FACTORS LIMITING ANAEROBIC PERFORMANCE IN ADOLESCENT MALES WITH CYSTIC-FIBROSIS

Forty-one adolescent males (11.1-18.3 yr) with cystic fibrosis (CF) an d 37 healthy adolescent males (11.1-17.9 yr) performed a Wingate Anaer obic Test (WAnT). The group with CF was subdivided by sexual maturity, nutritional status, and degree of airway obstruction. The subjects wi th CF had lower absolute power outputs than the healthy controls (mean power in Watts (mean +/- SD): 350.2 +/- 135.9 vs 424.5 +/- 120.4, P < 0.001; peak power; 525.2 +/- 178.4 vs 665.9 +/- 191.3, P < 0.001). Wh en absolute power was corrected for lean body mass, the subjects with CF had lower power outputs than the healthy controls (mean power in W . kg(-1) 8.9 +/- 1.7 vs 9.6 +/- 0.9, P < 0.05; peak power: 13.4 +/- 2. 1 vs 15.0 +/- 1.6, P < 0.05). The subgroup with CF with a higher body mass index (BMI > 17.5 kg . m(-2)) had higher peak and mean power outp ut than subjects with CF with a lower BMI in both absolute power and w hen power was expressed per lean body mass. When sexual maturation was considered, subjects with CF with salivary testosterone greater than 4.0 ng . dl(-1) had a higher mean and peak power in both absolute term s and relative to lean body mass than subjects with CF with salivary t estosterone less than 4.0 ng . dl(-1) Multiple regression analysis ind icated that the nutritional factor accounted for 70%-80% of the variab ility in power output in the subjects with CF, while testosterone acco unted for 10% of the variability. Pulmonary function was not a signifi cant independent correlate of anaerobic power. Our results suggest tha t nutritional status, and to a lesser extent maturational factors, may play a more important role than pulmonary function in determining ana erobic fitness in male adolescents with CF.