P.E.

Substituting 45 minutes of supervised school-based strength training for 2 of 3 regular PE classes significantly increased upper and lower body strength in healthy schoolchildren aged 10 to 14 years, and significantly increased daily spontaneous physical activity outside the training for boys.

An increase in time spent in physical education class helps kids develop stronger muscles and that increasing weekly physical activity does not increase the risk of bone fractures, says a new Swedish study. That's fine, but there's one problem: P.E. time in the U.S. is declining, not increasing, with predictable results.