How Muscle Fatigue Fries Your Brain And Your Legs
- Muscle fatigue to the point of exhaustion could affect your brain’s ability to learn new skills, according to research published in the journal eLife last year.
- Fatigue disrupts your brain’s formation of memories and strategies after training, which can carry over into other aspects of your everyday functioning.
“Practice make perfect,” the old saying goes. And as athletes, we tend to take this mantra to heart—waking up early to get those extra miles in, hitting the gym or the yoga studio to cross-train, all to get stronger and faster in the saddle. But according to new research, inducing muscle fatigue to the point of exhaustion and overexerting yourself—especially when it comes to learning a new skill—might be hurting your performance, not helping it get better.
Published in the journal eLife last year, the study had 120 participants learn what researchers called a pinch-force task during a two-day period. Participants were given a device to hold in their dominant hand between their thumb and index finger. When they pinched the device together, a signal was sent to a computer. They had to press the device with varying levels of force to move a cursor on the screen.
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On day one, a subgroup of participants were instructed to pinch the device together until their muscles felt fatigued. (The rest of the participants didn’t have to go until fatigue.) But on day two, no one had to go to the point of muscle fatigue.
The results: Those who had to pinch the device until their muscles were fatigued on the first day had a harder time on the second day, while those who didn’t have to go until the point of fatigue on either day performed better on day two. In fact, the participants who had to go until fatigue on day one needed two more days to catch up to everyone else’s performance.
Even more interesting, those whose muscles were overworked on day one were allowed to use their non-dominant hand where their muscles were fresh on day two, but were still unable to perform the task well.
Fatigue disrupts “the formation of memories after training,” according to study coauthor Pablo Celnik, M.D., director of the department of physical medicine and rehabilitation at Johns Hopkins University School of Medicine. “This suggests that people learning a motor skill in the presence of muscle fatigue might be forming wrong memories or strategies. The issue is that in subsequent training sessions, those suboptimal memories are recalled, leading to slower than normal learning,” Celnik told Bicycling.
Translation? Not only does your body get tired after endlessly practicing something new—like bunny hops or riding more technical terrain—but your brain does, too. And frying your brain working on that particularly tough skill could even affect your focus and performance at work or school.
So the bottom line is this: If you feel your muscles becoming exhausted from working a new skill over and over again, there’s a good chance your aptitude to learn other things that are unrelated to the skill could be affected, too.