We've exhausted our share of column inches (and readers) extolling moderate-intensity exercise as essentially all you need to stay fit. Sure, cranking it up with intervals, plyometrics and other boot-campish abuse can help boost your athletic performance and sculpt your body, but (we have long held) you don't really need to go hard simply for your health.
Well, we're not ready to unplant that flag just yet, but a recent study from Yale University showed that older women – we're talking grandma-age women whose main physical activities are knitting and channel surfing – got an elevated health benefit (in this case, an improvement in a key diabetes marker) when they exercised at high intensities, compared with women who worked out at moderate and low intensities.
The study, published in the January issue of the Journal of Applied Physiology, comprised 25 non-diabetic women ages 62 to 84 who were inactive but not obese. The high-and moderate-intensity groups exercised four days a week and used the same amount of energy – each person burned 300 calories per session – but at different paces. (The high-octane group worked at 80 percent of aerobic capacity; the moderates at 65 percent; and the lows stayed under 50 percent.) The study ran for nine months.
The high-and medium-intensity groups exercised primarily on a treadmill but also jogged on mini-trampolines and used rowing machines for variety.
Among other gains, the high-intensity group was the only one to show statistically significant improvements in glucose uptake, a critical measure of health. (Reduced glucose uptake is the factor responsible for diabetes, a disease nearly epidemic among American adults and a contributor to heart and kidney disease, circulation problems, blindness and other serious conditions.)
Imagine that cells needing glucose are protected by rusty locks that won't open, says lead study author Loretta DiPietro, an associate professor of epidemiology and public health at the John B. Pierce Laboratory at Yale. Exercise is “like the WD-40 that loosens everything up and lets the key back in that lock,” permitting the glucose to enter.
Note that the high-intensity group actually spent less time exercising – 55 minutes per session – than the moderate group (65 minutes).
So, do you really need to go a mile a minute to reap those benefits? No. If you're already in decent shape, shoot for 45 to 50 minutes of brisk walking (really puffing and huffing) four days a week. Similar but reduced benefit can be had by walking at a moderate pace (where you have trouble conversing due to shortness of breath) for around an hour.
Another finding of the study, DiPietro said, is that those who worked out hardest retained the health benefits for 72 hours. The moderate-intensity folks held onto those benefits for only one day. This suggests that those who work out harder can take off a day (or even two), while the moderate exercisers need to work out every day.
The important thing is to get moving, even if you must start with low-intensity strolls and build up from there. Don't forget that the study participants were all inactive when the research began.
