Effect of 6-Month High-Impact and Resistance Exercise on Regional Strength and BMD of Spine: A Clinical Trial Combined with a Finite-Element Study.

PURPOSE: Osteoporosis often leads to a site-specific vertebral fracture due to the regional heterogeneity of mechanical competence. High-impact combined with resistance exercise showed promise in improvement of volumetric bone mineral density (vBMD) at global spine-segment level. However, localized effects of such exercise on bone mineral density and mechanical strength remain under-explored.

METHODS

Thirty healthy postmenopausal women with low bone mass were recruited in randomized clinical trial of 6 months of high-impact and resistance exercises (ChiCTR2400081574). A voxel-based 3D registration method was designed to extract the identical seven anatomical sub-regions from QCT images scanned before and after this exercise. Seven finite-element models of each sub-region were developed to analyze the regional change of ultimate compressive strength (UCS) for the first time.

RESULTS

Regionally, significantly lower changes of BMD were observed in the exercise group (EG) than the control group (CG) in the inferior articular process, transverse process, and anterior vertebral body (p < 0.05), although the BMD losses were found in both groups. While significant increases of UCS (up to 4.58%) were observed due to exercise in the vertebral body, superior articular process, and inferior articular processes, compared to the decrease of the CG (up to - 1.24%). The exercise also reduced up to 24% inter-regional variability in strength, promoting a more balanced mechanical distribution across the lumbar spine.

CONCLUSION

Six-month high-impact and resistance training enhances mechanical integrity of the lumbar spine by preserving the density and disproportionately improving strength in vulnerable regions. These findings support the use of region-specific biomechanical assessments to evaluate exercise efficacy in osteoporotic populations.