Some studies favor low intensity, some high intensity—read the fine print, and opt for both

The physiology behind that speed where you start breathing much faster and deeper—and its implications for your training

A relaxed, athletic balance is crucial to good running form. Here's why and how to improve yours.

The 12 most common, performance-defeating fitness mistakes, and how to fix them

Meet Outside's Fittest (Real) Men in America. Emulation is encouraged.

Forget what you've heard about calories, pounds, carbs, or miles—the adventure athlete's real secret to optimal weight is all about energy management

Cold-weather battle plans from the nation's top fitness advisors

Adventure races have come into their own. Time to join the self-punishing fun and tackle your first one.