Muscle Strength and Muscle Endurance Required for Independent Walking in the Elderly

This study investigated minimal muscle strength on knee extension as well as muscle endurance required for independent walking. Seventy-seven elderly (29 males and 48 females, mean age: 81.3 years) participated in this study. Subjects were divided into two groups (the independent group and the dependent group) based on the Barthel index score. We measured muscle strength and muscle endurance on knee extension. Muscle endurance was evaluated using the‘sit-to-stand’test which measured the number of times the subject could rise from a chair within 30 sec. Muscle strength on knee extension was evaluated as a percentage of body weight, calculated from the maximal isometric strength of the knee extensors. The results showed a significant difference in muscle strength on knee extension and the number of repetitions on the ‘sit-to-stand’test (p<.0l) between the independent group and the dependent group. The discriminating criterion for muscle strength on knee extension between the two groups was 45.5%, while the number of repetitions on the ‘sit-to-stand’test was 5.6 times. This study suggested that the elderly may need to maintain their muscle strength on knee extension at 45.5% of their body weight and 'sit-to-stand’ ability at 5.6 times/30 sec to retain their ability to walk independently.