Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Horses damp the spring in their step


The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle–tendon units1,2.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints3,4. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle5. Despite being apparently redundant for such a mechanism5, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30–40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Equine distal forelimb (medial view) showing segments below the elbow, and the tendons and muscles that resist compression of the limb by the effect of gravitational and inertial forces during the stance phase of locomotion.
Figure 2: Plot of horizontal (in direction of locomotion) and vertical limb ground reaction force (GRF) against time for a 450-kg horse trotting at 3 m s-1 over a 6-mm-thick polyester/rubber-matting-covered conveyor-belt force plate.
Figure 3: Relationship between limb force and muscle length for an equine superficial digital flexor muscle loaded in situ in the unstimulated state (U), and two sequential cycles with maximal electrical stimulation (S1, S2).
Figure 4: Vertical and horizontal ground reaction force (GRF) data produced from the equine limb model described in the text in the reference condition (leg vertical, no muscle activation, loading on tarmac).
Figure 5: Plot of cycle work done on each cross-bridge in 10-21 J per cycle as a function of frequency (Hz) during a sinusoidal length change of 0.5%.

Similar content being viewed by others


  1. Dimery, N. J., Alexander, R. McN. & Ker, R. F. Elastic extension of leg tendons in the locomotion of horses (Equus caballus). J. Zool. 210, 415–425 (1986).

    Article  Google Scholar 

  2. Minetti, A. E., Ardigo, L. P., Reinach, E. & Saibene, F. The relationship between mechanical work and energy expenditure of locomotion in horses. J. Exp. Biol. 202, 2329–2338 (1999).

    CAS  PubMed  Google Scholar 

  3. Alexander, R. McN. & Bennet-Clark, H. C. Storage of elastic strain energy in muscle and other tissues. Nature 265, 114–117 (1977).

    Article  ADS  CAS  Google Scholar 

  4. Alexander, R. McN. Elastic Mechanisms in Animal Movement (Cambridge Univ. Press, Cambridge, 1988).

    Google Scholar 

  5. Biewener, A. A. & Roberts, T. J. Muscle and tendon contributions to force, work and elastic energy savings: a comparative perspective. Exercise Sport Sci. Rev. 28, 99–107 (2000).

    CAS  Google Scholar 

  6. Biewener, A. A. Muscle–tendon stresses and elastic energy storage during locomotion in the horse. Comp. Biochem. Physiol. B 120, 73–87 (1998).

    Article  CAS  Google Scholar 

  7. Biewener, A. A., Konieczynski, D. D. & Baudinette, R. V. In vivo muscle force-length behaviour during steady state hopping in tammar wallabies. J. Exp. Biol. 201, 1681–1694 (1998).

    CAS  PubMed  Google Scholar 

  8. Hof, A. L. In vivo measurement of the series elasticity release curve of human triceps surae muscle. J. Biomech. 31, 793–800 (1998).

    Article  CAS  Google Scholar 

  9. Kurokawa, S., Fukunaga, T. & Fukashiro, S. Behaviour of fascicles and tendinous structures of human gastrocnemius during vertical jumping. J. Appl. Physiol 90, 1349–1358 (2001).

    Article  CAS  Google Scholar 

  10. Grandage, J. Penniform muscles of the horses forelimb. J. Anat. Abstr. 132, 318 (1981).

    Google Scholar 

  11. Hermanson, J. W. & Cobb, M. A. Four forearm flexor muscles of the horse, Equus caballus: anatomy and histochemistry. J. Morphol. 212, 269–280 (1992).

    Article  CAS  Google Scholar 

  12. Stephens, P. R., Nunamaker, D. M. & Butterweck, D. M. Application of a Hall effect transducer for the measurement of tendon strains in horses. Am. J. Vet. Res. 50, 1089–1095 (1989).

    CAS  PubMed  Google Scholar 

  13. Herrick, W. C., Kingsbury, H. B. & Lou, D. Y. S. A study of the normal range of strain, strain rate and stiffness of tendon. J. Biomed. Mat. Res. 12, 877–894 (1978).

    Article  CAS  Google Scholar 

  14. Bogert, A. J., van den Gerritsen, K. G. M. & Cole, G. K. Human muscle modeling from a user's perspective. J. Electromyog. Kinesiol. 8, 119–124 (1998).

    Article  Google Scholar 

  15. van Weeren, P. R., van den Bogert, A. J., Back, W., Bruin, G. & Barneveld, A. Kinematics of the standardbred trotter measured at 6, 7, 8 and 9 ms-1 on a treadmill after 5 months of prerace training. Acta Anat. 146, 154–161 (1993).

    Article  CAS  Google Scholar 

  16. van den Bogert, A. J. & Schamhardt, H. C. Multi-body modelling and simulation of animal locomotion. Acta Anat. 146, 95–102 (1993).

    Article  CAS  Google Scholar 

  17. Lake, M. J., Coyles, V. R. & Lees, A. High frequency characteristics of the lower limb during running. Proc. 18th Congr. Int. Soc. Biomech. (eds Müller, R., Gerber, H. & Stacoff, A.) 200–201 (Laboratory for Biomechanics, ETH Zurich, 2001).

  18. Carter, D. R. Mechanical loading histories and cortical bone remodeling. Calcif. Tissue Int. 36(Suppl.), 19–24 (1984).

    Article  Google Scholar 

  19. Wang, X. T., Ker, R. F. & Alexander, R. McN. Fatigue rupture of wallaby tail tendons. J. Exp. Biol. 198, 847–852 (1995).

    CAS  PubMed  Google Scholar 

  20. Cheney, J. A., Liou, S. Y. & Wheat, J. D. Cannon bone fracture in the thoroughbred racehorse. Med. Bio. Eng. 11, 613–620 (1973).

    Article  CAS  Google Scholar 

  21. Nunamaker, D. M., Butterweck, D. M. & Provost, M. T. Fatigue fractures in thoroughbred racehorses: relationships with age, peak bone strain, and training. J. Orthop. Res. 8, 604–611 (1990).

    Article  CAS  Google Scholar 

  22. Dow, S. M., Leendertz, J. A., Silver, I. A. & Goodship, A. E. Identification of subclinical tendon injury from ground reaction force analysis. Equine Vet. J. 23, 266–272 (1991).

    Article  CAS  Google Scholar 

  23. Pratt, G. A. et al. Stiffness isn’t everything. Proc. 4th Int. Symp. Experimental Robotics, ISER, Stanford, California 173–178 (1995).

  24. Ettema, G. J. C. & Huijing, P. A. Frequency response of rat gastrocnemius medialis in small amplitude vibrations. J. Biomech. 27, 1015–1022 (1994).

    Article  CAS  Google Scholar 

  25. Kawai, M. & Brandt, P. W. Sinusoidal analysis: A high resolution method for correlating biochemical reactions with physiological processes in the activated skeletal muscles of rabbit, frog and crayfish. J. Muscle Res. Cell. Motil. 1, 279–303 (1980).

    Article  CAS  Google Scholar 

  26. Piazzesi, G. & Lombardi, V. A cross-bridge model that is able to explain mechanical and energetic properties of shortening muscle. Biophys J. 68, 1966–1979 (1995).

    Article  ADS  CAS  Google Scholar 

  27. Piazzesi, G. & Lombardi, V. Simulation of the rapid regeneration of the actin–myosin working stroke with a tight coupling model of muscle contraction. J. Muscle Res. Cell. Motil. 17, 45–53 (1996).

    Article  CAS  Google Scholar 

  28. van den Bogert, A. J. Computer Simulation of Locomotion in the Horse. Thesis, Univ. Utrecht, The Netherlands (1989).

    Google Scholar 

  29. van Soest, A. J. & Bobbert, M. F. The contribution of muscle properties in the control of explosive movements. Biol. Cybern. 69, 195–204 (1993).

    Article  CAS  Google Scholar 

  30. Gerritsen, K. G. M., van den Bogert, A. J. & Nigg, B. M. Direct dynamics simulation of the impact phase in heel–toe running. J. Biomech. 28, 661–668 (1995).

    Article  Google Scholar 

Download references


We acknowledge the assistance of R. C. Woledge in carrying out the cross-bridge model calculations and thank him for comments on the manuscript. We thank the Horserace Betting Levy Board, London, for funding this work.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Alan M. Wilson.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Wilson, A., McGuigan, M., Su, A. et al. Horses damp the spring in their step. Nature 414, 895–899 (2001).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing