The slowing is gradual enough that most people only notice it by comparison. The walk to the shops takes a few minutes longer. Keeping up with a grandchild on the pavement takes more effort than it used to. Walking speed is one of the most reliable predictors of healthy ageing there is — slower usual pace tracks with higher risk of almost everything — which makes the obvious question worth asking precisely: when a walk slows after seventy, what part of the stride is actually failing? A study published on 2 June in the European Journal of Applied Physiology gives an unusually specific answer [1]. The slowdown is not spread evenly across the whole stride. It concentrates in one place: the push-off at the ankle.
What the study did
The researchers took a three-dimensional gait dataset of 240 healthy adults and looked not at how people walk at their normal pace, but at how much they can change their walk when asked to speed up — the difference between a comfortable stride and a fast one. They broke that capacity to modulate down into its components using a statistical technique that finds the underlying patterns. Three components captured most of what was going on: overall speed modulation, shock absorption as the foot lands, and the propulsion generated at the ankle as the foot pushes off the ground at the end of each step.
Then they checked which of those three faded with age. The answer was clean. Distal ankle propulsion — the push-off — showed a clear negative association with age (a regression coefficient of −0.31, statistically robust). The other two components barely moved. And the decline was not a smooth, linear drift across the decades. It had a threshold quality: people aged seventy and over showed a markedly lower ability to generate that push-off than younger groups, a step down rather than a gentle slope.
Why the ankle, specifically
The push-off at the ankle is the part of walking that costs the most and is asked of the least in ordinary daily life. It is driven largely by the calf muscles, which fire at the end of the stance phase to launch the body forward into the next step. That propulsion is what gives a walk its spring and its speed. It is also the function that quietly atrophies when walks get shorter, slower, and flatter — the calf is rarely challenged by a stroll on level ground, so it fades from disuse on top of whatever ageing does on its own. The study’s authors frame this as mechanistic insight beyond simple gait-speed measurement: knowing that the deficit lives in ankle propulsion tells you where to look, rather than just telling you the person is slower.
The walk does not slow all over. It slows at the push-off — the one part of the stride driven by muscles a gentle stroll never asks much of.
The hopeful part
A deficit with a known location is a deficit you can target. Ankle push-off depends on calf strength and on actually using a brisk, propulsive stride rather than a shuffling one — and both respond to training, including in people well past seventy. This is where pace matters. A walk that never asks for a brisk effort never recruits the push-off the study found fading; a walk that includes deliberate stretches of brisk effort does. The Shinshu University interval-walking trial — 246 middle-aged and older adults over five months — reported a thirteen per cent gain in knee-extension strength and a seventeen per cent gain in knee-flexion strength in the interval group, alongside a nine per cent rise in peak aerobic walking capacity, against a steady-pace comparison [2]. Lower-limb strength and propulsive capacity are precisely the systems a paced walk loads and a flat amble does not.
The takeaway is not to worry about a number on a stopwatch. It is to recognise that the slowing has an address, that the address is trainable, and that the training is not exotic — it is a walk that occasionally asks the legs to push. The push-off you stop using is the push-off you lose. The reverse is also, encouragingly, true.
