The association between trunk muscle endurance, balance and falls self-efficacy in women with osteoporotic vertebral fractures: an exploratory analysis from a pilot randomized controlled trial

BACKGROUND: Trunk muscle endurance may be associated with balance and falls self-efficacy for people with osteoporosis. However, all previous studies have examined trunk muscle strength rather than endurance. PURPOSE: To explore the relationships between trunk muscle endurance and standing balance and falls self-efficacy for women with vertebral fractures. MATERIALS AND METHODS: This is an exploratory, secondary analysis of baseline data of a pilot randomized controlled trial in Ontario, Canada. Thirty-one women with osteoporosis, aged 65 years or older, with at least one vertebral fracture were included. The associations between balance (Balance Outcome Measure for Elder Rehabilitation) and trunk muscle endurance (Timed Loaded Standing Test) and falls self-efficacy (Falls Efficacy Scale International) and trunk muscle endurance were tested via Spearman rank order correlation with Fisher's z transformations. RESULTS: Trunk muscle endurance was correlated with better balance performance on the Balance Outcome Measure for Elder Rehabilitation [Spearman correlation coefficient, 0.71; 95% confidence interval: 0.47-0.85; p < 0.001], but not with falls self efficacy (Spearman correlation coefficient; -0.22; 95% confidence interval: -0.53 to 0.14; p = 0.23). CONCLUSIONS: Trunk muscle endurance was moderately associated with better standing balance performance but not falls self-efficacy, highlighting the importance of trunk muscle endurance for standing balance for older adults with osteoporosis and vertebral fractures.Implications for RehabilitationOlder adults with osteoporosis and vertebral fractures who have better trunk muscle endurance may also have better standing balance.There was no association between trunk muscle endurance and how confident a person is that they will not fall while completing various activities of daily living.Trunk muscle endurance training could be included as part of a standing balance rehabilitation program for this population.