How much strength training is enough? A large, long-running Harvard study offers a specific answer: 90 to 120 minutes a week, and not much more.
What the study found
Researchers drew on three decades of data from 147,374 adults enrolled in the Health Professionals Follow-up Study and the Nurses' Health Study cohorts, publishing their findings June 2 in the British Journal of Sports Medicine. Participants who did 90 to 120 minutes of strength training per week had a 13% lower risk of death from any cause compared with those who did none, according to the Harvard T.H. Chan School of Public Health. The same group showed a 19% lower risk of dying from cardiovascular disease and a 27% lower risk of death from neurological diseases such as Alzheimer's and Parkinson's.
"A moderate amount of strength training each week could boost longevity."
Harvard T.H. Chan School of Public Health
More isn't necessarily better
The benefit plateaued at around two hours a week — people who lifted weights well beyond 120 minutes didn't see additional mortality-risk reduction, according to ScienceDaily's coverage of the findings. The biggest reduction in mortality risk was seen among participants who combined roughly 150 minutes of weekly aerobic exercise with 90 to 120 minutes of strength training, outperforming either type of exercise alone.
The researchers note the study is observational, meaning it shows an association rather than proof that strength training alone causes people to live longer. Still, with such a large sample tracked over so many years, the findings add weight to public health guidance that already recommends two or more days of muscle-strengthening activity per week.