For years, many authorities have debated the dilemma of which aspect is the most important when schooling a young horse; rhythm or impulsion. I would like to voice my opinion and reasoning.
People favouring the impulsion dilemma suggest that everything comes from first going forward. Every lateral and collected movement should be followed by sending the horse forward. To bend a horse, he must first learn to go forward and straight. Without true engagement of the hindquarters the horse will never be properly on the bit but tend to become behind the bit or on the forehand.
The proponents of rhythm being the most important would argue that without first establishing the rhythm, asking for impulsion would most likely result in shorter and faster strides rather than longer, supple strides if the horse is sent forward with tension in its back.
I believe that both approaches are absolutely vital and must be blended with artful subtlety with every horse, at times with more impulsion and at other times rhythm being the foundation upon which all else is developed.
I see far too many performance horses that run rather than extend their stride because the rider either knows no difference or the judge demands to see something, even if it is a faster stride rather than a longer one. Unfortunately the increase in energy shown is deemed acceptable by many judges, often reinforcing what I believe is not only false but flawed training. In both collection and extension, the rhythm shouldn’t change.
The schooling of a horse should work on establishing rhythm as a foundation. The best way to test the rhythm is to challenge it to the point that there should be a permanent opposition between sending the horse forward to gain engagement, impulsion and collection and forces looking to maintain the horse in balance, rhythm and relaxation.
How much time you spend in either of these states depends where the horse has most resistance; If his is reluctant to go forward (often coming back to a rhythm if you cease sending him forward) then spend most of your time challenging impulsion. If the horse tends to get tense and run when you send him forward then spend more time establishing rhythm and relaxation. Either way, look for where your horse has greatest resistance (ie. difficulty) and work to expand that area.
Whichever is your greatest area of need, the essence of being able to achieve both of these together in a rhythmic, soft, powerful extension often comes down to how you use your hands (see previous article on pushing the horse towards the bit). Continuing to pull backwards will create tension and speed; capturing the impulsion in soft, elastic hands will more commonly enable the horse to remain soft while still going forward.