Biomechanics
Biomechanics is a field of science that integrates anatomy, physics, and engineering. It studies how organisms move and support themselves, as well as how they respond to physical stresses caused by forces such as gravity, the impact of another organism, or the impact of a leg striking the ground at high velocity and/or on uneven ground. The biomechanics portion of our program is carried out by Dawn Adrian, Ph.D. (UC Berkeley 1989), whose doctorate and primary research are in the field of biomechanics, with specialization in the biomechanics of locomotion in large vertebrate animals. Although it is possible for some people to “teach themselves” vertebrate anatomy and even the basic principles of Newtonian physics that underpin biomechanics, the fully-developed discipline itself is not easy to master. It requires advanced, graduate training in part because many of its most important applications in the real world are counter-intuitive.
As one example, we’re used to thinking that the most important things muscles do is make the bones they’re attached to — and thereby our body parts — move through space. But by far the most important thing muscles do is work to resist movement. The force of gravity is constantly acting upon the bodies of both horses and humans, pulling them down toward the earth. For us to stand up
without falling down or collapsing, we have to successfully resist the force of gravity. More importantly, we have to do it as we are moving, swaying, responding to a sudden gust of wind, the uneven load of a pile of books in one arm, or getting tired. So thousands of muscle fibers fire in small increments throughout different parts of our backs, hips, and legs as we simply “stand still” outside a building on a breezy day, holding a bag of groceries or some books while we talk to a friend. And various tissues such as tendons, ligaments, and fascia (that few people think very much about) work passively to resist significant parts of those loads from one moment to the next, too. We simply don’t realize how much activity is going on all the time in our musculo-skeletal system — and that’s particularly true when we’re riding.
In both horses and humans, the center of our body’s mass falls between our legs rather than over the top of one leg. Unless, of course, we’re walking, jogging, or running at the time, in which case our body mass may (or may not, depending on how we’ve been trained) pass briefly over the top of one leg every so often. It means that even if we’re very well-centered, our balance point moves through space continually. And the faster we move, or the more uneven our load is (say, if we are carrying a bag of groceries or a rider on our back), or the more uneven the ground is, the more widely variable our balance point is from one moment to the next. This creates so much stress on our body’s balancing act that we really have to work hard — all automatically — to keep from falling and even possibly injuring an ankle, leg, or knee. You may have heard that doing exercises to strengthen certain leg muscles can help prevent a joint injury when playing tennis or softball, and that’s why. The wildly-swinging, ever-changing, constantly accelerating and then decelerating forces of athletic movements generate tremendous stresses on tissues that sometimes simply fail as a result.
The meaningful part of this for equestrians is that when you ride, you change your horse’s balance point, and thereby alter your horse’s ability to balance itself without over-stressing tissues that eventually suffer acute or chronic injury as a result. Furthermore, as your horse struggles to compensate for your weight on its back, its movements translate back to you and into your own body in ways that impact your balance, in turn.
We often hear about how “heavy” a rider is, but the actual issue that matters isn’t weight but balance. Ask yourself: is it easier for you to hold a stack of six books against your body with both arms and hands, or to hold one book in one outstretched arm way out to the side of your body? If you ride in such a way that you make your horse work like you do when you hold a book out in the air, neither of you is going to enjoy it. And the more you do — trotting, jumping, dressage, using a heavy Western saddle, riding in wilderness terrain — the more important it is for you to ride in a way that helps your horse keep both of you balanced. It makes your ride more pleasant and your horse more willing, and it also reduces both your and your horse’s chances of accident, injury, or chronic inflammation.
Tapestry’s program offers you an opportunity to find out how you can better balance on your horse, and how your horse can better balance the two of you together. You can choose to have a simple and relatively inexpensive analysis carried out that points to the one, single most important issue in your balance as a rider on horseback, or to have a more thorough and therefore more expensive analysis carried out of both you and your horse. You can also choose to have only the analysis done, or to have follow-up guidance and feedback as you relearn your way out of habits of posture or movement that impede your ability to ride as well as you might. Whether you live in the Colorado Front Range area and can participate in person in the program, or live far away and participate by submitting video clips of your own, you’ll want to explore the option and look at the sample analysis to see which part of the program is right for you and your horse.
Image credits: Top image shows major forces acting on the human hip in a single-leg stance. This image was redrawn from Friederich Pauwels’ classic work Biomechanics of the Locomotor Apparatus (Springer Verlag New York 1980), and was published onine in Anatomy and Biomechanics of the Hip Relevant to Arthroplasty. Middle image shows the lines of stress in a model of the human femur, which replicate the orientation of microstructural bone elments called trabecullae in the femoral head. The image is redrawn from classic work on bone microstructure by Julius Wolff, and was published online by Christopher R. Jacobs, Ph.D., in “The mechanobiology of cancellous bone structural adaptation“.