The 1-min sit-to-stand test in cystic fibrosis - Insights into cardiorespiratory responses

BACKGROUND: We aimed to characterize the cardiopulmonary response during a 1-min sit-to-stand (STS) test and compare peak exercise cardiorespiratory variables to a maximal cardiopulmonary exercise test (CPET) in cystic fibrosis (CF). We further aimed to assess the validity of the STS power index (PowerSTS) as a measure of exercise capacity. METHODS: Fifteen adult CF patients performed spirometry, CPET and the 1-min STS test with respiratory gas analysis. RESULTS: Peak-exercise cardiorespiratory variables during the 1-min STS test correlated strongly (r=0.69-0.98) with those measured during the CPET. Oxygen uptake, carbon dioxide production, heart rate, ventilation, and tidal volume at peak exercise were 24%, 26%, 9%, 10% and 21% lower in the 1-min STS test, while respiratory frequencies were 14% higher. PowerSTS showed strong to very strong correlations with CPET-derived absolute peak oxygen uptake and maximal workload. CONCLUSIONS: The 1-min STS test elicits a substantial but lower cardiorespiratory response compared to a maximal cycle ergometry CPET. While PowerSTS and STS repetitions are both valid outcome measures of functional capacity, STS repetitions are clinically more practical