digital activation musculosketal problems

Digital activation musculosketal problems series#

These adaptations result in a substantial reduction in the energetic cost of locomotion ( Minetti et al., 1999 Roberts et al.,1997 Biewener et al.,1998), with the limb acting as a pogo-stick-like, tuned-spring system ( Blickhan, 1989 Cavagna et al., 1977 McMahon, 1985 McMahon and Cheng, 1990). The short fibres reduce the energetic cost of force generation. Tendinous tissue is elastic and returns about 93% of the energy stored in it( Ker, 1981), thus the long tendons and muscle aponeurosis are used to store and return elastic energy during the stance phase of locomotion( Alexander, 1988 Alexander and Bennet-Clarke,1977). The muscles of the distal limb associated with weight bearing have short muscle fibres, a pennate structure and significant passive elastic properties(Alexander et al., 1979, 1982 Biewener, 1998a Dimery et al., 1986). Large cursorial mammals have lengthened distal limb bones and tendons. These were 12.79 N kg -1 body mass (BM)(range 12.07-13.73 N kg -1 BM) for the lead forelimb and 15.23 N kg -1 BM (13.51-17.10 N kg -1 BM) for the non-lead forelimb. Finally, we determined the relationship between MCP joint angle and vertical ground-reaction force at trot and then predicted the forelimb peak vertical ground-reaction force during a 12 m s -1gallop on a treadmill. Secondly, we demonstrate that there is a linear relationship between limb force and metacarpo-phalangeal (MCP) joint angle that is minimally influenced by digital flexor muscle activation in vitro or as a function of gait in vivo. Firstly, we demonstrate that the distal, passive leg spring changes length by 127 mm(range 106-128 mm) at gallop and the proximal spring by 12 mm (9-15 mm).

Digital activation musculosketal problems series#

In this paper we report the results of a series of experiments testing the hypothesis that there is minimal scope for muscle contraction in either spring to adjust limb compliance. The forelimb anatomy means that the leg can be conceptually divided into two springs: the proximal spring, from the scapula to the elbow, and the distal spring, from the elbow to the foot.

The arrangement of the muscle-tendon units around the lever-like joints means that as the leg shortens the muscle-tendon units are stretched. A horse's legs are compressed during the stance phase, storing and then returning elastic strain energy in spring-like muscle-tendon units.