Running News: Short Distances Count; Heat Stroke a Bigger Danger Than Arrhythmia

By Larry Husten

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

Running just 5 minutes a day can extend one's life span. For endurance runners, heat stroke may be a bigger danger than cardiac disorders. These are the lessons learned from two new studies in the Journal of the American College of Cardiology.

In the first, researchers analyzed data from more than 55,000 adults. Compared with people who did not run, runners had a 30% reduction in all-cause mortality and a 45% reduction in cardiovascular mortality, resulting in a 3-year increase in life expectancy. Findings did not differ significantly based on running distance, duration, speed, or frequency. Editorialists advise physicians to offer a simple exercise prescription to patients: "15 min of brisk walking or 5 min of running is all it takes for most clinic patients."

In the second study, researchers retrospectively reviewed data from more than 137,000 runners who participated in endurance races in Tel Aviv. They found only two serious cardiac cases: one myocardial infarction and one hypotensive supraventricular tachycardia. However, serious cases of heat stroke (core body temperature above 104-105 degrees associated with multiorgan dysfunction) occurred in 21 runners; two cases were fatal, and 12 were life-threatening. The researchers say the diagnosis of heat stroke can be missed and mistaken for a cardiac disorder unless the core temperature — which can only be reliably obtained with a rectal measurement — is taken immediately.