Traditionally, it has been thought that performing mental activities and efforts before a sports activity could negatively affect our physical performance. This hypothesis is based on the idea that the feeling of mental fatigue generated by cognitive activity reduces the person's willingness to make additional efforts, including physical ones.
In a recent study, CIMCYC researchers Darías Holgado and Rafael Román Caballero, in collaboration with Cristian Mesquida (University of Dublin), show that this effect may be more limited than what has been reported in this literature or may not even be a true effect. The research demonstrates the existence of publication bias that would have favored the publication and dissemination of those articles showing that mental fatigue worsens performance. In addition, most of the available articles have small experimental samples, which compromises their statistical power (on average, 20% power, i.e., only a 20% probability of observing a significant result) and an increased risk of observing extreme results due to their low reliability. Taking all these problems into account, this new study suggests that in the best-case scenario the effect of mental fatigue on physical performance would be rather more modest than expected and that the evidence in favor of such an effect is inconclusive.
The problems detected in this effect are common to other similar literatures, such as ego depletion, which refers to the idea that self-control decreases after mentally demanding activity. Because of similar problems, the ego depletion hypothesis has been challenged and organized efforts by several laboratories to reproduce the result have failed.
In conclusion, the researchers point to the need for more evidence, with larger samples and with more transparent methodologies, following open science practices, in order to draw firm conclusions about this effect. Until that time comes, the authors urge caution in making claims or recommendations about how to counteract the detrimental effects of mental fatigue on physical performance.
Reference:
Holgado, D., Mesquida, C., & Román-Caballero, R. (2023). Assessing the evidential value of mental fatigue and exercise research. Sports Medicine, 1–15. https://doi.org/10.1007/s40279-023-01926-w
Contact:
Darías Holgado (@email)
Cristian Mesquida (@email)
Rafael Román Caballero (@email)