Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. Research has shown that, independent of motivation, mental fatigue will negatively impact your performance by increasing your perception of effort.
In 2009, Dr. Samuel Macora and his colleagues ran an early study demonstrating this, where athletes cycled to exhaustion at 80% of their peak power after either 90 minutes of a demanding cognitive task (a time-pressured sorting exercise on a computer) or 90 minutes of watching emotionally neutral documentaries (the control condition).
As reported in the Journal of Applied Physiology the athletes performed 15% worse when mentally fatigued compared to the control condition. Physiological responses such as heart rate and blood lactate levels and the psychological factors of self-reported success and intrinsic motivation were unaffected by prior cognitive activity. However, mentally fatigued subjects rated perception of effort during exercise to be significantly higher compared with the control condition. As ratings of perceived exertion increased similarly over time in both conditions, mentally fatigued subjects reached their maximal level of perceived exertion and stopped earlier than in the control condition.
In 2024, the journal BMC Physiology published an article entitled “Counteracting Mental Fatigue for Athletes: A Systematic Review of the Interventions” which reported on the now many studies that now link mental fatigue with decreased performance across cycling, swimming, running, soccer, and other sports. In addition to mental fatigue increasing perception of effort, it also has a detrimental effect on a player’s cognitive functions reflected in prolonged reaction times and reduced decision-making efficiency.
So what can we do as coaches and athletes about this? The answers fall into two buckets; reduce mental fatigue on race day, and develop approaches to counteract the mental fatigue that does occur.
Reducing mental fatigue on race day can take many forms, such as.
- Prior familiarization with the venue where possible
- A warm up routine and race plans that have been well practiced for weeks ahead of time
- Getting everything organized beforehand
- Pre-planning every step of the day ahead of time so you don’t have to be figuring things out in real time
- Thinking through different scenarios (such as race delays) and how you will think and react to those
- In the rowing world, cherishing your coxswain who takes care of the admin and details so you don’t fatigue yourself mentally!
What approaches can you take to counteract the mental fatigue that does occur? The authors of the 2024 review article noted that the science underlying “interventions” is still in its early stages but that approaches related to “self-regulation and attention resources can significantly counteract mental fatigue and improve subsequent sport-specific performance” are likely the most effective. Three practical approaches are supported by this are;
Developing mental toughness: A mentally tougher athlete will be able to better persevere in conditions of both physical and mental fatigue, and studies show that mental toughness is a teachable skill.
Promoting mindfulness; Mindfulness has been directly linked to the ability to counteract mental fatigue though the ability to better self-regulate emotions related to stress.
Encouraging self-autonomy; creating a culture that encourages self-autonomy is linked to stronger motivation to overcome mental fatigue and making better decisions when mentally fatigued.
A fourth approach, transcranial direct current stimulation (tDCS) where small electrical currents are delivered to the scalp has been proven (such as in this study on elite swimmers) to counteract the effect of mental fatigue in athletes by reducing their perception of effort… but it is hard to visualize how practical this approach is for many of us currently!
- Marcora et al. 2009. “Mental Fatigue Impairs Physical Performance in Humans.” Journal of Applied Physiology 106 (3): 857–64.
- Sun et al. 2024. “Counteracting Mental Fatigue for Athletes: A Systematic Review of the Interventions.” BMC Psychology 12 (1): 67
- Nikooharf et al 2022. Transcranial direct current stimulation reduces the negative impact of mental fatigue on swimming performance. J Mot Behav. 54(3):327–36