I feel this is an important post, and hopefully readers will enjoy it. I have been reading a very interesting paper that looks at forced versus voluntary exercise. Researchers took two groups of rats and had them do equal amounts of voluntary and forced exercise. They observed the amount of exercise performed in the voluntary group and then applied that to the forced group.
What's neat about this study was how they applied the exercise to forced group. The voluntary exercise group tended to exercise in short bursts with frequent rests. Researchers often ignore this natural pattern and try to duplicate it with even-paced, continuous exercise. In this study, researchers attempted to control for this by making the forced exercise group perform their exercise in similar bursts.
There was one problem with this: it didn't work. The rats in the forced exercise group were "reluctant to run" at high speeds. Instead, the forced rats chose a slower, more consistent pace for longer periods. These rats even developed anxiety-like behavior after being forced to exercise.
Therefore, the result was that while both groups ended up covering the same amount of distance, the average speed was much higher in the voluntary group. Here's a section from the paper:
"Running wheels allow rats to self-determine when, how often and for how long to exercise, whereas these parameters are pre-determined for forced runners who must exercise even if not motivated to do so. These inherent differences likely underlie the differential effects observed in the present study. Forced, but not voluntary exercise increased emotional defecation and anxiety-like behaviors."
The researchers also found that the rats in the voluntary group increased aerobic capacity (VO2max) to a greater extent. Here's another section:
"We suggest that intensity of exertion may be the most important difference between forced and voluntary exercise.... Voluntary exercisers ran at higher speed for less time, while forced exercisers ran at lower speed for a longer total period of time. The difference in intensity of exertion between the forced and voluntary exercisers may well contribute to the differential effects of these two paradigms on brain and behavior."
This is so intriguing that voluntary, freely-selected running will actually result in a higher average intensity. This is in contrast to common ideas that exercisers must be motivated and "pushed" to higher levels of performance. The anxiety finding is also important. If an exercise program increases anxiety, I doubt it will be sustainable in the long run.
I think most of the findings from this study can be directly applied to people and exercise. This research suggests that open or unscripted interval training will be more productive than a pre-determined set of interval speeds and durations. Freely-selected intervals can lead to a higher level of intensity, and therefore greater improvements in aerobic capacity. Also, open intervals will not have the anxiety of forced intervals, which should promote more enjoyment and adherence in the long run.
