People often compare education to exercise.  If exercise builds physical muscles, then education builds “mental muscles.”  If you take the analogy seriously, however, then you’d expect education to share both the virtues and the limitations of exercise.  Most obviously: The benefits of exercise are fleeting.  If you stop exercising, the payoff quickly evaporates.

I know this from bitter experience.  I was in weight-lifting class throughout high school.  The weights worked: After a few months, I had bigger muscles.  But after three months of summer vacation, my gains disappeared.  I was back where I started: scrawny.  Exercise physiologists call this detraining.  As usual, there’s a big academic literature on it.

Here‘s a simple example.  Researchers ran a weight-training experiment with 20 kids: 11 subjects, 9 controls.  The training lasted 8 weeks, followed by 8 weeks of detraining.  Results:


The solid circles show the experimental subjects; the empty circles the controls.

Even more depressing, as my own weight-training taught me, is that within a few months you asymptote to your maximum ability.  Smaller progress hurts more and more.  And there’re never more than a few months between giving up and going back to normal.

That’s why, now that I’m older and wiser, I only do exercise I enjoy.  A life of suffering to slightly exceed my natural state isn’t worth it.