Document Detail

Effects of intensity and duration of exercise on muscular responses to training of thoroughbred racehorses.
MedLine Citation:
PMID:  17255370     Owner:  NLM     Status:  MEDLINE    
This study examined the effects of the intensity and duration of exercise on the nature and magnitude of training adaptations in muscle of adolescent (2-3 yr old) racehorses. Six thoroughbreds that had been pretrained for 2 mo performed six consecutive conditioning programs of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 2.5 mmol/l (v2.5) and 4 mmol/l (v4), respectively] and durations (5, 15, 25 min). Pre- and posttraining gluteus muscle biopsies were analyzed for myosin heavy chain content, fiber-type composition, fiber size, capillarization, and fiber histochemical oxidative and glycolytic capabilities. Although training adaptations were similar in nature, they varied greatly in magnitude among the different training protocols. Overall, the use of v4 as the exercise intensity for 25 min elicited the most consistent training adaptations in muscle, whereas the minimal training stimulus that evoked any significant change was identified with exercises of 15 min at v2.5. Within this range, muscular adaptations showed significant trends to be proportional to the exercise load of specific training programs. Taken together, these data suggest that muscular adaptations to training in horses occur on a continuum that is based on the exercise intensity and duration of training. The practical implications of this study are that exercises for 15 to 25 min/day at velocities between v2.5 and v4 can improve in the short term (3 wk) the muscular stamina in thoroughbreds. However, exercises of 5-15 min at v4 are necessary to enhance muscular features related to strength (hypertrophy).
José-Luis L Rivero; Antonio Ruz; Silvia Martí-Korff; José-Carlos Estepa; Escolástico Aguilera-Tejero; Jutta Werkman; Mathias Sobotta; Arno Lindner
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-01-25
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  102     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-05-07     Completed Date:  2007-07-13     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1871-82     Citation Subset:  IM    
Laboratory of Muscular Biopathology, Dept. of Comparative Anatomy and Pathological Anatomy, University of Cordoba, 14014 Cordoba, Spain.
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MeSH Terms
Adaptation, Physiological*
Capillaries / physiology
Cell Size
Glycerolphosphate Dehydrogenase / metabolism
Horses / physiology*
Lactic Acid / blood
Muscle Fibers, Skeletal / physiology
Muscle, Skeletal / blood supply,  cytology,  metabolism,  physiology*
Myosin Heavy Chains / metabolism
Neovascularization, Physiologic
Physical Conditioning, Animal / methods*
Physical Endurance / physiology*
Random Allocation
Succinate Dehydrogenase / metabolism
Time Factors
Reg. No./Substance:
0/Myosin Heavy Chains; 50-21-5/Lactic Acid; EC 1.1.-/Glycerolphosphate Dehydrogenase; EC Dehydrogenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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