Handgrip strength, quadriceps muscle power, and optimal shortening velocity roles in maintaining functional abilities in older adults living in a long-term care home: a 1-year follow-up study

PURPOSE: To assess the relative role of handgrip strength (HGS), quadriceps muscle power (P(max)), and optimal shortening velocity (υ(opt)) in maintaining functional abilities (FAs) in older adults living in a long-term care home over a 1-year follow-up. SUBJECTS AND METHODS: Forty-one inactive older institutionalized adults aged 69.8±9.0 years participated in this study. HGS, P(max), υ(opt), cognitive function using the Mini-Mental State Examination, depressive symptoms using the Geriatric Depression Scale, nutritional status using the Mini Nutritional Assessment (MNA), and physical activity (PA) using the Seven-Day Physical Activity Recall Questionnaire were assessed at baseline and at 1-year follow-up. FAs were assessed with activities of daily living (ADL), instrumental ADL, and Timed Up & Go test. RESULTS: Both at baseline and at follow-up, FAs were related to age, HGS, P(max)/kg, υ(opt), MNA, and PA. These associations were generally similar in both sexes. As revealed in multiple regression analysis, υ(opt) was the strongest predictor of FA, followed by P(max)/kg, PA, and MNA. FA deteriorated after 1 year as measured by ADL and Timed Up & Go test. P(max) and υ(opt), but not HGS, also decreased significantly after 1 year. Nevertheless, 1-year changes in FAs were not related to changes in HGS, P(max), υ(opt), or PA. CONCLUSION: The 1-year period of physical inactivity among older institutionalized adults was found to have a negative effect on their FAs, P(max), and υ(opt). The present study demonstrates that P(max) and, especially, υ(opt) correlated with FAs of older adults more than HGS, both at baseline and at follow-up. Despite this, 1-year natural fluctuations of PA, P(max), and υ(opt) are not significant enough to influence FAs in inactive institutionalized older adults.