One common dilemma that many athletes face is whether or not too much cardio will cause them to lose precious muscle mass.

The first rule of thumb is that each goal will require different cardio sessions, including intensity, frequency and duration. Someone looking to build muscle mass or maintain their current weight should be undertaking more conservative cardio sessions than someone whose primary goal is fat loss.

Although every goal will require different training demands, cardiovascular activity is always recommended as a basis. Cardio helps fitness models reach extreme levels of leanness, even if their main focus is on building lean muscle mass - it also accelerates fat loss for anyone on a weight loss program.


Cardio and weight training

Cardiovascular activity can complement a weight training program by boosting endurance. Exercise speeds up the transfer of nutrients from blood into cells and enhances muscular development. Improved endurance will also increase your rate of recovery between sets when training. The fitter you are, the less time you will need to rest and recover.

Cardio and fat loss

When we exercise, our bodies utilize stored carbohydrate (glycogen) in the muscles and fat to give us the energy needed to complete the physical activity. If there’s any excess protein in the body that’s not being used, it can also be broken down and converted into glucose to be burned as energy. The body only ever burns muscle instead of fat as a survival mechanism if you’re not consuming enough overall calories. This explains why many dieters on low-calorie diets regain all the weight they lost when they stop dieting, since their bodies burnt muscle mass as fuel, rather than fat. Following a well-balanced diet with an adequate intake of protein and calories will ensure you protect your muscle mass and prevent it from being burnt.

How much is too much?

As mentioned, each goal will have a unique set of requirements. For muscle development or maintenance, a conservative approach could consist of a 20-30 minute workout a few times a week. Maximal fat loss could require anything from one hour cardio sessions five or six days a week upwards. The closer you get to your fat loss goals the harder you will have to work and the more cardio will be required. Some fitness models do cardio up to twice a day to achieve their goals. Endurance athletes do hours of cardio a day, but support their exercise with a high caloric intake.

Final thoughts

Regardless of your goals or how much cardiovascular activity you perform, your body will only ever burn muscle mass if you don’t meet your caloric requirements and underfeed your body. You are much more likely to lose muscle mass by following a low-calorie diet and doing no exercise than you are by pushing yourself to the limits at the gym and fueling your workouts with a well-balanced diet. Start pushing yourself and hit the treadmill!