Determinants of Aerobic and Anaerobic Exercise Performance in Cystic Fibrosis

Abstract

We examined aerobic and anaerobic exercise performance in 17 subjects with cystic fibrosis (CF) (age 25+/-10 [SD] yr; 47% females; FEV1 62+/-21% pred) and 17 age- and sex-matched control subjects (age 25+/-8 [SD] yr; 41% females; FEV1 112+/-15% pred) in relation to pulmonary function and nutritional status. Aerobic capacity was determined as maximal oxygen consumption (VO2max) (ml/kg/min) and anaerobic threshold (AT; ml VO2/kg/min) from a graded exercise stress test on an electronically braked bicycle ergometer. Anaerobic performance was assessed from the average work of two bouts of pedaling to exhaustion at a load corresponding to 130% Vo2max from graded exercise. Both aerobic and anaerobic performances were decreased in subjects with CF (p < 0.001). The duration of anaerobic exercise in subjects with CF was similar to control subjects. In control subjects, pulmonary function did not correlate to aerobic or anaerobic exercise. In subjects with CF significant relationships between FEV1, vital capacity, and FEF25-75% to AT were found, suggesting the pulmonary limitation to aerobic capacity. In both patients with CF and control subjects, lean body mass and arm muscle area significantly correlated with anaerobic performance but not with VO2max or AT. We conclude that nutritional status, rather than pulmonary function, is the major determinant of anaerobic exercise capacity in CF. The preserved duration of anaerobic exercise at equivalent workloads (corresponding to 130% of VO2max from graded exercise) suggests that readily available energy stores in muscle may be similar in CF and normal individuals.

Skeletal Muscle Metabolism in Cystic Fibrosis and Primary Ciliary Dyskinesia

“…Our research team has recently demonstrated the expression of CFTR in human skeletal muscle (7). In addition, evidence suggests that impaired anaerobic performance (8), abnormal anaerobic metabolism (9), and decreased maximal muscle strength and power (10 -12) occurs in CF patients. Recently, [ 31 P]phosphorus magnetic resonance spectroscopy ( 31 P-MRS) to assess muscle metabolism has been used in vivo (13,14) to assess the function of creatine kinase, oxidative phosphorylation, and anaerobic glycolysis pathways during exercise and recovery.…”

Symptoms, lactate and exercise limitation at peak cycle ergometry in adults with cystic fibrosis

“…Peak exercise performance is reduced in patients with CF [1][2][3][4][5][6][7][8][9][10]. Pulmonary function correlates with peak aerobic and anaerobic exercise capacity [8][9][10], and this relationship has been interpreted as indicating a pulmonary limitation to exercise in CF.…”

Clinical Exercise Testing in Children and Adolescents with Cystic Fibrosis

“…Furthermore, exercise testing has been used as an outcome measure of therapy and exercise programmes, as well as for prognostic purposes (1)(2)(3)(4)(5)(6). It has been established, that aerobic and anaerobic capacity is reduced in most patients with CF when compared to their healthy counterparts, with impaired respiratory function and malnutrition being likely contributing factors (7)(8)(9)(10). It has also been documented that children with CF with higher activity levels have a better aerobic and anaerobic fitness and nutritional status, and a significantly lower disease severity (11).…”

“…There is little doubt that aerobic and anaerobic capacity is reduced in CF individuals, when compared to their healthy counterparts (7)(8)(9)(10). This reduction may be explained by an impaired lung function and malnutrition.…”