Strength training benefits may peak at about two hours a week

Adults who did about 90 to 119 minutes of strength training each week had a lower risk of death over long-term follow-up, according to research published in the British Journal of Sports Medicine. BMJ Group said the findings also support combining resistance work with aerobic exercise for stronger health benefits.

The study followed 147,374 participants for up to 30 years using data from the Health Professionals Follow-up Study, the Nurses' Health Study and the Nurses' Health Study II. The research included 31,540 men and 115,834 women, with an average age of 54 at the start.

What the study measured

Participants reported their exercise habits every two years, according to BMJ Group. Aerobic activity included brisk walking, running, jogging, swimming, cycling, tennis, squash, strenuous outdoor work and stair climbing.

Resistance training included weight-based and body-weight exercise, such as press-ups, squats and lunges, BMJ Group said. The researchers then compared long-term exercise patterns with deaths from all causes and from specific causes.

At baseline, participants who reported more strength training tended to be younger, weighed less, had healthier lifestyles and did more aerobic activity than people who reported no strength training, according to BMJ Group. The study also found that 74% of participants exceeded the equivalent of 150 minutes of moderate-intensity aerobic exercise a week, measured as 7.5 MET hours, and 46% reported some strength training.

Risk reductions varied by exercise type

During the follow-up period, 35,798 participants died, according to BMJ Group. After adjusting for other factors, researchers found that people doing 90 to 119 minutes of resistance training a week had a 13% lower risk of death from any cause.

That same weekly range was linked to a 19% lower risk of death from cardiovascular disease and a 27% lower risk of death from neurological disease, BMJ Group said. The researchers did not find extra risk reduction above 120 minutes of strength training a week.

The pattern differed for cancer mortality. BMJ Group said participants reporting 1 to 29 minutes of weekly resistance training had a 21% lower risk of cancer death, while those doing 30 to 59 minutes had an 18% lower risk.

Cardio plus strength showed the strongest pattern

Compared with people who did less than 7.5 MET hours of aerobic activity per week and no strength training, participants who did 1 to 59 minutes or 60 to 119 minutes of strength training had a 7% to 11% lower risk of death, according to BMJ Group. Aerobic exercise above 7.5 MET hours a week was associated with a 26% to 43% lower risk.

The lowest mortality risks appeared among people who combined higher aerobic activity with strength work, BMJ Group said. Participants who logged 30 to 44 MET hours of aerobic activity and 60 to 119 minutes of strength training per week had a 45% lower risk of death.

Among people reporting at least 45 MET hours of weekly aerobic activity, the risk of death was 53% to 58% lower regardless of their strength-training amount, according to BMJ Group.

Limits to the findings

The researchers described the work as observational, meaning it cannot prove resistance training caused the lower mortality risks. BMJ Group said the study also relied on self-reported exercise, which can be inaccurate.

The analysis did not include some activities such as calisthenics and Pilates, according to BMJ Group. The researchers also lacked information on the length and intensity of individual strength-training sessions, which could have affected the results.

This story draws on original reporting from ScienceDaily.