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 V-O2), 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 V-o2 were, respectively, 71 12,0 10, 93 29, and 62 +/- 16% of predicted. The STS test had moderate associations with peak V-o2 (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 x 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 x body weight outcome as a useful submaximal exercise parameter in CF.