Horses damp the spring in their step

Wilson, Alan M.; McGuigan, M. Polly; Su, Anne; Bogert, Antonie J. van den

doi:10.1038/414895a

Cited by 220 publications

(213 citation statements)

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“…Specialist hoppers and runners, such as wallabies and horses, have distal architecture that facilitates economy through short, pinnate fibre arrangement and long tendons [34,35]. However, wallaby distal muscles do not increase work output on an incline [36], and horse digital flexors may be limited to a high-frequency damping function [37]. Furthermore, horse distal tendons are prone to injury and heat damage [38,39].…”

Section: Discussionmentioning

confidence: 99%

Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl

Daley

Biewener

2011

Phil. Trans. R. Soc. B

110

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Here, we used an obstacle treadmill experiment to investigate the neuromuscular control of locomotion in uneven terrain. We measured in vivo function of two distal muscles of the guinea fowl, lateral gastrocnemius (LG) and digital flexor-IV (DF), during level running, and two uneven terrains, with 5 and 7 cm obstacles. Uneven terrain required one step onto an obstacle every four to five strides. We compared both perturbed and unperturbed strides in uneven terrain to level terrain. When the bird stepped onto an obstacle, the leg became crouched, both muscles acted at longer lengths and produced greater work, and body height increased. Muscle activation increased on obstacle strides in the LG, but not the DF, suggesting a greater reflex contribution to LG. In unperturbed strides in uneven terrain, swing preactivation of DF increased by 5 per cent compared with level terrain, suggesting feed-forward tuning of leg impedance. Across conditions, the neuromechanical factors in work output differed between the two muscles, probably due to differences in muscle-tendon architecture.LG work depended primarily on fascicle length, whereas DF work depended on both length and velocity during loading. These distal muscles appear to play a critical role in stability by rapidly sensing and responding to altered leg-ground interaction.

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Section: Discussionmentioning

confidence: 99%

Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl

Daley

Biewener

2011

Phil. Trans. R. Soc. B

110

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“…absorb potentially damaging impact energy when the limb collides with the ground (Wilson et al, 2001), while the tendons provide elastic energy recovery. The short-fibered architecture of these highly pinnate muscles also greatly reduces the cost of force generation ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…High work output and low force economy/elastic savings are observed in longer-fibered muscles that operate over larger shortening strains, whereas low work output but high force economy and the capacity for elastic savings exist for short-fibered muscles that operate over more limited ranges of fascicle strain. Even though in vivo experimental data do not exist for horse digital flexor muscles, the extreme architecture of these distal MTUs demonstrates a design for limited work output, but economical force generation and recovery of elastic energy from long tendons (Biewener, 1998a;Wilson et al, 2001). Experimental studies of human MG during walking and running based on ultrasound imaging in relation to joint moment patterns (Lichtwark et al, 2007) and recent musculoskeletal modeling analysis (Arnold et al, 2013) reinforce this pattern: proximal human muscles contract over larger lengths and perform the majority of lower extremity work compared with distal MTUs that contract with more limited length change, favoring economical force generation and tendon energy recovery.…”

Section: −1mentioning

confidence: 99%

“…Although recent work shows that the passive elasticity of a free tendon or aponeurosis may protect a muscle's fibers from potential damage when rapidly stretched (Konow et al, 2012;Roberts and Azizi, 2010) and can also modulate the F-V effects of the muscle's fibers to produce force with greater efficiency (Lichtwark and Wilson, 2005;Roberts, 2002), passive elasticity of connective tissue in series with a muscle's fibers limits the ability of the fibers to control movement at a skeletal attachment site. Extreme examples are the very short (6-12 mm) pinnate fibered superficial (SDF) and deep digital flexor (DDF) and plantaris (PL) muscles of horses and other large ungulates, which attach to the distal phalanges via long (∼600 mm) tendons (Alexander, 2002;Biewener, 1998b;Wilson et al, 2001). The >60-fold length of the muscle's tendon means that a 2-3% strain of the tendon, commonly experienced during locomotion in a variety of animals (Alexander, 2002;Biewener, 1998b;Biewener and Baudinette, 1995;Fukunaga et al, 2001;Lichtwark et al, 2007), represents a 200% strain of the fibers, well beyond their physiological range for effectively generating force.…”

Section: Introductionmentioning

confidence: 99%

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Locomotion as an emergent property of muscle contractile dynamics

Biewener

2016

Journal of Experimental Biology

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Skeletal muscles share many common, highly conserved features of organization at the molecular and myofilament levels, giving skeletal muscle fibers generally similar and characteristic mechanical and energetic properties; properties well described by classical studies of muscle mechanics and energetics. However, skeletal muscles can differ considerably in architectural design (fiber length, pinnation, and connective tissue organization), as well as fiber type, and how they contract in relation to the timing of neuromotor activation and in vivo length change. The in vivo dynamics of muscle contraction is, therefore, crucial to assessing muscle design and the roles that muscles play in animal movement. Architectural differences in muscle-tendon organization combined with differences in the phase of activation and resulting fiber length changes greatly affect the time-varying force and work that muscles produce, as well as the energetic cost of force generation. Intrinsic force-length and forcevelocity properties of muscles, together with their architecture, also play important roles in the control of movement, facilitating rapid adjustments to changing motor demands. Such adjustments complement slower, reflex-mediated neural feedback control of motor recruitment. Understanding how individual fiber forces are integrated to whole-muscle forces, which are transmitted to the skeleton for producing and controlling locomotor movement, is therefore essential for assessing muscle design in relation to the dynamics of movement.

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“…While tendons that link muscle to bone can act merely as force transmitters to position limbs, a specific subgroup of tendons whose function is to store elastic energy contributes to efficient locomotion by acting as springs, while the associated muscle fibers serve primarily to dampen vibrations (1,59). The Thoroughbred racehorse is a prime example of an elite animal athlete both in terms of evolution and subsequent genetic selection and conditioning.…”

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confidence: 99%

Can exercise modulate the maturation of functionally different immature tendons in the horse?

Kasashima

Takahashi²,

Birch³

et al. 2008

Journal of Applied Physiology

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Tendons can be considered in two functional groups, those contributing to energetics of locomotion and those acting solely to position the limb. The energy-storing tendons in both human and equine athletes have a high frequency of injury with similar pathophysiology. In previous studies, high-intensity exercise appears to induce a disruption of the matrix rather than functional adaptation in adults. Here we explore the hypothesis that the introduction of controlled exercise during growth would result in an adaptive response without deleterious effects. Young horses were given a controlled exercise program similar to that previously shown to induce matrix changes in energy-storing tendons of skeletally mature animals. The tendons were assessed in relation to mechanical properties, molecular composition, and morphology. Results showed a significant increase in cartilage oligomeric matrix protein (COMP) in the positional tendon but not in the energy-storing tendon. Other matrix properties and mechanical properties were not significantly changed. While the imposition of high-strain-rate exercise in immature horses failed to augment the development of the energy-storing tendon over and above that induced by normal pasture exercise, it did not induce deleterious changes, supporting an earlier introduction of athletic training in horses.adaptation; hypertrophy; cartilage oligomeric matrix protein; biomechanics TENDON OVERUSE INJURIES are not only responsible for considerable loss of athletic potential in both horses (30,35,58) and humans (64), but their prevalence appears to be increasing, with a doubling in Achilles tendinopathy in recent years (26,27,34,37,38). While tendons that link muscle to bone can act merely as force transmitters to position limbs, a specific subgroup of tendons whose function is to store elastic energy contributes to efficient locomotion by acting as springs, while the associated muscle fibers serve primarily to dampen vibrations (1, 59). The Thoroughbred racehorse is a prime example of an elite animal athlete both in terms of evolution and subsequent genetic selection and conditioning. The superficial digital flexor tendon (SDFT) in the horse is an energy-storing tendon with functional and compositional similarities to the Achilles tendon in humans (7). This tendon is highly susceptible to injury, accounting for 93% of all tendon and ligament injuries in a study by Ely et al. (15) and thus can be used as a "natural" model to study tendon development and degeneration (51). The common digital extensor tendon (CDET) in contrast is a good example of a positional tendon analogous to the anterior tibialis in the human (3, 62).Over the last two decades there has been a great increase in the scientific understanding of the response of bone and muscle to mechanical loading. The mechanobiology of tendon, however, is less well understood. Effects of exercise on tendon properties have been studied in various species, including mouse (36), rat (49, 55), rabbit (61), chicken (2), guinea fowl (8), miniatur...

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Horses damp the spring in their step

Cited by 220 publications

References 24 publications

Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl

Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl

Locomotion as an emergent property of muscle contractile dynamics

Can exercise modulate the maturation of functionally different immature tendons in the horse?

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