While I don’t personally use dog parks, I have noticed that most of the parks in my area are now equipped with “agility” like equipment including A-frames, jumps, weave poles, and tunnels. Pet dogs can have a bit of fun weaving, jumping and negotiating the obstacles, but what effect does this type of exercise have on their muscles and does it expose them to risk of a soft tissue injury?

In highly trained dogs who participate in competitive agility, soft tissue injuries like strains, sprains and contusions are common. Frequently, these injuries occur in the shoulder and forelimbs.

A 2017 study of canine agility athletes sought to understand the relationship between muscle activation and risk of injury, specifically in the forelimbs. The study measured the muscle activation in four forelimb muscles while dogs performed two common agility tasks: A-frame and jumps.

Study design

Eight (8) healthy Border Collies, all agility trained with at least two years agility experience participated in this study. Fine-wire electromyography technique was used to measure muscle activation while the dogs walked, performed the A-frame at two different heights and negotiated two jumps.

The study measured muscle activation of four (4) forelimb muscles: Biceps Brachii, Supraspinatus, Infraspinatus, and the long head of the Brachial Tricep. Muscles involved in shoulder and elbow joint motion and shoulder stabilisation.

Findings

Peak muscle activations for all four muscles occurred when the dog was jumping. During this activity, muscle activation was 3 – 10 times greater than when the dogs were walking. Likewise, the muscle activations, ascending and descending the A-Frame were significantly higher than at a walk.

In terms of peak activations of individual muscles for each activity, when jumping the Brachial Tricep and Biceps Brachii had the greatest activations. While the Brachial Triceps had the lowest activation when the dogs were descending the A-frame. Likewise the activation of the Brachial Bicep was lowest when landing a jump and descending the A-frame.

The activations of the Supraspinatus were highest when leaving the A-frame and jumping but lowest while preparing for take-off into a jump and landing a jump.

The study also analysed muscle activations through the stance and swing phase of the dog’s gait as they performed the three tasks (walking, jumping and A-frame). This analysis was significant because eccentric contractions, where the muscle releases slowly to allow better muscle control, are known to contribute to injury and fatigue (See blog on Delayed Onset Muscle Soreness ) and occurs through the various phases of the gait.

The study observed that the longest stance time across the activities occurred when the dogs were descending the A-frame. Peak activations of the Biceps Brachii, Supraspinatus and Infraspinatus occurred during the stance of these strides. This finding supports the understanding that forelimbs exert stronger braking forces downhill to facilitate front to back body balance.

Peak activations of the Biceps Brachii and Brachial Tricep occurred during the swing phase of the jumping transition stride to flex the shoulder and elbow joints. During this phase of the gait, these muscles are performing concentric contractions (muscles shorten or lengthen to create joint movement) to extend the shoulder and flex the elbow to clear the jump. In preparation for landing, these joint motions are reversed. Accordingly, the Brachial Triceps and Biceps Brachii are active during both stretch and shortening contraction cycles of the muscle. The study concluded that the most demanding part of the jump across all four forelimb muscles was the transition stride where the dog lifts off the ground to clear the jump and reaches forward with the forelimb to land.

The study also concluded that descending the A-frame was as demanding in terms of muscle activation as jumping. However, as competition agility courses have far more jump obstacles than A-frames, the risks of injury from these two obstacles may be considered in terms of muscle overuse vs overload on the A-frame.

Key points for all dog owners

The risk of muscle injury increases when muscles are overused or overloaded. Activities like jumping, ascending and descending sharp inclines activate the muscles in the shoulder up to 10 times more than walking on flat surfaces.

The action of jumping, ascending or descending is not isolated to agility equipment. It is reflected in everyday actions our dogs perform including jumping onto furniture, into the car, and negotiating stairs.

Ways to prevent muscle strain in dogs include:

• Limit the amount of times the dog performs these functions to reduce the risk of overloading muscles. For example, only let the dog on the bed in the evening, when the family to going to bed rather than them hopping up and down through the day.

• Manage the environment in which the dog is jumping, ascending or descending to reduce the muscle load. For example, reduce the height from which the dog is jumping up or down by adding a step, lift the dog in and out of the car or use a ramp.

• Manage other factors like the floor surface, the dog’s weight and joint health to reduce muscle load and the risk of injury.

If your dog has experienced a soft tissue injury, please contact me to discuss how a myofunctional treatment may benefit your dog. Full Stride provides canine myofunctional therapy including massage and exercise therapy in Brisbane’s north. We offer in home consultations or treatments in my clinic.

Until next time, enjoy your dogs.

Source:

Cullen,K.L, Dickey, J.P, Brown, S.H.M, Nykamp, S.G, Bent, L.R, Thomason J.J and Moens, N.M.M, 2017 “The magnitude of muscular activation of four canine forelimb muscles in dogs performing two agility-specific tasks” BMC Veterinary Research (http://bmcvetres.biomedcentral.com/articles/10.1186/s12917-017-0985-8)