2. A Cup of Joe
Studies that demonstrate performance-enhancing benefits of caffeine often imply that drinking coffee will give you a boost. Not so, according to the latest research. Scientists put nine endurance runners through five trials after ingesting either a capsule (caffeine or placebo) or coffee (decaffeinated, decaffeinated with caffeine added or regular coffee). Only the caffeine capsule increased endurance. Researchers think that other compounds in coffee may counteract some of the benefits of caffeine. Upshot: Have your cup of coffee if you need it to get moving, and your stomach can tolerate it, but don’t expect it to keep you going through a long workout.