Document Detail

Muscular and metabolic responses to moderate-intensity short-term training.
MedLine Citation:
PMID:  10659274     Owner:  NLM     Status:  MEDLINE    
The objectives of this study were to determine the effects of 10 consecutive days of moderate-intensity training on 1) the muscular metabolic response to exercise at 100% of the pre-training maximum rate of oxygen consumption (VO2max); and 2) mitochondrial enzyme markers (citrate synthase, CS; succinate dehydrogenase, SDH; 3-hydroxy-acyl-CoA dehydrogenase, HAD) of oxidative capacity in middle gluteal muscle. Six mature, unfit Thoroughbred horses completed both incremental (for determination of VO2max) and high-intensity exercise protocols before (HI1) and after (HI2) training. Training consisted of 10 consecutive days of running at 55% VO2max for 60 min per day (13-14 km/day). For the HI, horses completed a 10 min warm-up, followed by exercise at 100% of pre-training VO2max (mean speed 9.8 m/s) until fatigue. Training resulted in an 8.9% increases in VO2max (Pre: 142 +/- 4 ml/kg bwt/min; Post: 155 +/- 4 ml/kg bwt/min) and a 24% increase in run time to fatigue during HI. Whereas VO2 during HI was not altered by training, peak values for VCO2 and R were significantly lower following training. Compared to HI1, there was a 45% reduction in the net rate of muscle glycogenolysis during HI2. Peak (end exercise) values for plasma and muscle lactate concentrations decreased by 22 and 23%, respectively, after training. Training also attenuated the exercise-associated increase in plasma norepinephrine, but there was no effect on plasma epinephrine concentrations. Maximal activities of CS, SDH, and HAD were unaltered by training. We conclude that 10 days of moderate-intensity exercise results in decreases in muscle glycogenolysis and anaerobic metabolism during high-intensity exercise at the same absolute workload. Furthermore, development of measurable increases in mitochondrial oxidative potential may not be required for expression of these metabolic adaptations in early training.
R J Geor; L J McCutcheon; H Shen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Equine veterinary journal. Supplement     Volume:  -     ISSN:  -     ISO Abbreviation:  Equine Vet J Suppl     Publication Date:  1999 Jul 
Date Detail:
Created Date:  2000-03-02     Completed Date:  2000-03-02     Revised Date:  2013-05-16    
Medline Journal Info:
Nlm Unique ID:  9614088     Medline TA:  Equine Vet J Suppl     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  311-7     Citation Subset:  IM; S    
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Canada.
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MeSH Terms
3-Hydroxyacyl CoA Dehydrogenases / metabolism
Adaptation, Physiological
Body Weight
Citrate (si)-Synthase / metabolism
Exercise Test / veterinary
Horses / metabolism*
Mitochondria / enzymology
Muscles / metabolism*
Oxygen Consumption
Physical Conditioning, Animal*
Succinate Dehydrogenase / metabolism
Reg. No./Substance:
EC CoA Dehydrogenases; EC Dehydrogenase; EC (si)-Synthase

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