Osteoporosis and Musculoskeletal Health: What You Need to Know

How Bone Remodels Throughout Life

Bone is a living tissue in a continuous state of renewal. The process of bone remodelling involves two cell types working in opposition: osteoclasts, which resorb old or damaged bone by secreting acids and enzymes to dissolve the mineralised matrix, and osteoblasts, which synthesise new bone by laying down collagen matrix subsequently mineralised with calcium hydroxyapatite. In healthy adults, this cycle maintains bone mass and repairs microdamage accumulated through daily loading. Bone mass peaks in the mid-to-late twenties; thereafter, the balance between resorption and formation gradually shifts toward net loss, particularly in women following menopause when oestrogen withdrawal dramatically accelerates osteoclast activity.

What Is Osteoporosis?

Osteoporosis is defined by the World Health Organisation as a bone mineral density (BMD) T-score of −2.5 or below at the femoral neck, total hip, or lumbar spine on dual-energy X-ray absorptiometry (DEXA) scan — a measurement expressing BMD as the number of standard deviations below the mean of a young adult reference population. Osteopenia (T-score between −1.0 and −2.5) represents a transitional state of below-average but not yet osteoporotic bone density. These definitions have important limitations: BMD alone is an imperfect predictor of fracture risk, which is why the FRAX tool — integrating BMD with clinical risk factors — provides a more complete ten-year fracture probability estimate.

The fractures most consequential in osteoporosis are vertebral compression fractures, distal radius fractures (Colles' fracture), and hip fractures. Hip fractures carry a 20–30% one-year mortality rate in elderly patients and a profound impact on independence and quality of life — underscoring the importance of prevention.

Risk Factors

The major modifiable risk factors include low dietary calcium and vitamin D intake, physical inactivity, cigarette smoking, excess alcohol consumption, and long-term corticosteroid use. Non-modifiable factors include female sex, advancing age, Asian or Caucasian ethnicity, low body weight, a family history of osteoporotic fracture, and prior fragility fractures. Secondary causes of osteoporosis — including rheumatoid arthritis, inflammatory bowel disease, coeliac disease, premature menopause, and male hypogonadism — should always be excluded before attributing low BMD to age-related changes alone.

Exercise as a Therapeutic Intervention

Bone responds to mechanical loading through the process of mechanotransduction — osteocytes within the bone matrix detect strain and orchestrate an osteoblastic response that lays down new bone in the loaded region. This is why weight-bearing and resistance exercise — not swimming or cycling — are osteogenic. The bone-loading hierarchy places impact activity (jumping, running, step aerobics) highest, followed by resistance training with progressively heavy loads, and then weight-bearing walking. A meta-analysis of exercise interventions for osteoporosis found that high-intensity progressive resistance training and impact exercise significantly increase femoral neck and lumbar spine BMD in postmenopausal women.

For patients already diagnosed with osteoporosis or osteopenia, exercise programming must balance osteogenic loading with fracture risk mitigation. High-impact activities are appropriate for those without vertebral fractures; those with existing vertebral fractures require modified programming avoiding end-range spinal flexion (sit-up style movements, toe touches) which increase vertebral body compressive loading. Fall prevention training — balance exercises, single-leg stance, reactive stepping — is as important as bone-loading exercise in the osteoporotic patient, as preventing falls prevents fractures regardless of BMD.