It's never just tight hamstrings
Tight hamstrings is a very common issue in horses, but simply treating the tightness might do more harm than good.
Tight hamstrings are most often caused by faulty biomechanics due to pelvis area dysfunction.
Tight hamstrings is something we see very often in horses. It's an issue that's easy to spot and since a lot of horses will be very sensitive when the hamstrings are tight, it's easy to mark that as the big issue. Overdeveloped and tight hamstrings often go hand in hand with weak and atrophied quadriceps. And since the hamstrings are the muscles that provide pushing power, and the quadriceps has a carrying function, it is easy to say »this horse is pushing too much and not carrying enough«. The antidote? Release the tight hamstrings and work on transitions, hill work, cavalletti and so on. Problem solved. But is it really? Most cases of tight hamstrings are not that simple and by following that recipe you might actually be doing more harm than good. Here's why.
Tension in soft tissues is primarily a protective measure. The body would rather injure a muscle or fascia than a structure like a nerve or blood vessel. This is why the body will often give the order for the soft tissues in a dysfunctional area to tighten – it protects the more vital structures that have a harder time regenerating. So, whenever we see muscular and fascial tension, we need to ask ourselves, what is this tension protecting? Thinking back to the hamstrings, a very common scenario is something like this. The horse has a loss of range of motion in the hind end, which limits the range of motion in the pelvic area. Because of this, he cannot lower the hind end and flex the joints of the hindlimb to achieve greater carrying capacity. If we still ask this horse to produce movement that requires a level of collection, the horse will »fake it« by simply making the stride longer by »borrowing« range of motion from the hip and knee joint. When this happens, the hamstrings will be asked to work from an overlengthened position. This puts strain on the nerves and blood vessels and they do not like that. Nerves and vessels don't like being stretched or compressed, so the body responds by tightening the hamstrings. Now the range of motion of the leg is reduced even more and the horse starts to short stride.
Tight hamstrings are usually a symptom of a bigger issue.
If we simply take the tension in the hamstrings away, we are not addressing the real cause. Worst case scenario, we might be making the horse even more uncomfortable by taking away his protective mechanism. This is why we can never isolate a problem. Everything we are dealing with is a body wide issue. A good spot to start with when dealing with tight hamstrings is the SI area, the diaphragm, the quadratus lumborum and the psoas muscles. Since hind end dysfunction often goes hand in hand with thoracic sling issues, we need to address those too. And since both of those issues have a direct connection to the hooves, we need to look at that too. And so on ad infinitum. It is always the whole horse.
If we want to successfully manage tight hamstrings, we need to look at the whole horse.