A Theory About Exercise

I am not aware of any serious research on this idea, but I have noticed something that seems to hold true in my own personal experience...

Most of the benefits of exercise (weight loss, increased muscle mass, improved blood sugar control, increasing VO2 max, etc.) seem to be at their most pronounced levels when a person is undertaking something new. That is, when you first begin an exercise regimen, for the first, say, two or three weeks, one will notice major gains in muscle, major drops in body fat, major improvements in blood sugar, and so forth. But as that exercise regimen continues over 4, 5, 6 weeks, and beyond, the improvements become far less pronounced. In my personal observation, they even reverse in some cases.

To avoid losing out on all the progress I gain as I work out, I have taken to making major changes to my exercise regimen every two or three weeks. This might come in a variety of forms. For example, when I developed a case of tendonitis recently, I first switched to jump rope as my preferred cardiovascular exercise. When I reached the point of diminishing returns, though, I switched to a rowing machine and again started feeling good and healthy. Recently I reached the point of diminishing returns there, too, and so I've been focusing on interval workouts using an elliptical machine. Now I find I'm maxing out there, and my legs feel a lot better, so I am making plans to start running again.

For strength training, it's been the same way. I committed to making major changes to my weight lifting routine every week or two. The result is, at least so far, muscles that continue to get larger and better-toned, and stronger.

Of course, what I'm talking about here is basically the "muscle confusion" principle upon which P90X and other fitness programs are based. So there is at least a community of people out there who seem to have noticed the same thing I have.

But, I have no scientific evidence for this, and what evidence I have seen thus far looks more like marketing than exercise physiology. Perhaps I'll never know the answer to this question, but I can say at least this much: It seems to hold true for me.

What is your own experience with this phenomenon?