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Home / Equine Research Bank / Biol Open / Standing horse posture: a longer stance is more stable.
Biology open2022; 11(4); bio059139; doi: 10.1242/bio.059139

Standing horse posture: a longer stance is more stable.

Abstract: Horses stand for most of each day. Although they can use various leg configurations (postures), they usually stand with vertical legs. Why? We addressed this question with a 2D quasi-static model having three rigid parts: a trunk, massless fore-limbs and massless rear limbs, with hinges at the shoulders, hips, and hooves. The postural parameter we varied was ℓg, the distance between the hooves. For a given ℓg, statics finds an equilibrium configuration which, with no muscle stabilization (i.e. using minimal effort) is unstable. We assume a horse uses that configuration. To measure the neuromuscular effort needed to stabilize this equilibrium, we added springs at the shoulder and hip; the larger the springs needed to stabilize the model (kmin), the more neuromuscular effort needed to stabilize the posture. A canted-in posture (small ℓg), observed habitually in some domestic horses, needs about twice the spring stiffness (representing twice the effort) as is needed with vertical or slightly splayed-out (large ℓg) legs. This relationship of posture and stability might explain the prevalence of vertical or slightly splayed-out legs in wild and healthy domestic horses and leaves as a puzzle why some horses stand canted-in.
© 2022. Published by The Company of Biologists Ltd.
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Publication Date: 2022-05-12 PubMed ID: 35545924PubMed Central: PMC9115912DOI: 10.1242/bio.059139Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study explores why horses usually stand with their legs vertical rather than adopting different postures. The researchers used a 2D model to propose that horses stand with vertical legs because it requires less neuromuscular effort, thereby providing better stability.

Research Methodology

  • The researchers employed a two-dimensional quasi-static model to simulate the standing posture of a horse. This model is made up of three rigid parts, representing the trunk of the horse and the two pairs of legs, both the fore-limbs and rear limbs.
  • The model included hinges at the shoulders, hips, and hooves to allow the simulation of different leg configurations.
  • The main variable manipulated in the model was the distance between the hooves (ℓg), which determined the width of the stance adopted by the model horse.

Findings and Observations

  • Through static analysis, the study found that the equilibrium configuration for a particular hooves distance does not provide stability without muscular stabilization. Therefore, the study presumed a horse maintains this configuration using its muscles.
  • The researchers added springs at the shoulder and hip joints in the model. The stiffness of the springs provided an estimate of the neuromuscular effort required to stabilize the equilibrium of the horse’s stance.
  • The study observed that a canted-in posture, which involves having the legs closer to each other, requires approximately twice the muscular effort compared to when the legs are vertical or slightly splayed out.

Implications and Conclusion

  • This research suggests that the reason horses typically stand with their legs vertical or slightly splayed out is because it requires less muscular effort and provides more stability, making it a more efficient posture for standing over extended periods.
  • The findings also question why some horses adopt a canted-in stance, considering it requires twice as much effort to maintain. This could be a subject for further research, as understanding the precise reason for this behavior could provide more insight into equine physiology.

Cite This Article

APA
Gellman K, Ruina A. (2022). Standing horse posture: a longer stance is more stable. Biol Open, 11(4), bio059139. https://doi.org/10.1242/bio.059139

Publication

Biology open
ISSN: 2046-6390
NlmUniqueID: 101578018
Country: England
Language: English
Volume: 11
Issue: 4
PII: bio059139

Researcher Affiliations

Gellman, Karen
  • Maximum Horsepower Research, Ithaca, NY, USA.
Ruina, Andy
  • Mechanical Engineering, Cornell University, Ithaca, NY 14853, USA.

MeSH Terms

  • Animals
  • Horses
  • Postural Balance / physiology
  • Posture / physiology

Conflict of Interest Statement

Competing interests The authors declare no competing or financial interests.

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Citations

This article has been cited 8 times.
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