Clocking up 90 to 120 weekly minutes of strength (resistance) training may be the sweet spot for lowering the risk of death, suggests a 30 year study, published online in the British Journal of Sports Medicine.
The effects were amplified by the addition of aerobic exercise, but no further benefit was apparent above 120 minutes a week of strength training—an amount that was specifically associated with, respectively, 19% and 27% lower risks of dying from cardiovascular and neurological diseases.
The benefits of aerobic physical activity on lowering the risk of death are well known, but less clear is the role of muscle strengthening exercise in reducing the risks of death from all and specific causes, solely or jointly with aerobic exercise, say the researchers.
To explore this further, they drew on 30 years of monitoring data from 3 large groups of study participants: the Health Professionals Follow-up Study, 1992–2022 ; the Nurses' Health Study, 2002–21 ; and the Nurses' Health Study II, 2003–21 , comprising a total of 147,374 participants (31,540 men and 115,834 women).
Participants were quizzed every 2 years on the amount of time they spent on strength training and aerobic exercise every week for up to 30 years. Aerobic exercise included brisk walking, running, jogging, swimming, cycling, tennis, squash, strenuous outdoor work and stair climbing, while strength training included exercises using weights or body weight, such as press ups, squats, and lunges.
The average age of participants at study entry was 54. Those who clocked up more strength training tended to be younger, weigh less, have a healthier lifestyle, and do more aerobic exercise than those who did no strength training.
Three quarters (74%) of participants did more than the recommended 150 minutes/week of moderate intensity aerobic exercise, measured as 7.5 MET hours over the long term. METs express the amount of calories expended per minute of physical activity, relative to calories expended at rest. And nearly half (46%) of participants did some strength training.
During the 30 year monitoring period, 35,798 study participants died. A higher weekly long term level of strength training was associated with a lower risk of death.
After adjusting for potentially influential factors, 90–119 minutes/week of strength training was associated with a 13% lower risk of death from any cause, with no further benefit observed above 120 minutes/week.
And 90-119 weekly minutes of strength training was specifically associated with a 19% lower risk of dying from cardiovascular disease, and a 27% lower risk of dying from neurological disease.
A reduced risk of cancer was seen only at lower levels: 1–29 mins/week (21% lower) and 30–59 mins/week (18% lower).
Compared with those participants with fewer than 7.5 MET hours/week of aerobic exercise and no strength training, those doing 1–59 and 60–119 mins/week of strength training alone had a 7–11% lower risk of death.
Aerobic activity alone at any level above 7.5 MET hours/week was associated with a 26–43% lower risk of death.
And the lowest risk was observed among those with both high aerobic activity and strength training levels every week: 45% lower risk for 30-44 MET hours/week of aerobic exercise plus 60–119 mins/week of strength training, and 53%-58% lower risks among those with 45+ MET hours/week of aerobic activity, irrespective of strength training level.
This is an observational study, and as such, no firm conclusions can be drawn about cause and effect. And the researchers acknowledge various limitations to their study.
These include the self reported nature of the data; the exclusion of strength training activities, such as calisthenics and Pilates; no information on the duration of each exercise session or the intensity of strength training, any or all of which might have influenced the findings.
Nevertheless they conclude: "Our findings on different dose-response relationships between long-term resistance training with all-cause and cause-specific mortality suggest that different amounts of resistance training may be needed to optimise benefits across outcomes.
"The observed pattern that adding resistance training further reduced mortality risk across all levels of aerobic activity up to 45 MET hours/week supports current recommendations encouraging both types of activity to maximise mortality benefits."
