How Does Running Affect Your Muscular Strength?

Running has an unexpected relationship with muscle strength. While it is understandable to associate running with the building of strong legs, the connection is actually more complex. Running has the capacity to use muscle rather than fat for energy. When thinking of your body's strength, consider how much running you do, how it affects your muscles and what exercises you can do to mitigate muscle loss.

  1. Running Myth

    • It is a common assumption that running creates strong legs, says exercise physiologist Holly Perkins, writing for Fitness.com. This relationship is true but only to the extent of your physical activity. Your leg muscles get stronger until they are accustomed to handling your level of activity; after that, running contributes less to muscle strength. Instead of making muscles stronger, running then helps your body build endurance.

    Cardio and Muscles

    • Men's Fitness points out that running does not contribute much to muscle mass -- and can even cause muscle loss in some cases -- due to the nature of energy expenditure in cardio. This kind of exercise so effectively burns calories that it doesn't leave an adequate amount for muscle-building. Your running session will burn through fat calories first, then turn to muscle for an energy source, putting you at risk for muscle loss. If you are a morning runner, it's especially imperative to eat prior to your run. If you run on empty, you set your body up to burn nothing but muscle for energy because it does not have any other energy source. The same is true if you engage in excessive cardio workouts.

    Keep the Muscle

    • You can still run while maintaining -- and even building -- some muscle. Runners can strength train their lower body to support efficient running and maintain muscle strength. If you want to build leg muscle, you will also likely need to increase your calorie intake a bit so your body will have the necessary fuel, says Perkins.

    Next Steps

    • The website Competitor recommends four exercises to help strengthen and build runners' leg muscles. Squats, in which you repeatedly lower your body until your thighs parallel the floor, help strengthen and tone your legs. The single-leg squat is the same as the squat, but with one leg extended as your lower your body. Doing core exercises, such as planks or side planks increase your running efficiency and build muscle. Single leg deadlifts are done by holding a weight and leaning forward on one leg, extending the other leg behind you. These exercises contribute to muscle gain and maintenance while keeping the benefits of regular running.