UBC Theses and Dissertations
Studies of fall risk and bone morphology in older women with low bone mass Liu-Ambrose, Teresa Yeong Lih
Introduction: Osteoporotic fractures are a major health care problem. Fracture risk can be largely divided into two domains: fall risk and bone health, and both can be influenced by exercise. Purpose: 1) To examine the role of different types of exercise on both fall risk and bone health in older women with low bone mass. 2) To explore fall risk factors that may be unique to women with low bone mass. Methods: Subjects: Women aged 65 to 75 years with osteoporosis for Parts I and II. Women aged 75 to 85 years with low bone mass (i.e. osteoporosis or osteopenia) for Parts III, IV, and V. Study Design: Parts I and II are cross-sectional studies. Parts III, IV, and V involved a 25-week randomized controlled trial of resistance training, agility training, and stretching (sham exercise). Results: Parts I & II: Back pain was negatively associated with both postural stability (r² = 0.09, p = 0.04) and functional mobility (r² = 0.12, p = 0.001). Compared to their counterparts without osteoporosis, older women with osteoporosis had 11 to 18% greater fall risk by composite balance score and quadriceps strength (both p < 0.03). Part III to V: Both high-intensity resistance training and agility training significantly reduced fall risk compared to a general stretching program (both p < 0.01). The resistance training program reduced fall risk by 57% and the agility training program reduced fall risk by 48% without any serious adverse effects. Both exercise programs also significantly increased cortical bone density (by pQCT) in the appendicular skeleton. Fear of falling was also reduced after 13 weeks of participating in both exercise programs. Conclusions The cross-sectional studies suggest that back pain may warrant scrutiny as a fall risk factor in older women with osteoporosis and that older women with osteoporosis may be at greater risk of falls than is often recognised. The RCT indicates that in women aged 75 to 85 years with low bone mass both high-intensity resistance training and agility training reduce fall risk compared to general stretching. Also, both types of training have the potential to increase cortical bone density in a site-specific manner despite the population being elderly. Change in balance confidence may not correlate closely with changes in physiological measures of fall risk. Further studies in high-risk populations should be powered for falls as the primary outcome.
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