When most people think of exercise, they tend to compartmentalize things into separate categories, dividing exercise into different "types:" Strength training, explosiveness training, flexibility workouts, interval training, sports-specific training, and- the subject of this article- cardio.

Cardio in particular seems to most people to be something very different from strength training, to the extent that it's a popular misconception that some kind of balance is needed between the two- you need your strength training sessions, and then you need your cardio sessions, for example. Or there's the belief that at low intensities, muscles run solely on oxygen (aerobic) and at higher intensities on glycogen (anaerobic). But it's a broad, continuous scale that this happens on; there's no metabolic "switch" to flip in the cells. They don't say to themselves, "we're doing cardio now, let's use only oxygen!" It's all metabolism.

Another cardio misconception is that the heart and lungs can be trained to improve performance. But the heart is always working exactly as strong as it needs to at any moment, and the lungs are not even muscles at all.

Work Smarter, Not Harder

What can be improved, however, is muscle metabolism, or how efficiently your muscles work to turn fuel into energy, remove waste products, and recover from effort. When your muscles are not running efficiently, any small effort (going up a flight of stairs, for example) will overwhelm them, and they'll scream for the heart to pick up the pace to bring oxygen and nutrients, and you'll become out of breath and your heart will start pounding. Improve that efficiency, and you won't get winded so quickly. You'll have more stamina and endurance.

And what's the safest, quickest way to improve the functioning of your muscles? Strength training. By putting your muscles under meaningful load for just a few minutes once or twice a week, your body will adapt by getting stronger and more efficient.

Don't Do This If You Want to be Strong...

The worst way to build strength, on the other hand, is cardio. Cardio sessions tend to be longer and lower in intensity than proper strength training, so you never get a chance to use your strongest, "fast-twitch" muscle fibers- and those are the ones you need to use in order to increase your muscular strength and efficiency.

In fact, if all you do is cardio, your strongest muscle fibers will waste away, because you're never using them. And this can leave you weaker, putting your joints at risk.

...Or Lose Weight

You'll also stall your fat loss for two reasons: 1) in your body's drive to become more efficient, it will slow your metabolism to compensate for the increased activity of chronic cardio, and 2) lower muscle mass also means slower metabolism.

But What If I Like It?

So does this mean no one should ever do cardio? Not necessarily. If you enjoy (and can afford the time for) cardio, then feel free to do it. But don't neglect strength training, as that will send the signal to your body to hold on to your strongest muscle fibers. Strength training will also reduce the likelihood of joint injuries, as joints work better when they are surrounded by strong muscle.

Don't Beat Yourself Up!

But if you hate hours of boring cardio, if you're constantly having to take time off due to sore feet, knees, hips and back, then don't stress out about "not exercising." Spend your fitness time and money getting the best "bang for your buck" by doing proper, safe, evidence-based exercise: strength training the TimeSaver Strength way, and improve your overall health much faster than by spending time on a treadmill!