Why walking is not enough for your bones

If you have had a bone density result come back lower than you wanted, you have probably been told to walk more.

It is sensible-sounding advice and it is not useless. But if the goal is to build bone rather than hold on to what you have, ordinary walking is not the thing that does it.

What bone actually responds to

Bone responds to load. Not to steps, not to a supplement on its own, and not to gentle movement.

Habitual walking, at the pace most of us actually walk, sits at around four kilometres an hour. At that pace it is a maintenance-level stimulus. It is not associated with meaningful bone density change at the femoral neck in older adults.

Walk faster, at five or six kilometres an hour, or add running or jumping, and the picture changes. Those do show bone density increases in postmenopausal women. The difference is not the walking. It is the size of the load going through the bone.

Why this gets urgent around menopause

Oestrogen does a specific job in bone that is worth understanding, because it explains the timing.

Bone is not static. It is constantly being broken down and rebuilt by two sets of cells working against each other. Oestrogen acts as a brake on the cells that break bone down.

At menopause that brake comes off. The breaking-down side speeds up, it starts outpacing the rebuilding side, and the result is the rapid bone loss seen in the first five to ten years after menopause. That mechanism is well established and not in dispute.

Which is exactly the window in which most women are told to take it easy.

The LIFTMOR trial

In 2018 a trial called LIFTMOR was published in the Journal of Bone and Mineral Research. It matters because it tested the thing everybody assumes is dangerous.

Postmenopausal women with low bone mass, a T-score below minus one, were randomly assigned to one of two programs for eight months. One group did a low-intensity exercise program at home. The other did supervised high-intensity resistance and impact training: twice a week, thirty minutes, five sets of five reps at over eighty five per cent of their one-rep maximum, plus jumping.

That is genuinely heavy lifting, in exactly the population most often warned off it.

The heavy group came out with significantly greater improvements in bone density at both the lumbar spine and the femoral neck, plus better bone geometry and better physical function, than the low-intensity group.

The trial also reported it was safe. No serious adverse events, in a group many clinicians had assumed was too fragile to lift.

What LIFTMOR did not prove

I want to be straight about the limits, because this study gets oversold and that does nobody any good.

It was a relatively small, single-site trial. It ran eight months, not years. It was supervised throughout, which is not the same as somebody working alone in a gym. And the women in it had already volunteered for a heavy-lifting study, which makes them an unusually motivated group.

Most importantly, it measured bone density, bone geometry and function. Those are surrogate markers. It did not measure fractures. So LIFTMOR shows heavy resistance training improves the markers associated with fracture risk. It is not proof that it prevents fractures, and anybody telling you it is has gone further than the evidence.

There is also honest disagreement about how heavy is heavy enough. LIFTMOR used loads above eighty five per cent. Some research suggests considerably lighter work can help if the effort is high. The strongest and most repeated signal comes from the heavier end, but the minimum effective dose is genuinely still argued about.

What this means here

It is the reason nobody here is handed light dumbbells and a set of repetitions to get through.

It is also the reason the first session is a screening. Loading a body properly requires knowing what that body can currently tolerate, and that is not something you can guess at from a form. You build the capacity to lift heavy safely. You do not start there.

If you have diagnosed osteoporosis, talk to your doctor. Training is not a replacement for medical treatment and I would never position it as one. Bring me into the conversation alongside them, not instead of them.