Peripheral muscle strength in young males with cystic fibrosis.

BACKGROUND: In children with cystic fibrosis there is a decrease in peak work capacity and oxygen consumption on maximal exercise testing when compared to controls. Previous studies have shown that peripheral muscle force is decreased in children with cystic fibrosis even in those with minimal changes in lung function. However, no studies have examined peripheral muscle strength using isokinetic dynamometry which permits measurement of muscle strength throughout range and is considered the gold standard in orthopaedics and sports medicine.
METHODS: Isokinetic muscle strength was measured in the knee flexors and extensors and shoulder flexors and extensors at two speeds of movement in children with cystic fibrosis and matched controls. Activity levels in both groups were calculated.
RESULTS: Thirteen subjects and 13 age and height matched controls were assessed. Average peak torque was calculated and expressed in terms of body weight. There was a significant difference in peak torque/body weight in children with cystic fibrosis when compared to controls. FEV1 was significantly correlated with knee muscle strength and shoulder flexion at 90 degrees /s in subjects with CF.
CONCLUSION: Children with CF had lower muscle strength than control subjects. Airflow limitation was associated with decreased muscle strength. The relationship between muscle strength and exercise tolerance requires investigation.