Scientists find the strength training “sweet spot” for a longer life

Strength training has long been seen as something you mainly do to build muscle or look good. But a new study adds to a growing body of evidence that shows lifting weights does far more than change how we look. It may help us live longer – even if you don’t spend hours each day in the gym.

The study drew on three long-running US studies that followed nearly 150,000 nurses and other health professionals for up to 30 years. Every couple of years, participants reported how much time they spent on strength training and aerobic exercise such as walking, cycling and swimming. Over the three decades almost 36,000 of them died, which let the researchers track how muscle-strengthening activity related to the risk of dying early.

They found a clear sweet spot. People who did around 90 to 120 minutes of strength training a week – or roughly an hour and a half to two hours – had about a 13% lower risk of dying from any cause than those who did none.

The benefit of strength was strongest for two of our biggest killers: a 19% lower risk of dying from cardiovascular disease (which includes heart disease and stroke) and a 27% lower risk of dying from neurological conditions, mainly dementia.

Interestingly, more wasn’t necessarily better. Beyond about two hours of weightlifting a week, risk didn’t fall any further.

The lowest risk of all was seen in people who paired strength training with regular aerobic exercise – measured across everyday activities such as walking, jogging, cycling and swimming. Doing at least the recommended amount of moderate aerobic activity (around 150 minutes a week) was on its own linked to between a 26% and 43% lower risk of death.

But combining plenty of aerobic activity with one to two hours of strength training brought the risk down furthest of all – by around 45%. Aerobic exercise still did most of the heavy lifting, but the two clearly work best together, not as rivals.

There was one exception to the pattern: for cancer deaths, only smaller amounts of strength training (under an hour a week) were linked to lower risk.

Muscle and mortality

So why would weightlifting help us live longer? The answer lies in muscle – and what muscle actually does, beyond simply helping us move around.

Muscle, specifically the skeletal muscle we build through resistance training, is one of the body’s most metabolically active tissues. After a meal, it’s where most of the sugar, or glucose, in our blood is sent. Insulin, the hormone released when we eat, signals muscle to absorb glucose from the bloodstream, and it mops up around 80% of it – either burning it for energy or storing it as glycogen, a ready fuel reserve, rather than letting it circulate or be stored as fat.

Keeping muscle strong and plentiful therefore helps the body manage blood sugar and protects against type 2 diabetes, itself a major driver of heart disease and early death.

Muscle is also an organ in its own right. When muscles contract, they release hormone-like messengers called myokines into the bloodstream. These help to dampen the chronic, low-grade inflammation that quietly underlies heart disease, diabetes and many cancers.

Myokines also allow muscle to communicate with the liver, fat tissue, blood vessels, bone and even the brain. They send out signals that influence how those organs burn fuel, control blood flow and stay healthy. In effect, every time we use our muscles, they release a burst of chemical signals that benefit the rest of the body.

The heart and circulatory system benefit too. Over time, regular resistance training can help lower blood pressure and keep arteries flexible rather than stiff, which protects against cardiovascular disease.

Strength itself is also a remarkably good barometer of health. Grip strength – how hard you can squeeze with your hand – is widely used as an indicator of whole-body strength. In one large international study, grip strength predicted the risk of dying early even more accurately than blood pressure. Stronger muscles also mean fewer falls and fractures, more independence in later life and less frailty as we age – all of which shape how long, and how well, we live.

The link between strength training and brain health is newer and less certain, but plausible. Resistance training appears to drive beneficial changes in the brain. The same improvements in blood sugar and blood vessels that protect the heart are also tied to a lower risk of dementia. That may help explain the 27% drop in deaths from neurological disease the study found.

It’s worth being clear about what this study can and can’t tell us. It was observational, so although it can show a strong link between strength training and a longer life, it can’t prove that one directly causes the other.

People who lift weights may be healthier in other ways, though the researchers adjusted for many such factors, including diet, smoking and aerobic activity. Strength training was also self-reported, and the study couldn’t capture how hard people trained.

The encouraging message is that the amount linked to a longer life is genuinely achievable. You don’t need a gym membership or a heavy barbell, either. Two short sessions a week where you work all the major muscle groups, alongside some aerobic exercise each day, appears to be plenty when it comes to improving your overall health and longevity.

Reporting from ScienceDaily contributed to this story.