Effects of an exercise program in children with cystic fibrosis: are there differences between females and males?

Objective: To investigate the adaptive responses of an in-patient exercise program in children with cystic fibrosis (CF) and evaluate the effects of sex.

Study Design: In total, 158 female and 186 male subjects with CF (age, 12 to 43 years) were studied during a 6-week rehabilitation course. A maximal incremental cycling test was used to determine exercise capacity and responses after 6 weeks of exercise training. Measures included lung function, peak oxygen uptake, peak workload, and peak heart rate.

Results: Lung function values were lower in males (P < .05). Females had a lower aerobic capacity (P < .05) at the beginning and at the end of the exercise training program. Similar training effects (P > .05) were seen between sexes in peak oxygen uptake (mL/min, mL/kg/min) and peak heart rate (beats/min) but not in peak workload (Watts, W/kg).

Conclusions: The exercise program improved the fitness level similarly in females and males with CF. Basic physiological sex differences were still seen at the beginning and end of the training, despite the better lung function in females. Moreover, the finding suggested that fitness level and not lung function determined the response to training in CF, with those who were less fit at baseline having the largest response to training.