Health Notes: High-intensity intervals not best for all, brisk exercise combats obesity

High-intensity intervals may not be best choice for all goals although it does help aerobic fitness, and bicycling can be comparable to brisk walking for weight control.

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>> High-intensity intervals may not be best choice for all goals

Over the years, coaches and others have promoted brief exercise filled with short, very high-intensity intervals as one way to gain fitness and health. But a recent study has found that kind of training -- also found these days in some exercise equipment programs -- may not be the answer for everybody.

The study had healthy, untrained men (average age, 31) do either 12 weeks of intense interval training that equaled 40 minutes a week, extended and more moderate running that equaled about 150 minutes a week, or strength training of heavy resistance twice a week.

For the intervals, participants did a five-minute warm-up followed by five intervals of two minutes at near-maximal running (95 percent-plus of heart rate max) alternated with two minutes of easy jogging. For the extended running, participants ran for an hour at 80 percent of heart rate maximum. Both groups were scheduled to workout three times a week, but due to injuries in the interval group, participants completed an average of two a week; due to injuries in the extended running group, participants completed an average of 2.5 a week. For the strength-trainers, the program included three to four sets of six exercises that covered the whole body.

Interval participants had a greater improvement in cardiorespiratory fitness than among either of the other two groups. But the interval training program was less effective than prolonged running at lowering resting heart rate, body fat percentage, and the ratio between good and bad cholesterol. Plus, total bone mass and lean body mass remained unchanged in the interval group, while both of these parameters were increased with strength-training.

So what? Short workouts spotted with super high-intensity training may not be the best for improving health or losing weight if it is the only workout you do. In this group, it also caused more injuries than with other workout methods.

For the scientifically minded: The study out of Denmark ran in the October 2010 issue of Medicine & Science in Sports and Exercise, a peer reviewed journal by the American College of Sports Medicine -- 42 (10): 1951-1958. Click here to see the issue’s table of contents; scroll down to the article (“High-Intensity Training versus Traditional Exercise Interventions for Promoting Health”) to read a free abstract of the study. 

>> Bicycling comparable to brisk walking for weight control

Walking has long been the go-to for many women, but cycling can also help control weight, a recent study found in comparing the two activities among pre-menopausal women.

The results were drawn from a 16-year follow-up study of 18,414 women as part of the Nurses’ Health Study II looking at weight change from 1989 to 2005. For the women, any bike riding -- even as little as five minutes a day -- helped control weight, with overweight and obese women benefitting the most. Among walkers, only those who walked briskly (at least 3 mph or 20-minute miles) were able to control their weight.

"This study shows that more bicycling predicts less weight gain," said Rania Mekary, research associate in the HSPH Department of Nutrition. "Small daily increments in bicycling helped women control their weight. But the more time women spent bicycling, the better. Women with excess weight appeared to benefit the most.”

Over the 16-year period, women in the study gained an average of 20.5 pounds. Women who cycled more than four hours a week in 2005 were 26 percent less likely to gain more than 5 percent of their initial body weight. Overweight and obese women who cycled as little as two or three hours a week were 56 percent less likely to gain weight.

So what? For some, cycling may be a better exercise either outside or inside. And indoor cycles of any kind do tend to take less space than larger treadmills for those who choose to workout indoors.

For the scientifically minded: The study was published in the Archives of Internal Medicine – 170 (12): 1050-1056, 2010. Click here to access a free abstract of the study.

--Therese Iknoian