The forelimb in walking horses: 2. Net joint moments and joint powers

Abstract

The objective was to measure the net joint moments and joint powers for the joints of the equine forelimb during the walk. Videographic and force data were combined with morphometric information using an inverse dynamics method. During stance phase the predominant joint moment was on the palmar aspect of all forelimb joints except the shoulder, where the peak moment was considerably higher than at any other joint. The entire forelimb showed net energy absorption in both stance and swing phases. The elbow was the only joint that showed net generation of energy, which was used to maintain the limb in extension in early stance as the horse's body vaults over the limb and to drive protraction and retraction of the limb during swing. The carpus aligned the limb into a supportive strut, but did not play an important role in energy absorption or generation. A small burst of positive work on the flexor aspect at the start of breakover indicated that the carpus played an active role in initiating breakover during walking. The fetlock functioned elastically to store and release strain energy during stance. The coffin joint acted as an energy damper during most of stance with a small burst of energy generation on the flexor aspect as the joint flexed during breakover. The magnitude of the peak joint power during swing decreased in a proximal to distal sequence. It is concluded that the elbow joint is the main site of energy generation. The shoulder and coffin joints act as energy dampers during stance. The distal joints had very low joint powers and appeared to be driven by inertial forces during the swing phase. This information will be applied to describe how horses compensate for different lamenesses in terms of redistributing the functions of energy generation and absorption between joints.

Relationship between muscle forces, joint loading and utilization of elastic strain energy in equine locomotion

“…The peak vertical GRF for trotting at 1.4ms -1 (8.4±0.2Nkg -1 ) found in this study is similar to that extrapolated from data reported by ) (Dutto et al, 2004). We estimated the maximum torques developed about the AC, MCP and DIP joints to be 0.42±0.10, 0.53±0.03 and 0.10±0.03Nmkg : 0.6, 0.75 and 0.4Nmkg -1 (Clayton et al, 2000a), again considering the differences in gait speeds. For trotting, we estimated the maximum torques to be 0.73±0.20, 0.93±0.14 and 0.10±0.03Nmkg -1 for the AC, MCP and DIP joints, respectively, which are consistent with the results obtained by Dutto et al for trotting at 2.5-3.25ms -1 : 1.0, 1.1 and 0.2Nmkg -1 (Dutto et al, 2006).…”

“…Our results suggest that tendon work in trotting and galloping is much more significant than in walking (Fig.5), but more detailed studies are needed to see if tendon work increases with speed in the faster gaits. Long tendons may have other energetic benefits for the horse because they allow for a relatively long and light distal limb, reducing the energy required for limb protraction during normal gait (Clayton et al, 2000a).…”

Joint work and power for both the forelimb and hindlimb during trotting in the horse

“…Work done by one hindlimb was 0.34·J·kg -1 , which was greater than that observed during walking [0.16·J·kg -1 (Clayton et al, 2001)] and less than during jumping [0.71·J·kg -1 (Dutto et al, 2004b); 1.25·J·kg -1 (Bobbert and Santamaría, 2005)]. Like the forelimb, the three distal joints of the hindlimb contributed little work to the limb, as it behaved elastically (Fig.·7C).…”

Forelimb muscle activity during equine locomotion

“…The patterns of net muscular torques developed over one gait cycle have been calculated for a wide variety of species using measurements of joint kinematics and ground reaction forces (Clayton et al, 2000;Colborne et al, 1997;Dogan et al, 1991;Fowler et al, 1993;Perell et al, 1993;Pandy et al, 1988;Witte et al, 2002). Individual muscle forces also have been determined, albeit for a smaller selection of animals, using detailed muscle-actuated models of the limbs (e.g.…”