Acute effect of consumption/omission of breakfast on exercise tolerance in adolescents.
The purpose of this study was to determine the acute effects of the consumption or omission of breakfast on exercise tolerance in adolescents. Physically active adolescents (14 males and 21 females) were randomly assigned to receive a breakfast (B) or placebo (P) after an overnight fast. Exercise tolerance tests were done 1.5 hours (test 1) and again 4 hours (test 2) after consuming B or P and consisted of cycling on a stationary bike for 4 minutes at each of four consecutive power settings: 25, 50, 75, and 100 watts. Blood glucose and beta-hydroxybutyrate concentrations were measured before both tests. VO2 and VCO2 were measured during minute 3 of cycling at loads 50 and 75 watts and were used to compute the respiratory exchange ratio (RER). Heart rates (HR) were monitored throughout the test and ratings of perceived exertion (RPE) were made at the end of each 4 min interval. Repeated measures ANOVA revealed that there were no differences in RPE; however, differences for HR and RER did exist. Mean RER values were higher for the males receiving B vs males receiving P during test 1. For females, HR were higher for P compared B, and beta-hydroxybutyrate was significantly elevated for P before test 2. The data suggest that exercise tolerance as indicated by the ratings of perceived exertion are unaffected by prior ingestion of a breakfast but breakfast does affect the physiologic responses to exercise.
Horswill
C
C
Children's Hospital, Columbus, OH.
Cromer
B
B
Stein
A
A
Thornton
D
D
D000293:Adolescent; D001786:Blood Glucose / Q000032:analysis; D004435:Eating / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005215:Fasting / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009747:Nutritional Physiological Phenomena / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011897:Random Allocation; D012737:Sex Factors
D001786:Blood Glucose