The federal answer to how much strength training an adult needs is two days a week: the Physical Activity Guidelines for Americans recommend muscle-strengthening activity of moderate or greater intensity that works all the major muscle groups on two or more days a week. The research on long-term health adds a useful detail. In a meta-analysis of 16 cohort studies, the lowest risk of early death, cardiovascular disease and cancer showed up at roughly 30 to 60 minutes of muscle-strengthening activity a week, which fits comfortably inside those two sessions.

What the guideline asks for

The HHS guidelines treat strength work as a separate requirement from aerobic activity, which is 150 to 300 minutes a week at moderate intensity or 75 to 150 at vigorous intensity. Muscle-strengthening counts when it works the legs, hips, back, abdomen, chest, shoulders and arms, and when it is done until another repetition would be hard. Weights, machines, resistance bands, body-weight moves and heavy gardening all qualify. Older adults are asked to fold balance training into the same week.

The American College of Sports Medicine's position stand fills in the details for a session: train each major muscle group two to three days a week, two to four sets per exercise, about 8 to 12 repetitions for strength, and 10 to 15 for people who are older or just starting. Leave at least 48 hours between sessions for the same muscle group.

What the long-term data show

The meta-analysis, published in the British Journal of Sports Medicine in 2022 by researchers in Japan, pooled prospective cohort studies of adults without serious illness. Doing any muscle-strengthening activity was associated with a 10 to 17 percent lower risk of death from any cause, cardiovascular disease, total cancer, diabetes and lung cancer, independent of aerobic activity. The dose curve was J-shaped: the benefit peaked at about 30 to 60 minutes a week and was unclear at much higher volumes. For diabetes the curve kept falling up to about 60 minutes a week. No association was found for colon, kidney, bladder or pancreatic cancer. People who did both strength and aerobic work had the lowest risk of all.

The authors declared no competing interests. Because every study in the pool was observational, the results describe associations: people who lift may differ from people who do not in ways the studies could not fully adjust for. The J shape at high volumes rests on few people and should not be read as evidence that more lifting is harmful.

What two sessions can look like

A session that meets both documents can be short. Pick one move for each major area, for example a squat or leg press, a hip hinge such as a Romanian deadlift, a push (push-up or bench press), a pull (row or lat pulldown), an overhead press and a plank. Do two sets of 8 to 12 repetitions each, with a load that makes the last two repetitions hard. That is roughly 25 to 30 minutes, and two of them a week lands in the 30 to 60 minute band the cohort data point to.

For someone lifting once a week now, the meta-analysis suggests the next step is a second short session rather than a longer single one. Progress by adding repetitions first, then load, and keep a log so the next session has a number to beat.

This article reports research and expert guidance. It is not medical advice. Talk to your clinician before changing medication, treatment or a medical diet.

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