The Variables of Jump Biomechanics in Canine Agility Dogs

Understanding the biomechanics and demands of agility is critical for evaluating agility dogs, as well as developing rehabilitation programmes that will allow them to return to sport.

 

Jump biomechanics during canine agility will be affected and changed by many variables, including the experience of the dog and handler, jump height, the distance between jumps, and the approach and exit from the jump, to name a few. There is a large body of data already published on how these variables affect jump kinetics and kinematics in the dog.

 

In a two-hour webinar, Arielle Pechette Markley discusses available research on the kinetics and kinematics of canine agility. Below, we discuss some of the variables, and the research finding, on jumping in canine agility, as shared in the webinar.

 

What is Canine Agility?

Canine agility is a sport where a dog is directed by a handler through a preset obstacle course within a certain time limit. The handler guides the dog without touch, treats or toys through the course, as accurately and quickly as possible.  This requires a high level of training on the part of the dog, and a high level of accuracy from the handler.

While there is variety in how agility courses are set up between organisations and regions, there are two main kinds of courses – jumping courses, which predominantly includes a variety of jumps, tunnels and weaves, and obstacle courses, which include jumps, A-frames, dog walks and teeters, weaves and tunnels.

 

Canine Agility Athletes in Rehabilitation

As veterinary rehabilitation therapists or veterinary physiotherapists, we might see agility athletes for a variety of reasons, including:

• severe injury or lameness
• mild intermittent lameness
• changes or problems in performance
• preventative care and conditioning
• pre-season evaluations.

Injuries in competitive agility dogs are very common, with 41% of agility dogs experiencing injuries that remove them from competition for a period of time.

 

Biomechanics of Jumping during Canine Agility

Most of the kinetic and kinematic data we have available on agility concerns jumping. Most people and trainers assume that dogs naturally know how to jump, and jump technique is therefore usually not trained as extensively as the other components of an agility course. However, dogs don’t necessarily know how to jump correctly at speed, and we see a significant difference in jump technique between young and inexperienced dogs, and experienced dogs.

Many variables can and will influence and change jumping biomechanics, including:

• extension vs collection
• change in direction and turning
• dog experience level
• distance between obstacles
• speed
• approach angle
• exit angle
• type of jump
• handling technique
• timing of cues
• surface

Jumps are the most common obstacles on an agility course, with each jump differing in some way, whether in approach, angles and turns, direction, speed of approach, width of jump, or kind of jump. These jumps and their variations need to be completed at an incredible speed.

 

The phases of a jump during canine agility

To better discuss the biomechanics of a jump, we divide the jump into five phases:

1. Approach

This includes the stride before take-off. The approach phase is affected by experience and by the handler. The dog needs the relevant information for the jump at least one stride before take-off, including the direction the dog will need to travel following the jump. Once they have taken off, they are committed to the jump.

2. Take-off

This is where the dog leaves the ground, starting with the forelimbs and ending when the hind paws lose contact with the ground. Once the dog is in take-off, the jump trajectory is committed and the dog cannot change their trajectory, even though they might try.

3. Flight

During the aerial phase, the dog travels over the obstacle. They are relying heavily on body awareness and core strength to allow them to clear the obstacle. The dog’s form may vary, depending on the different variables of the jump. A change in a dog’s normal aerial phase technique may be an indicator of injury.

4. Landing

The forelimbs will take the most force as the dog touches down to the ground, with asymmetric forces between the two forelimbs. One limb will lead, while the other limb trails. We want the dog to land in a position that is optimal for the next obstacle in its path.

5. Recovery

This is the stride following landing, and will usually include a return to a normal stride. Acceleration is usually initiated in this phase. 

The jumping arc will be determined by the extension or collection of the dog. The arc should be symmetrical on both sides of the jump, whether collected or extended.

When jumping in extension, the dog is travelling straight towards and away from the jump. When a turn is added directly after a jump, the dog will need to collect. An extended jump starts much further away from the obstacle than do other jumps; the dog will probably extend its hind limbs out behind it, its body will be straight, and very little deceleration should occur. In collection, the dog is usually preparing for a turn – it will add an additional stride closer to the jump as it decelerates, turn its head and body partially during take-off, have a much smaller jump arc, and turn during the landing phase.

 

Limb dynamics during agility jumping

During landing, the trailing forelimb lands first and acts as a strut, while the leading forelimb extends and lands further ahead. The trailing limb experiences greater peak vertical forces and is responsible for higher accelerative impulse in the recovery phase of the stride. Young and inexperienced dogs are more likely to land with their forelimbs together, while experienced dogs will land with more asymmetrically.

How does turning impact jump biomechanics?

Dogs can maintain a stable contact point with the paw as they travel on a curve as the radius and ulna allows rotation.  This allows them to maintain their speed around a curve, unlike horses, who lose speed.

When the dog is jumping and turning, the strut like action of the trailing forelimb goes out the window, and the stiffness of all the limbs remains lower, with a higher level of dampening. Almost all of the translational speed is lost during the combination of jump and turn. The outer limbs are the primary contributors to the turn, experiencing higher lateral forces. The inside limbs are more stabilising and will have a longer stance duration. During take-off, the inner hindlimb will have an almost exclusively braking effect, while the outer hindlimb will have a small braking and then accelerating effect. During landing, the hindlimbs will generate impulse in the new direction.

The forelimbs during take-off have somewhat of a strut like function which is two times greater in the outer limb than in the inner forelimb. During landing, the outer forelimb experiences higher forces, higher impulses, and a shorter stance duration, which drives the turn.

How does experience affect the agility dog’s jump technique?

Experience is important and will affect jump technique.

Beginner dogs will have a reduced stride frequency with a decreased ability to maintain speed. During take-off, they will have a larger compression of the hindlimbs, with more flexion through the joints, as well as a decreased synchronicity of the hindlimbs.

During take-off, advanced dogs will have maximally extended rear limbs at the point where their toes are leaving the ground, which are also very synchronised with one another. This increases the efficiency of the jump, and allows them to maintain speed better through the jump.

During landing, beginner dogs have a more synchronised forelimb placement than advanced dogs do, which decreases the efficiency of the landing phase, breaking their velocity and speed. The strut like action that advanced dogs are able to achieve with the trailing forelimb allows them to maintain their speed and recover from the jump much faster. Beginner dogs also have a higher compression or flexion of the forelimbs during landing, which increases the eccentric muscle contraction within the forelimb. This has a decreased mechanical advantage, and may also lead to an increased risk of injury and fatigue in the forelimbs, especially in the shoulder.

During jumping and turning, advanced dogs are able to achieve an outer forelimb lateral impulse that is four times higher in landing than in take-off. They are also able to maintain a much tighter jump angle during all phases of the jump. There is an increased asymmetry between the inner and outer forelimbs, allowing them to recover faster.

• Beginner dogs lack the prerequisites for jumping at speed, lacking the coordination required to switch within one step from an alternating gallop to synchronous jumping. They will take longer to re-establish their gallop pattern.
• Beginner dogs may tire more quickly, which can increase their risk of soft tissue injury, especially to the shoulder.

This leaves us with the following questions:

Could we use these jump parameters as objective measures of jumping skill?

Can we use these to measure training progress?

Can we speed the progression of limb dynamics from beginner to advanced through jump training and conditioning?

 

How does jump biomechanics change with different jump heights?

Jump height will differ depending on the organisation you jump with. Jump height for a particular dog will be determined by the height of their whithers.

There are different kinematics as the height and length of the jump changes. Higher jumps will result in a steeper landing angle and a peak vertical force and impulse. There are also changes in the craniocaudal impulses, with potentially higher joint moments in higher jumps.

The highest PVF when landing from a higher jump is four-and-a-half times the bodyweight of the dog.

At higher jump heights, the neck will have greater extension during the approach phase. During take-off, the extension of the tarsus and SIJ increases as jump height increases, while there is an increase in flexion of the elbow and shoulder.

During the aerial phase, there is increased flexion of the shoulder and the elbow.

During landing, as the jump height increases, neck extension will increase together with lumbar spine extension.

As the height increases, the speed and length of the trajectory will decrease.

 

How does the distance between jumps affect jumping biomechanics?

With greater distances between jumps, in this case 5 m, the take-off and landing distances will increase, as will the speed during these phases. There will be greater forelimb compression, while hindlimb compression decreases. There is no change in peak vertical force or vertical impulse.

At shorter distances, 3.6 m and 4 m, there is an increased neck extension and an increased should flexion in the aerial phase, in large breed dogs.

 

How does speed affect jump biomechanics?

There are no studies that specifically evaluate the effects of speed, but some studies report on speed as a byproduct of their other objectives.

With increasing speed, the distance to the jump increases with a flatter jump trajectory, there is an increased PVF, decreased stance duration, the limb length at toe down decreases and hindlimbs have an increased limb compression.

 

What effect does breed and conformation have on jumping technique?

Most of the studies have used border collies, as there is more data on this breed. However, not all dogs jump in the same way. There are studies that evaluate the difference in kinetics and kinematics in different breeds at a walk and trot, which report many differences.

Within agility, we know that border collies are faster and have a longer jump distance than other breeds. Border collies also have a greater topline angle than other breeds during jumping.

Even within one breed, there are different conformations or conformation variables that may change the biomechanics.

 

How does the angle of approach and exit from a jump affect jump biomechanics?

We do not have any data on the differences in approach and exit, but some of the different approaches and exits include:

• straight-line approach
• slice
• back-side jump

Each approach will result in different jump biomechanics.

 

How does handling technique and timing of cues affect jump biomechanics?

The involvement of a handler makes agility very difficult to study. The skill and experience of the handler have a dramatic effect, both on how the dog will complete a course and their risk of injury. The handling technique and the timing of cues will affect the line of the dog, which will affect its biomechanics.

The handler is responsible for getting the dog the information it needs, on time. If the dog does not get the relevant information in time as they approach a jump, the risk of injury is increased, as well as the risk of faults.

 

How does the surface of the agility course affect jump technique?

In humans and in horses there is a massive body of data on the correlation between surface, biomechanics and injury risk. This is an area that needs to be further investigated in agility dogs.

 

Conclusion

When it comes to jumping biomechanics, there is already a large body of data available that investigates the normal biomechanics of jumping, as well as how different variables start to affect jump biomechanics. Some variables are relatively simple to study, such as the differences in collection and extension, while others are far more complex, such as the effect of the handler and their technique. There are pronounced differences between experienced and inexperienced dogs; this may give us some indication of how we might manage and train or rehabilitate dogs differently at different phases of their career to reduce the risk of injury or re-injury as they develop their skills.

 

Resources

To learn more about the variables and the research discussed in this article, as well as the data available on the other obstacles in agility, please watch the webinar series with Arielle Pechette Markley in the Onlinepethealth Small Animal Members portal here:

 

Introduction to Canine Agility and Biomechanics: Part 1

 

Here are some other webinars that might interest you:

Common Sports Injuries, Leslie Eide

Managing sport dog owners, Leslie Eide

Pre-sport Assessment, Leslie Eide

Fitness Plans for Injury Prevention, Leslie Eide

Introduction to Canine Sports Medicine and Rehabilitation, Chris Zink

Common Conditions in Sports Medicine, Caroline Adrian

Managing and Treating Osteoarthritis in the Canine Athlete, Matt Brunke

Structure and Biomechanics of the canine athlete, Chris Zink

Conditioning of the Canine Athlete, Chris Zink

Functional Rehabilitation for Performance Dogs, Andrea Henderson