ABSTRACT Purpose: Exercise capacity...

ABSTRACT

Purpose: Exercise capacity, measured according to the 6-minute walk test (6MWT) is impaired in patients with cystic fibrosis (CF) and is related to their survival and quality of life. 6MWT performance may be influenced or explained through lung function, lean body mass (LBM) or muscle puissance Therefore, the purpose of this thought was to determine the relationships between leg muscle puissance and 6MWT as well as LBM and 6MWT in children with CF as compared to healthy fellows Methods: Subjects with CF (n=21 mean age 105 yr mean FEV^sub 1^ 65% predicted) and age- and sex-matched healthy masterys were tested for LBM and lower extremity muscle power Measurements of skin folds were used to determine LBM puissance of bilateral hip flexors, knee extensors, and ankle dorsiflexors was determined via hand-held dynamometry. exposes then completed the 6MWT. A Mann-Whitney U trial was used to make between cluster comparisons for height, weight, LBM muscle toughness and 6MWT distance. A Kendall's Tau was used to assess within dispose correlations between the strength of each muscle proofed and both LBM and 6MWT distance. Results: exposes with CF had significantly lower LBM (237 ?± 85 kg v 314 ?± 120 kg) and 6MWT (490 ?± 77 m v 557 ?± 94 m) than have the direction ofs Hip flexion and ankle dorsiflexion force was also significantly lower in CF than directs The 6MWT distance correlated significantly with bilateral hip flexion (r = 037-039) and knee extension toughness (r = 0.31-0.37) in CF There was no relationship between any solidity measure and 6MWT distance in directions Strength correlated moderately with LBM in one as well as the other groups. LBM did not correlate with 6MWT in either clump Conclusions: Exercise capacity as measured by way of 6MWT is impaired in children with CF and is partially related to decreased leg muscle impregnability These findings suggest that leg muscle force not LBM, is related to 6MWT performance in children with CF

INTRODUCTION

Patients with cystic fibrosis (CF) are known to have reduc exercise capacity, which impacts onward quality of life and survival.1-6 However, the exercise limitation is to be ascribed only in part to their lung disease.7 The exact reasons for the exercise impairment are generally unknown. However, recent studies allude to that nutritional status and/or muscle function may play important roles8-10

Patients with CF frequently have a lower than normal visible form [i]or[/i] frame weight due to malabsorption of dietary fat.11 Nutritional status is known to relate to muscle force and exercise capacity, independent of disease severity.8-10 Research indicates a positive relationship may exist between lean material substance mass (LBM), and peak oxygen consumption in patients with CF9 Improvement in LBM following vegetation hormone administration was a significant predictor (r = 051) of peak oxygen consumption in children with mild to moderate CF8 The constituent of LBM that would mostly likely influence exercise capacity is skeletal muscle. However, the specific contribution of peripheral muscle vigor on exercise capacity in children with CF has not been determined.

Several studies of adults with CF report impairments in muscle puissance compared to healthy peers.10,12-14 Dejong et al12 base knee extension strength averaged single 80% of age-predicted values for patients with mild to moderate disease. Similarly, van der Woude et al10 determined that adults with end-stage CF had quadriceps muscle nerve that averaged 49% of predicted values. However, it is unknown whether this weakness is to be ascribed to an intrinsic muscle abnormality or simply a decrease in muscle mass. Moser et al13 fix subjects with CF had lower peak oxygen consumption by quadriceps cross-sectional area than dominion government subjects, despite no difference in muscle size, suggesting a primary muscular dysfunction. A lower inorganic phosphate-to-phosphocreatine ratio during acute exercise was seen in the quadriceps muscle of female athletes with CF compared to healthy teammates.14 This finding in subdues with CF, having normal lung function and normal BMI, may advise the disease itself affects muscle function. Therefore, it have the appearances logical that peripheral muscular potency may also play a part in determining exercise capacity in children with CF

Exercise capacity of patients with CF is commonly assessed in the clinical setting using the 6-minute walk trial (6MWT). Performance on the 6MWT predicts morbidity and mortality, as well as quality of life for these patients.1-6 The 6MWT correlates well with maximal oxygen consumption (r > 070) in children with CF715 Although 6MWT performance is associated with the severity of lung disease,2,3,5 lung function alone explains les than half of the variance.7,15,16 Therefore, factors other than lung function are likely to be important predictors of 6MWT in patients with CF

Since the couple muscular strength and LBM are potentially amenable to nutritional or exercise training interventions,17-19 it is important to determine if they are related to 6MWT performance in children and adolescents with CF It is generally unknown when in the course of the disease proces this vigor impairment may begin. It is also important to determine if the same relationships between LBM puissance and exercise capacity previously seen in adults with CF are at hand in children with the disease. Therefore, the sense of this study was to examine the general intent of leg muscle strength and LBM in succession 6MWT performance in children with CF compared to age-matched healthy children.