| A signalling role for muscle glycogen in the regulation of pace during prolonged exercise. | |
| | |
MedLine Citation:
|
PMID: 15618337 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
INTRODUCTION: In this study we examined the pacing strategy and the end muscle glycogen contents in eight cyclists, once when they were carbohydrate loaded and once when they were non-loaded. METHODS: Cyclists completed 2 hours of cycling at approximately 73% of maximum oxygen consumption, which included five sprints at 100% of peak sustained power output every 20 minutes, followed immediately by a 1 hour time trial. Muscle biopsies were performed before and immediately after exercise, while blood samples were taken during the 2 hour steady state rides and immediately after exercise. RESULTS: Carbohydrate loading improved mean power output during the 1 hour time trial (mean (SEM) 219 (17) v 233 (15) W; p<0.05) and enabled subjects to use significantly more muscle glycogen than during the trial following their normal diet. Significantly, the subjects, kept blind to all feedback except for time, started both time trials at similar workloads ( approximately 30 W), but after 1 minute of cycling, the workload average 14 W higher throughout the loaded compared with the non-loaded time trial. There were no differences in subjects' plasma glucose and lactate concentrations and heart rates in the carbohydrate loaded versus the non-loaded trial. Of the eight subjects, seven improved their time trial performance after carbohydrate loading. Finishing muscle glycogen concentrations in these seven subjects were remarkably similar in both trials (18 (3) v 20 (3) mmol/kg w/w), despite significantly different starting values and time trial performances (36.55 (1.47) v 38.14 (1.27) km/h; p<0.05). The intra-subject coefficient of variation (CV) for end glycogen content in these seven subjects was 10%, compared with an inter-subject CV of 43%. CONCLUSIONS: As seven subjects completed the time trials with the same end exercise muscle glycogen concentrations, diet induced changes in pacing strategies during the time trials in these subjects may have resulted from integrated feedback from the periphery, perhaps from glycogen content in exercising muscles. |
| | |
Authors:
|
H G L Rauch; A St Clair Gibson; E V Lambert; T D Noakes |
Related Documents
:
|
2678897 - Resynthesis of glycogen in different muscle fibre types after prolonged exhaustive exer... 16896727 - Creatine supplementation does not enhance submaximal aerobic training adaptations in he... 9118987 - Effect of muscle glycogen availability on maximal exercise performance. 3549287 - Effects of dietary manipulations on blood glucose and hormonal responses following supr... 23197587 - The relationship between freely chosen cadence and optimal cadence in cycling. 6132727 - The effects of hibernation stress on the heart rate and metabolic rate of citellus late... |
Publication Detail:
|
Type: Clinical Trial; Journal Article; Randomized Controlled Trial |
Journal Detail:
|
Title: British journal of sports medicine Volume: 39 ISSN: 1473-0480 ISO Abbreviation: Br J Sports Med Publication Date: 2005 Jan |
Date Detail:
|
Created Date: 2004-12-24 Completed Date: 2005-02-18 Revised Date: 2009-11-18 |
Medline Journal Info:
|
Nlm Unique ID: 0432520 Medline TA: Br J Sports Med Country: England |
Other Details:
|
Languages: eng Pagination: 34-8 Citation Subset: IM |
Affiliation:
|
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Sports Science Institute, Boundary Road, Newlands, Cape Town 7700, South Africa. lrauch@sports.uct.ac.za |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Adult Bicycling / physiology* Biopsy / methods Blood Glucose / analysis Dietary Carbohydrates / administration & dosage Exercise / physiology* Exercise Test / methods Glycogen / metabolism* Heart Rate / physiology Humans Lactic Acid / blood Male Muscle, Skeletal / metabolism* Oxygen Consumption / physiology Physical Endurance / physiology |
| Chemical | |
Reg. No./Substance:
|
0/Blood Glucose; 0/Dietary Carbohydrates; 50-21-5/Lactic Acid; 9005-79-2/Glycogen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Injuries in martial arts: a comparison of five styles.
Next Document: An analysis of the pacing strategy adopted by elite competitors in 2000 m rowing.