Hyperflexion leads to unnatural activation of the ventral neck muscles
13 Feb 2015
Riding the horse behind the vertical with a narrower poll angle mainly activates ventral neck muscles that the horse would not naturally use to carry its head. Riding with a more open poll angle, in front of the vertical strengthens the topline and builds on the muscle groups of the horse that are naturally activated during free self-carriage. These are the findings of a recent study at Ruhr University Bochum.
When horses in the study were hyperflexed, they mainly worked muscles in their ventral neck. When the horses’ heads were in a “natural” position with no contact, the topline muscles were significantly more active. When the horses worked on the bit with their nose slightly in front of the vertical, similar to the relaxed position, it was the topline neck muscles that were significantly more activated.
It is generally considered that the role of the topline muscles (m. splenius and m. trapezius) is to carry the head and neck against gravity while the role of the ventral muscle (m. brachiocephalicus) is to activate the shoulder joint.
Strengthening the horses’ top line muscles through gathered contact just in front of the vertical could help strengthen the horses’ natural carriage and be beneficial for the horse’s ability to carry a rider, the researcher noted.
Riding the horse in a hyper flexed position behind the vertical has been observed in previous studies to cause discomfort to the horse. In 2010, due to animal welfare concerns, the FEI amended its dressage rules to discourage the practice of hyperflexion for long periods of time.
Kienapfel, K. (2015), The effect of three different head–neck positions on the average EMG activity of three important neck muscles in the horse. Journal of Animal Physiology and Animal Nutrition, 99: 132–138. doi: 10.1111/jpn.12210