The Well blog at the New York Times often has articles on physical education, nutrition & fitness. The health section of the newspaper has interesting articles.
Game theory. From the Economist magazine. "Addressing the politics, economics, science and statistics of the games we play and watch."
Directory of sports blogs from Yahoo.
Nutrition blog network. A list, with links, of nutrition blogs written by dieticians.
The Science of Sport blog is written by two exercise physiologists.
Obesity Panacea, a blog from the Public Library of Science.