Bone: A Case Study in Conditional Protection

The benefit accrues to the skeleton that was loaded, not to the skeleton generally.

This matters most for anyone whose sport was non-impact. Cycling, swimming and rowing build extraordinary cardiovascular capacity and do not deliver the mechanical loading that builds bone — and in some cycling populations, bone density findings have been notably unfavourable rather than merely neutral.

So a twenty-year cycling history is a cardiovascular history, a metabolic history, and specifically not a bone history. That is not intuitive, and it is the sort of thing a person can carry an unexamined assumption about for decades.

This is the finding that matters most and is known least.

Research on retired elite gymnasts found that a history of amenorrhea compromised the exercise-induced benefits that loading should have produced — in both cortical and trabecular bone. Half the gymnasts in that study had such a history.

Read that carefully, because the implication is uncomfortable: two women with the same demanding loading history can arrive at 50 with materially different skeletons, and the thing separating them is what happened to their fueling and their cycles during the training years. The sport did its part. The energy deficit undid some of it.

The same mechanism applies in men, where it is far less studied and almost never asked about. More on under-fueling that carried forward.

Bone is a slow-moving problem that becomes visible late. Loss accelerates around the menopausal transition in women and proceeds more gradually in men, and the first indication for many people is a fracture from something that should not have caused one.

Screening is generally not discussed with people in their forties. For most of the population that is a reasonable default. For someone with a low-fuel history, a non-impact sport background, or years of amenorrhea, the default is wrong — the relevant exposure happened thirty years ago and nobody has asked about it.

Asking earlier does not require doing anything drastic. It requires knowing whether you are in the group where the reassurance applies.

We cannot perform a DEXA scan. We do no imaging of any kind. Where a history warrants formal bone density assessment, that is a referral, and we will make it rather than leaving the question open.

What we can do is take the history that determines whether one is warranted — the sport and its loading profile, the fueling years, menstrual history and its timing, fracture history, family history — and read a baseline panel alongside it. Vitamin D, calcium, thyroid function and hormonal status all bear on bone and are all on the panel.

What protects bone from here is mostly not pharmacological: impact and resistance loading, adequate fueling, and correcting nutrient deficiencies where they exist. Where the perimenopausal picture is part of it, hormone therapy is prescribed for eligible patients after evaluation, with monitoring.