The Application of Acoustic Myography in Canine Muscle Function and Performance Testing

Abstract

SOJ Veterinary Sciences Open Access Research Articlebegin to walk at a faster pace, the limbs begin to impact with the ground and in so doing behave elastically [5]. Clearly, there is then an inverse relation between limb stiffness and an ability to convert potential energy into kinetic energy thus stiffness decreases as speed increases.In the trot, the body's center of mass behaves differently. Rather than being raised in the first half of the stance phase, it is lowered and the body moves as a wave, often with minimal oscillation in those breeds of dogs that are used to trotting for long periods of time [6]. Here potential energy is converted into elastic energy and stored upon impact with the ground by passive stretching of tendons and muscles, to be released later on in the stance phase. This is the spring-mass model described by Blickhan [3]. The study undertaken by Gregersen and colleagues not only confirms this spring-mass model, it also reveals that the work performed by every joint of the fore-and hind-limbs is more efficient due to a reduced "cost" of physical activity resulting from the release of elastic energy [7]. Indeed, in the trot three quarters of the work performed by dogs is recoverable [7].Muscles used in locomotion are stretched prior to shortening while producing a force. Compared to concentric contractions (shortening), eccentric contractions (lengthening) result in the highest force with the lowest energy costs due to the higher energy absorption [7,2]. Subsequently, the stored energy can be converted back to kinetic energy in the rebound [1,2]. One of the situations in which this is used to great effect is in the very rapid protraction of a horse's fore-limb during periods of galloping, when elastic energy stored in the biceps muscle is released as a burst of energy that results in a catapult action propelling the fore-limb forward [8].Acoustic Myography (AMG), which directly measures muscle contractions, was recently documented as being a useful diagnostic tool for rapidly determining muscular injury in the veterinary clinic [9,10]. Indeed, this technique has been used in the assessment of veterinary clinical diagnosis and monitoring of such dysfunctions or diseases as lameness, kissing spine, crookedness and muscular atrophy as well as post surgery/ trauma monitoring (distance measurement) or retraining/ healthy daily training (http://www.myodynamikequine.com/ AbstractIt is generally known that muscles have the ability to store and convert energy making certain types of movement highly efficient with regard to muscle work. The principle behind this concept is summarized in what has become known as the "spring-mass" model. Whilst evidence of a change in gait from walk to trot has been documented for more than 35 years, quantitative measurements of comparable changes in muscle function remain elusive. In a study involving 11 Labrador dogs, looking at muscle function as assessed by acoustic myography, changes in muscle efficiency/coordination as well as both spatial-(fiber recruitment) a...