Spoke with the redoubtable Alwyn Cosgrove for a piece I'm writing about fat loss and strength training (spoiler: the one is affected by the other. Shhhh...). In passing, he mentioned something I found fascinating, one of those "Can't prove it yet, but this seems to be happening" hunches that thoughtful coaches get about ten years before science catches up with them.
Now let's see if I can explain it.
Most people are familiar with the following effect: you go for a run, or sprint session, or some form or other of workout. You work up a sweat. You figure you got a workout, good enough, go home. Then, a few days later, you get pulled into some kind of game: basketball, tennis, racquetball, volleyball, doesn't matter what. And you notice, either at the time or the next day, when your muscles are sore as hell, that you worked way harder chasing the little ball around or competing with your pals than you did 'working out' on your own.
Makes sense, doesn't it? Give someone some context and some motivation--a reason for all that sweat and effort, and bango, he finds he's got way more in reserve than he ever believed.
But Cosgrove's as-yet-unproven theory goes even further: he believes that even if you controlled for every physical factor: speed, direction, force of movement, duration, and on and on, a mentally-engaged workout would still burn more calories than a mentally-disengaged one.
Unpacking that a little: say you played a hard, hour-long game of indoor soccer. And say a computer--or, better yet, a clone of you--could retrace every step you took in the game at the same speed and with the same timing, but without the other players, or the crowd, or the thrill of competition that goes along with those things.
The theory is that you'd get a better workout than your clone.
This is a hard theory to test, but to me it makes intuitive sense: when your brain is turned on, more of your body is too. When an activity is engaging and stimulating on many levels, it doesn't just make the workout go by faster, it makes it inherently more effective.
Yet more (preliminary) evidence that we need to make finding physical activities that inspire passion--not just that burn calories or build muscle--a priority.