Energy cost of physical activity in cystic fibrosis.
OBJECTIVE
The purpose of this study was to compare the energy cost of standardized physical activity (ECA) between patients with cystic fibrosis (CF) and healthy control subjects.


METHODS
Cross-sectional study using patients with CF and volunteers from the community.


METHODS
University laboratory.


METHODS
Fifteen patients (age 24.6+/-4.6 y) recruited with consent from their treating physician and 16 healthy control subjects (age 25.3+/-3.2) recruited via local advertisement.


METHODS
Patients and controls walked on a computerised treadmill at 1.5 km/h for 60 min followed by a 60 min recovery period and, on a second occasion, cycled at 0.5 kp (kilopond), 30 rpm followed by a 60 min recovery. The ECA was measured via indirect calorimetry. Resting energy expenditure (REE), nutritional status, pulmonary function and genotype were determined.


RESULTS
The REE in patients was significantly greater than the REE measured in controls (P=0.03) and was not related to the severity of lung disease or genotype. There was a significant difference between groups when comparing the ECA for walking kg radical FFM (P=0.001) and cycling kg radical FFM (P=0.04). The ECA for each activity was adjusted (ECA(adj)) for the contribution of REE (ECA kJ kg radical FFM 120 min(-1)--REE kJ kg radical FFM 120 min(-1)). ECA(adj) revealed a significant difference between groups for the walking protocol (P=0.001) but no difference for the cycling protocol (P=0.45). This finding may be related to the fact that the work rate during walking was more highly regulated than during cycling.


CONCLUSIONS
ECA in CF is increased and is likely to be explained by an additional energy-requiring component related to the exercise itself and not an increased REE.
Richards
M L
ML
School of Human Movement Studies, Queensland University of Technology, Brisbane, Australia. ml.richards@qut.edu.au
Davies
P S
PS
Bell
S C
SC
D000328:Adult; D000886:Anthropometry; D002153:Calorimetry, Indirect; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000503:physiopathology; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D009752:Nutritional Status; D010101:Oxygen Consumption; D012420:Running; D016138:Walking