The 1-minute sit-to-stand test in children with cystic fibrosis: cardiorespiratory responses and correlations with aerobic fitness, nutritional status, pulmonary function, and quadriceps strength

To characterize physiological responses to a 1-minute sit-to-stand test (STS) and assess correlations with cardiopulmonary exercise test (CPET) variables, nutritional status, pulmonary function, and quadriceps muscle strength in cystic fibrosis (CF) patients.
Subjects aged 6–18 years with a genetic diagnosis of CF were enrolled in this cross-sectional study. After collecting demographic, anthropometric, and clinical data the following tests were performed: pulmonary function (spirometry), aerobic fitness (CPET), STS, and isometric quadriceps muscle strength (hand-held dynamometry). Data collection was performed on the same day.
The study sample comprised 17 children (9.8 ± 1.6 years) and adolescents (13.7 ± 1.5 years) with a mean forced expiratory volume in one second (FEV1) of  − 0.80 ± 1.61 (z-score). In the CPET, peak exercise oxygen consumption (VO2peak) was 35.1 ± 4.2 mL.kg−1.min−1, while in the STS mean number of repetitions was 32.5 ± 6.2 and total work (repetitions × body mass) was 1326.9 ± 379.6. At peak exercise, CPET elicited higher heart rate (p = .001) and subjective sensation of dyspnea (p = .001) compared to STS, though no significant differences were observed in peripheral oxygen saturation. Moderate and significant correlations were identified between total workload (CPET) and repetitions adjusted for body weight (r = 0.684; p = .002) and between STS repetitions and muscle strength corrected for body weight (r = 0.531; p = .034). No significant correlations were found with nutritional status (BMI), pulmonary function (FEV1), or other aerobic fitness variables (VO2 at ventilatory threshold or VO2peak).
In children and adolescents with CF, compared to CPET, the STS test elicits a submaximal cardiorespiratory response that is mostly dependent on quadriceps muscle strength.