Reductions in Muscle Strength and Range of Motion Cause Locomotion Disability via Locomotion-Related Functional Limitation in Japanese Older Adults: A Cross-Sectional Study

Abstract

Background. Functional issues (impairments, functional limitations, and disabilities) gradually occur with age. Nonetheless, maintaining physical capability may help prevent locomotion disabilities at an older age. The present study aimed to determine whether reductions in muscle strength and range of motion (ROM) cause locomotion disability via locomotion-related functional limitations among healthy older adults. Methods. Data from a total of 144 participants (61 men, 83 women) were analyzed. To assess locomotion disability, the locomotor domain of the activities of daily living (ADLs) survey from the Ministry of Education, Culture, Sports, Science, and Technology of Japan was used. Muscle strength (grip strength) and two ROMs (hip flexion and knee flexion) were measured. To measure locomotion-related functional limitations, participants underwent a 10 m hurdle walking test and side-step test. Thereafter, path analysis was conducted for testing the hypothetical model. The goodness of fit in the model was assessed using statistical parameters, such as the chi-square value, goodness of fit index (GFI), adjusted goodness of fit index (AGFI), comparative fit index (CFI), and root mean square error of approximation (RMSEA). Results. The analysis revealed a nonsignificant chi-square value (chi-square = 41.885; $p=0.113$ ), as well as high values of GFI (0.944), AGFI (0.904), CFI (0.970), and RMSEA (0.046), indicating that locomotion disability was caused by locomotion-related functional limitations, which were influenced by muscle strength and ROM. Conclusions. The present study demonstrated that decreased muscle strength and ROM caused locomotion disability via locomotion-related functional limitations. Older adults should participate in physical exercise programs that focus on strengthening muscles and improving ROM to counteract age-related locomotion disability.