Effects of extended exercise and carbohydrate feedings on substrate oxidation and muscle glycogenolysis
Year: 2006
Type: dissertation
Abstract: PURPOSE: The purpose of this study was to examine the effects o f exogenous carbohydrate intake during eight hours o f prolonged exercise on muscle giycogenolysis and whole-body substrate oxidation.METHODS: Eight recreationally-trained males participated in two 8-hour exercise trials.During each hour, subjects repeated 25 minutes cycle ergometer exercise, 5 minutes rest, 25 minutes treadmill exercise, and 5 minutes rest.Each 25 minute exercise segment consisted o f two steady state and three interval work bouts.Muscle biopsies were obtained pre-and post-exercise.Blood samples were collected pre-exercise, after hour 4, and post-exercise.Metabolic gases were collected during hours 1 ,4 ,5 , and 8. Every 15 minutes, subjects ingested 150 mL o f either a 10% carbohydrate solution (CHO) or a sweetened placebo (PLA).Subjects were provided with a standardized breakfast and lunch.Data were analyzed using repeated-measures ANOVA and statistical significance was set at p<0.05.RESULTS: There was a significant difference in the rate o f muscle giycogenolysis between trials (9.4 ±2.1 and 13.7 ± 4.6 mmol kg wet wt.' hr ' for CHO and PLA, respectively).Rates o f whole-body carbohydrate oxidation demonstrated a general maintenance throughout exercise for the CHO trial but showed a decline throughout the PLA trial.Blood glucose and insulin were higher for CHO after hour 4 and post exercise compared to PLA.CONCLUSION: The results fi'om this study suggest that regular exogenous carbohydrate feedings during prolonged, intermittent exercise attenuate muscle giycogenolysis while maintaining plasma glucose and insulin concentrations and rates of whole-body carbohydrate oxidation.
Source: The Mathematics Enthusiast
Author: J. Wagner
Language: English
Subfield: Nutrition and Dietetics
Field: Nursing
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1442438880