When the mind is tired, legs get heavy

study published in the journal Medicine & Science in Sports & Exercise examined the effects of mental fatigue on runners. It concluded that when runners are mentally tired, their performance suffers. For the study, ten male athletes were divided into two groups. One group was watching emotionally-neutral documentaries 90 minutes before the exercise, while the other was doing cognitive tests for the same amount of time. During the subsequent running protocol, the tested, mentally-fatigued group performed sluggishly when compared to the documentary-watching group. They had lower average pace and lower oxygen consumption. In other words, they ran as if they were physically tired.

But, if tiresome concentration-demanding work translates into tired legs, then the clear, well rested mind should have the opposite effect, right? That’s why running when you’re mentally well-rested feels so effortless. Hence that breezy, post-holidays run!

I used to run in the evening after work and although I had some good runs, overall they felt more demanding than the morning runs. I blamed my heavy legs on the long commute to and from work. What else could it be? I worked in the office, spending the whole day sitting and typing on a computer keyboard. There was no reason to feel physically tired; I never thought that my tired mind could slow me down.

The remedy is to run when the mind is fresh, either first thing in the morning after a good night’s rest, or after an afternoon nap. Even if you’re not a morning person and can’t wake up in pre-dawn hours to squeeze in a run before work, don’t give up on evenings. It may be tougher to get through the run, but you will feel much better afterward.