Study Links Hyperflexion to Decline of Well-Being in Horses

Hyperflexion, in which a ridden horse’s head is pulled tightly to its chest, has come under fire as being uncomfortable and intimidating for equines. Sometimes used as a training aid to stretch the horse’s neck muscles, hyperflexion is thought of by some trainers as a legitimate tool as long as the rider does not force the horse to prolong this extreme position.

Journal of Animal Physiology and Animal Nutrition recently published reports of two German studies of hyperflexion. In the first study, an endoscope was used to make video images of the larynx when horses were at rest and also when their necks were stretched, held in a working position, and in hyperflexion. Regardless of a horse’s age, training level, or anatomical variation, the larynx was shown to be compressed, with a reduction in the area of its opening, when the horse was in hyperflexion. Because air must pass through the larynx as a horse inhales and exhales, hyperflexion could impede the horse’s ability to breathe freely.

The second study looked at the relationship between head/neck positions and stress parameters. Eighteen horses were used in the study in which heart rate, heart-rate variability, and blood cortisol levels were compared when horses were at rest and when they were ridden with their necks in a working position or in hyperflexion. Heart rate and heart-rate variability did not change significantly with changes in neck position in ridden horses, but blood cortisol levels, a common indication of stress, rose significantly in hyperflexed horses. Both the rider and an observer noted declines in behavior and rideability among horses ridden in hyperflexion. The researchers concluded that hyperflexion led to adverse effects on the well-being of horses ridden in this position.