Fun and Fitness for the 40-Something

We’ve all seen middle-age spread, possibly in the mirror. Many of us believe running can help combat it, but data from a massive study of runners suggests that they need to boost their mileage over time to outdistance increasing total weight and waist circumference.

The National Runners Health Study was established in 1991 to determine the health benefits of running. It includes more than 120,000 runners and will span 20 years. Over the years, the researchers have looked at different aspects of the relationship between running and health.

To determine whether middle-age weight gain occurs regardless of activity level, the researchers examined the association of “adiposity” (i.e., fat) with age in 4,769 male runners, aged 18-49. Runners’ waist sizes provide an estimate of upper-body fat, and previous studies have found that every 10-mile increment in weekly mileage was associated with a significant apparent reduction in waist size.

These researchers observed that average waist size and BMI increased with age at all levels of running (ranging from less than 10 miles per week to more than 40 miles per week). The average rate of weight gain was the same in men running less than 10 miles per week and those exceeding 40 miles—about 3.3 pounds and about 3/4 inches around the waist per decade in a six-foot tall man. Notably, the percentage of moderately overweight runners increased from 21 percent before age 30 to 30 percent between ages 45 to 49.

The researchers concluded that age-related weight gain and exercise-induced weight loss are independent effects. Middle-aged runners are leaner than more sedentary men because exercise-induced weight loss offsets weight gain during middle age—not because the processes that promote age-related weight gain are abated.

The findings suggest that male runners who maintain consistent weekly distances through middle age can expect to increase their total weight and waist circumference (and, presumably, the dangerous intra-abdominal fat). The researchers explain that distance must increase annually—by 1.4 miles per week—to compensate for the expected increase in waist circumference between ages 20 and 50. Thus, runners who average 10 miles per week at age 30 should increase their weekly running distance to 24 miles by age forty “if they plan to still fit into the tuxedo they bought ten years earlier.”

So it appears that the way to dodge age-related weight gain is to offset it with exercise-induced weight loss. That makes sense. I don’t know about that 1.4-mile per week annual increase, though. I currently run about 18 miles each week; it’s hard to imagine running 32 miles per week in 10 years, when I’m 52. It might counter weight gain, but what about the orthopedic effects? Quite the Catch-22: weight gain or musculoskeletal breakdowns.

This entry was posted on Thursday, April 30th, 2009 at 8:00 am and is filed under Running. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.