Document Detail

Muscle glycogenolysis and resynthesis in response to a half Ironman triathlon: a case study.
MedLine Citation:
PMID:  19124898     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To describe the degrees of muscle-glycogen depletion and resynthesis in response to a half Ironman triathlon. METHODS: One male subject (38 years of age) completed the Grand Columbian half Ironman triathlon (1.9-km swim, 90-km bike, 21.1-km run, Coulee City, Wash). Three muscle biopsies were obtained from his right vastus lateralis (prerace, immediately postrace, and 4 hours postrace). Prerace and postrace body weight were recorded, in addition to macronutrient consumption before, during, and after the race. Energy expenditure and whole-body substrate oxidation were estimated from linear regression established from laboratory trials (watts and run pace relative to VO2 and VCO2). RESULTS: Body weight decreased 3.8 kg from prerace to postrace. Estimated CHO energy expenditure was 10,003 kJ for the bike segment and 5759 kJ for the run segment of the race. The athlete consumed 308 g of exogenous CHO (liquid and gel; 1.21 g CHO/min) during the race. Muscle glycogen decreased from 227.1 prerace to 38.6 mmol . kg wet weight-1 . h-1 postrace. During the 4 hours postrace, the athlete consumed a mixed diet (471 g CHO, 15 g fat, 64 g protein), which included liquid CHO sources and a meal. The calculated rate of muscle-glycogen resynthesis was 4.1 mmol . kg wet weight-1 . h-1. CONCLUSION: Completing a half Ironman triathlon depends on a high rate of muscle glycogenolysis, which demonstrates the importance of exogenous carbohydrate intake during the race. In addition, rates of muscle-glycogen resynthesis might be dampened by the eccentric damage resulting from the run portion of the race.
Trevor L Gillum; Charles L Dumke; Brent C Ruby
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of sports physiology and performance     Volume:  1     ISSN:  1555-0265     ISO Abbreviation:  -     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2009-01-06     Completed Date:  2009-11-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101276430     Medline TA:  Int J Sports Physiol Perform     Country:  United States    
Other Details:
Languages:  eng     Pagination:  408-13     Citation Subset:  IM    
Human Performance Laboratory, University of Montana, Missoula, MT 59812, USA.
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MeSH Terms
Dietary Carbohydrates / administration & dosage,  metabolism*
Dietary Fats / administration & dosage,  metabolism
Dietary Proteins / administration & dosage,  metabolism
Energy Metabolism
Glycogen / biosynthesis,  metabolism*
Linear Models
Muscle Contraction*
Muscle Fatigue
Nutritional Status
Oxygen Consumption
Physical Endurance*
Quadriceps Muscle / metabolism*,  pathology
Time Factors
Weight Loss
Reg. No./Substance:
0/Dietary Carbohydrates; 0/Dietary Fats; 0/Dietary Proteins; 9005-79-2/Glycogen

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