Bone: the damage you cannot feel

Almost everything that goes wrong from under-fuelling comes back when you start eating properly. Metabolic rate recovers. Cycles return. Training quality returns. Bone is the one that keeps the bill.

It is also the only item on that list with no symptom at all until something breaks.

Why cycles and bone are the same problem

This connection is the reason the older framing put them in one triad rather than treating them as separate issues.

The same mechanism operates in any sport that combines years of weight cycling with low energy availability, which is why this page is also relevant to jockeys.

Everything here applies more from the forties onward, when oestrogen decline accelerates the loss: female athletes over 40.

Menstrual disruption driven by low energy availability produces oestrogen deficiency. Oestrogen is directly involved in bone metabolism: it restrains the breakdown side and supports the building side.

Remove it and the balance tips toward loss.

So a fighter with irregular or absent cycles is not having a reproductive problem that happens to occur alongside a skeletal one.

She is having one problem with two visible faces, and only one of those faces is visible at all.

The finding that runs the other way

Before the warnings, something that should be said first, because it is genuinely good news and it is rarely mentioned.

Combat sports athletes generally show higher bone mineral density than endurance athletes and than untrained comparison groups. Judo, wrestling, taekwondo and boxing all appear in this pattern. Studies in young female judo and taekwondo athletes have found higher density at the lumbar spine and femoral neck than in runners and swimmers of the same age.

The reason is the loading. Impact, weight-bearing work, throwing, being thrown, and resistance training are all osteogenic. The sport itself builds bone, and it does so more effectively than most of the activities people think of as healthier.

Elite judoka show both elevated bone density and elevated bone formation markers. Short periods of weight cycling shift the balance temporarily toward resorption, and the density holds anyway, because the training stimulus is doing more than the cycling is undoing.

What overturns the protection is prolonged low energy availability and disrupted menstrual function, sustained long enough that the hormonal environment stops supporting the bone the training is trying to build. One hard camp rarely does it.

Which is why the monitoring described further down this page is about cycles and energy rather than about bone directly.

By the time density has fallen, the thing that caused it has been running for a long time.

The picture in female combat athletes specifically follows the same pattern. Studies of women in boxing, MMA, judo and wrestling report bone density above sedentary comparison groups and above many endurance athletes, at the whole body and at the sites that matter most, the lumbar spine and the femoral neck.

The explanation is the same combination: impact, resistance loading and comparatively high lean mass.

What removes the advantage is also the same, and it is the reason this page does not end here.

Low energy availability, disrupted menstrual function and repeated hard cuts, sustained together, can cancel out what the training built.

What a stress fracture actually means

In a female athlete with irregular cycles, a stress fracture is a signal about energy availability that arrived through the skeleton because every earlier signal was missed or dismissed, and treating it as a plain training-load problem misses that.

Prolonged menstrual dysfunction has been linked to increased incidence of musculoskeletal injury, and stress fractures sit at the centre of that.

Which changes what should happen next. A physician needs the cycle history and the training history together, not just the imaging.

Treating the bone and returning to the same energy availability produces the same outcome again, in a different bone.

The window that closes

Bone density is built earlier in life than most athletes realise, and the years in which a young fighter is competing are also the years in which peak bone mass is being laid down.

That overlap is the whole argument in weight cutting under 18.

Which makes this a particular concern for anyone making weight in the teenage years. Deficits accumulated then cannot simply be corrected later, because the opportunity to build was itself the thing that was lost.

That is worth saying to coaches of junior athletes more than to anyone else on this page.

What supports bone, in order

Adequate energy availability, first and by a distance. Nothing further down this list compensates for a shortfall. Supplements do not fix a deficit; they fill gaps in an otherwise adequate diet.

Calcium and vitamin D at adequate intakes. Worth checking rather than assuming, particularly for athletes training indoors through a winter, and particularly where dairy has been cut for energy reasons during camps.

Loading, which this sport provides. Impact and resistance work stimulate bone. Combat sports do this well, and it is one of the few structural advantages the sport has here.

Protein. Bone is not only mineral. Adequate protein supports the matrix that the mineral sits in.

Where the evidence thins out

Most of what is known about bone in this context comes from endurance athletes, from mixed cohorts, and from the general female athlete literature rather than from combat sports specifically.

There is no good body of work on bone density in professional female boxers or mixed martial artists across a career of repeated weight cycling.

That study has not been done, and it is one of the more important gaps in this whole field.

So what follows is read across, and I would rather say so than present borrowed certainty.

What I would put in front of a doctor

Three things, together, because separately they each look like nothing.

• Cycle history across the past 6 to 12 months, including which camps coincided with changes
• Training and competition load over the same period
• Any bone injury, including ones that were dismissed as shin splints or a niggle that resolved

A physician looking at those three together can see a pattern that none of them shows alone. A physician hearing "I've had a sore shin" cannot.

The tracking sheet in the guide exists for exactly this, and an appointment is where it earns its keep.

The reason I put this article last

Because it is the one with the least urgency and the most consequence, and those two things almost never occur together.

Nothing on this page will affect how you feel next week. It affects whether you are still competing at 34, and whether the years after that are comfortable.

Fighters are excellent at enduring things that hurt now. This is the opposite problem: a cost that never hurts until it is already paid.

On the supplement side of the same picture, including why athletes who manage their weight are flagged as a risk group, see vitamin D.