Strength training and longevity: half an hour a week, or two?

TL;DR: in June 2026 the British Journal of Sports Medicine published a Harvard study of 147,374 participants followed for up to 30 years. It matched weekly strength-training volume against the odds of reaching the end of follow-up. The odds looked best for people doing 90–119 minutes of strength training a week. At 120 minutes and above, risk stayed below that of people who trained not at all, but no longer declined. That is noticeably more than the "30–60 minutes" we quoted last time — and the disagreement is more instructive than either number.

What was measured

Who: three large US health-professional cohorts — the Health Professionals Follow-up Study, the Nurses' Health Study, and Nurses' Health Study II. 147,374 people in total (31,540 men, 115,834 women), median age 54 at baseline.
How long: up to 30 years of follow-up, 35,798 deaths recorded.
The key difference from earlier work: training was not reported once at entry but repeatedly — every two years in the male cohort, every two to four years in the female ones.

Dose against risk

What fell	Strength dose	Association
Overall risk	90–119 min/wk	−13% (HR 0.87, 95% CI 0.81–0.95)
Heart and vessels	90–119 min/wk	−19% (HR 0.81, 0.67–0.97)
Neurological disease	90–119 min/wk	−27% (HR 0.73, 0.58–0.92)
Cancer	1–29 min/wk	−9% (HR 0.91, 0.86–0.97)
Cancer	30–59 min/wk	−12% (HR 0.88, 0.81–0.97)
Physical-activity-related cancers	1–29 min/wk	−21% (HR 0.79, 0.69–0.90)
Physical-activity-related cancers	30–59 min/wk	−18% (HR 0.82, 0.68–0.99)

Every row is about the risk of dying from that cause over the follow-up years. Estimates are adjusted for aerobic activity. Adjustment removes the most obvious confounding, but it does not turn an observation into proof: residual differences between people and the healthy-user effect do not go away.

Cancer: an association only at low doses

For cancer the association appeared only at low doses — under an hour a week — and lost statistical significance beyond that. Both cancer endpoints behave this way: overall cancer mortality, and the separately counted cancers that the literature links to physical activity. There is no confident explanation: the authors mention a possible role for IGF-1 while stressing the uncertainty.

Two similar endpoints are easy to mix up. In several write-ups following the press release, −21% and −18% (the physical-activity-related cancers) were presented as the figures for cancer overall — where the real numbers are −9% and −12%.

Strength together with cardio

The reference point in every comparison below is people with inadequate aerobic activity (under 7.5 MET-hours a week) and no strength training at all.
The lowest risks belong to people doing both: HR 0.55 at 30 to under 45 MET-hours of aerobic activity a week plus 60–119 minutes of strength work.
But at 45 MET-hours and above, risks were about as low (HR 0.53–0.58) at any level of strength training. At very high aerobic volume, adding strength work changed little.
For scale: the WHO minimum (150 minutes of moderate activity) is about 7.5 MET-hours. The 30-to-45 band is four to six times that; 45 and above is six times and up, with no ceiling.

Why the estimates may disagree

We previously quoted "30–60 minutes a week" from a 2022 meta-analysis. Nobody has compared the two directly, so what follows is plausible explanation rather than established fact:

Most earlier studies measured training once, at baseline. Habits change over twenty years, and a single snapshot blurs the difference between doses — the curve flattens sooner.
Here the measurement was repeated, so the "dose" is closer to an average across the follow-up years.
The studies also differed in their cohorts, their definition of training, and their set of outcomes.

The two studies cannot be merged into a single "longevity dose". A cautious read: an association with lower risk is already visible at half an hour a week, and in the longest study to date the lowest risks landed at an hour and a half to two hours.

What the study does NOT say

These are associations, not established causation. It is an observational cohort: how many years of life strength training adds is something this design did not and could not measure.
The participants are not "average people": mostly white health professionals of middle and older age, 78% of them women.
Training was self-reported on a questionnaire every two to four years.
The questionnaire never asked about working weight, sets and reps, rest between them, or intensity. Ninety minutes is ninety minutes, whatever you did in them.
Calisthenics and Pilates did not count as strength training, so some participants trained more than their reported dose.

What to do on Monday

Two or three strength sessions of 30–45 minutes a week fall inside the band where the lowest risks landed. This study does not make that a "longevity protocol".
People train more than two hours a week for strength, muscle mass, and sport. The data shows no further reduction in risk beyond that.
In this study, combining cardio and strength went with the lowest risk — until aerobic volume gets very high.

Where to find your weekly volume in Spodi

Spodi tracks the duration of every workout, and the activity map shows which muscle groups you haven't trained in a while. The weekly stats show how many strength sessions there were and how long they took.