Public-health campaigns regularly plug exercise as a sure-fire way to avoid an early grave. But that message may be too simplistic. For an unhappy few, even quite strenuous exercise may have no effect on their fitness or their risk of developing diseases like diabetes.
“There is astounding variation in the response to exercise. The vast majority will benefit in some way, but there will be a minority who will not benefit at all,” says Claude Bouchard of Louisiana State University in Baton Rouge, US.
At the Australian Health and Medical Research Congress in Sydney, Australia, last week Bouchard reported the results of a study assessing the role of genes in fitness and health changes in response to exercise.
In the study, 742 people from 213 families were put through a strict 20-week endurance training programme. The volunteers had not taken regular physical activity for the previous six months. Exercise on stationary bikes was gradually increased so that by the last six weeks the volunteers were exercising for 50 minutes three times a week at 75% of the maximum output they were capable of before the study.
Previous reports indicated that there are huge variations in “trainability” between subjects. For example, the team found that training improved maximum oxygen consumption, a measure of a person’s ability to perform work, by 17% on average.