But won’t cardio burn up my muscle??
I hear this question a lot. So I am going to attempt to explain why aerobic activity will NOT cause muscle loss IF adequate calories are consumed. Cardiovascular activity forces oxygen thru your body, increasing the number and size of your blood vessels. Blood vessels transport oxygen and nutrients(proteins) to your muscles and carry waste products away for muscular growth, repair and recovery. Without aerobic activity in your program your body cannot create any new supply routes for your newly developing muscle tissue.
There are also metabolic changes that take place during aerobic training. At the cellular level, there is an increase in the size and amount of mitochondria, (each cells powerhouse,where fat is burned), as well as an increase in myoglobin content. Myoglobin is a protein that transports oxygen from the bloodstream into the muscle fibers. Finally, aerobic adaptation increases the level and activity of the enzymes involved in the metabolism of glucose. Lower insulin levels (blood glucose or sugar) means a lower percent of bodyfat storage.
All of these factors combined equals a boost in fat burning and muscle building capacity for the bodybuilder.
Now, that being said, just because some cardio is beneficial does not mean MORE is better. Over doing cardio can have the opposite effect - muscle loss or slowed growth. When the body senses it is under a lot of stress, as it does when cardio is of a long duration, the adrenal hormone cortisol is released in greater amounts. Cortisol causes a breakdown of protein in the muscles…which is the opposite goal of a bodybuilder or anyone trying to add muscle. This is why 3 days per week HIIT (high intensity interval training) sessions are so prevalent among those wanting to build muscle, yet burn fat. Yes its true, sometimes less is more!
June 16, 2009 at 3:45 pm
WOOHOO…GREAT BLOG GEMMA!!! Since you have had me doing the HIITS i can notice the difference…it majorly kicks my butt though…lol!! ITS ALL GOOD!
June 16, 2009 at 3:54 pm
Very helpful. Thank you. I’m reaching a point where I want to slow down my weight loss and spend more time developing lean muscle mass. I was going to go down from 3- 1 hr cardio sessions to one, but I’m going to take your advice and continue to incorporate cardio into my weekly program. Thank you!
June 16, 2009 at 3:58 pm
Great advice! I just completed a program that did incorporate HIIT with strength training and I had great results. Now I know why and will continue to use the cardio to my advantage. Thank you.
June 16, 2009 at 3:59 pm
Great post!
June 16, 2009 at 4:04 pm
Great informative post. HIIT is a God-send plus it seems to make the time pass quicker. Thanks for the info.
June 16, 2009 at 4:43 pm
ur pure genious!! when r u gonna write a fitness book LOL
June 16, 2009 at 5:56 pm
physiology in a nutshell! good job!! i like it!
June 16, 2009 at 6:52 pm
It’s official. You’re amazing:) I love how you broke things down, sounds professional but on a level that in understandable to those of us not necessarily familiar with medical terminology. You rock and this is a blog all cardio queens NEED to read!