How Exercise Makes You More Resilient to Mental Fatigue

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Photo: Peathegee Inc/Blend Images

Life, as you may have heard, is not always so easy, and so it’s important to practice being comfortable with being uncomfortable. One of the most reliable ways to do that — as Science of Us reported last month — is by pushing yourself physically: People who undertake and endure exercise challenges tend to perform better in hard, yet ostensibly unrelated, areas of their lives, such as quitting smoking or remaining calm during final exams.

The scientific theory underlying this phenomenon is called the “cross-stressor adaptation hypothesis.” In layperson’s terms, exercise — likely due to its unique combination of being hard on the body (this hurts), being hard on the brain (I want to quit but I’ll keep going), and the physiological changes it elicits (e.g., decreased blood pressure) — makes people more resilient not only to physical stress, but also to emotional and cognitive stress. It is for these reasons that scientists have written that “exercise is associated with emotional resilience to acute stress in healthy adults” and that exercise has been called a keystone habit, or an activity that leads to positive changes in other areas of life.

A new study, published in PLOS ONE, lends further support to the spillover benefits of exercise. For the study, a team of researchers compared the performance of 11 professional cyclists and 9 recreational cyclists on something called a “Stroop test.” Stroop tests, which require subjects to quickly and correctly name colors appearing in the text of other colors — for example, the word “blue” written in red text — are often used to test what scientists call inhibitory control, commonly referred to as willpower.

Sure enough, the professional cyclists — a group that is expert at managing willpower (the entire sport of cycling revolves around making one’s body push through pain when it is screaming “stop!”) — outperformed the recreational cyclists on the Stroop test. In addition, the professional cyclists also performed better (against a relative baseline) than the recreational cyclists in a hard bike ride following the Stroop test. In the words of the researchers, the professional cyclists showed both “stronger inhibitory control than the recreational cyclists” as well as “greater resistance to the effects of mental fatigue.”

Samuele Marcora, director of research at the University of Kent’s School of Sport and Exercise Science and one of the study’s authors, says that “the two effects go hand in hand, because becoming resistant to mental fatigue bolsters self-control.” He speculates that resistance to mental fatigue — in other words, not giving in when your brain tells you to — is especially trainable through practice.

Of course, the sample size in this study was small, and it’s hard to say if partaking in extreme cycling improves willpower, or if those who naturally have strong willpower gravitate toward and excel in cycling. Still, as the researchers conclude, the challenges professional cyclists endure on the road may improve their ability to perform in highly demanding situations off the road.

Brad Stulberg is a columnist for Outside Magazine, where he writes about health and the science of human performance. Follow him on Twitter @Bstulberg.