At What Age Do You Start Losing Muscle?

Picture a man in his late fifties. He looks fine. A little softer around the middle than at thirty, but he still plays the occasional game of football and carries his own groceries. Then one evening he trips on a broken pavement edge, and for the first time in his life, his leg doesn't get there in time. He goes down hard. Nothing breaks. But something has shifted, and he knows it. His body didn't answer when he called.

Here is the short answer to the question in the headline: your physical capacity peaks somewhere between your late twenties and your mid-thirties, then slides for the rest of your life. But the part nobody tells you is what slides first. It isn't your muscle. It's your power. And power is the thing that catches you when you trip.

How do we actually know when the slide begins?

In the late seventies, researchers in Sweden picked 427 teenagers, all born in 1958, and started measuring them. Lung capacity on a cycle. Endurance on a bench press. Explosive power in a vertical jump. Then they measured the same people again, and again: five rounds of testing stretched over 47 years. The teenagers were 63 by the last round.

When the results were published in 2025, they settled the question for good. Fitness and strength peak at around 35, and the slide starts there, however much you exercise. By 63, the group had lost between 30 and 48 percent of their peak capacity, depending on the measure. Muscle power started fading earliest of all: early thirties in women, a few years later in men.

But the study's best line belongs to its lead author, Maria Westerstahl of Karolinska Institutet: it is never too late to start moving. The people who went from inactive to active in adulthood clawed back 6 to 11 percent of their capacity, at whatever age they started.

So what fades first: muscle, strength, or power?

You may have seen the chart: five declining lines, muscle mass on top, leg power at the bottom, shared all over Instagram. Here it is in motion, from the account that put it together. I am not quoting its exact percentages in this article, because the figures I stand behind come from the published research — but the shape it sketches is confirmed by that research. In the Swedish study, vertical jump, the power measure, had fallen 41 to 48 percent by age 63. Nearly half of peak jumping power, gone before most people consider themselves old.

Read that again. Nearly half of peak jumping power, gone by 63, while muscle mass has faded far more slowly. That gap, between what your muscles look like and what they can actually do, is the whole story.

Here is the number worth sitting with: strength fades two to five times faster than muscle mass. At around seventy-five, mass declines at under one percent a year while strength falls at three to four percent a year. And power, which is force produced quickly, declines earlier and more steeply than either mass or maximal strength, according to a 2026 review in The Lancet Healthy Longevity.

Power is the most practical of the three. It is rising from a low chair without using your hands. Climbing stairs without pausing. The split second when you trip and your leg has to catch you before your face meets the floor. None of those ask your muscles to be big. They ask them to be fast.

And the reason is only partly in the muscle. With age, the wiring changes: motor units shrink, fewer fibres get recruited, the signal slows. The muscle is still there. The message just arrives late.

Why do researchers obsess over your grip?

It sounds almost insulting, the idea that your handshake could predict your lifespan. But researchers pooled 42 long-term studies, three million people in total, and found that weaker grip strength predicts higher all-cause and cardiovascular mortality, independent of everything else they adjusted for.

Nobody cares about your hands, though. Grip is a window into the whole system. It is cheap to measure, impossible to fake, and it tracks the same wiring decline happening everywhere else. When your grip fades, it is rarely just your hands getting weaker.

Grip strength is one of the first things to fade, and one of the most telling. That is not a hand problem. It is a whole-system problem with a convenient handle.

Can you actually push back?

Remember the Swedes. The ones who stayed active kept far more of everything: strength, endurance, power. And the gap between the active and the inactive grew enormous with age. At sixteen the group looked similar. By sixty-three, some had held on and others had collapsed. The difference was what they did in between.

The prescription is unglamorous. Moderate-to-hard strength training, twice a week, whole body, with gradual progression. That is what slows the slide. And here is the encouraging part: training improves strength, power and everyday function even when muscle size barely changes. You do not need bigger muscles. You need better wiring, and wiring answers to training at any age.

But most programmes miss the point. They train strength and ignore power, the very thing falling fastest. So some of your training should be fast: brisk chair stands, step-ups, stair climbs taken two at a time if your knees allow. Slow heavy lifting builds the engine. Fast light movement keeps the reflexes.

What should you actually do about it?

In order of return on effort:

1. Strength train twice a week, whole body, moderate to hard. Legs, pushing, pulling, carrying. If you are new to it, our guide to progressing workouts safely explains how to start without hurting yourself.
2. Add power, not just strength. Once or twice a week, do a few sets of something fast: brisk sit-to-stands from a chair, step-ups, quick stair climbs. This is the training most people over forty are missing entirely.
3. Eat protein at every meal. Muscles need raw material to maintain themselves, and most adults eat less than their muscles would like, especially at breakfast.
4. Walk daily, but do not mistake walking for strength work. Walking is excellent for the heart, the lungs and the habit of moving. It does not load your muscles enough to preserve strength or power.
5. If function is already slipping, read our full piece on sarcopenia. It covers what sarcopenia is, who is at risk, and the complete programme for fighting back at any age.
6. If you are unsure where you stand, get assessed. Our free Self-Assessment asks the same screening questions a physiotherapist would ask and tells you plainly when you should come in.

"By your sixties, nearly half your peak power can be gone. The mirror lies; the staircase doesn't."

The mirror lies about ageing. It shows you the mass, which fades slowly, and hides the power, which fades fast. Train for what the mirror cannot see.

Frequently asked questions

At what age do you start losing muscle?
Muscle mass begins declining in your thirties, slowly at first and faster after sixty. Strength and power fade on a steeper curve than mass itself, which is why everyday function can slip even while you look the same.

Can you build muscle after sixty?
Yes. Resistance training increases strength, power and everyday function at any age, even in people whose muscle size barely changes. The nervous system keeps adapting throughout life.

Is walking enough to stop muscle loss?
Walking protects the heart and keeps you mobile, but it does not load muscles heavily enough to preserve strength or power. You need resistance training, ideally with some fast, powerful movements included.