Two types of exercise may be needed to preserve muscle mass during weight loss

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While obesity presents a number of health risks for older adults, weight loss is often accompanied by a reduction in muscle tissue and loss of strength. A team led by researchers at Baylor College of Medicine set out to determine whether more exercise or specific types of exercise would help preserve muscle during weight loss.

The researchers randomly assigned 103 obese women and 57 obese men over age 65 to one of four groups. Three groups participated in a reduced-calorie diet plus one of three exercise programs — aerobic training, resistance training, or combined aerobic and resistance training — while the fourth, a control group, only received information on healthful eating.

After 26 weeks, people in each of the exercise groups had lost an average of 9% of their weight, while those in the control group had no change. Performance scores — a measure of ability to do daily activities — increased more among the people who did a combination of aerobic and resistance exercise than among those who did only one type. However, all three exercise groups had better performance scores than the control group did. Aerobic capacity — the ability to metabolize oxygen — increased more in the combination and aerobic groups than in the resistance group. However, the people in the combination and resistance groups showed a greater increase in strength and retained more muscle mass, compared with those in the aerobic group.

The results, published May 18, 2017, in The New England Journal of Medicine, add to evidence that resistance exercise, in addition to aerobic exercise, is essential as we age, especially when we're losing weight.

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