Energy metabolism during anaerobic exercise in children with cystic fibrosis and asthma.

PURPOSE: The nature of a child's daily physical activity requires both aerobic and anaerobic energy metabolism. Aerobic exercise becomes compromised with advancing airway obstruction in children with cystic fibrosis (CF) and asthma (AS). Whether children with CF will have altered metabolic responses to supramaximal exercise when compared with asthmatics or healthy controls is still undetermined. METHODS: Twenty-five children with CF, 22 with AS, and 23 healthy controls (CN) performed an incremental graded aerobic and Wingate anaerobic test (WAnT) on a cycle ergometer. Analysis of gas exchange and ventilatory data was collected and averaged every 5 s to estimate ventilatory kinetics and energy system contributions during both tests. RESULTS: The CF and AS groups had mild lower airway obstruction (FEF25-75% < 80%) as compared with the CN. All three groups demonstrated similar anaerobic (mean and peak power during the WAnT) and aerobic exercise performance (peak oxygen consumption). In contrast to the AS or CN groups, children with CF used a lower percentage of their peak VO2 and V(E) during each phase of the WAnT, suggesting a preferential use of ATP/phosphocreatine and glycolytic energy stores compared with aerobic pathways. Greater reliance on anaerobic pathways during the WAnT in children with CF could be due to the physiologic sequelae underlying chronic obstructive lung disease. CONCLUSIONS: Oxygen uptake kinetics appeared similar for all three groups. Although the energy needed to perform the WAnT can be met by subjects with CF, abnormalities in energy metabolism may exist for this group during exercise.

Postexercise immune correlates in children with and without cystic fibrosis.

INTRODUCTION: Previous studies have shown that children with cystic fibrosis (CF) are capable of mounting a normal immune response after the stress of exercise. However, few data are available regarding the underlying mechanisms by which this immune modulation occurs. METHODS: In this study, lymphocyte and leukocyte cell counts were measured before and immediately after a single bout of exhaustive exercise in 25 children (ages 8-17 yr; 12 with CF and 13 healthy controls). Catecholamine, cortisol, and insulin levels, age, nutritional parameters, and static and dynamic lung function were measured as potential correlates for immune modulation. We hypothesized that catecholamine levels would be associated with the immune changes seen after exercise in children with CF. RESULTS: Our results demonstrated positive correlations between age and the change in cell counts after exercise for white blood cells (r = 0.44, P < 0.03), lymphocytes (r = 0.60, P < 0.002), monocytes (r = 0.43, P < 0.03), and CD3-CD16+CD56+ cells (r = 0.61, P < 0.002). Lower increases in the lymphocyte and CD3-CD16+CD56+ cells were observed in the CF group. Changes in pre- and post-exercise norepinephrine levels were weakly correlated with the changes in granulocyte, lymphocyte, and monocyte cell counts. Changes in cortisol levels correlated with lymphocyte and CD19+ cell count changes for the CF group but not for the healthy controls. Within the CF group, the severity of lung disease (as indicated by a FEV1) was negatively correlated with changes in lymphocyte (r = -0.66, P < 0.02) and CD3-CD16+CD56+ cell counts (r = -0.67, P < 0.02). CONCLUSION: The results suggest that postexercise changes in cell counts occur in an age dependent, norepinephrine associated manner. Disease severity for children with CF also appears to enhance the postexercise leukocytosis with pronounced increases seen in natural killer cells.

Parental attitudes about exercise regarding their children with cystic fibrosis.

Despite the well-recognized benefits of exercise on general health and pulmonary function, lack of participation in regular exercise remains a concern with respect to children with cystic fibrosis (CF). Data are lacking regarding parental perceptions about exercise in children and adolescents with CF. Sixty-nine parents of children with CF and 70 parents of healthy children completed the 'Exercise Benefits/Barrier Scale" self administered inventory. Fifteen additional items addressing exercise issues for people with CF were also included. Data were reported as total score, and subdivided into barriers and benefits scales for analysis. Data on the CF specific questions were also reported. Parents of children with CF scored lower on both the total score and benefits portion of the inventory and scored slightly greater on the barriers portion (p < .05) representing less favorable perception of the benefits of exercise along with increased barriers. The presence of a healthy child in addition to a child with CF appeared to increase both the total score and benefits score as well as resulting in a more positive outlook on exercise related uses in CF. It appears that significant differences in parental perceptions regarding exercise indeed exist not only when compared to healthy children but within varying intra-structures of families with a child who has CF.

Anaerobic exercise testing in children with asthma.

Twenty-two males with asthma and 22 healthy males (7-18 years old) performed a Wingate Anaerobic Test. The subjects with asthma had a lower mid-maximal expiratory flow rate (78.3+/-25.3 vs. 100.1+/-24.5%, p < 0.01) than the controls. Aerobic and anaerobic exercise performance (peak power: PP; mean power: MP) were similar for the two groups whether expressed in absolute or relative terms to body weight. The subgroup with asthma with a lower percent body fat (<25%) had a higher PP and MP than the subjects with a higher percent body fat (>25%). Pulmonary function or maturation were not independent correlates of anaerobic power. Our results fail to show differences in anaerobic exercise performance in children with asthma compared to healthy controls. Nutrition appears to be an important factor for performance during this test.

Immune modulation following aerobic exercise in children with cystic fibrosis.

Previous studies have demonstrated altered immune response following exercise in healthy adults and children. As data are lacking in children with cystic fibrosis, we evaluated the immune response following acute exercise and hypothesized that acute increases in cellular changes would be seen but would be blunted in subjects with CF. Leukocytes, lymphocytes, and their subsets as well as natural killer cell number and activity were determined before, immediately after, and one hour post exhaustive exercise in 15 children with cystic fibrosis (8-21 yrs, FEV1 69.5+/-18.0%, colonized with P aeruginosa) and 15 healthy controls (8-18 yrs, FEV1 107.5+/-10.7%). At baseline the cystic fibrosis group had greater leukocytes (9.25+/-2.83 vs. 5.17+/-0.96 x 10(9) cells/liter). Immediately post exercise, the cystic fibrosis group demonstrated increases in cell counts for leukocytes (32.4%), lymphocytes (61.8%), granulocytes (36.4%), monocytes (76.2%), and natural killer cells (315%). Similar percentage increases were seen in cell counts for the controls (leukocytes: 39.5%, lymphocytes: 78.5%, granulocytes: 32.0%, monocytes: 75.9%, and NK cells: 442%). Natural killer cell activity also increased by 57.9% in the group with cystic fibrosis and by 43.6% in the healthy controls. Except for elevated leukocyte and granulocyte counts, values returned to baseline at one hour post-exercise. In conclusion, the cellular immune response to acute exercise in children with mild to moderate cystic fibrosis appears normal.