Grip strength is associated with a range of health outcomes, from type 2 diabetes to depression. Here’s how to check yours.
In a world of technologically-driven longevity clinics with their increasingly sophisticated imaging scans, some of which can cost tens of thousands of dollars, it turns out that one of the best assessments of muscle strength and quality is to simply sit in a chair and squeeze a tennis ball.
That's the recommendation offered by Joshua Davidson, a strength and conditioning researcher at the University of Derby who studies hand grip strength, a metric increasingly recognised as one of the most reliable markers of human health.
When testing grip strength in clinical trials, scientists typically use a hand dynamometer, a device which you squeeze as hard as possible to measure the force generated by the muscles in your hand and forearm. Several companies are now attempting to take the dynamometer out of the clinic and into the home, combining easy-to-use devices with mobile apps to let anyone chart their grip strength over time.
However, according to Davidson, you can still get a decent idea through a simple "squeeze test" with a tennis or stress ball. "All you need is any object that you can grasp and can be deformed without causing pain or discomfort," he says. "Simply squeeze it for as long as you can before your grip fatigues. Being able to maintain a maximal squeeze on something like a tennis ball for 15-30 seconds would be a good standard to strive for." Noting down how long you can squeeze can help you track your grip strength over time.
Back in 2022, Peterson led a study which assessed the grip strength of 1,275 men and women and compared these results to an analysis of their DNA. The team found that those with lower grip strength scores showed signs of accelerated ageing. Specifically, they had differences in their DNA methylation patterns – tags associated with our DNA which can alter the way it is read over our lifetimes. Methylation patterns often change in response to environmental or lifestyle factors, such as obesity, pollution or even social stress, among many other things.
Wrist curls: Improve your grip strength
Begin by sitting with your arms on your lap. Grip a can in your hand, with your palm facing upwards. Then slowly bring the can upwards towards your body, without moving your arm. Hold it there for a second, and carefully lower it back down. With practise, aim to build up to doing five sets of 20 repetitions.
For Paré this is unsurprising, as he says he sees grip strength as a key marker of both disease resilience and likelihood of recovering from chronic illnesses. For example, research in cancer patients shows that those with poorer grip strength are more likely to experience sudden weight loss or cachexia – extreme muscle or fat loss, despite eating normally – and thus worse prognosis and survival outcomes.
"It means that once we have a disease, our ability to fight it is limited," says Peterson. "For example, the risk of dying from a pneumonia is much increased in individuals with lower grip strength, which makes sense considering the importance of good muscular health to properly clear the airways of sputum [the saliva and mucus coughed up from the respiratory tract as a result of infections]."
Grip strength isn't just something to be aware of in later life, either. Researchers have even found that the average grip strength of a population tends to correlate with how many medals a country is likely to win at the Olympic Games. Meanwhile, Paré says that teenagers and young adults who have poorer grip strength are likely to be more prone to health issues at an earlier age. One study in Brazil showed that teenagers who spent more time on their screens, either on their phones or other devices, tended to have worse grip strength.