Mental fatigue hinders exercise

A 2009 study published in the Journal of Applied Physiology tried to answer this question

It’s the end of a long, stressful work day where there have been lots of projects, planning and mental processing.

Maybe you are a student and you’ve been bogged down with hours of studying or writing a term paper. The last thing you probably feel like doing is exercising.

You’d rather relax and watch a movie or close your eyes for a while. Even if you do go to the gym you probably feel that you session seems harder and more sluggish. Is there a link between mental fatigue and how it affects how we exercise or perform in sports?

A 2009 study published in the Journal of Applied Physiology tried to answer this question. The researchers took a group of subjects and had them ride a stationary bike to exhaustion. Prior to the bike session they undertook either a challenging 90 minute mental task or in the other trial they watched a documentary movie.

The subjects who took the cognitive test ended up reaching exhaustion sooner and rode for 16 per cent less time than the other group.

One might think that the group who performed the mental task burned up more glucose and did worse on the cycling test because of lack of fuel.

But all the physiological responses such as heart rate, lactic acid and oxygen consumption were the same for both groups. The researcher’s conclusions were that the physical performance was limited more by the mental fatigue and perception of effort than physical factors.

There have been a number of other recent studies that have shown that mental fatigue or inhibition is a dominant factor in physical limitation.

These studies demonstrate that being mentally active and fatigued prior to a physically demanding event or sport can decrease performance. And in the world of elite sports, a decrease of five to 18 per cent can have great consequences in the outcome of the event.

The results of these studies would suggest that athletes who are due to play an important game would do better to mentally rest in the hours prior to the event. Most sports psychologists have recommended a variety of mentally restive routines to athletes that range from meditation to mental imagery to listening to music.

You may notice that often on a televised hockey or football game for instance, prior to the game the players will be wearing ear-buds listening to music before getting to the dressing room.

For the non-athlete working individual you may want to consider these results – especially for those people who are beginners to exercise, trying to establish a permanent consistent routine but who find themselves failing when they attempt to exercise after work.

These people may find it helpful to exercise first thing in the morning when they are mentally and physically rested, or exercise on a lunch break if the situation permits.

However, if you can get yourself to exercise after work, it can be an excellent stress reliever and can also help you sleep better, especially when weight training is involved.

And if you schedule a fun activity after work, like recreational sports or other activities that you might enjoy, this can help you to overcome that mental fatigue you might be feeling.

Once an exercise routine is established, then you may find that you have less stress, more quality sleep and are less mentally tired at the end of the day which in turn gives more exercise options and a better quality of life.


Kerry Senchyna holds a bachelor of science degree in kinesiology and is owner of West Coast Kinesiology.