Performing When Fatigued
by Doug Stewart
It has been proposed since the early 90s that endurance running performance is influenced by VO2Max, running economy and lactate threshold. However, often the focus of tests in the lab is on athletes when fresh, and not assessing these qualities when fatigued. The concept of fatigue resistance/durability/physiological resilience (the naming of this is heavily debated) has more recently been discussed and researched. This theory focusses on the ability to perform well in a fatigued state – with the hypothesis being that, if two athletes who have identical Vo2Max, running economy and lactate threshold line up at the start line, then race for 3 hours (for example), the one with greater durability would win, as they would see less of a drop in their physiological areas mentioned.
TMR Athlete Poppy & Coach Doug © Steve Ashworth Media
Clearly, elements linked to nutrition, psychology, gender, ability to deal with environmental conditions, how well rested the athlete is, and (in longer events) dealing with sleep deprivation, plus other factors, all have considerable parts to play in endurance performance. As a coach, I think it is important to consider as many of these components as possible. However, just focussing on the physiological resilience of an athlete for now, studies on cyclists have shown large variances between individuals. Whilst the average drop in Critical Power (highest steady state of power achievable) after 2 hours of cycling at a heavy intensity is 10%, it can vary from a 1% decrease to a 32% decrease. Why this varies so much is not fully understood.
A recently published paper provides an excellent summary and discussion on the latest research in this area. Whilst it is too long to go into here, the interventions are likely of interest to athletes, as they can give us ideas on what may help improve fatigue resistance:
1. High rates of carbohydrate oxidation – achieved through high muscle glycogen pre-race (carb loading) coupled with ingesting high levels of carbohydrates during the race
2. Caffeine can impact fatigue development, and subsequently, when taken during a race, it may provide an improved resistance to fatigue
3. Training programmes, or specific sessions, aimed at developing durability have not been researched and remain unknown (from an academic perspective – likely a lot of anecdotal views may carry a lot of weight such has efforts at the end of an endurance session).
4. It appear training consistently for a long time, potentially with high volume, may help enhance durability. Pyramidal training programmes may be helpful.
5. Long endurance training sessions at close to race intensity (high specificity to race conditions) may also be helpful.
6. Strength and conditioning (focussing on runners) that focusses on maintaining running form when fatigued may help
7. Mental fatigue should not be discounted and psychological skills training may help improve fatigue resistance
Having personally completed a number of experiments in the lab (involving tests after two hours of running at marathon race pace) I was informed I maintained running economy better than most (likely due to being older than the other participants, or as the researcher kindly put it ‘because you are old!’) but my Vo2Max fell more than anyone else in the experiment (!). In part, this is likely linked to me seldom running at marathon race pace on a treadmill, whilst all the other participants were road marathon runners. However, this small sample size suggests that the fatiguing element varies from person to person (for me a key limiter being Vo2Max dropping), and so interventions to improve durability will likely have to be individualised, just as any other component of training.
References:
Jones, A. M. (2023). The fourth dimension: physiological resilience as an independent determinant of endurance exercise performance. The Journal of Physiology.