I was asked a great question this morning from one of our dedicated male boot campers about doing extra cardio after the boot camp in order to burn more calories. I applaud him for wanting to do some extra work, but I cautioned him that it would be counterproductive in several ways. Now I gave him the cliff notes version, but I will provide you several reasons why extra cardio and just traditional cardio in general is counterproductive, especially in regards to losing bodyfat.

But before I go any further, please understand that I don’t completely dismiss cardio as a fitness tool. It’s a must for addressing metabolic disorders, such as diabetes and high blood pressure, and is a necessary tool when training for long duration events such as a marathon. However, for losing weight and body fat, cardio is just plain inneffective. Here’s why:

Studies have shown that results plateau after 8-weeks

When you apply stress to the body it tries to find a way to adapt to the stress as fast as it can. The human body hates to be energy inefficient so it will adapt accordingly to become energy efficient. Basically, if you used to burn 500 calories during a 30-minute run, after 8-weeks your body has adapted and you may now only burn 400 calories during those 30-minutes. Your heart health is improving and becoming more efficient, however the ability to burn calories is decreased.

It decreases muscle strength and power

This is associated with the type of stress put on to the working muscles. There are slow-twitch muscle fibers and fast-twitch muscle fibers. Slow-twitch muscle fibers are normally referred to as our endurance muscle fibers or Type 1 fibers, and fast-twitch muscle fibers are normally referred to as our strength/power muscle fibers, or Type 2 fibers. The more continuous cardio you do causes your slow-twitch fibers to dominate the adaptation process. Slow-twitch fibers produces the least amount of force, but are very energy efficient.

Fast-twitch fibers are classified under two types, Type 2a and 2b. Type 2a fibers are a hybrid of Type 1 and Type 2b. Because of the hybrid characteristics if more aerobic work is done then Type 2a’s will behave more like Type 1’s, and on the flip side if more strength is done then they will behave more like Type 2b’s. Type 2a fibers are also most responsible for increases in muscle gain. To illustrate, who has more body fat an Olympic sprinter or a marathoner? Most people would answer the marathoner because on the outside they look lean and thin. However, many strength coaches have demonstrated that when measuring the body fat of a sprinter versus a marathoner, the sprinters have less body fat.

Type 2b fibers are most responsible for generating all out power, but are highly inefficient and depending on the type of strength training you are doing Type 2b’s can convert to Type 2a’s. Let’s compare again a sprinter and a marathoner, who has more strength and power? This should be obvious in that sprinters are explosive and have good muscle mass.
Simply put, cardio can make your body slow and weak.

It increases oxidative stress

Oxidation is a process in which free radicals form in the body. With adequate amounts of antioxidants in your nutrition this shouldn’t be a problem, because you’re body will normally neutralize the effects of free radicals. However, if the body is exposed to too much free radicals, which is produced by excessive cardio then you’re body will have an extremely difficult time combating this process. Too much oxidative stress has shown to accelerate aging!

Can impede proper hormonal function

First, too much cardio can stress your adrenal glands, which are responsible for the delicate balance of hormones. Fatigue the adrenal glands and you’ll quickly experience symptoms such as chronic fatigue, insomnia, decrease in ability focus on tasks, anxiety, and decreased immunity just to name a few.
Secondly, it can negatively affect testosterone and cortisol ratio’s. If the testosterone/cortisol ratio is lowered your ability to build muscle is decreased. Why? Because, muscle is essentially your metabolism. The more muscle you have the more calories you can burn. The inability to build more muscle simply makes your ability to lose weight harder.

Are you experiencing any of the negative effects stated above? Are you finding your hitting a fitness plateau? Take a good look at your workouts and observe the ratio of cardio to strength training. You might just be wasting your time and efforts if you’re trying to lose weight.