An interesting study from July set out to examine the link between mental and physical fitness. Caveats first: it was a small study, no placebo (almost impossible here) and they didn't add caffeine or any other stimulants to check their effect. But, the result is interesting.

If you were training for an endurance event you might assume that it was just the final exam based on all your studying - which in this metaphor is training. Your on the day performance is just a summation of your training. Or is it? What if it turned out quitting around 9% earlier may be down to what you watched before hand?

That was, in essence, the finding of the study. They took 18 participants and had them cycle at 80% peak power output to failure after watching a documentary. They ran an EMG analysis of 10 muscle groups in their legs while they performed the task.

At least 72 hours later, but not more than a week, they had them come back in. This time they performed a Stroop test for the hour before doing the same test. The Stroop test aims to have your brain override automatic responses. The test shows a colour word printed in a different ink colour, and you name the ink. The end result is a very fatigued brain.

When tasked with the same endurance test they reached failure on average around 9% earlier. The EMGs showed no difference in muscle activation. Which points to the brain, not the legs.

Earlier work suggests single event, explosive sports such as high jumping or weightlifting don't seem to be impacted. Sports with fine motor skills such as tennis or football are affected though. Which is easy to imagine.

As we said, it's a small study but maybe it's worth avoiding that incredibly complex Huberman podcast you were going to try and make sense of on the way to the race. 

Full study here.