Electrical Activity and Relative Length Changes of Dog Limb Muscles as A Function of Speed and Gait

Abstract

Electrical activity and length changes of 11 muscles of the fore- and hind- limbs of dogs walking, running, and galloping on a treadmill, were measured as a function of forward speed and gait. Our purpose was to find out whether the activity patterns of the major limb muscles were consistent with the two mechanisms proposed for storage and recovery of energy within a stride: a ‘pendulum-like’ mechanism during a walk, and a ‘spring-like’ mechanism during a run. In the stance phase of the walking dog, we found that the supraspinatus, long head of the triceps brachii, biceps brachii, vastus lateralis, and gastrocnemius underwent only minor length changes during a relatively long portion of their activity, Thus, a major part of their activity during the walk seems consistent with a role in stabilization of the joints as the dog ‘pole-vaulted’ over its limbs (and thereby conserved energy). In the stance phase of trotting and/or galloping dogs, we found that the supraspinatus, lateral head of the triceps, vastus lateralis, and gastrocnemius were active while being stretched prior to shortening (as would be required for elastic storage of energy), and that this type of activity increased with increasing speed. We also found muscular activity in the select limb flexors that was consistent with storage of kinetic energy at the end of the swing phase and recovery during the propulsive stroke. This activity pattern was apparent in the latissimus dorsi during a walk and trot, and in the biceps femoris during a trot and gallop. We conclude that, during locomotion, a significant fraction of the electrical activity of a number of limbs muscles occurs while they undergo little or no length change or are being stretched prior to shortening and that these types of activities occur in a manner that would enable the operation of pendulum-like and spring-like mechanisms for conserving energy within a stride. Therefore these forms of muscular activity, in addition to the more familiar activity associated with muscle shortening, should be considered to be important during locomotion.

Kinematic form and scaling: Further investigations on the visual perception of lifted weight.

“…There is considerable evidence that mammalian movement is organized so that gravity or the elastic components of the actuators can be used to store mechanical energy and return it, thereby reducing metabolic energy consumption (Cavagna et al, 1977; Fedak et al, 1982; Heglund et al, 1982; Hof et al, 1983; Taylor, 1980). For instance, walking is organized as a combination of inverted and upright pendulums (Alexander, 1977; McMahon, 1984; Mochon & McMahon, 1980), while running takes advantage of the elastic compliance of muscles and tendons (Alexander, 1984; Giovanni et al, 1980; Goslow, Seeherman, Taylor, McCutchin, & Heglund, 1981; Taylor et al, 1980). Such organization produces preferred frequencies that reflect the optimal frequencies at which mechanical energy can be conserved via the particular storage medium (Cavagna et al., 1977; Mochon & McMahon, 1980).…”

Legs as linkages: an alternative paradigm for the role of tendons and isometric muscles in facilitating economical gait

“…Note that, in contrast with the previous consideration of a single four-bar linkage tuned to achieve very nearly straight-line motion, the approach here (and below, for the hindlimb) calculates the series of linkages – each with a different muscle ray as one of the links – that achieves exactly straight-line motion, the joints of each linkage undergoing infinitesimally small changes in angle over the course of its engagement. The isometric but active nature of the triceps during weight support has previously been alluded to through geometric analysis and EMG recordings ( Goslow et al, 1981 ); however, at that time, the functional implication of such loading was constrained to an assumption of benefit from elastic loading and recoil. The paradigm proposed here is that the broadly isometric loading of the triceps contributes to near-straight-line, vertical-force, low-power weight support.…”

Development of outcome measures according to dystrophic phenotypes in canine X-linked muscular dystrophy in Japan

“…It has been reported that forelimb and hindlimb gait movements strongly influence thoracic and lumbar motion, respectively [ 133 ]. In the standing position, the load in the vertical direction is more strongly applied to the forelimb than to the hindlimb, with a ratio of at least 6:4 [ 133 , 134 , 135 , 136 , 137 ], which suggests that the forelimbs are mainly loaded from the early stage at the initiation of walking. Owing to the strut load, dystrophic dogs might experience muscle involvement, especially in the forelimb, before the onset of muscle weakness, which could lead to reduced acceleration in the thoracic region.…”