In-hand training of Piaffe and passage with leg stimulation: A literature-based biomechanical argument for why this method fails to produce true collection.

In-hand training of piaffe and passage via tactile leg stimulation (Handarbeit mit Touchieren) is widely practised in dressage, yet consistently produces horses that elevate their legs without achieving collection - a pattern termed Schenkelgänger (leg-movers) in classical German equitation. Based on published kinetic, kinematic, and electromyographic literature, this review argues that tactile leg stimulation activates the spinal nociceptive withdrawal reflex, an unloading movement mechanistically opposed to the elastic tendon rebound and ventral muscular chain activation that define true collection. Repetitive reflex conditioning will reinforce dorsal extensor dominance (M. longissimus dorsi), suppress the abdominal-serratus suspension mechanism, and produce the characteristic postural markers: croup-higher-than-withers topline geometry, and thorax lowering in the absence of spring-loading. Concurrent head restraint will amplify this pathomechanism via brachiocephalicus overactivation. Collection training should prioritise trunk-first engagement and hindlimb loading over peripheral leg stimulation.