What Is Bone Density?
Women can lose up to 20% of bone density in the five years around menopause. Learn the exact training strategy proven to slow and reverse the loss.
Last updated
The short answer
What is bone density? Bone density (or bone mineral density, BMD) is a measure of how much calcium and other minerals are packed into a given volume of bone. It peaks in the late 20s, plateaus, then declines sharply in women during and after menopause. Bone is living tissue, constantly remodeled by osteoblasts (build) and osteoclasts (break down).
Why it matters for women 40+
Women lose up to 20% of their bone mass in the five to seven years surrounding menopause — the fastest skeletal decline of adult life. Low bone density leads to osteopenia, then osteoporosis, then fractures. A hip fracture after 65 carries a one-year mortality rate of 20–30%, making this a longevity issue, not just a mobility one.
The training choices you make in your 40s and 50s largely determine how strong your skeleton is at 75.
The full explanation
Bone is living tissue, constantly remodeled by osteoblasts (build) and osteoclasts (break down). Estrogen restrains osteoclast activity, so when estrogen falls in perimenopause, breakdown outpaces build, and bone density drops. The skeleton responds to two stimuli: mechanical loading and impact.
Heavy resistance training — especially compound lifts that load the spine and hips like squats, deadlifts, and overhead presses — produces strain forces that signal osteoblasts to lay down new bone. Impact activities (jumping, hopping, plyometrics, running) produce ground reaction forces that further stimulate bone, particularly at the hip. The LIFTMOR trial showed that heavy resistance training plus impact work, twice a week, increased lumbar spine and hip BMD in postmenopausal women with low bone mass — without injuries.
Walking alone, swimming, and cycling are excellent for cardiovascular health but do not load bone enough to halt loss. Adequate protein (1.2–1.6 g/kg), vitamin D (1,000–2,000 IU daily), and calcium (1,000–1,200 mg from food when possible) are the nutritional foundation.
What to do about it
Ask your doctor for a DEXA scan at age 50 or sooner if you have risk factors. Then lift heavy two to three times a week — barbell squats, hinges, presses — and add brief impact work like 20–50 jumps or hops a few times a week. This combination is more effective at preserving bone than any supplement.
Related terms
Resistance Training
Resistance training (also called strength or weight training) is any form of exercise that uses external load — barbells, dumbbells, machines, bands, or body weight — to make muscles work against opposition. It is the foundational training modality for women 40+.
Read guideProgressive Overload
Progressive overload is the gradual increase in training stress — heavier weights, more reps, or harder variations — applied over weeks and months to keep the body adapting. It is the single most important principle for building strength and muscle.
Read guideSarcopenia
Sarcopenia is the age-related loss of skeletal muscle mass, strength, and function. It typically begins in the 30s but accelerates sharply in women after menopause as estrogen — a muscle-protective hormone — declines.
Read guideFrequently asked
Start paying attention at 40. The window to build peak bone mass closes in the late 20s, but the window to preserve it is wide open — and the choices you make in perimenopause matter most.
Not on its own. Walking helps general health but produces ground reaction forces too small to stimulate bone remodeling meaningfully. You need heavy load (lifting) or impact (jumping) for the signal.
Yes. Heavy resistance training combined with impact work has been shown in randomized trials to increase hip and spine BMD in postmenopausal women with osteopenia and osteoporosis — without HRT.
Key takeaways
- Bone Density matters because women lose up to 20% of their bone mass in the five to seven years surrounding menopause — the fastest skeletal decline of adult life.
- Ask your doctor for a DEXA scan at age 50 or sooner if you have risk factors.
- Apply this consistently — small weekly actions compound over months in perimenopause.
- Track what you do; without data, you cannot tell progress from drift.