How do you put running reins on a horse?

The left & right reins are attached to the bottom of the surcingle. There is often a ring or tag there for attachment. Until your horse is accustomed to the running reins , they should be run on the outside of the legs, threaded through the bit & back to the surcingle. Depending on what your running reins are like, you will probably have an adjustable buckle that clips to the reins & the top of the surcingle. Start the reins on a very lose setting on the lunge & gradually shorten over time once the horse begins to understand that lowering its head brings the greatest relief & comfort. It is important to always keep the horse thinking forward. Often the inside rein will be set shorter than the outside one to encourage flexion. Once the horse is experienced the reins can be run between the legs rather than on the outside of the legs.