Best Protocol for the Sit-to-Stand Test in Subjects With COPD

Background: Different protocols for the sit-to-stand test (STS) are available for assessing functional capacity in COPD. We sought to correlate each protocol of the STS (ie, the 5-repetition [5-rep STS], the 30-s STS, and the 1-min STS) with clinical outcomes in subjects with COPD. We also aimed to compare the 3 protocols of the STS, to verify their association and agreement, and to verify whether the 3 protocols are able to predict functional exercise capacity and physical activity in daily life (PADL).

Methods: 23 subjects with COPD (11 men; FEV 53 ± 15% predicted) performed 3 protocols of the STS. Subjects also underwent the following assessments: incremental shuttle walking test, 6-min walk test (6MWT), 4-m gait speed test (4MGS), 1-repetition maximum of quadriceps muscle, assessment of PADL, and questionnaires on health-related quality of life and functional status.

Results: The 1-min STS showed significant correlations with the 6MWT (r = 0.40), 4MGS (r = 0.64), and PADL (0.40 ≤ r ≤ 0.52), and the 5-rep STS and 30-s STS were associated with the 4MGS (r = 0.54 and r = 0.52, respectively). The speed differed for each protocol (5-rep STS 0.53 ± 0.16 rep/s, 30-s STS 0.48 ± 0.13 rep/s, 1-min STS 0.45 ± 0.11 rep/s, = .01). However, they presented good agreement (intraclass correlation coefficient ≥ 0.73 for all) and correlated well with each other (r ≥ 0.68 for all). More marked changes in peripheral oxygen saturation ( = .004), heart rate ( < .001), blood pressure ( < .001), dyspnea ( < .001), and leg fatigue ( < .001) were found after the 1-min STS protocol. Furthermore, the 3 protocols were equally able to identify subjects with low exercise capacity or preserved exercise capacity.

Conclusions: The 1-min STS generated higher hemodynamic demands and correlated better with clinical outcomes in subjects with COPD. Despite the difference in speed performance and physiological demands between the 5-rep STS and 1-min STS, there was a good level of agreement among the 3 protocols. In addition, all 3 tests were able to identify subjects with low exercise capacity or preserved exercise capacity.