Vigorous Exercise Is Moderately Better Than Moderate Exercise . . .

There are plenty of studies showing that moderately intense exercise improves the likelihood of cardiovascular disease and cardiac events (i.e. heart attack, stroke, severe angina, sudden cardiac death).  But what about more intense, vigorous exercise?   Does it do more good, or actual harm?  Answers to these questions were offered by Harvard researchers at the EPI/NPAM 2010 congress (Abstract 2), sponsored by the American Heart Association. 

Physical activity levels were collected from 43,600 participants in the Health Professionals Follow-Up Study, and again at 2-year intervals for 18 years.  The weekly time spent exercising and the weekly number of MET hours (metabolic-equivalent-task hours) were determined.  “Vigorous exercise” was defined as being more than 6 METs.  The end-points of interest were total cardiovascular disease, fatal coronary artery disease, nonfatal heart attack, and fatal and nonfatal stroke.

Participants were classified according to the number of hours/week of vigorous activity: 0, 0.1-0.9, 1-1.9, 2-4.9, 5-6.4, and 6.5 or more.  In  these groups, the rates of nonfatal heart attack, fatal heart disease, and stroke were, compared with that for 0 METs = 1: 1.0, 0.91, 0.91, 0.84, 0.83, and 0.76.  In other words, there was a significant “dose-dependent” decrease in cardiac events with more vigorous exercise.  However, the effect was not very mark – moderate, in fact.

The good news here, according to the lead researcher, Dr Chomistek, is that individuals who have worried that long amounts of endurance activity can damage the heart can now relax – there was no evidence that too much vigorous exercise was harmful to the cardiovascular system, though 7.9 hours a week should be enough to get the best effect. 

For those in training but having difficulty in finding enough time to do what they consider enough, high-intensity interval training (HIT) is a solution.  Canadian scientists have shown that, for instance, that doing 10 one-minute sprints on a stationary bike with about one minute of rest in between, three times a week, works as well in improving muscles as 30 minutes five days a week of conventional (less strenuous) biking.  “No time to exercise” is no longer an excuse.