How does Warwick Schiller approach counter-canter in the context of a nervous or tight-backed horse?

Warwick Schiller's perspective on counter-canter with nervous or tight-backed horses reflects his broader principle that collection and gymnastic exercises should not be attempted when the horse's nervous system is activated, because a horse that is tight, anxious, or holding tension in its topline cannot genuinely develop balance and collection through any exercise — it is managing its anxiety rather than learning. A horse with a tight back in counter-canter is a horse that has reached or exceeded its manageable level of challenge. The tightness tells the rider that the exercise is producing tension rather than development, and Schiller's prescription is to reduce the demand — less curve, shorter duration, or returning to correct-lead canter — until the horse can perform the current level of counter-canter with a loose, swinging back before progressing. For genuinely nervous horses, Schiller suggests introducing counter-canter only after the horse has confirmed its ability to lope freely, loosely, and without tension for extended periods on both correct leads. A horse that is consistently tense in normal canter work is not ready for counter-canter, because counter-canter adds difficulty to an already-difficult situation for that horse. His observation about nervous horses in counter-canter is that the typical training response — more pressure to maintain the counter-lead when the horse shows resistance — often produces exactly the opposite of the intended result with a sensitive horse. A horse that is tense and breaking from counter-canter due to anxiety needs pressure reduced rather than increased, and the skill in training a nervous horse in counter-canter is reading the difference between a horse that needs gentle encouragement to maintain the exercise and one that needs the demand reduced to stay within its processing window. Schiller also notes that horses with genuine back pain or sacroiliac discomfort often show counter-canter difficulty before showing obvious difficulty in correct-lead work, because counter-canter places more demand on the horse's ability to engage and carry its hindquarters actively. Counter-canter resistance that appears suddenly in a horse that previously performed it well is worth a veterinary assessment before assuming it is a training issue.