Do Swimmers Live Longer than Runners?

Results from a recent University of South Carolina study lead by Professor Steven N. Blair may create waves in the running community.

After thoroughly examining medical and physical activity data on 40,000 men (ages 20 to 90), Dr. Blair and his crew have concluded that in addition to having 53% lower mortality rates than their sedentary peers (no big surprise there), swimmers ALSO have a 49% lower mortality rate than runners! In other words, according to the findings, swimmers have a 49% better chance of staying alive this year than runners. Hmmmm, could there be something fishy in these chlorinated water results?

If true, this information could be quite revealing because most people probably assume that all forms of exercise provide similar health benefits. But, I'm always skeptical of studies, so let's "peek under the hood" of this one to determine where the results are coming from:

Dr. Blair's group of 40,547 men (average age of 47) were selected from patients of a preventative medicine clinic in Dallas, TX (Cooper Clinic). Of the 40,000+ men, 15,883 were deemed sedentary (ie, couch potatoes), 20,356 were runners (15min./mile pace or faster), 3,746 were walkers (15min./mile pace or slower) and 562 were swimmers (actual swimmers, not water aerobics, water joggers etc.). Over the course of 13 years, a total of 3,386 of these 40K Cooper Clinic patients died: 1747 sedentary (11%); 292 walkers (7.8%); 1336 runners (6.6%); and only 11 swimmers (1.9%). Wow, that's quite a difference! And, the fact that the sedentary mortality rate is significantly higher than walkers, and walkers higher than runners lends credibility to these figures in my opinion.

Professor Blair and his team do not offer any hypothesis regarding the significantly lower swimmer mortality number stating only, "These lower rates compared with walkers and sedentary men might well be expected, but it is unclear why we also observed lower mortality in swimmers than in runners."

Making the lower mortality rate even more perplexing are the results from an earlier study of Dr. Blair's that found swimmers having a higher BMI (Body Mass Index), higher fasting-blood glucose, and higher blood pressures. Swimmers were found to have a lower total cholesterol and higher HDL (good cholesterol), however.

Although the study was partially funded by the National Swimming Pool Foundation, I find no obvious stretches of data or leaps of faith to doubt the findings--the numbers are what they are.

This one study may not cause runners to immediately exchange their shoes for fins, but cross-training in the pool a couple days a week may be the right combination to improve your overall fitness and keep you alive longer than the rest of the members in your jogging group.