IS CARDIO REALLY KILLING YOUR MUSCLE GAINS?

Cardio is hardio, actually cardio is fairly hard on your body for multiple reasons. Long has the idea been held that elevating your heart rate over a certain amount will directly eat away at lean muscle mass. While the treadmill will not literally take a bite out of your biceps it could play a major role in preventing you from adding an extra inch to your sleeve size. There is a fine line in maintaining athletic prowess and maximizing the hours spent in the gym, and I will discuss that with you.

First and foremost, a discussion about a process that makes fat oxidation and one that makes muscle growth possible within the confines of human physiology is needed. While there are a plethora of routs in which both of the aforementioned processes can be impacted, cardiovascular activity has direct influences on a couple. Adenosine monophosphate-activated kinase (AMPK) and mechanistic receptor of rapamycin (mTOR), the former being an enzyme involved in fat oxidation and the latter being a receptor that is activated when muscles synthesize protein. AMPK is a rate limiting enzyme in fat oxidation, meaning that as more is present and activated the more the body can burn fat as fuel. This is important to note as more AMPK is present, the more motor receptors are deactivated, and limits initiations of muscle protein synthesis.

As one can see from the competition of physiologic pathways, cardiovascular exercise and muscle building do not innately go hand in hand. The twist to the equation is that the more aerobically fit an individual is the better they are at supplying their muscle mass with nutrients necessary to grow. Therefore, getting better at cardio is preventing muscle from growing, but not doing cardio is also derailing future lean muscle gains. So how do you incorporate cardiovascular exercise without risking your hard work?

The answer lies in the application of the cardiovascular activity, such components such as intensity and duration, are paramount in this equation. As a rule of thumb, when looking at exercise intensity in terms of cardio, when increasing intensity the duration should be decreased. For example the amount of muscle catabolism incurred at an hour of walking is much less than an hour of running. In order to maximize aerobic capacity, higher intensities must be pushed to achieve continued progress. Making sure to limit sessions working harder than a brisk walk (slower with a steeper incline) to no more than 30-45mins maximum will ensure minimal amounts of muscle mass is compromised. This time frame confines interval style of training as well, with rest periods included sessions should be limited to the same timeline as steady state cardio.