Dogs recovering from surgery and injury or dogs with chronic conditions such as hip dysplasia, stifle conditions (luxating patella, partially ruptured cruciate ligament) and osteoarthritis can benefit from remedial exercises to strengthen muscles that support the hip and stifle joints. With the wide variety of remedial exercises, which ones should you focus on to strengthen hind limb musculature?

A recent study analysed muscle activation patterns of three hind limb muscles (Vastus Lateralis VL, Bicep Femoris BF, and Gluteus Medius GM) in 12 dogs with no injury, lameness, pain or gait abnormalities. Measurement of muscle activities were gathered when dogs performed the following:

• stance,

• walking,

• trotting

and the following therapeutic exercises:

• elevation of forelimbs on 30cm platform

• elevation of forelimbs on 30cm platform and hind limbs on 15 inflatable platform

• standing on 91 cm balance board

• up and over – walking onto 30 cm platform and off the platform

• backward dancing – raised forelimbs and walking backward

• limb weight added to one hind leg when walking and trotting

The three muscles were selected because they are the major stabilisers of the hip and stifle and tend to atrophy in response to orthopaedic disease or injury. Here is a brief overview of each of these muscles.

Vastus Lateralis (VL)

The vastus lateralis forms part of the femoral quadriceps group and as such its role is to extend the stifle and flex the hip. The vastus lateralis originates in the craniolateral part of the proximal femur in a large tendinous sheath. The muscle fibres extend medially and cranially. The caudal fibres extend to the lateral stifle joint where the tendinous portion unites with the joint capsule.

The activity of the vastus lateralis is consistent with stifle extension during the stance phase of the walk, trot and gallop. At the trot and gallop gait, the vastus lateralis stretches on foot touch down and shortens to extend the stifle. This pattern allows alternate storage of energy and then release during locomotion.

Bicep Femoris (BF)

The bicep femoris is a large muscle located laterally on the thigh. It originates on the ischial tuberosity and inserts at the femorotibial joint laterally over the vastus lateralis. It has two heads: the cranial superficial head attaches to the patella, patellar ligament and tibial tuberosity. The action of the cranial head is associated with the paw placement in the stance phase and as a hip extensor and to a lesser extent stifle extension. The caudal deeper head attaches at the cranial border of the tibia and it exhibits two bursts of activity. The first is the antigravity action the same as the cranial head during the stance phase. The second is associated with stifle extension at the start of the swing phase and involves tarsal joint extension.

Gluteus medius (GM)

The gluteus medius (GM) originates at the ileum and extends over the deep gluteal and ends via a short, thick tendon on the trochanter major. The large part of this muscle lies deep in the gluteal fascia and only the caudal part is covered by the superficial gluteal muscle. The action of the gluteus medius is to extend the hip, rotate the hip medially (toward the mid line) and prevent lateral hop rotation during weight bearing.

Best conditioning exercises to activate the dog’s hind leg muscles

In all exercises, the BF had significantly higher mean activity levels followed by the VL and GF. The BF was most activated during dancing backwards and the up and over exercise.

The VL was most activated during the up and over exercise and dancing backwards. This level of activity is thought to be due to the additional load on muscles to push the dog’s body weight vertically in the up and over exercise which is a similar activity to walking up stairs. Dancing backwards also resulted in elevated VL muscle activity due to the additional force on the two hindlimbs which increased stifle flexion compared with dancing forwards.

The GM was most active during leg weight trotting and dancing backward exercises due to increased hip extension. During the trotting exercise there is a 5 degree increase in hip extension and a 28 degree increase in hip extension during the dancing backward exercise compared with walking.

A surprising result showed that there was diminished mean and maximum muscle activity during leg weight trotting. The reasons for this result may include:

• Limited amount of weight applied

• Recruitment of other muscle groups to assist advancing the limb

• Change of gait to accommodate leg weight. The observable changes included shortened stride length, shortened stance time and increased weight shifting to the unweighted limb. During this exercise, the dogs’ gait became asymmetric. The dogs compensated for the leg weight by shifting their weight to the opposite hind limb and contralateral forelimb.

This study indicates for the three muscles measured, the most effective exercises for increasing muscle activity are the up and over exercise and dancing backwards. Before starting an exercise routine for muscle strengthening with your dog, there are other considerations including:

• Number of repetitions

• Frequency of sessions per week

• Rest between sets

• Velocity of performing the movements

• Load when performing the movements

In the next article some of these considerations will be discussed. For other reading of remedial exercises please see:

http://www.fullstride.com.au/blog/exercise-to-build-your-dog-muscles

https://www.fullstride.com.au/blog/home-exercises-or-a-walk-which-is-better

Full Stride offers remedial massage treatments and home exercise programmes to assist dogs recover from injury and keep dogs with chronic conditions pain free and exercising regularly.

Until next time, enjoy your dogs.

Image by Romuald Gałęcki from Pixabay