Q: I walk for at least 45 minutes every day. Recently I read that strength training may be more important for overall health. Should I change my routine?
A: I wouldn’t say that strength training with weights or machines provides more health benefits than brisk walking or other aerobic exercise. But for too long, strength training has not received the emphasis that it should.
Strength training maintains and may even increase muscle mass, which people tend to lose as they age. Boosting your muscle mass speeds up your metabolic rate, so you burn more calories — even when you’re not exercising.
Burning more calories helps you avoid weight gain, which keeps your heart healthier than if you pack on pounds. And strength training may be especially important for keeping off belly fat. This so-called visceral fat, which surrounds your internal organs, is particularly unhealthy. Abdominal fat is linked to heart disease, diabetes, bone loss, and decreased bone strength.
A study done by researchers at the Harvard T.H. Chan School of Public Health found that healthy men who did 20 minutes of daily weight training had less of an age-related increase in abdominal fat compared with men who spent the same amount of time doing aerobic activities.
Changes within muscles seem to promote these benefits. Muscles store glycogen, a molecule that breaks down into glucose (sugar) to fuel strenuous activity like weight lifting. After a workout, your body gets busy restoring that glycogen and has to rely on fat as an energy source. Strength training also increases the number of mitochondria, the energy-burning structures inside cells.
Strength training can help control blood sugar levels by drawing glucose from the bloodstream to power muscles. High blood sugar is the hallmark of type 2 diabetes. Building more muscle mass also makes the body more sensitive to the effects of insulin, the hormone that regulates blood sugar levels.
For my patients, I still recommend at least 150 minutes of aerobic exercise per week and additional 60 minutes of strength training. If possible, divide the strength training into two separate 30 minute sessions. You can use resistance bands, small hand weights, or weight machines.
A well-rounded program works all major muscle groups: legs, hips, back, abdomen, chest, shoulders, and arms. Start by warming up for a few minutes by moving your muscles without weights, and don’t forget to stretch at the end.
(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)
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