Physical activity: does long-term, high-intensity exercise in horses result in tendon degeneration?
Abstract: This study explores the hypothesis that high-intensity exercise induces degenerative changes in the injury-prone equine superficial digital flexor tendon (SDFT), but not in the rarely injured common digital extensor tendon (CDET). The horse represents a large-animal model that is applicable to human tendon and ligament physiology and pathology. Twelve age-matched female horses undertook galloping exercise three times a week with trotting exercise on alternative days (high-intensity group, n = 6) or only walking exercise (low-intensity group, n = 6) for 18 mo. The SDFT, suspensory ligament, deep digital flexor tendon, and CDET were harvested from the forelimb. Tissue from the mid-metacarpal region of the right limb tendons was analyzed for water, DNA, sulfated glycosaminoglycan and collagen content, collagen type III-to-I ratios, collagen cross-links, and tissue fluorescence. Left limb tendons were mechanically tested to failure. The analyses showed matrix composition to have considerable diversity between the functionally different structures. In addition, the specific structures responded differently to the imposed exercise. High-intensity training resulted in a significant decrease in the GAG content in the SDFT, but no change in collagen content, despite a decrease in collagen fibril diameters. There were no signs of degeneration or change in mechanical properties of the SDFT. The CDET had a lower water content following high-intensity training and a higher elastic modulus. Long-term, high-intensity training in skeletally mature individuals results in changes that suggest accelerated aging in the injury-prone SDFT and adaptation in the CDET.
Publication Date: 2008-10-02 PubMed ID: 18832761DOI: 10.1152/japplphysiol.00717.2007Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov\'t
Summary
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The study investigates the long-term effects of high-intensity exercise on horses. It focuses particularly on the hypothesis that such cardiovascular activity can lead to degenerative changes in tendons typically prone to injury.
Study Design and Parameters
- The research utilized twelve equine subjects, all age-matched females, for the experiment. They were divided into two groups: one that underwent high-intensity exercising (involving galloping three times a week and trotting in between the days) and another which adhered to a low-intensity regimen (walking exercise only).
- Four tissue types were harvested from each horse’s forelimb after 18 months: the superficial digital flexor tendon, deep digital flexor tendon, common digital extensor tendon, and suspensory ligament. The mid-metacarpal region of the right limb tendons was used for analysis, while left limb tendons were subjected to mechanical tests.
Analysis and Findings
- The researchers evaluated various aspects of the harvested tissues, including water content, DNA, sulfated glycosaminoglycan (GAG) and collagen content, as well as collagen type III-to-I ratios, collagen cross-links, and tissue fluorescence.
- The findings revealed a notable diversity in matrix composition among the different functioning structures. Moreover, the identified structures showed variable responses to the level of exercise.
- Of significance, the high-intensity training group showed a significant reduction in GAG content within the superficial digital flexor tendon. However, there was no identifiable change in collagen content, even with a decrease in collagen fibril diameters observed.
- Despite these variances, there were no visible signs of degeneration or change in mechanical properties in the superficial digital flexor tendon.
Conclusion
- The common digital extensor tendon possessed less water content following high-intensity training and a higher elastic modulus.
- In summary, the results imply that long-term, high-intensity training in mature individuals may induce changes that appear similar to accelerated aging in injury-prone superficial digital flexor tendons. However, it may also encourage adaptation in rarely injured common digital extensor tendons.
Cite This Article
APA
Birch HL, Wilson AM, Goodship AE.
(2008).
Physical activity: does long-term, high-intensity exercise in horses result in tendon degeneration?
J Appl Physiol (1985), 105(6), 1927-1933.
https://doi.org/10.1152/japplphysiol.00717.2007 Publication
Researcher Affiliations
- Institute of Orthopaedics & Musculoskeletal Science, Univ. College London, Stanmore Campus, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore HA7 4LP, UK. h.birch@ucl.ac.uk
MeSH Terms
- Animals
- Biomechanical Phenomena
- Body Water / metabolism
- Collagen / analysis
- Collagen / biosynthesis
- DNA / biosynthesis
- DNA / genetics
- Elasticity / physiology
- Extremities / pathology
- Female
- Glycosaminoglycans / metabolism
- Horses / injuries
- Horses / physiology
- Microscopy, Fluorescence
- Physical Conditioning, Animal / adverse effects
- Physical Conditioning, Animal / physiology
- Tendon Injuries / etiology
- Tendon Injuries / pathology
- Tendon Injuries / veterinary
Grant Funding
- S20242 / Biotechnology and Biological Sciences Research Council
Citations
This article has been cited 13 times.- Peserico A, Barboni B, Russo V, Bernabò N, El Khatib M, Prencipe G, Cerveró-Varona A, Haidar-Montes AA, Faydaver M, Citeroni MR, Berardinelli P, Mauro A. Mammal comparative tendon biology: advances in regulatory mechanisms through a computational modeling. Front Vet Sci 2023;10:1175346.
- Wang K, Zhao L. The Influence of Different Modes of Exercise on Healthy and Injured Tendons. Stem Cells Int 2022;2022:3945210.
- Citeroni MR, Ciardulli MC, Russo V, Della Porta G, Mauro A, El Khatib M, Di Mattia M, Galesso D, Barbera C, Forsyth NR, Maffulli N, Barboni B. In Vitro Innovation of Tendon Tissue Engineering Strategies. Int J Mol Sci 2020 Sep 14;21(18).
- Best R, Standing R. The Spatiotemporal Characteristics of 0-24-Goal Polo. Animals (Basel) 2019 Jul 16;9(7).
- Youngstrom DW, Rajpar I, Kaplan DL, Barrett JG. A bioreactor system for in vitro tendon differentiation and tendon tissue engineering. J Orthop Res 2015 Jun;33(6):911-8.
- Russo V, Mauro A, Martelli A, Di Giacinto O, Di Marcantonio L, Nardinocchi D, Berardinelli P, Barboni B. Cellular and molecular maturation in fetal and adult ovine calcaneal tendons. J Anat 2015 Feb;226(2):126-42.
- Snedeker JG, Gautieri A. The role of collagen crosslinks in ageing and diabetes - the good, the bad, and the ugly. Muscles Ligaments Tendons J 2014 Jul;4(3):303-8.
- Rich T, Henderson LB, Becker DL, Cornell H, Patterson-Kane JC. Indicators of replicative damage in equine tendon fibroblast monolayers. BMC Vet Res 2013 Sep 11;9:180.
- Buckley MR, Sarver JJ, Freedman BR, Soslowsky LJ. The dynamics of collagen uncrimping and lateral contraction in tendon and the effect of ionic concentration. J Biomech 2013 Sep 3;46(13):2242-9.
- LaCroix AS, Duenwald-Kuehl SE, Lakes RS, Vanderby R Jr. Relationship between tendon stiffness and failure: a metaanalysis. J Appl Physiol (1985) 2013 Jul 1;115(1):43-51.
- Guest DJ, Birch HL, Thorpe CT. A review of the equine suspensory ligament: Injury prone yet understudied. Equine Vet J 2025 Sep;57(5):1167-1182.
- Altmann N, Bowlby C, Coughlin H, Belacic Z, Sullivan S, Durgam S. Interleukin-6 upregulates extracellular matrix gene expression and transforming growth factor β1 activity of tendon progenitor cells. BMC Musculoskelet Disord 2023 Nov 22;24(1):907.
- Shojaee A. Equine tendon mechanical behaviour: Prospects for repair and regeneration applications. Vet Med Sci 2023 Sep;9(5):2053-2069.
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