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Veterinary sciences2025; 12(11); 1028; doi: 10.3390/vetsci12111028

Locomotory Profile, Heart Rate Variability, and Blood Parameters Reveal Adaptive Responses in Endurance Horses Trained on Deep Sand.

Abstract: Training on deep sand is commonly employed in endurance horses, but its physiological adaptation remains poorly characterized. This study aimed to characterize locomotor adaptations during a 7 km controlled-speed canter on deep sand in eighteen endurance horses, to identify heart rate variability (HRV) components, and to investigate changes in hematological variables before and after exercise. Stride frequency (SF) and stride length (SL), HRV, and hematological profiles were recorded during exercise and recovery with a fitness tracker. Associations between maximum speed and locomotor parameters were assessed by linear regression, while Pearson's correlation assessed HRV relationships, also with physiological parameters. Hematological parameters were assessed with paired t-test before and after training. SL percentage change was the strongest predictor of speed (β = 0.677). HRV analysis revealed delayed parasympathetic reactivation; the parasympathetic recovery index (PNS REC) was correlated with mean RR interval on the ECG (r = 0.968) and heart rate (r = -0.964) during recovery. Post-exercise rectal temperature showed correlations with HRV recovery indices. Hematological evaluation revealed post-exercise increases in red blood cell count, hematocrit, hemoglobin, and corpuscular indices. SL plays a predominant role in achieving higher speeds on deep sand, while PNS REC emerges as a practical and accessible marker of autonomic recovery and fatigue. Horses with enhanced thermoregulation recover better. Hematological results confirm a physiological stress response that may optimize oxygen delivery. Integrating locomotor, cardiovascular, and hematological monitoring may improve management and welfare in endurance training.
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Publication Date: 2025-10-23 PubMed ID: 41295665PubMed Central: PMC12656824DOI: 10.3390/vetsci12111028Google Scholar: Lookup
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  • Journal Article

Summary

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Overview

  • This study investigates how training endurance horses on deep sand affects their movement patterns, heart rate variability, and blood parameters to understand physiological adaptations and recovery.

Study Objectives and Rationale

  • Training on deep sand is a common method used to condition endurance horses, yet the physiological adaptations to this specific substrate have not been well studied.
  • The study aimed to:
    • Characterize locomotor adaptations during a 7 km controlled-speed canter on deep sand.
    • Identify key components of heart rate variability (HRV) during exercise and recovery as markers of autonomic nervous system function.
    • Assess changes in hematological parameters induced by exercise on deep sand to evaluate physiological stress and recovery responses.

Methodology

  • Participants: Eighteen endurance horses trained and tested on deep sand.
  • Exercise: Horses performed a 7 kilometer controlled-speed canter on deep sand.
  • Data Collection:
    • Locomotion data: Stride frequency (SF) and stride length (SL) were tracked using fitness trackers during exercise.
    • Heart Rate Variability (HRV): Measured before, during, and after exercise to assess autonomic nervous system activity, specifically parasympathetic reactivation.
    • Hematological Parameters: Blood samples taken before and after exercise to measure red blood cell count, hematocrit, hemoglobin, and other corpuscular indices.
  • Statistical Analysis:
    • Linear regression evaluated the link between maximum speed and locomotor parameters (SF, SL).
    • Pearson’s correlation assessed relationships between HRV components and physiological parameters such as heart rate and rectal temperature.
    • Paired t-tests compared hematological values before and after exercise.

Key Findings

  • Locomotor Adaptations:
    • The percentage change in stride length (SL) was the strongest predictor of achieving higher speed on the deep sand (β = 0.677).
    • This suggests that horses adapt to the more resistant surface primarily by increasing their stride length rather than stride frequency.
  • Heart Rate Variability and Autonomic Recovery:
    • HRV analysis revealed a delay in parasympathetic reactivation during recovery after exercise.
    • The parasympathetic recovery index (PNS REC), a measure of vagal tone return, correlated strongly with mean RR interval (r = 0.968) and inversely with heart rate (r = -0.964) during recovery.
    • Higher post-exercise rectal temperatures correlated with HRV recovery indices, suggesting horses with better thermoregulation recover more effectively.
  • Hematological Changes:
    • Post-exercise blood analyses showed increased red blood cell count, hematocrit, hemoglobin, and corpuscular indices.
    • These changes reflect a typical physiological stress response which likely serves to optimize oxygen delivery during and after exertion.

Implications and Conclusions

  • Stride length adjustment is a key locomotor strategy for endurance horses to maintain speed on challenging substrates like deep sand.
  • Parasympathetic recovery index (PNS REC) is a practical and accessible measure to monitor autonomic recovery and fatigue in endurance horses post-exercise.
  • Efficient thermoregulation supports better recovery, indicating that managing body temperature is critical in training and conditioning.
  • The hematological changes confirm that exercise on deep sand induces a measurable physiological stress response, potentially enhancing oxygen transport to tissues.
  • Overall, integrating locomotor, cardiovascular, and hematological monitoring provides a comprehensive approach that can help optimize endurance training, improve horse welfare, and prevent overtraining or injury.

Cite This Article

APA
(2025). Locomotory Profile, Heart Rate Variability, and Blood Parameters Reveal Adaptive Responses in Endurance Horses Trained on Deep Sand. Vet Sci, 12(11), 1028. https://doi.org/10.3390/vetsci12111028

Publication

Veterinary sciences
ISSN: 2306-7381
NlmUniqueID: 101680127
Country: Switzerland
Language: English
Volume: 12
Issue: 11
PII: 1028

Researcher Affiliations

Grant Funding

  • Codice 2022Z39C97, CUP J53D23010670 006 / Founded by the European Union - Next Generation EU - Missione 4, Componente 2 - Investimento 1.1 - MUR-PRIN2022, ECOS (Equine resilience and welfare in Climate change and stressful scenarios using Omic technologies and innovative low cost Sensors - ECOS)

Conflict of Interest Statement

The authors declare no conflicts of interest.

References

This article includes 40 references
  1. Nagy A, Murray JK, Dyson SJ. Horse-, rider-, venue- and environment-related risk factors for elimination from Fédération Equestre Internationale endurance rides due to lameness and metabolic reasons.. Equine Vet. J. 2014;46:294–299.
    doi: 10.1111/evj.12170pubmed: 24033509google scholar: lookup
  2. Hinchcliff KW, Kaneps AJ, Geo RJ, Van Erck-Westergren E. Equine Sports Medicine and Surgery: Basic and Clinical Sciences of the Equine Athlete. 3rd ed. Elsevier; St. Louis, MO, USA: 2025.
  3. Robert C, Goachet A-G, Fraipont A, Votion D-M, Van Erck-Westergren E, Leclerc J-L. Hydration and electrolyte balance in horses during an endurance season.. Equine Vet. J. Suppl. 2010;42:98–104.
    doi: 10.1111/j.2042-3306.2010.00198.xpubmed: 21058989google scholar: lookup
  4. Marlin D, Nankervis KJ. Equine Exercise Physiology. 1st ed. John Wiley & Sons; Hoboken, NJ, USA: 2002.
  5. Cottin F, Barrey E, Lopes P, Billat V. Effect of repeated exercise and recovery on heart rate variability in elite trotting horses during high intensity interval training.. Equine Vet. J. Suppl. 2006;38:204–209.
    doi: 10.1111/j.2042-3306.2006.tb05540.xpubmed: 17402419google scholar: lookup
  6. Munsters C, Siegers E, Sloet van Oldruitenborgh-Oosterbaan M. Effect of a 14-Day Period of Heat Acclimation on Horses Using Heated Indoor Arenas in Preparation for Tokyo Olympic Games.. Animals 2024;14:546.
    doi: 10.3390/ani14040546pmc: PMC10886293pubmed: 38396514google scholar: lookup
  7. Paris A, Accorroni L, Pepe M, Cappelli K, Chiaradia E, Mecocci S, Tognoloni A, Passamonti F, Pilati N, Cercone M. Retrospective study of standardised field exercise test on injury development, blood lactate and recovery time in endurance horses.. Comp. Exerc. Physiol. 2024;20:109–120.
    doi: 10.1163/17552559-20220059google scholar: lookup
  8. Kapteijn CM, Frippiat T, van Beckhoven C, van Lith HA, Endenburg N, Vermetten E, Rodenburg TB. Measuring heart rate variability using a heart rate monitor in horses (Equus caballus) during groundwork.. Front. Vet. Sci. 2022;9:939534.
    doi: 10.3389/fvets.2022.939534pmc: PMC9723354pubmed: 36483490google scholar: lookup
  9. ter Woort F, Dubois G, Didier M, Van Erck-Westergren E. Validation of an equine fitness tracker: Heart rate and heart rate variability.. Equine Vet. J. 2021;17:189–198.
    doi: 10.3920/CEP200028pmc: PMC10078706pubmed: 35138653google scholar: lookup
  10. Sandercock GRH, Brodie DA. The use of heart rate variability measures to assess autonomic control during exercise.. Scand. J. Med. Sci. Sports. 2006;16:302–313.
    doi: 10.1111/j.1600-0838.2006.00556.xpubmed: 16774653google scholar: lookup
  11. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M. Training adaptation and heart rate variability in elite endurance athletes: Opening the door to effective monitoring.. Sports Med. 2013;43:773–781.
    doi: 10.1007/s40279-013-0071-8pubmed: 23852425google scholar: lookup
  12. Brenner IK, Thomas S, Shephard RJ. Autonomic regulation of the circulation during exercise and heat exposure. Inferences from heart rate variability.. Sports Med. 1998;26:85–99.
    doi: 10.2165/00007256-199826020-00003pubmed: 9777682google scholar: lookup
  13. Zhang DY, Anderson AS. The Sympathetic Nervous System and Heart Failure.. Cardiol. Clin. 2014;32:33–45.
    doi: 10.1016/j.ccl.2013.09.010pmc: PMC5873965pubmed: 24286577google scholar: lookup
  14. Younes M, Robert C, Barrey E, Cottin F. Effects of Age, Exercise Duration, and Test Conditions on Heart Rate Variability in Young Endurance Horses.. Front. Physiol. 2016;7:155.
    doi: 10.3389/fphys.2016.00155pmc: PMC4852288pubmed: 27199770google scholar: lookup
  15. Bitschnau C, Wiestner T, Trachsel DS, Auer JA, Weishaupt MA. Performance parameters and post exercise heart rate recovery in Warmblood sports horses of different performance levels.. Equine Vet. J. Suppl. 2010;42:17–22.
    doi: 10.1111/j.2042-3306.2010.00260.xpubmed: 21058977google scholar: lookup
  16. McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. 8th ed. Lippincott Williams & Wilkins; Philadelphia, PA, USA: 2015.
  17. Equimetre. [(accessed on 20 August 2025)]. Available online: https://training.arioneo.com/en/equimetre-2-0-our-sensors-big-changes/
  18. Calle-González N, Lo Feudo CM, Ferrucci F, Requena F, Stucchi L, Muñoz A. Objective Assessment of Equine Locomotor Symmetry Using an Inertial Sensor System and Artificial Intelligence: A Comparative Study. Animals 2024;14:921.
    doi: 10.3390/ani14060921pmc: PMC10967470pubmed: 38540019google scholar: lookup
  19. Savoini B, Bertolaccini J, Montavon S, Deriaz M. Convolutional neural network for early detection of lameness and irregularity in horses using an IMU sensor. arXiv 2025.
    doi: 10.48550/arXiv.2503.13578google scholar: lookup
  20. Parmentier JIM, Aarts RM, Hernlund E, Rhodin M, van der Zwaag BJ. Detecting and measuring respiratory events in horses during exercise with a microphone: Deep learning vs. standard signal processing. arXiv 2025.
    doi: 10.48550/arXiv.2508.02349google scholar: lookup
  21. ter Woort F, Dubois G, Didier M, Van Erck-Westergren E. Validation of an equine fitness tracker: ECG quality and arrhythmia detection. Equine Vet. J. 2022;55:336–343.
    doi: 10.1111/evj.13565pmc: PMC10078706pubmed: 35138653google scholar: lookup
  22. Franklin SH, Van Erck-Westergren E, Bayly WM. Respiratory responses to exercise in the horse. Equine Vet. J. 2012;44:726–732.
    doi: 10.1111/j.2042-3306.2012.00666.xpubmed: 23106622google scholar: lookup
  23. van Vollenhoven E, Fletcher L, Page PC, Ganswindt A, Grant CC. Heart Rate Variability in Healthy, Adult Pony Mares During Transrectal Palpation of the Reproductive Tract by Veterinary Students. J. Equine Vet. Sci. 2017;58:68–77.
    doi: 10.1016/j.jevs.2017.08.013google scholar: lookup
  24. Akoglu H. User’s guide to correlation coefficients. Turk. J. Emerg. Med. 2018;18:91–93.
    doi: 10.1016/j.tjem.2018.08.001pmc: PMC6107969pubmed: 30191186google scholar: lookup
  25. O’Halloran J, Hamill J, McDermott WJ, Remelius JG, Van Emmerik REA. Locomotor-respiratory coupling patterns and oxygen consumption during walking above and below preferred stride frequency. Eur. J. Appl. Physiol. 2012;112:929–940.
    doi: 10.1007/s00421-011-2040-ypubmed: 21701846google scholar: lookup
  26. Cottin F, Metayer N, Goachet AG, Julliand V, Slawinski J, Billat V, Barrey E. Oxygen consumption and gait variables of Arabian endurance horses measured during a field exercise test. Equine Vet. J. Suppl. 2010;42:1–5.
    doi: 10.1111/j.2042-3306.2010.00184.xpubmed: 21058974google scholar: lookup
  27. Butler PJ, Woakes AJ, Anderson LS, Roberts CA, Marlin DJ. Stride length and respiratory tidal volume in exercising thoroughbred horses. Respir. Physiol. 1993;93:51–56.
    doi: 10.1016/0034-5687(93)90067-Kpubmed: 8367616google scholar: lookup
  28. Binnie MJ, Dawson B, Pinnington H, Landers G, Peeling P. Sand training: A review of current research and practical applications. J. Sports Sci. 2014;32:8–15.
    doi: 10.1080/02640414.2013.805239pubmed: 23968257google scholar: lookup
  29. Puccetti M, Beccati F, Denoix J-M. Bone stress injuries and fatigue fractures of the pelvis in endurance horses. Equine Vet. J. 2022;54:1064–1075.
    doi: 10.1111/evj.13536pubmed: 34738269google scholar: lookup
  30. Schrurs C, Blott S, Dubois G, Van Erck-Westergren E, Gardner DS. Locomotory Profiles in Thoroughbreds: Peak Stride Length and Frequency in Training and Association with Race Outcomes. Animals 2022;12:3269.
    doi: 10.3390/ani12233269pmc: PMC9741461pubmed: 36496790google scholar: lookup
  31. Hautala A, Tulppo M.P, Mäkikallio T.H, Laukkanen R, Nissilä S, Huikuri H.V. Changes in cardiac autonomic regulation after prolonged maximal exercise. Clin. Physiol. 2001;21:238–245.
    doi: 10.1046/j.1365-2281.2001.00309.xpubmed: 11318832google scholar: lookup
  32. Goldberger J.J, Challapalli S, Tung R, Parker M.A, Kadish A.H. Relationship of heart rate variability to parasympathetic effect. Circulation 2001;103:1977–1983.
    doi: 10.1161/01.CIR.103.15.1977pubmed: 11306527google scholar: lookup
  33. Mourot L, Bouhaddi M, Tordi N, Rouillon J.-D, Regnard J. Short- and long-term effects of a single bout of exercise on heart rate variability: Comparison between constant and interval training exercises. Eur. J. Appl. Physiol. 2004;92:508–517.
    doi: 10.1007/s00421-004-1119-0pubmed: 15461995google scholar: lookup
  34. Hinchcliff K.W, Kaneps A.J, Geor R.J. Equine Exercise Physiology: The Science of Exercise in the Athletic Horse. Elsevier; St. Louis, MO, USA: 2008.
  35. de Siqueira R.F, Fernandes W.R. Dynamic Hematological Responses in Endurance Horses: Unraveling Blood Physiological Markers of Exercise Stress and Recovery. Int. J. Equine Sci. 2024;3:74–81.
    doi: 10.64292/ijes.116google scholar: lookup
  36. Lindblom H, Pernett F, Schagatay E, Holmström P. Effect of exercise intensity and apnea on splenic contraction and hemoglobin increase in well-trained cross-country skiers. Eur. J. Appl. Physiol. 2024;124:2057–2067.
    doi: 10.1007/s00421-024-05428-zpmc: PMC11199288pubmed: 38393417google scholar: lookup
  37. Hodgson D.R, McKeever K.H, McGowan C.M. The Athletic Horse: Principles and Practice of Equine Sports Medicine. 2nd ed. Saunders Elsevier; St. Louis, MO, USA: 2014.
  38. Vlaeva R, Sabev S, Ivanova Z. Hematological parameters in endurance horses pre and post 120 km race. Rev. Ciênc. Agroveterinár. 2023;22:72–77.
    doi: 10.5965/223811712212023072google scholar: lookup
  39. Witkowska-Piłaszewicz O, Malin K, Dąbrowska I, Grzędzicka J, Ostaszewski P, Carter C. Immunology of Physical Exercise: Is Equus caballus an Appropriate Animal Model for Human Athletes?. Int. J. Mol. Sci. 2024;25:5210.
    doi: 10.3390/ijms25105210pmc: PMC11121269pubmed: 38791248google scholar: lookup
  40. Zandoná Meleiro M.C, de Carvalho H.J.C, Ribeiro R.R, da Silva M.D, Salles Gomes C.M, Miglino M.A, de Santis Prada I.L. Immune Functions Alterations Due to Racing Stress in Thoroughbred Horses. Animals 2022;12:1203.
    doi: 10.3390/ani12091203pmc: PMC9104563pubmed: 35565629google scholar: lookup

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