There are two general gait categories in the racehorse.
- Symmetrical gait (walk, trot, pace).
- Asymmetrical gait (canter-3 beat gallop, and gallop-4 beat gallop).
There are two variations of asymmetrical gait.
- Rotary gallop (used at slower speeds and in the accelerating racehorse).
- Transverse gallop (used at fast and full speed)
In full gallop the racehorse uses the transverse gallop so we’ll go over this in more detail as it is the most relevant to the sprinting racehorse and is directly related to respiration.
In the transverse gait the racehorse places its feet in a particular order to form a pattern of foot-fall on the ground that allows the racehorse to move quickly without the legs colliding. This can be done with either the right leg or left leg leading.
- First the trailing hind leg contacts the ground (picture A)
- Second is the other hind leg, the leading hind leg (picture B).
- Third is the trailing forelimb, same side as first leg (picture C).
- Forth is the leading forelimb, also called the ‘lead’ leg (picture D).
This transverse gallop is further divided into the stance phase and suspension phase to form the horses stride length.
The stance phase occurs when one or more hooves is/are in contact with the ground. The suspension phase occurs when the horse is fully airborne. There is a direct relationship between the stride and breathing in the racehorse – one stride=one respiratory cycle.
The gallop phases are related to respiration due to the bodily movements during galloping. When the forelimbs contact the ground (pictures C and D) the compressive loading excerpted through the legs forces the ribcage upward, squeezing the air out of the lungs. At the same time the head and neck are lowering and the internal organs (behind the diaphragm) move forward to squeeze the lungs further during exhalation. This is occurring during the stance phase. This process reverses during the suspension phase (Picture E) and the racehorse inhales. The process is repeated over and over.
It is now recognised that respiration in the racehorse is synchronised to the transverse gallop i.e. the racehorse breathes in during the suspension phase and breathes out during the stance phase. Therefore, to put it simply, respiration rate equals stride rate and, the duration of the suspension phase and the stance phase should be equal in order for the racehorse to breathe in oxygen and expel carbon dioxide efficiently. It is well known that efficient gaseous exchange between the blood and the lungs is vital for optimum performance and, it therefore follows that optimum musculoskeletal function is required for the racehorse to breathe to the best of its ability.
This is why we ensure our racehorses are assessed and treated regularly for musculoskeletal dysfunction using chiropractic and physiotherapy.