In short, mental exhaustion and the cues that it sends your body might have a stronger influence on perceived physical exhaustion than previously thought. The author references the work of Samuele Marcora on the relationship between mental fatigue and physical fatigue. I read the article in RW with interest, and sought the original publications that detail Marcora's research.
Marcora, along with Walter Staiano, and Victoria Manning studied two groups of cyclists. The test group was asked (essentially) to play a very tedious video game (RW suggests this one, and suggests doing it for 30 minutes). The control group watched a movie about trains. The findings are striking: mental fatigue raises the rate of perceived exertion (RPE) and the average heart rate and shortens the time to exhaustion. Put another way, mental fatigue can have as strong an effect on physical performance as actual physical fatigue.
What does this have to do with music, you're probably wondering. I suspect that a) musicians might make good endurance athletes because of the mental discipline that practicing an instrument conveys. We spend hours a day in a practice room, repeating the same passages over and over again. If that doesn't result in mental fatigue, I don't know what does. This ability to withstand mental fatigue under solitary conditions undoubtedly would translate to distance running or cycling (or whatever else). b) the idea of inducing mental fatigue prior to a practice session and training the mind (and body) to work through that fatigue could be an essential component of audition and competition preparation. There are all kinds of books written on the mental aspects of musical performance (I'm thinking of Kenny Werner'sEffortless Mastery and Barry Green'sThe Inner Game of Music; however, these books are written from a more general psychological--almost spiritual--perspective. Marcora's experiments suggest laboratory-tested methods of inducing and coping with fatigue.
For as much time as we spend training our bodies to shift accurately, to play without injury, and so on, perhaps mental training of the sort suggested by Marcora and his colleagues should become a part of the practicing musicians' toolkit.