Does cardio burn or build muscle?

Get two training experts in a room, and before long the argument will start. “Cardio costs you muscle.” “No, cardio is essential. Without it, you simply won’t grow.” For years, there have been no clear answers – until now.

Researchers measured cardio training’s influence on the size and function of muscles. Study participants underwent ergometer training, doing no other form of workout. After 12 weeks, average quadriceps muscle volume increased by 12 percent and average power generated from the knee extensor increased by 55 percent. Biopsies showed that the cardio training alone increased participants’ type I muscle fiber size by up to 21 percent and increased type I fiber power generation by 28 percent.


This study is a smoking gun! Not only is cardio important just for general health, but this study shows that it helps physically change the structure of muscles, leading to “pronounced muscle hypertrophy.” So be sure to incorporate cardio into your training program. It’s no longer a question of if you should do cardio to build muscle, but only one of when and how much.


Harber MP. Konopka AR. Douglass MD, et al. Am J Physiol Regul Integr Comp Physiol. 2009 Nov;297(5):R1452-9. Epub 2009 Aug 19.

← Older Post | Newer Post →