Strength training and health: even 30 to 60 minutes a week makes a difference

Working your muscles regularly does more than shape your body. Japanese researchers led by Haruki Momma pooled 16 cohort studies that followed adults for years, publishing their analysis in the British Journal of Sports Medicine. People who did muscle-strengthening activities – with dumbbells, machines, bands or their own body weight – had a 15 percent lower risk of dying during follow-up. Their risk of cardiovascular disease was 17 percent lower, of cancer overall 12 percent lower and of diabetes also 17 percent lower.

The dose is striking: the greatest benefit – a risk reduction of roughly 10 to 20 percent – appeared at around 30 to 60 minutes of strength training per week. Beyond that, the association with mortality, cardiovascular disease and cancer did not get stronger; the researchers describe a J-shaped curve and consider the effect of very high volumes unclear. The difference was largest when strength and aerobic training were combined: the risk of death was then 40 percent lower than among people who did neither.

The study's limits: the data are observational, training time was mostly self-reported, and most studies came from the United States – so cause and effect cannot be separated with certainty, and the authors rate the certainty of evidence as very low. Independently of this, the World Health Organization recommends that adults strengthen all major muscle groups on two or more days a week, on top of at least 150 minutes of moderate aerobic activity. Anyone with pre-existing conditions or who has been inactive for a long time should discuss getting started with a doctor.