A horse may go from a canter to a gallop for a number of reasons including a rider's leaning forward, squeezing with the legs, or inadvertently applying spurs. How a rider responds will determine what happens thereafter. If the rider simply pulls on the reins, the horse will likely lean on the bit and run faster, especially if the rider tries to hold on with his legs. If the rider jerks on the reins, the horse may throw its head or even buck. A better response would be a resist and give application of one or both reins. Turning the horse in a circle can help regain control by gradually slowing the horse's forward movement.
A balanced, relaxed, and following seat always aids in the stability of the rider. It also helps the horse relax. A horse moving with relaxed muscles is much easier to ride than one moving with tense muscles. By releasing any tension in his muscles, a rider takes on a much more stable position. The torso is allowed to expand and the bones of the spine align vertically with their natural shock absorbing curves. Relaxed muscles around the pelvis allow the rider to sink deeply into the saddle, lowering the center of gravity. Relaxed muscles around the pelvis and throughout the legs and feet, allow the rider's legs to wrap around the horse's body with adhesion but without gripping. As gravity pulls a rider downward, the stirrups support the balls of the rider's feet while the heels sink deeper without the rider needing to push them down. With such a stable seat, the rider can relax and follow the movements of his horse's body.
When the rider does this, the horse begins to release tension in its body. The horse's movements become softer and smoother. As the horse becomes accustomed to the rider's body following the movements of its body, the horse also begins to change the movements of its body to match those of the rider when the rider consciously changes his balance and movement. Gross cues are no longer needed. The horse begins to respond to subtle aids with smooth and almost effortless changes in its movement.