Muscle Burns More Calories: “Fat burns almost nothing at rest,” says exercise physiologist Pete McCall, “whereas muscle uses oxygen. If you increase lean muscle mass, you’ll increase the body’s ability to use oxygen and burn more calories.” Your body typically uses about 4.5 to seven calories per pound of muscle every day. If a 160-pound runner with 20 percent body fat increases his muscle mass and lowers his body fat to 15 percent, he’ll burn an extra 36 to 56 calories a day at rest—simply by adding muscle.
You’ll Be More Efficient: Strength training can help you run faster, longer, and more efficiently. A study published last year in the Journal of Strength and Conditioning Research showed that runners who add three days of resistance training exercises to their weekly program increase their leg strength and enhance their endurance. Obviously, runners with better endurance can run longer—and burn more calories. You’ll also be able to recover faster from those long runs because strength training makes your body more efficient at converting metabolic waste into energy. “It’s like being able to convert car exhaust into gas,” says McCall.
You’ll Be Less Injury-Prone: “If you increase your strength, you’ll also increase your joint stability, reducing your risk of repetitive stress injuries,” says McCall, citing a study in the Journal of Strength and Conditioning Research, which showed that incorporating moves such as squats, single-leg hops, and ab work into a workout can not only prevent lower-body injuries, but improve performance as well. Leg exercises are particularly important when it comes to reducing injury: These exercises strengthen muscles around the knees and hips — two areas that often cause problems for runners