Could the strength of your handshake be a better indicator of how long you’re going to live than your blood pressure?
With the growing popularity of measuring biological age, it’s often the sciencey-sounding tests that get the headlines. But a humble grip-strength measuring device (a dynamometer) gives the blood tests and epigenetic clocks a run for their money.
The principle is simple: you squeeze as hard as you can (much harder than I’d actually recommend for a handshake) and the device gives you a reading in kilograms. If you perform well for your age, that bodes well for your future healthspan and lifespan generally.
The effectiveness of grip strength is one reason why strength training is having a moment. Traditionally seen as the preserve of iron-pumping gym bros, it’s increasingly being emphasised for everyone from diabetes sufferers and patients undergoing cancer treatment, to people just trying to optimise their healthy longevity.
Adding weight to the case for strength training are massive ‘cohort studies’, where scientists follow large groups of people for decades, watching what they do, what they eat and more, and then correlating that with what ails and eventually kills them.
A recent study of retired healthcare professionals in the US found that participants who exercised lived longer – and that the optimal combination was a mixture of cardio and strength training.
The researchers found that 1.5–2 hours a week of strength training was associated with a 13 per cent lower risk of death. That figure was even higher when looking at specific diseases: a 19-per-cent reduction in risk for death from heart disease, and 27 per cent for neurological diseases like dementia.
Even better, this stacks with cardio – unless you’re already in the most active cardio group (people running about five hours a week, or walking for ten), adding some strength training can make you live longer.
What makes muscle so important
So why might lifting heavy weights help increase your lifespan? Well, that’s actually the first myth about strength training: the weights don’t need to be heavy.
They don’t even need to be the plates and bars you find at a gym. Strength training is something you can do at home: bodyweight exercises such as planks, sit-ups and squats are a great way to get started.
More on that later, but first, some biology. Skeletal muscle is usually the body’s largest organ: it makes up around 30–40 per cent of body mass in a healthy adult. (It’s called ‘skeletal’ because it’s the muscle attached to our bones that exercise can affect.)
Looked at that way, it’s not surprising that muscle can have such a big effect on our health and how we age.
Muscle is critical for gobbling up glucose – the sugar found in our blood after a meal. Indeed, around 80 per cent of post-meal glucose is locked away in your skeletal muscles.
If you’ve seen the hype online about trying to avoid ‘glucose spikes’ after eating, one of the best hacks is to have more, and more efficient, glucose-absorbing muscles.
And there’s good evidence that exercise can help: if you have diabetes, which means your blood glucose tends to be higher, strength training can reduce it – and, the stronger you get, the more it’s reduced.
One study even found that strength training was better than cardio for blood sugar in diabetes though, in general, it seems both are important.
It’s an open question whether people without diabetes should worry about glucose spikes, but building muscle is one of the better hacks out there and comes with a range of other benefits too.
Skeletal muscle also secretes a lot of signalling molecules known as ‘myokines’. Again, because it’s our biggest organ, these secretions seem to matter.
For example, exercised muscle secretes a molecule called interleukin 6 (IL-6), which is usually associated with inflammation, but, in this context, seems to be anti-inflammatory.
IL-6 also reduces the amount of visceral fat – the type associated with diabetes and accelerated ageing. There’s even been a trial showing this: exercise reduced visceral fat, but not if participants were given a drug that blocks the action of IL-6.
There are also myokines that influence the brain, liver, skin and bones, and this may be one of the ways that exercise can have positive effects on our biology beyond our muscles and cardiovascular system.
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How muscle can help your bones
Speaking of bones, strength training can strengthen them, too. This is particularly important for women because, after the menopause, a woman’s changing hormones can cause significant loss of bone density and strength.
Resistance exercise can help counter that loss: the delightfully named LIFTMOR trial gave women in their 60s with low bone mass either eight months of supervised high-intensity resistance and impact training twice a week, or low-intensity home exercise.
The people in the former group significantly increased bone density in two key areas: the lower spine and the head of the femur (where your leg connects to your hip). A similar trial in men found that guys can benefit too.
The reason that this is so critical is because falls resulting in broken hips are a huge cause of ill health and even death in older people. Where a young person might shrug off a fracture after a month in a cast, an older person who breaks their hip has a 15–30-per-cent chance of dying within a year.
But exercise can help reduce this risk. Training balance can make it less likely that we fall in the first place, but functional and strength training can improve both muscles and neuromuscular connections, giving us the speed and strength to react.
Better still, stronger bones mean that a fall is more likely to result only in injured pride and not a break.
How to start building muscle
It’s almost a shame skeletal muscle mass is so important, because, starting in our late 30s, we lose 0.5–1 per cent of it each year. That might not sound like much but, over decades, this can result in significant losses.
Strength drops around 2–5 times faster than muscle mass and, by age 75, we’re losing 2–4 per cent of it per year.
The good news is, resistance training can help, and it’s never too late to start: one study gave an eight-week strength training programme to a small group of 90-somethings in a nursing home (the oldest was 96).
Their strength almost tripled, their leg muscles grew by about 10 per cent, and their walking speed increased by 50 per cent.
It can even help people who are very seriously ill: exercise is now a recommended part of cancer treatment, easing fatigue and improving quality of life during chemo- and radiotherapy.
The other piece of good news is we don’t need overwhelming amounts to make a difference: the benefits climb steadily with the amount you do, then plateau at around two hours a week, so there’s no need to overdo it.
You don’t even need to hit the gym: the NHS's strength routine is built around a chair, a wall and a couple of filled water bottles. A few things to try:
- Sit-to-stand: Fold your arms across your chest and stand up from a chair and sit back down using just your legs. This isn’t just exercise: if you count how many of these you can do in 30 seconds, it’s a measure of frailty.
- Wall sits: slide your back down a wall into a seated position and hold that position. This is one of several ‘isometric’ static holds that are good for lowering blood pressure.
- Biceps curls: With a filled bottle in each hand, curl slowly up to the shoulder and back down. You can graduate to dumbbells when you’re ready, but starting light with slow movements can still build muscle strength.
While strength training is definitely having a moment, it’s also important to maintain a diversity of exercise.
The same study showing that strength training reduced risk of death found that aerobic exercise can do much of the heavy lifting, and other studies have found that a mixture of exercise types is most beneficial.
That’s because, while longevity literally just means how many years we live, what matters more is our healthspan, which encompasses lots of different things: freedom from disease, but also strength, balance, stamina, bone density and more.
Grip strength is a great example: it would be all too easy to read about its importance, and then decide to spend the ages squeezing those grip strengthener things to optimise it. But that’s just training to the test.
Grip strength is a great predictor of mortality not because strong hands directly influence your risk of cancer or dementia, but because having a generally healthy, fit, strong body protects you from many age-related problems, and improves your grip as a side-effect.
There’s also a more pragmatic point: enjoying a buffet of varied activities probably makes it easier to stay active over decades, rather than smashing out the same reps at the gym every year.
The best longevity drug we have isn’t a drug. It's whatever exercise you'll still want to be doing 20 years from now.
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