increasing metabolic stress without changing absolute load or intensity.
Most team sports are characterized by intermittent bursts of high-intensity exercise, but that does not mean traditional aerobic conditioning or continuous moderate-intensity exercise training cannot play a role. Cross-training using novel exercises or approaches (e.g., rowing, swimming, cycling uphill) can be a great way to maintain cardiorespiratory fitness while reducing the absolute load on muscles and joints that are habitually utilized to perform sport-specific activities, while also providing a mental break from the sameness of routine training.
Freelap USA: Repeated sprints require a lot of intensity. What do you think is a great field test for coaches wanting something practical in soccer or American football? Do you have any practical recommendation for coaches who don’t have much equipment besides electronic timing and a video camera?
Dr. Martin Gibala: Repeated sprint ability, or the capacity to perform intermittent bursts of intense exercise with limited recovery, is an important attribute for many team-sport athletes. I like simple, practical tests that simulate the event-specific work as closely as possible: recovery patterns are important to objectively track performance capacity (and changes over time, in order to evaluate the effectiveness of specific training programs and interventions). Such tests can be tailored to athletes who play different positions and thus are subject to different task demands.Recovery patterns are important to objectively track performance capacity (and changes over time). Click To Tweet
One example is six to eight repeats of 20-meter “all out” sprints with 20 seconds of recovery. This protocol has been used to distinguish performance between forwards, midfielders, and defenders, and was also shown to be a valid marker of competitiveness, such that higher scores were associated with a higher caliber of play. Another test involving five repeats of 30 meters with 30 seconds of recovery was shown to be a reliable measure of performance in young male soccer players.
Freelap USA: Satellite cells. You did a research study on eccentric training and type II fibers—could you explain how this information is useful to both sports medicine staff and strength and conditioning coaches?
Dr. Martin Gibala: This work was done in collaboration with McMaster colleagues and investigated the extent to which muscle stem cells, or satellite cells, are involved in mediating responses to nonhypertrophic exercise stimuli. There is evidence that satellite cells play a role in skeletal muscle remodeling in response to resistance exercise. This is consistent with the theory that following mechanical stress, such as weightlifting exercise, satellite cells are activated and contribute to the repair and formation of new functional muscle fibers.Satellite cells may play a role in skeletal muscle remodeling in response to resistance exercise. Click To Tweet
Our research examined the possible involvement of satellite cells in response to cycling-based high-intensity interval exercise, which does not result in significant muscle hypertrophy. The results showed an expansion of the muscle satellite cell pool and suggested stem cells may play a role in the remodeling of muscle fibers after nonhypertrophic exercise. These findings are not of direct relevance to clinicians, trainers, and coaches, but are important to establish the underlying mechanisms that govern skeletal muscle adaptation. This is essential for understanding how skeletal muscle remodels in response to different exercise stimuli and may have significant implications for conditions such as aging and various pathologies.
Freelap USA: Many teams are using β-Alanine for repeated work capacity. Can you share your thoughts on how this supplement fares under scientific scrutiny?
Dr. Martin Gibala: A recent review by researchers, including those affiliated with the Australian Institute of Sport, identified beta-alanine as an “established” supplement, along with four others: caffeine, creatine, nitrate, and bicarbonate. This designation meant the researchers deemed there was “robust evidence that (the) supplements can enhance sports performance when used according to established protocols.” Beta-alanine is the rate-limiting precursor to carnosine, an amino acid derivative that acts as an intracellular buffer in skeletal muscle.
Daily supplementation in the form of oral ingestion of 3.2-6.4 g/kg of beta-alanine for several weeks can increase muscle carnosine content by ≥50%. This has been associated with small but statistically significant performance improvements of 2-3% in laboratory-based continuous and intermittent exercise tasks lasting from ~30 seconds to 10 minutes in duration. The relative improvement appears to be somewhat smaller in more highly trained individuals, and there is less evidence available based on sport-specific or “field” type settings that more closely simulate normal athletic competition.
Dosing typically involves smaller amounts spread throughout the day (e.g., 0.8 to 1.6 g/kg every few hours) or the use of slow-release formulations, in order to reduce the potential for side effects, which can include itchiness and transient numbness or a “pins and needles” sensation. Similar to most nutritional compounds, there is considerable individual variability in the responsiveness to supplementation.