Caffeine can counter the effects of an extended workout
It makes sense that a vigorous workout leaves your muscles feeling tired, but why does a few hours of cycling have to take the rest of your body with it? Exercise can leave various motor systems out of whack, right down to the muscles that control your eyes. This phenomenon, called “central fatigue,” is more tied to your nervous system than your muscles though, which means opens the door to some simple manipulation, such as drinking coffee.
Most of the tiredness you notice after exercising is directly tied to muscles’ exertion. Muscle tissue demands a supply of adenosine triphosphate as it works, which is slowly diminished and replaced by lactic acid as the workout continues. This process can leave you feeling sore, but it’s not so demanding that it should necessarily affect less stressed muscles, much less your central nervous system. Those feelings of wear and tear are thanks to your neurology.
Keeping exercise from becoming exhaustion
Central fatigue isn’t completely understood, but it stems from a shift in your neurotransmitters rather than the direct buildup of lactic acid in your bicep. The best guess is that our bodies respond to continued exertion in this way to slow us down before we hit a point of absolute exhaustion. Hitting your limit may be exciting in the safety of a gym, but our ancestors certainly didn’t want to be surprised during a hunt by suddenly collapsing when their body had no strength left to give. A number of neurotransmitters seem to be in on this dynamic, including serotonin and dopamine.
A quick fix, if you’re looking to rebound after a workout that leaves you drowsy, is as simple as some coffee. Moderate doses of caffeine were found to alleviate the measured eight percent drop in test-subjects’ eye movement, helping them feel perkier while the adenosine was blocked in their brains. Since this dynamic takes place outside your exercised muscles, it shouldn’t impact the benefits of the workout, assuming you don’t use the coffee as an excuse to bike another couple of hours and really burn yourself out.
Source: Exercise doesn’t just tire your muscles—it makes your eyes sleepy by Ian Randall, Science Magazine
