The influence of chair seat height on the performance of community-dwelling older adults' 30-second chair stand test

Background and aims Although chair seat height affects the performance of sit-to-stand movement, no previous study has examined the influence of chair seat height on the 30-second chair stand test (CST). Methods Fifty-five community-dwelling older adults (age 70.0 +/- 6.3 years) performed the test from the standard height of 43 cm and then from five randomly ordered seat heights from 80 to 120 % of each participant's lower leg length. Results Chair seat height significantly influences the performance of community-dwelling older adults' 30-s CST (F = 57.50, p<0.001). The mean score for standard conditions was significantly lower from those at 120, 110, and 100 % conditions (p<0.05). No significant difference was observed between the standard and 80 % conditions (p>0.95) and between the standard and 90 % conditions (p = 0.353). When comparing the scores between the randomly ordered chair seat heights, all comparisons were significantly different (p<0.001) except for the difference between the 120 and 110 % conditions (p = 0.104). Conclusion Chair seat height's relation to the lower leg length should be considered when interpreting 30-s CST scores. Additionally, it is necessary to optimize the chair seat height when using the 30-s CST as an outcome measure for exercise intervention or to screen for people with weaker lower extremities.