Exercise performance in children and adolescents with cystic fibrosis with and without abnormal glucose tolerance: a single center cross-sectional study

Background: Abnormal glucose tolerance (AGT) in cystic fibrosis (CF) affects lung function and clinical parameters, including aerobic fitness. However, its effects on physical activity level (PAL), anaerobic power (AP), and muscle strength (MS) in children and adolescents are unknown. Purpose: To investigate aerobic fitness, PAL, AP, and MS in pediatric patients with mild-to-moderate CF and AGT. Methods: The study included children and adolescents with CF aged 10–18 years. Participants underwent a pulmonary function test, quadriceps, and handgrip MS measurement, vertical jump test to assess AP, and six-minute walk test (6MWT) to assess aerobic fitness. Bouchard’s Three-Day Physical Activity record was used to determine PAL. Results: Height z-score (p = .006), 6MWT (p = .024), handgrip (p = .028), quadriceps MS (p = .044), and AP (p = .036) were significantly lower in AGT (n = 21) than normal glucose tolerance (NGT) (n = 19). In the AGT group, glycosylated hemoglobin (HbA1c) was significantly associated with forced expiratory volume in one second (FEV₁) (p = .046). 6MWT distance (6MWD) was associated with height (p = .008), FEV₁ (p = .001), forced vital capacity (FVC) (p = .001), forced expiratory flow from 25% to 75% (FEF_25-75%) (p = .030), handgrip MS (p = .012), and PAL (p = .034). After adjusting for height and FEV₁, the groups had similar 6MWD, MS, and AP (p > .05); also, insulin was associated with MS and AP but not with 6MWT or quadriceps MS. Conclusion: Measures of aerobic fitness, MS, and AP are lower in AGT, but after adjusting for height and FEV₁, aerobic fitness, MS, and AP do not show substantial differences. Insulin sensitivity and resistance are associated with MS and AP.