However, I don't believe in absolutes. I question overconfident trainers who think that only one form of exercise is right for every person, especially with the industry's habit of changing its mind. Fitness isn't black or white and if there is one thing I have learned throughout seven years of industry experience, it's that every answer comes with a big fat "but."
So allow me to offer a more detailed explanation. There has been a lot of talk in the industry over the idea that cardio will make you fat. I know, it seems REALLY counter intuitive. This has been said for three main reasons:
1. It raises cortisol (a stress hormone)
3. It causes you to lose muscle
Let's Tackle these Points
Cardio raises cortisol in the body because physical stress releases this hormone from the adrenal gland. However, every exercise does this. Should you stop exercising? Heck no! BUT (there's the keyword) you have to know how to manage exercise and balance your nutrition to control the release of cortisol. Many fitness professionals now believe that strength training will achieve every result that you could ever want and while it certainly is a staple in any regimen, it's not the be all and end all of fitness. It's just not...
When you look at groups of exercisers as a whole (not on an individual basis) different exercises produce different body types:
-People who only run look a little like noodles.
-Weight lifters have muscle but also tend to look stocky and have a hard time losing stomach flab.
-Dancers, Yogis and Martial Artists have very well-balanced body types with strong, long limbs and amazing flexibility and balance BUT they practice highly technique-based art forms, which require professional instruction. However, these activities incorporate all of the components of fitness to achieve these overall results.
***Before giving up cardio and strength training in favor of one of these, take classes and use the fundamental components of fitness (cardio, weights and stretching) to build your strength, endurance and flexibility for these activities. People who train in these disciplines have been instructed on ways to prevent repetitive strain injuries, muscle tears etc. Do not think you can surpass this step.
Next point against cardio: It will make you eat more...
It sure does but again, so does exercise in general. If you think that gives you the freedom to eat whatever you want then okay, cardio will make you fat! Running for an hour burns about 500 calories, which is a good sized meal. Without replenishing these lost nutrients you will feel weak, tired and back to the first point, cortisol will be released. Not to mention that skipping meals will lead to over eating.
It will make you lose muscle
The metabolic process and the science behind hormones is so freakin' complicated that it surprises me that anyone who is not a specialist in these particular sciences can offer a confident response. However to be as basic as possible without venturing into realms beyond my complete understanding I will say this much:
When we exercise we burn through our lunch first (carbohydrates or glycogen) and then we burn through fat, (about 20 minutes after exercise) which is our body's primary fuel source. Then we burn protein, otherwise known as muscle. However, the metabolic and fat burning process is not simple. Nothing is ever simple! We are burning everything at once but more of one or the other, as a source of fuel, depending on the duration and type of exercise. To burn muscle you would have to do cardio for a very long time. It is generally believed that keeping cardio under 1 hour is safe.
Finally, the other Side of the Coin
This point of view is mostly believed by body builders who are afraid of losing the muscle that they have worked hard for. Unfortunately many body builders place so much emphasis on aesthetics that they have terrible cardiovascular health!
I truly believe that no one should ever blindly trust their personal trainer, nutritionist or the guy that looks good in the weight room with their body. Please read, research and experiment with different types of exercise. I will end this post with a few articles that share both viewpoints. I wanted to post articles that were really against cardio but I had a hard time finding reputable sources that I would feel comfortable sharing. So here you go:
This article has a lot of links to studies on long-term runners.
Another well-rounded from Body Building