Preexercise Feeding in Untrained Adolescent Boys Does Not Affect Responses to Endurance Exercise or Performance

Hendelman, D.; Ornstein, Kirk; Debold, Edward P.; Volpe, Stella L.; Freedson, Patty S.

doi:10.1123/ijsn.7.3.207

Cited by 12 publications

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“…This study is unique in that we examined the metabolic responses of intermittent 13 C-labeled GLU exo ingestion during prolonged (i.e., 2 h) exercise in adolescent boys. Hendelman et al (1997) have shown that a pre-exercise CHO feeding does not modify R levels or improve exercise performance during 75 min of moderate exercise in adolescent boys. We recently found, however, that the intermittent ingestion of GLU exo contributes to @10% of the total energy supply during 60 min of exercise in adolescent boys with and without IDDM (Riddell et al 2000).…”

Section: Discussionmentioning

confidence: 92%

“…FAT total contribution was signi®cantly less in the GT than in the CT at 70, 90, 100, and 120 min of exercise (all P < 0.001) Asano and Hirakoba 1984;Rowland et al 1987;Martinez and Haymes 1992). Although a large body of literature exists indicating that CHO intake modi®es substrate utilization and improves exercise performance in adults (Coggan and Coyle 1991), few studies have investigated substrate utilization during CHO intake in children and adolescents (Hendelman et al 1997;Riddell et al 2000). The main ®nding of the present study is that the intermittent ingestion of exogenous glucose spares endogenous CHO and fat, elevates blood glucose concentrations, and contributes markedly to the energy demands of prolonged exercise in healthy but untrained adolescent boys.…”

Section: Discussionmentioning

confidence: 95%

“…The inuence of CHO intake either before or during exercise in children and adolescents is currently unclear. Previously, Hendelman et al (1997) showed that a pre-exercise CHO feeding snack does not alter the respiratory exchange ratio (R), prolong fatigue, or increase cycling time to exhaustion during 75 min of exercise in healthy adolescents. On the other hand, using 13 C-labeled glucose, we have shown that the intermittent ingestion of 6±8% glucose during 60 min of moderate-intensity exercise contributes to @10% of the total energy provision in adolescent boys both with and without Type 1 diabetes mellitus (Riddell et al 2000).…”

Section: Introductionmentioning

confidence: 99%

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Substrate utilization in boys during exercise with [ 13 C]-glucose ingestion

Riddell¹,

Bar‐Or²,

Schwarcz

et al. 2000

European Journal of Applied Physiology

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The influence of glucose ingestion on substrate utilization during prolonged exercise in children and adolescents is currently unknown. In the present study we determined the effect of intermittent exogenous glucose (GLUexo) ingestion on substrate utilization during prolonged exercise, in adolescent boys ages 13 17 years. Healthy untrained volunteers performed four 30-min exercise bouts on a cycle ergometer, separated by 5-min rest periods (approximately equal to 60% maximum O2 consumption), on two occasions spaced 1-4 weeks apart. Two trials were performed, a control trial (CT), in which subjects ingested water intermittently during the exercise, and a glucose trial (GT), in which subjects ingested a 13C-enriched GLUexo drink (approximately egual to glucose kg body mass(-1)), also intermittently during the exercise. Total free fatty acids (FATtotal), glucose (GLUtotal) and carbohydrate (CHOtotal) oxidation was determined from indirect calorimetry, while GLUexo oxidation was calculated from the 13C/12C ratio in expired air after 5-10 min and 25-30 min of exercise in each bout. Heart rate and rating of perceived exertion (RPE) were determined at the same time intervals. The oxidation of CHOtotal was 169.1 (12.9) g x 120 min(-1) and 203.1 (15.9) g x 120 min(-1) (P < 0.01) and that of FATtotal was 31.0 (4.2) g x 120 min(-1) and 17.1 (2.5) g x 120 min(-1) (P < 0.01) in CT and GT, respectively. GLUexo oxidation in GT was 57.8 (4.3) g x 120 min(-1), or 34.2 (2.2)% of that ingested. Endogenous glucose oxidation was 169.1 (12.9) g x 120 min(-1) and 145.3 (11.9) g x 120 min(-1) (P < 0.01) in CT and GT, respectively. Insulin and glucose concentrations were higher in GT than in CT by 226% and 37%, respectively (both P < 0.05). Free fatty acids and glycerol concentrations were lower in GT than in CT, by 27% and 79%, respectively (both P < 0.05). Heart rate was similar between trials, but RPE was lower in GT vs CT at both 115 and 135 min. Thus, under these experimental conditions, GLUexo intake spares endogenous carbohydrate and fat by 16% and 45%, respectively, contributes to approximately 25% of the total energy demand of exercise, and lowers the RPE.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Substrate utilization in boys during exercise with [ 13 C]-glucose ingestion

Riddell¹,

Bar‐Or²,

Schwarcz

et al. 2000

European Journal of Applied Physiology

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“…In contrast to much of the adult literature, one of the first studies in young people to examine the effects of CHO ingestion immediately before exercise reported no effect on performance (Hendelman et al 1997). Three hours after a standardised breakfast, 15 year old untrained adolescent boys consumed a candy bar, fat-free fig bars or a sweetened drink (placebo) 10 min before exercise.…”

Section: Performancementioning

confidence: 96%

Sport Nutrition and Youth

2016

Sports Nutrition Needs for Child and Adolescent Athletes

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“…Riddell et al (2001) and Hendelman et al (1997) both studied the effects of exogenous CHO feedings in children and found no effect on cycling performance. The lack of a positive finding could be explained by the inherent variability of the tests such as the rather short performance test (2,500 m time trial after 75 min of cycling at 60% peak VO 2 ) used by Hendelman et al (1997). Based on reported CVs obtained in adult endurance cyclists, a low CV in their sample was assumed.…”

Section: Introductionmentioning

confidence: 99%

The reproducibility of an endurance performance test in adolescent cyclists

2005

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The purpose of the study was to measure the reproducibility of a performance test in well-trained adolescent cyclists. Eight male and one female cyclist [mean age 15.7 (0.7) y] participated in the study. Lactate threshold (LT) and peak VO2 were assessed. The performance test was repeated on three separate days and consisted of 30 min of steady state (SS) cycling at 80% of individual LT. Immediately after the SS cycling a time trial (TT) started with the cyclists having to complete a fixed amount of work as fast as possible. Reliability was assessed for the TT with the coefficient of variation (CV) as the (SD/mean)*100 for each participant, intraclass correlation coefficients (ICC) and typical error (SD of the difference in mean /radical2). The group mean (SD) times for the TT were TT1 1889 (306), TT2 1857 (283) and TT3 1953 (279) s respectively. Individual CV varied from 0.25% to 10%. The ICC for TT1/2 and 2/3 were r = 0.78 and 0.93 (P<0.05). The typical errors, expressed as a CV% on the log transformed performance times, were 7.3 and 3.7% for TT1/2 and TT2/3 respectively. The largest individual CVs were observed between TT1 and TT2. The differences in CV and SD among the three TTs indicate that trial two and three were more reliable than TT1, suggesting a habituation trial is needed. It is concluded that the present performance test is reliable in adolescent cyclists with lower variation between trials 2 and 3.

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Preexercise Feeding in Untrained Adolescent Boys Does Not Affect Responses to Endurance Exercise or Performance

Cited by 12 publications

References 0 publications

Substrate utilization in boys during exercise with [ 13 C]-glucose ingestion

Substrate utilization in boys during exercise with [ 13 C]-glucose ingestion

Sport Nutrition and Youth

The reproducibility of an endurance performance test in adolescent cyclists

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