Light Exercise Trumps Intense, According to Study

Spring is here—and with it comes the parade of runners and joggers—working out on the theory that exercise is good medicine. But how much exercise is optimal? According to John Naish, writing for the London Daily Mail, Danish investigators have found that light joggers—not marathon runners—have the lowest rates of death. The Danish study suggests extremely strenuous exercise causes telomeres to shorten.

The 2013 study, published in the Lancet, found that moderate exercise produced a healthy stimulus that helped to promote the growth of telomeres when combined with a healthy diet. The lead researcher on the study, Peter Schnohr, M.D., a cardiologist, said, “If your goal is to improve life expectancy, jogging a few times a week at a moderate pace is a good strategy. Anything more may be harmful.”

Maish wrote that this contrast in benefit and risk between light and strenuous exercise has also been highlighted by recent studies on the brain.

Japanese scientists have reported that two weeks of low-intensity exercise such as brisk walking boosts activity in the hippocampus, a brain region important for forming new memories. However, intense exercise appears to provide no such benefits.

A Chinese study has shown that exercising to the point of exhaustion may cause chemical imbalances that kill brain cells in the hippocampus and reduce surviving cells' ability to communicate with each other. Other research has shown that too much exercise appears to cause an overload of the brain chemical glutamate, which may cause problems with memory and thinking in athletes.

Australian researchers at Queensland University found that strain on the body from intense exercise can cause a drop in the blood levels of infection-fighting T-cells.

Anthony D'Silva, M.D., a cardiovascular science clinical research fellow said, “Evidence suggests that beyond an optimal level of fitness, the principle of diminishing returns applies. Exercise appears to most benefit people who are least active.” In other words, moderation in all things.