Spending just 30-60 minutes a week on muscle strengthening exercises could be enough to significantly reduce your risk of dying, according to a new study – even with no extra cardio exercise like running or cycling added in.
Based on an analysis of 16 previous studies, covering up to 25 years of research and sample sizes up to nearly 480,000 people, muscle strengthening activities were associated with a 10-20 percent lower risk of death from all causes. The risks of cardiovascular disease (CVD), diabetes, and cancer were particularly affected.
While this link has been reported on before, in this case the scientists wanted to see if there was a sweet spot in terms of how much muscle building activity would be best in terms of reducing mortality risk.
What they found was that the benefits of muscle strengthening for more than an hour a week aren't quite as clear when compared with various causes of death – here the curve tends to be J-shaped, so the change in risk is less noticeable over that 60-minute mark.
"Muscle strengthening activities were inversely associated with the risk of all-cause mortality and major non-communicable diseases including CVD, total cancer, diabetes, and lung cancer," the researchers write in their paper.
"However, the influence of a higher volume of muscle strengthening activities on all-cause mortality, CVD, and total cancer is unclear when considering the observed J-shaped associations."
As always with studies like this, it's important to be cautious about assuming causation. The research highlights a link between muscle strengthening exercises and longer life, but there's not enough data yet to say these exercises directly cause that longevity.
There might be some other factor involved that will need further research to reveal – something that means people stay healthy for longer but also gives them more time and opportunity to work out regularly.
Previous studies have associated muscle strengthening activities with skeletal muscle strength, and skeletal muscle strength with a lower mortality risk, so that could be one of the reasons why this association is showing up.
Guidelines from the World Health Organization (WHO) already recommend that adults should carry out muscle strengthening exercises at least two days a week: think squats, push ups, lifting weights, and even some serious gardening (digging and shoveling).
It's accepted that these exercises are generally good for you, but the 30-60 minute time frame gives us a new perspective on them.
One of the questions that remain is how much impact cardio exercises have when done in tandem with muscle strengthening ones. Here, when the team looked at three studies that combined them both together, it was found to lower the risk of death by 40 percent over the pooled samples.
Most of the studies used were carried out in the US, the researchers report, and used observational rather than clinical approaches. What's more, only a handful of studies could be combined for each outcome. These are limitations to bear in mind when it comes to any future research.
"The combination of muscle-strengthening and aerobic activities may provide a greater benefit for reducing all-cause, CVD, and total cancer mortality," write the researchers.
"Given that the available data is limited, further studies – such as studies focusing on a more diverse population – are needed to increase the certainty of the evidence."
The research has been published in the British Journal of Sports Medicine.