Here’s What We Know About Mental Fatigue

Here’s What We Know About Mental Fatigue

Alex Hutchinson

Back in 2009, a research team at Bangor University in Wales published a study showing that mental fatigue impairs physical performance. Subjects spent 90 minutes sitting in front of a computer screen either watching a bland documentary or playing a simple but focus-demanding computer game. Afterwards, when they hopped on an exercise bike for a time-to-exhaustion test, those who’d played the computer game immediately reported higher levels of perceived effort, and gave up 15 percent earlier than the documentary watchers.

The results might seem predictable, but the magnitude of the effect was a surprise. In performance terms, sitting at a computer for 90 minutes was roughly equivalent to the negative effects on your leg of jumping off a 14-inch box 100 times. Mental fatigue, a topic that had been mostly neglected by exercise physiologists since the late 1800s, suddenly became a hot topic. This year alone, there have been studies of its effects on soccer, swimming, table tennis, and cycling.

The big practical question, of course, is how to avoid or counteract the effects of mental fatigue. There are several ideas out there, but it’s hard to draw any firm conclusions when the feeling itself remains a black box. What exactly does it mean to be mentally tired? What’s actually happening in your brain? Proposing an answer to these riddles is the challenge that a new paper in Sports Medicine, from a team at the University of Canberra led by Kristy Martin...