The impact of seat-height on 1-minute sit to stand test performance in COPD: A randomised cross-over trial

Study question: Is there a difference in the number of repetitions on the 1-minute sit to stand (1MSTS) test using an individually adapted seatheight to 90-degree knee flexion (1MSTSIND), compared with the commonly used standard chair seat-height of 46cm (1MSTSSTD), in people with COPD.

Intervention: After a learning 1MSTS, all participants performed two 1MSTS tests in random order on consecutive days. Participants were blinded, as they did not receive detailed information on the testing protocols.

Results: 49 individuals with COPD (47% female) participated. In a regression model adjusted for sequence-period and subject, 1MSTS test performance was lower on 1MSTSIND compared to 1MSTSSTD (-0.78 repetitions, 95% CI, -1.47 to -0.11). In a second regression model additionally including the knee angle and an interaction term (1MSTSIND x knee angle), the interaction term was significant: 0.18 (95% CI, 0.05 to 0.30). The limits of agreement were between -5.5 to 4 repetitions.

Conclusion: Although we observed a statistically significant difference between 1MSTSIND and 1MSTSSTD on a population level, the difference is negligible. Further studies may be needed to determine if individual adaptation of seat-height is needed for very tall or short people to ensure a valid assessment of 1MSTS test performance in COPD.