It was three in the morning, and once again I couldn’t sleep. As I usually do when I can’t sleep, I turned on the TV and flipped to the most boring program I could find.
Since it was three in the morning, I ended up watching infomercials.
“Are you ready for the INSANITY challenge?!?”
“I took the challenge and lost 40 pounds!”
“You’ll be in the best shape of your life!”
Ah, the fitness infomercial. I wouldn’t normally want to cover a product like this in a science column, but sometimes a useful way of figuring out the good science is comparing it to the bad.
This one is particularly bad. Essentially, the “Insanity” work out consists of two months of high-intensity exercise six days per week, with short periods of moderate exercise between work outs as a rest. This sort of plan may work if you’re already fairly in shape, but the infomercial and the before-and-after pictures on their website show that they’re targeting people who don’t normally exercise (the before-and-after pics also showed that they apparently offered free tanning services to one of the clients, but that’s beside the point).
Obviously, they didn’t talk much to fitness scientists before developing their plan; when there’s money to be made from people’s insecurities, who would? According to a 2007 study from the University of Guelph, the most effective way to become more fit and lose fat is interval training, a method in which short bursts of intense activity is interspersed with longer stretches of moderate exercise. In the study, both inexperienced people and athletes were able to benefit from interval training over intensive training, especially in cardiovascular health. They also increased the amount of fat burned during the work out compared to constant intense exercise.
So, add interval training to that New Year’s resolution you made a month ago, avoid late-night fitness DVD scams and the pounds will start coming off, right? Well, as usual, it’s a little more complicated than that (I should just make that phrase the tagline of this column).
The fact is, it’s uncommon to lose very much weight when a person first starts a fitness regimen unless they have a great deal of weight to lose. Exercise alone doesn’t do much for weight loss; you may improve how capable you are of losing weight, but if you’re eating too many calories, the weight will stay on.
That’s not to say you won’t receive any benefit from exercise alone. Even if you never lose a pound, the benefit to your heart health is well worth the effort. The problem is that improved heart health doesn’t exactly have the same boost to the ego as weight loss and isn’t as easily visibly apparent.
There’s another problem that advocates of long, intensive exercise have to deal with, especially in people who weren’t particularly fit at the start — injury. On a biomechanical level, an injury happens when the load applied to a tissue, such as a muscle, exceeds its failure tolerance. If the failure tolerance of a muscle is low (especially if you haven’t tried a regular exercise regimen before), then it’s far easier to surpass that breaking point.
Even interval training can cause injury if you aren’t careful. It’s even easier to reach the point of injuring yourself if you purposely try to get close to your breaking point, as the Insanity work out advocates.
A mistake in a work out is more likely than people think. Yes, persevering through mild discomfort is important to fitness. When the body is doing something completely new that requires effort, it takes practice to make exercise normal. Muscle soreness is a common side effect. However, “just push through the pain” is how you go from mild discomfort to an injury that delays your work out goals more than pacing yourself could have delayed you.
It’s easy to see where the logic is coming from in this fitness plan. It makes sense on the surface to say, “Well, a moderate work out is good, but I’m not losing much weight. If I work out even harder, I should lose more weight!”
Unfortunately, becoming fit is a slow, frustrating process that probably won’t be solved by $145 in DVDs of a ripped guy yelling at you to “push it.” It will take the discipline to change your diet, the patience to realize you’ll probably only lose about two pounds per week and the realization that the benefit to your health extends beyond simple weight loss.
AMY STEWART can be reached at science@theaggie.org.
