The 1-minute sit-to-stand test in adults with cystic fibrosis: Correlations with cardiopulmonary exercise test, 6-minute walk test, and quadriceps strength

BACKGROUND: Exercise testing is part of the regular assessment of patients with cystic fibrosis (CF). We aimed to evaluate (1) the convergent validity of the 1-min sit-to-stand (STS) test in CF by investigating its relationships with peak oxygen uptake (peak VO2), quadriceps strength, and quality of life and (2) to compare these associations with those of the 6-min walk test (6MWT). METHODS: Twenty-five adults with CF (FEV1 = 59 ± 24%) performed the STS test, the 6MWT, quadriceps strength assessment, and cardiopulmonary exercise test (CPET). Physical activity level, quality of life, and self-esteem were assessed by questionnaires. RESULTS: STS repetitions, 6-min walk distance, quadriceps strength, and peak VO2 were, respectively, 71 ± 12, 90 ± 10, 93 ± 29, and 62 ± 16% of predicted. The STS test had moderate associations with peak VO2 (r = 0.56, P =.004), quadriceps strength (r = 0.52, P =.008), and some questionnaire items (eg, perceived physical strength, r = 0.67, P <.001) only when repetitions were expressed as a product of body weight. Overall, these associations were weaker than those obtained from 6-min walk distance × weight. Oxygen desaturation during the STS test was strongly associated with oxygen desaturation during CPET (r = 0.80, P <.001). Peak heart rate was lower during the STS test as compared with CPET (P <.001) and the 6MWT (P =.009). CONCLUSIONS: The STS test cannot be used as a replacement for CPET to accurately assess peak exercise capacity in CF. The STS test may have utility in detecting patients with CF who may exhibit a high level of oxygen desaturation during heavy exercise. Further studies should identify the factors contributing to STS performance to confirm the potential interest of STS repetitions × body weight outcome as a useful submaximal exercise parameter in CF.