Beyond Bone Density: The Impact of Structured Exercise Training on Bone Metabolism and Fracture Risk Prevention in the Postmenopausal Period

Abstract

Background: Postmenopausal osteoporosis, driven by oestrogen deficiency and low-grade inflammation, is a primary cause of skeletal fragility. While exercise is a critical non-pharmacological intervention, the hierarchy of exercise efficacy and its direct impact on clinical outcomes remain under debate.

Objective: To synthesise evidence regarding different exercise modalities on bone mineral density (BMD) and bone turnover markers (BTMs) in postmenopausal women, while evaluating the certainty of fracture reduction data.

Methods: A systematic review with narrative synthesis was conducted following PRISMA 2020 guidelines was conducted for 21 high-quality source documents. Analysis focused on site-specific BMD changes, biochemical markers, and the moderation effects of supervision and detraining.

Results: High-intensity resistance training (HI-RT; $\ge$ 70–80% of one-repetition maximum [1RM]) and high-impact loading consistently yielded the greatest increases in BMD at the lumbar spine (LS) and femoral neck (FN). High-intensity interval training (HIIT) protocols demonstrated synergistic effects on BTMs—specifically osteocalcin (OC), bone-specific alkaline phosphatase (s-BAP), and procollagen type 1 N-terminal propeptide (P1NP)—when combined with Vitamin D. Epidemiological data suggest regular exercise is associated with a 24% lower risk of developing osteoporosis. Importantly, BMD served as the primary surrogate outcome in the majority of included studies. While bone gains are well-documented, direct evidence for fracture reduction remains a secondary, less certain endpoint.

Conclusions: Supervised, high-intensity exercise is the first-line prescription for improving BMD. However, clinicians should exercise caution in over-interpreting these gains as definitive fracture prevention.