Body by Science

Moreover, because running for long periods burns primarily fat, technically, he’s not tapping his glycogen stores to any significant degree, with the result that his insulin sensitivity is going to go down over time with this type of behavior. That’s going to put him at increased risk for coronary disease—the very thing that he foolishly believes he is taking steps to alleviate by engaging in his low-intensity, steady-state activities.

If the intensity of exercise is too low, nothing much in the way of a stimulus is presented to the body.

The key findings in these studies indicate that in terms of overall health, a workout requiring six to nine minutes a week produced the same muscle enzymes (which are essential for the prevention of type 2 diabetes) as a workout requiring four and a half to six hours per week.