Relationships among Ground Reaction Forces During Single and Repeated Sit-to-stands and Physical Fitness Tests in Female Elderly

Abstract

　Determination of the adequate number of movement repetitions for the evaluation of physical function in the elderly is required to establish a leg muscle function test using ground reaction force during sit-to-stand (STS) movement. Conducting STS movements repeatedly may impose a larger physical burden on the elderly and induce their joint disability. A lower repetition number is suitable for the elderly. This study aimed to examine the relationships among ground reaction forces during single and repeated STS movements and physical fitness tests. Nineteen healthy female elderly conducted both STS tests and physical fitness tests developed by the Ministry of Education, Culture, Sports, Science and Technology. Subjects performed an STS movement or 5-consecutive movements as fast as possible. Five parameters regarding stomping force and movement speed were calculated using time course data of ground reaction force during both STS movement. The parameters during each STS movement and the sum of 5 repetitions for the repeated STS test were used for analysis. Significant and moderate correlations were found in the peak values of the ground reaction force, impulse rate and maximal rate of force development between the single STS test and the repeated STS test (r = 0.76-0.78). Significant and moderate correlations between performances of both of the above tests and each movement of the latter repeated STS test were found in all parameters except for achieving time and impulse rate per unit time. Correlations between the peak value of the ground reaction force and the maximal rate of force development in both STS tests and sit-ups and 10-m barricade walking physical fitness tests were significant and moderate (ǀ r ǀ = 0.47-0.72). In conclusion, the relationships between both STS tests were relatively high, and they showed similar relationships with physical fitness tests. Thus, a single STS test can evaluate similar physical functions as the repeated STS test. Due to the light physical burden, it may be desirable to use the single STS test to evaluate leg function of the elderly.