All runners understand the importance of rest and how physical fatigue can negatively impact us on race day. But how important is mental fatigue in preventing us from reaching a PB? Recent research into running psychology would suggest it can be quite significant.
One recent study (MacMahon, Schucker, Hagermann and Strauss) compared 3km running times of experienced runners under both mentally fatiguing and non-fatiguing (control) conditions. In the fatiguing condition, runners had to complete a mental task before running the 3km. On average, they found that run times were over 10 seconds slower in the mentally fatiguing condition than in the control condition. These results also came despite no changes in actual heart rate or blood lactate levels of the runners between each running condition. The authors concluded that the mental task led to mental fatigue, which increased perceptions of exertion (irrespective of the internal states of the runners) leading to slower performances.
Based on this evidence, sports psychologists suggest athletes should avoid mentally draining activities before big events. This should reduce the impacts of mental fatigue on race day performances. It might be best to ditch the crossword with your pre-race coffee!
Another study (McCarron and Co) found that increasing mental demands mid-run led to poorer self-pacing and race performance. Self-pacing requires a substantial amount of brain attention and focus. When extra mental tasks were added on top of this, runners became mentally fatigued and developed ‘brain drain’ leading to poorer pacing performances. While you’re running, don’t overload yourself with mental tasks or thoughts about work, go out and actually ‘clear your head’ for better self-pacing.
If diet can alter the effects of physical fatigue, can it be used to improve mental fatigue?
It is actually very hard to conclusively link dietary supplements or practices to a reduction in mental fatigue. Some of the strongest evidence points towards branched-chain amino acids (BCAAs) more commonly associated with the weight-lifting world. BCAA’s are alleged to reduce mental fatigue in the following way:
- Running has been shown to cause a biochemical cascade of events thought to increase levels of the neurotransmitter serotonin.
- Increases in serotonin are speculated to cause fatigue due to serotonin’s involvement in sleep regulation.
- Some studies have suggested that BCAAs may be helpful in reducing ‘excessive’ serotonin levels induced by exercise, reducing perceptions of exertion.
However, BCAA supplements may increase race-day performance in slower runners only. Non-elite marathon runners supplied with a BCAA drink ran, on average, 5-6 minutes quicker than their non-BCAA drinking counterparts. BCAA drinks appeared to offer no advantage to elite marathon runners. It is suggested that this is because better-trained runners are generally more resistant to feelings of muscular and mental fatigue. This is consistent with further recent studies finding no effect of BCAA supplementation in experienced marathon runners.
Ultimately, mental fatigue can negatively affect race-day performance because it exaggerates our perceived work effort, so we think we are working harder than normal. To prevent mental fatigue it appears we should avoid mentally-demanding tasks both before and during races. Additionally, for less-experienced runners, BCAA supplementation could help reduce feelings of fatigue, if taken as part of a balanced diet which meets the dietary needs of a runner.
There are many different mental techniques that runners use to pace their way through a race. For some, self-pacing through mentally calculating the time they should cross each mile marker really works. For those of us who are less mathematically gifted, Pacebands could form part of an important routine for reducing mental fatigue on race day. Anything which enhances preparation, promotes relaxation and reduces stress could help us to prevent mental fatigue from limiting our performance.
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