What occurs during the first phase of the stride at the canter and gallop?

During the first phase of the stride at the canter and gallop, the hind legs are positioned underneath the horse, and the ribcage expands to accommodate the movement and breathing. This positioning of the hind legs is crucial as it provides stability and propulsion for the horse. The expansion of the ribs is also significant, as it allows for greater lung capacity and assists in the breathing process, enabling the horse to take in more air during exertion. This phase is characterized by the horse's powerful push-off from its hindquarters, which is essential for maintaining speed and balance. Understanding this phase helps riders and handlers appreciate the mechanics of the horse's movement and enhances their training and conditioning methods.