Tired Brain? Prepare for a Harder Workout

So you’ve just spent the last 1.5 hours completely engrossed in a challenging (perhaps slightly frustrating) problem at work. A problem that requires focus, the use of your critical thinking and problem solving ability, and thus, mental stamina. Following work, you head to the gym to complete your regular post-work workout. Yet, today you feel completely zonked.

This is not an uncommon experience based on the results of a 2009 study conducted at Bangor University in Wales. Researchers asked 16 volunteers to ride a stationary bicycle to exhaustion following one of two conditions. Those in the first condition watched a 90 minute television program while participants in the other condition engaged in a 90 minute cognitive test.

Participants that engaged in the cognitive test reached exhaustion (i.e. stopped performing exercise) at around 10 minutes and 40 seconds, a good minute and 54 seconds before the television watchers. Researchers concluded that the difference was not due to varying physiological responses as participants in both conditions responded almost identically to exercise with similar increases in heart rate, oxygen consumption and blood lactate.

So what accounted for the difference? Why did participants in the cognitive test condition finish earlier? Basically, it comes down to perception. The results of this study suggest that cognitive test-takers perceived the exercise task to be more challenging than the television watchers. And interestingly enough, the part of the brain responsible for perception of effort during exercise (the anterior cingulate cortex) is also the region of the brain activated during the cognitive test.

Thus, while our muscles may be in prime condition for a workout due to prolonged bouts of sitting at work, our brain may not be. Our brain may be tapped out, overused, exhausted, ready for a snooze – you get the picture.

However, the purpose of this post is not to encourage you to NOT work out after work (eek, double negative). The purpose is to provide a possible explanation for why you feel so whipped following a hard day at the office. And, more importantly, that it’s OK to have a shorter, less intense workout every once in a while.

Happy Monday.



Hutchinson, Alex. 2011. Which Comes First, Cardio or Weights? McClelland & Stewart: Toronto.


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