Electromyographic activity of cubital joint muscles in horses during locomotion.

The research conducted electromyographic (EMG) studies on four Thoroughbred horses to analyze the activity of four different muscles located in the cubital joint during various stages of movement, both with and without a rider. It identified the different roles these muscles play during various movements, with a focus on their behavior during the swing and stance phases of a horse’s gait.

Methodology

• The study used electromyographic (EMG) techniques to record the strained intensity of four different muscles found in the cubital joint of the horse, which is located in the forelimb near the elbow. These muscles include the biceps brachii, brachialis, caput longum, and caput laterale of the triceps brachii.
• Bipolar fine wire electrodes were inserted into the muscles of the horses. Additionally, strain gauges were placed on the hoof wall to measure any changes in the strain during different forms of locomotion.
• The tests were conducted on horses both with and without a rider to observe any changes in muscle activity.
• The recordings were synchronized with motion-picture capture to collect precise kinematic data (study of motion).

Findings

• When horses were standing, the biceps brachii muscle exhibited tonic (continuous) activity, while the other three muscles showed no electromagnetic activity.
• In the stance phase (when the hoof is in contact with the ground), the biceps brachii showed EMG activity while the brachialis muscle showed activity from the end of the stance phase to the middle of the swing phase (when the hoof is in the air).
• In contrast to the biceps brachii muscle, the brachialis muscle mainly performed a flexor role in the cubital joint during locomotion, which implies that the brachialis is primarily responsible for the bending movement at the joint.
• The EMG activity of the caput laterale and the caput longum muscles of the triceps brachii varied, with the former beginning to show activity in the midswing or late-swing phase and ceasing in the early stance or mid-stance phase, while the latter displayed activity from the midswing phase to the early stance phase.
• Different patterns of EMG activity were observed depending on the phase of the gait, particularly noticeable when horses were cantering – the brachialis and caput longum muscles, which primarily act during the swing phase of the canter, showed different patterns of EMG activity across the leading and trailing forelimbs.
• The study also highlighted that these differences in muscle activity are consistent whether a rider is present or not.