I’m trying to build muscle but I also don’t want to get fat. How much cardio can I add into my program without killing my gains? Or is this just a myth?
There’s two parts to this answer. First, you shouldn’t care more about gains than general health, so yes you should absolutely do some form of cardio. Secondly, doing too much cardio too often might negatively affect muscle power production and hypertrophy gains. You should stick to high-intensity sprints and circuits with short rest periods as opposed to steady state cardio. This delivers all of the desired heart and health benefits without negatively affecting your gains.
If you don’t have room or the desire for sprints you can still do steady state cardio, just keep sessions to about 20-mins and no more than 3-4 days per week. Longer or more frequent sessions can actually induce central fatigue which will negatively impact your resistance training performance.
Balabinis, C. P., Psarakis, C. H., Moukas, M., Vassiliou, M. P., & Behrakis, P. K. (2003). Early phase changes by concurrent endurance and strength training. Journal of Strength and Conditioning Research, 17(2), 393-401.
Wilson, J. M., Marin, P. J., Rhea, M. R., Wilson, S. M., Loenneke, J. P., & Anderson, J. C. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. The Journal of Strength & Conditioning Research, 26(8), 2293-2307.