Capacity 03 · Maintain Function
Signal · BMD / T-score
The skeleton that holds you is built by decades of load.
Bone mineral density is the mineral-per-area in your skeleton. The T-score compares you to a healthy young adult. Unlike muscle, bone turns over slowly — every decade of consistent mechanical load matters, and the windows to build it are finite.
The ranges that matter
Three bands. One direction.
What matters most is the direction over time under the same conditions — is the number trending toward the Fit band, or drifting away from it?
Fit / Optimal
T-score ≥ 0.0
Strong bone reserve. Meets or exceeds the healthy young-adult reference. Low fracture risk into aging.
Well
T-score −1.0 to 0.0
Average bone density. Still within 'normal,' but with less reserve than optimal. Load matters.
Sick / At Risk
T-score ≤ −1.0 (severe ≤ −2.0)
Osteopenia at −1.0 to −2.5; osteoporosis below −2.5. Fracture risk rises steeply past these thresholds.
What it reveals
Bone remembers the load.
Bone is a living tissue. It is constantly being broken down and rebuilt — but slowly. Peak bone mass is set in the late twenties; after that, maintenance requires consistent mechanical loading, adequate protein, and sufficient vitamin D, calcium, and sex hormones.
The T-score expresses your density in standard deviations away from a healthy young adult. Zero is the reference. −1.0 is low-normal. Below −2.5 is osteoporosis, where fracture risk rises sharply — often for the first time through a trivial fall.
Bone responds to load that is heavier than daily life. Walking preserves; running maintains; lifting heavy and jumping build. Unloaded cardio, while valuable for other capacities, is not sufficient to protect bone.
BMD belongs in Maintain Function because the skeleton carries everything else. A hip fracture in the later decades is one of the single worst life-course events, independent of the bone itself. Protect the scaffolding.
On the floor
If your T-score is drifting, the signal is not to be afraid of load — it is that load needs to be the prescription. Bone does not build from caution. It builds from appropriate, progressively heavier mechanical stress.
What moves it
Work the system, not the number.
First levers
- Resistance training with progressive load — squats, deadlifts, overhead press.
- Impact work — jumping, hopping, plyometrics — 2–3 sessions per week.
- Protein at 0.7–1.0 g per pound of target weight; protein builds bone matrix.
- Vitamin D sufficiency (typically 40–60 ng/mL); calcium intake from diet.
Second levers
- Manage sex hormones proactively through midlife and menopause.
- Avoid chronic under-eating; energy deficiency quietly demineralizes bone.
- Limit excess alcohol; it impairs osteoblast function.
- Re-scan every 2–3 years. Bone moves slowly; measure on bone time.
Why it sits with "Maintain Function"
BMD sits among four Maintain Function markers. Read with
ALMI,
Grip Strength, and
Body Fat % — together they describe the scaffold and reserve that carry you.
Go deeper
Coaching and education only. Not medical diagnosis or treatment. Excerpts welcome with attribution to metabolicradar.com.