Novel Strain Gage Application in the Measurement of Rein Tension during Horseback Riding Hilary M. Clayton, Wesley H. Singleton, Joel L. Lanovaz and Gary L. Cloud* College of Veterinary Medicine and *College of Engineering, Michigan State University, East Lansing, MI 48824 During horseback riding one of the main methods of communication between rider and horse is through tension in the reins, which imposes pressure on the oral tissues of the horse. Trainers often ask equestrian students how much ‘weight’ they have in each rein, since one of the goals of training is to equalize the tension in the left and right reins. The amount of tension also has implications for the well-being of the horse, since excess tension can lead to injuries to the mouth of the horse. This paper describes the application of strain gage technology to provide dynamic measurement of rein tension during riding activities. A pilot study indicated that tension spikes in the range of 200 N could be expected. To allow an adequate margin of safety, a transducer was selected that was accurate up to 445 N and would withstand 667 N before being damaged. The transducer is intercalated between the ring of the bit and the rein using a rigid metallic connector. A telemetry system, carried by the rider in a belt pack, provides power to the transducers and transmits data from them to a laptop computer. The rein tension is displayed in real time on a screen that can be observed by the rider for immediate feedback. Video data can be recorded simultaneously with the force data and stored for future analysis. Custom software has been developed to display the video images synchronously with the tension data in the left and right reins. Rein tension is characterized by a series of spikes that are related to the footfalls of the horse. The frequency of the tension spikes varies with the horse’s gait. The trot, which has a two-beat rhythm, usually shows two spikes per stride that are evenly spaced in time and coincide with the footfalls of the diagonal limb pairs. The canter, which has a three beat rhythm, usually shows two distinct peaks coinciding with the second and third beats of the stride, which occur as a couplet. The spikes seem to coincide with the cyclic downward nodding motion of the horse’s head, which is restricted by the holding action of the rider’s arms. The magnitudes of the spikes in the left and right reins varies with the training level of the horse and the skill level of the rider. In addition to the rhythmic spikes generated by the horse, it is also possible to recognize wider peaks in rein tension that represent cues given by the rider to indicate that the horse should turn or change speed. This novel application of force transducers is yielding valuable information describing the non-verbal communications between rider and horse, and is proving useful as a practical training aid by providing immediate feedback during riding activities.