Training · Ageing
You lose the capability faster than you lose the tissue
Muscle mass declines slowly with age. Strength declines several times faster than mass, and power, meaning the ability to produce force quickly, faster than strength. That gap is the single most useful fact on this page, because it explains why a person can look unchanged on a body composition scan while steadily losing the things that scan is supposed to stand for.
It also explains why the mortality cohorts keep finding that strength predicts and muscle size does not. They are not measuring the same thing, and they come apart with age.
What has been measured
randomised
In frail 87 year olds, strength more than doubled while muscle size barely moved
Measured in
100 frail nursing home residents, mean age 87.1 and ranging to 98, randomised to progressive resistance training, a nutritional supplement, both, or neither, for 10 weeks, with 94% completing
Muscle strength rose 113% in those who trained against 3% in those who did not. Gait velocity rose 11.8% while declining in non-exercisers, and stair-climbing power rose 28.4% against 3.6%. Thigh muscle area changed 2.7% against minus 1.8%, which did not reach significance at p = 0.11. The nutritional supplement on its own did nothing to any primary outcome.
HumanExercise training and nutritional supplementation for physical frailty in very elderly people (1994)What this does not show
That the tissue did not change at all, since ten weeks is short and the trial was not powered for muscle area. What it demonstrates, inside a randomised trial in the frailest population anyone has tested, is that the strength and the size came apart. Function more than doubled while the muscle got barely bigger, which is the same lesson the mortality cohorts teach from the other direction.
randomised
Four days of not using a leg, and the older men had not recovered a week later
Measured in
11 young men averaging 24 years and 11 older men averaging 67, all recreationally active and healthy, given 4 days of lower limb disuse followed by 7 days of active recovery, with strength and rate of force development measured throughout
Four days is nothing: a bad flu, a minor injury, a long trip. It was enough to reduce mechanical muscle function in both groups, and after a week of active recovery the younger men had returned to baseline while the older men had not.
HumanAging impairs the recovery in mechanical muscle function following 4 days of disuse (2014)What this does not show
A large study, at 11 men per group, and these were healthy recreationally active people rather than anyone frail. The asymmetry it points at is the practical thing: the cost of ageing here is not that older muscle is lost faster during a short lay-off, it is that it comes back more slowly afterwards.
The trial that should be better known than it is
In 1994 a team put 100 frail nursing home residents, average age 87 and the oldest 98, through ten weeks of progressive resistance training. Their strength rose 113%. The comparison group changed by 3%. Gait velocity improved, stair-climbing power improved by 28%, and 94 of the 100 finished.
Two details in that result deserve more attention than the headline. The first is that thigh muscle area moved 2.7% and did not reach statistical significance. In the most cited training trial in the frailest population anyone has studied, strength more than doubled while the muscle got barely bigger. Whatever more than doubled, it was mostly not tissue: it was the nervous system learning to use what was already there.
The second is the arm everyone forgets. The trial also tested a nutritional supplement, on its own and alongside the training. Alone, it did nothing to any primary outcome. That is one trial, and it is a pointed one for a field that sells a great deal of protein powder to older adults on the premise that the powder is the intervention.
Why a bad fortnight matters more at seventy
Four days of disuse is a moderate flu, a sprained ankle, or a long stretch of sitting after a procedure. In a study that gave exactly that to young and older men and then gave them a week to recover, both groups lost mechanical muscle function and only the younger group got it back.
That asymmetry is worth building a habit around. The risk in later life is not a single dramatic decline, it is a series of small interruptions each followed by an incomplete recovery, with the floor slightly lower every time. Which makes the practical priority less about the perfect programme and more about how quickly somebody starts moving again after each interruption.
Questions people ask about this
- How much muscle do you lose with age?
- Less than you lose in capability, which is the important part. Longitudinal studies consistently find strength declining several times faster than muscle mass does, so a person can look much the same on a scan while losing a great deal of what the muscle could do. Power, meaning force produced quickly, falls faster still.
- Is it too late to start in your eighties?
- The trial that settled this enrolled 100 nursing home residents with a mean age of 87, ranging up to 98. Ten weeks of progressive resistance training more than doubled their strength, improved gait velocity and stair-climbing power, and 94% of them finished the study.
- Does a protein supplement help without training?
- In that same trial, the nutritional supplement given without exercise did nothing to any primary outcome. That is one trial in one population, and it is a pointed result: the supplement alone did not reduce weakness or frailty, and the exercise did.
- Why does a short illness set older people back so much?
- Recovery, more than loss. In a study comparing young and older men through four days of disuse and a week of recovery, both groups lost mechanical muscle function, and the younger men were back to baseline after the recovery week while the older men were not. The lay-off costs both groups something. Getting it back is what changes with age.
- Should older adults train for strength or for power?
- Power is the faster-declining quality and the one that predicts fractures independently of bone density, which argues for training that includes moving a load quickly rather than only moving it. That reasoning runs ahead of the trial evidence comparing the two approaches for hard outcomes, and we would rather say so than imply it is settled.