During a dressage clinic I once gave in Canada, I met a rider whose horse was ridden with a strong contact and constraint. The horse was pacing (losing the four-beat rhythm of the steps) in the walk.
To improve the situation, I asked him to ride his horse in a shoulder-in at the walk. The thought alarmed him. The rider refused the exercise, with the explanation that his horse would then start to amble (do a totally lateral walk). Finally, I convinced him to loosen the noseband and try walking with a softer contact. To his surprise, the horse relaxed and the walk got better.
This example is a very useful one as it shows us two things: First, there’s a direct correlation between a strong hand, a blocked back and finally, the quality of the walk.
Second, riders are often not aware of these correlations and do not act accordingly. Many riders are afraid of getting to the root of the trouble….This is neither easy nor done in a short time as it means changing a whole concept of equitation, which might be the reason why some riders would rather live with bad marks in the walk than get to the root of the trouble.
Colonel Christian Carde, “Walk: The Queen of Gaits”, Practical Horseman, August 2014