Participants in an exercise study were more likely to keep up moderate, rather than intense, physical activity in the long term.
While intense exercise gives the most health benefit, it is important to be realistic and focus on what people can, and will, do. Researchers at Duke University have studied what happens when people are taken through supervised exercise of differing intensity. A group of 87 'couch potatoes' was assigned to either high, moderate, or low intensity exercise for nine months. The high intensity activity involved the equivalent of 18 miles a week of brisk walking or jogging, moderate was 11 miles of the same, while low intensity was just 11 miles of walking.

When they finished the program, a high proportion of the group kept up their exercise. But those in the high intensity group cut back on time spent, while those in the low intensity group increased the intensity of their exercise. This suggests that people do tend to gravitate to a moderate level of activity. Those who abandoned their exercise gave lack of time as the main reason. Walking was the preferred activity, although some used elliptical trainers and other machines, or went swimming.