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Recruitment pattern of muscle fibre type during high intensity exercise (60-100% VO2max) in thoroughbred horses.
Abstract: To consider the optimal training programme for Thoroughbred horses, we examined the recruitment pattern of muscle fibres including hybrid muscle fibres in well-trained Thoroughbred horses. The horses performed exercise at three different intensities and durations; i.e., 100% VO2max for 4 min, 80% and 60% VO2max for 8 min on a treadmill with 10% incline. Muscle samples were obtained from the middle gluteal muscle before, during (4 min at 80% and 60% VO2max), and after exercise. Four muscle fibre types (types I, IIA, IIA/IIX, and IIX) were immunohistochemically identified, and optical density of periodic acid Schiff staining (OD-PAS) in each fibre type, and the glycogen content of the muscle sample, were determined by quantitative histochemical and biochemical procedures. The changes in OD-PAS showed that the recruitment of all fibre types were identical at the final time stage of each exercise bout, i.e., 4 min running at 100% VO2max, and 8 min running at 80% and 60% VO2max. The changes in OD-PAS of type IIA/IIX fibre were very similar to those of type IIX fibre. The recruitment of these fibres were obviously more facilitated by 4 min running at 100% VO2max than by 4 min running at 80% or 60% VO2max. Short duration with high intensity exercise, such as 4 min running at 100% VO2max or 8 min running at 80% or 60% VO2max, is effective to stimulate type IIX fibre and IIA/IIX fibres that have the fastest speed of contraction.
Publication Date: 2005-06-29 PubMed ID: 15992837DOI: 10.1016/j.rvsc.2005.04.006Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Clinical Trial
- Journal Article
Summary
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This research study explores the muscle fibre recruitment patterns during high intensity exercise in well-trained Thoroughbred horses, aiming to inform optimal training programs. The researchers found that short-term-high intensity exercises at 100% VO2max effectively stimulate the Type IIX and IIA/IIX fibres that contract the fastest.
Methodology and Execution
- Well-trained Thoroughbred horses performed exercises at three different intensities – 100%, 80%, and 60% VO2max on a treadmill inclined at 10%. The exercise durations were 4 minutes for 100% VO2max, and 8 minutes for both the 80% and 60% VO2max levels.
- Muscle samples were taken from the middle gluteal muscle of the horse at different stages – before, during (at 4 minutes at 80% and 60% VO2max), and after exercise.
Fiber Types and Quantification
- Four types of muscle fibers were identified in the samples – I, IIA, IIA/IIX, and IIX – using immunohistochemical methods.
- The density of a special staining method, periodic acid Schiff (PAS), was determined in each fiber type. This optical density (OD-PAS) along with the muscle sample’s glycogen content were quantified using histochemical and biochemical procedures.
Findings and Implications
- The OD-PAS change demonstrated that all fiber types were similarly recruited by the end of each exercise bout regardless of intensity (i.e., 4 minutes running at 100% VO2max, or 8 minutes running at 80% and/or 60% VO2max).
- The changes in OD-PAS in type IIA/IIX fibers were very similar to changes in type IIX fibers, implying they were similarly affected and recruited by the exercise.
- It was specifically noted that the recruitment of fibers IIA/IIX and IIX was more notably facilitated by 4 minutes of running at 100% VO2max, as compared to 4 minutes of running at 80% or 60% VO2max.
- The findings suggest that short, high-intensity exercises, like 4 minutes of running at 100% VO2max or 8 minutes of running at 80% or 60% VO2max, are effective at stimulating the fastest-contracting fibers – Type IIX and IIA/IIX.
- This insight may consequently guide the formulation of more effective and targeted training programs for Thoroughbred horses.
Cite This Article
APA
Yamano S, Eto D, Hiraga A, Miyata H.
(2005).
Recruitment pattern of muscle fibre type during high intensity exercise (60-100% VO2max) in thoroughbred horses.
Res Vet Sci, 80(1), 109-115.
https://doi.org/10.1016/j.rvsc.2005.04.006 Publication
Researcher Affiliations
- Department of Biological Sciences, Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8515, Japan.
MeSH Terms
- Animals
- Female
- Horses / classification
- Horses / physiology
- Male
- Muscle Fibers, Fast-Twitch / physiology
- Muscle Fibers, Slow-Twitch / physiology
- Muscle, Skeletal / physiology
- Physical Exertion / physiology
Citations
This article has been cited 5 times.- Ohmura H, Mukai K, Takahashi Y, Takahashi T. Metabolomic analysis of skeletal muscle before and after strenuous exercise to fatigue. Sci Rep 2021 May 27;11(1):11261.
- de Meeûs d'Argenteuil C, Boshuizen B, Oosterlinck M, van de Winkel D, De Spiegelaere W, de Bruijn CM, Goethals K, Vanderperren K, Delesalle CJG. Flexibility of equine bioenergetics and muscle plasticity in response to different types of training: An integrative approach, questioning existing paradigms. PLoS One 2021;16(4):e0249922.
- Yamano S, Kawai M, Minami Y, Hiraga A, Miyata H. Differences in Muscle Fiber Recruitment Patterns between Continuous and Interval Exercises. J Equine Sci 2010;21(4):59-65.
- Heinonen I, Nesterov SV, Kemppainen J, Fujimoto T, Knuuti J, Kalliokoski KK. Increasing exercise intensity reduces heterogeneity of glucose uptake in human skeletal muscles. PLoS One 2012;7(12):e52191.
- Liu Y, Liu Y, Bai D, Dugarjaviin M, Zhang X. Transcriptomic Profiling Reveals Lysine-Mediated Proliferative Mechanisms in Mongolian Horse Myogenic Satellite Cells. Animals (Basel) 2025 Jun 9;15(12).
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