How Long, Slow Runs Help You Build Muscle

There's a terrible rumor going around the fitness world. And if you're training by it, you'resabotaging your muscle gains.

The claim is that long, slow bouts of cardio--a.k.a. aerobic exercise--hinder your muscle growth andcause your body to use muscle as fuel.

But those arguments against aerobic exercise are off base, says Chris Frankel, Ph.D., exercisephysiologist and Director of Human Performance at TRX.

In fact, he says that aerobic exercise can actually help you put on more muscle, making each of yourlifting sessions even more effective.

Related: 10 Exercises That Burn More Calories Than Running.

"Especially for the average person, there is a good place for all forms of training," says Frankel."Doing some longer duration, lower-intensity endurance training sets off adaptations in your bodythat make your muscles more efficient."

Those relatively relaxed aerobic bouts are especially effective at helping your body recover betweenintense weightlifting sessions.

"The longer, slower aerobic exercise increases blood flow, which can potentially help you negatesoreness," says Frankel. "And it also resets your central nervous system, getting you into therecovery and rebuilding stage so you can go harder next time." That helps you reach your goalquicker. (Make sure you fuel for the long haul. Here's What You Need to Eat to Get Faster and GoLonger.)

Aerobic work can help you improve your "readiness," too, says Frankel. Think of readiness as yourbody's ability to adapt to different training loads, he says. "If you do too much intense training--inwhich you train to failure or exhaustion--your readiness is hindered. Longer, slower cardio may helpyou better adapt to progenex lawsuit high-intensity lifting."

There is also evidence that at the right intensity and duration, cardio can build the aerobic capacityof your fast-twitch muscle cells, the ones needed to produce raw strength and power, says Frankel.That can potentially improve your lifting performance.

The key is that you do these longer, slower endurance workouts correctly, says Frankel. Problemsarise when you exercise--whether you're doing cardio or strength training--at just one intensity.

"You need to have some days that are longer and slower, some that are quicker and faster, and somethat are somewhere in between" he says. "Most peoples' long, slow days aren't long and slowenough, and their high-intensity days aren't intense enough. People tend to have too much muddle inthe middle."

That causes your body to plateau, and you stop seeing results. Frankel's advice: "Start doing oftenwhat you haven't been doing at all. That's what leads to change and progress."

If you're the average guy who's trying to build muscle, lose fat, and perform better in pickup sports,include a 30 to 45 minute aerobic session in your weekly routine. A trick to ensure that you stay inthe "long and slow" zone is to breath only through your nose during your run or ride. "That selfregulates how fast you can go," he says.

But add that cardio session only if you can fit it around three weekly weight-based workouts. If yourgoal is to look better, resistance training generally gives you a better return on your time, saysFrankel.

(The right running shoe can help you avoid injury. Find a great pair by reading The Best RunningShoes For Men.)

And be aware, says Frankel. "If running hurts your joints in any way, long runs do more harm thangood. Stick to activities like cycling, swimming, or the elliptical for your long and slow cardio."