How much strength training is enough for longevity?

Momma and colleagues pooled 16 prospective cohort studies that asked people about muscle-strengthening activity and followed them for deaths and disease (Momma 2022). Against doing none, doing any went with a relative risk of all-cause mortality of 0.85, about 15% lower. That figure came from 7 studies and 263,058 people.

The same comparison gave 0.83 for cardiovascular disease, 0.88 for total cancer and 0.83 for diabetes. A relative risk of 0.85 means the rate was 85% of the comparison group’s. Like a hazard ratio, it is relative: it says nothing on its own about how large your absolute risk is.

The dose-response analysis found the lowest all-cause risk, a relative risk of 0.83, at about 40 minutes a week. In practice, 40 minutes is two sessions of 20 minutes, or one longer one. Risk stayed below the no-training baseline up to about 140 minutes a week. Above that the curve rose again, the J-shape that gets reported as "too much lifting is bad for you".

It does not show that. The shape at high volumes is uncertain, and it is not evidence of harm from more training.

Combining the two matters. People who did both strength and aerobic activity had a relative risk of cardiovascular death of 0.54 against people who did neither. The WHO’s 2020 guidelines recommend both: 150–300 minutes of moderate aerobic activity a week, or 75–150 vigorous, plus muscle strengthening (WHO 2020).

Not very far. Every study in the pool relied on people reporting their own training, mostly in US cohorts. The all-cause estimate had high heterogeneity (I² 83%), meaning the studies disagreed with each other a lot. The GRADE rating for all-cause mortality, a standard grade of how certain the evidence is, was very low.

There is also residual confounding. People who lift weights may differ from those who do not in income, diet, smoking and health, and adjustment never removes all of that. These are associations. Nobody was assigned to train for 40 minutes a week and followed for death.

So the honest reading is narrow. Doing some strength training is linked to living longer, the link is fairly consistent across outcomes, and the shape suggests most of it comes with a modest weekly amount. The exact minutes are not known.

The firmer evidence is about strength itself, from training studies. A meta-analysis of 47 studies and 1,079 people aged 50 and over found that resistance training raised strength by 29% on the leg press, 24% on the chest press, 33% on knee extension and 25% on the lat pull-down (Peterson 2010). Absolute gains ranged from 9.8 to 31.6 kg, and higher intensity gave larger gains. Some included studies were not randomised.

At the far end of life, ten nursing-home volunteers aged about 90 did eight weeks of heavy training, and nine finished (Fiatarone 1990). Their strength rose 174% on average, mid-thigh muscle area by 9.0% and tandem gait speed by 48%. It is a tiny study with no control group. It makes one point well: strength stays trainable very late.

Ageing wears down physiological safety margins, moving people towards the thresholds where everyday movement becomes hard (Young 1997). Near a threshold, small changes in capacity matter a lot; well above it, they matter little.

The researchers who followed 6,089 men of the Honolulu Heart Program for 25 years describe good midlife strength as giving "a greater safety margin above the threshold of disability". Men in the lowest grip third in midlife had 2.87 times the odds of walking very slowly decades later (Rantanen 1999). In 409 adults aged 60–96, leg strength was unrelated to gait speed in the stronger people and related to it in the weaker ones. Training in midlife is a way of building that margin before you need it. That is reasoning from observational data, not a tested promise.

Longstanding does not prescribe a weekly strength dose, because the evidence for any particular dose is weak. When a test is behind its line, the app suggests one short cue for it, a few minutes added to what you already do. There is no program to buy.

What the app can show is whether training is working. Re-testing every 13 weeks, it plots each strength test against the line you need for your age-85 goal and, once you have two results, how fast the gap is closing. A line that is behind is not a verdict; the trials above say strength responds at every age. The app cannot say that closing the gap adds years, and it does not.

If you have a heart condition, joint problems or have not trained before, talk to a clinician before starting heavy lifting. This is not medical advice.