Biochemical changes and endocrine responses in cystic fibrosis in relation to a marathon race

Biochemical changes and endocrine responses during the New York Marathon (42195 m) were investigated in three 18-year-old male adolescents with cystic fibrosis (CF) and three healthy men who accompanied the CFs during the race. The ambient temperature was 20 degrees-28 degrees C and the relative humidity 98%-75% during the run. The CF patients, who had Shwachman scores of 60, 85 and 95 completed the run without major problems in 6.10, 4.42, and 4.32 h, respectively. Serum concentrations of Na and Cl decreased slightly, but the values were still within normal range. Na and Cl excretions in the urine decreased to very low levels in the CF adolescents during the run. All the other biochemical changes were similar to the changes in the controls. Aldosterone concentration increased to a higher level and maintained this increase for a longer time after the race in the CFs. Testosterone concentration decreased more in the CFs during the race compared with the controls. Growth hormone concentration showed individually varying changes in response to the exercise. This study demonstrates that patients with CF may participate in strenuous prolonged exercise even in humid and hot conditions, without untoward effects. The observed differences in hormonal responses to exercise might be explained by differences in age, training status, and relative exercise intensity rather than by hormonal or other disturbances in CF.