The Biomechanics of Jumping Position
By
Alexis Soutter, DVM
There is much debate
these days about the “best” jumping position.
For over thirty years now, it has been very common for riders in the
hunters, equitation divisions, and even the jumpers to favor a position in
which they lean their upper body well forward onto the horse’s neck. The most common explanation for this position
is that it in some way allows a better release of the horse’s mouth. Very little attention has been paid in many
circles as to what this does to the rest of the horse, however.
A horse’s center of gravity is slightly
variable depending on its build, but is typically a little behind and above the
elbow.
Horses carry 60% of
their weight on their front legs, and only 40% on their hind legs. Most riders
will weigh at least 10% of their horse’s body weight, so that is not an
inconsiderable burden. If we stay
balanced over their center of gravity, the impact we make on their front legs
is relatively minor. However, if we
bring that weight forward onto their neck, we are increasing the job the front
limbs have to do considerably. And
that’s just on the flat!
So, now let’s think about what a horse has to
do, physically, to get over a jump. As
he approaches the jump, he needs to lighten his front end to allow the hind end
to come underneath himself. This means
he shortens his neck, raises his head, and lifts his shoulders. His weight shifts backwards, and his hind
legs coil underneath the body to gather the energy needed to power up and
across the jump. (The next several
photos came from a wide range of venues; not all of these rider positions
should be emulated.)
As you can see, as
the horse lifts the front end, the front legs are tucked back towards his body,
creating a more aerodynamic shape that requires less force for the hind end to
propel upwards.
When the horse pushes off, the hind legs
extend fully. The back also extends, but
the horse tries to keep the neck relatively short. Presumably, this allows the horse to keep its
weight closer to the center of gravity.
Once the horse is in the air, he extends his
neck out to act as a balance arm and help him to “reach” over the fence. The knees bend and come up, and the shoulder
rotates forward. This is the “bascule”
phase of the jump. The best chance the
horse has to get his whole body over a large jump is to arch his back, stretch
his neck forward and slightly down with his nose pointing out, and bring all
four legs up as close to the trunk as possible.
Horses with tighter legs can manage to jump flatter over larger jumps,
but if the jump gets big enough, all horses need to be able to “crack their
back” to maximize their clearing ability.
 |
| Daryl Kinney on Union |
Next comes the
landing. At this point, the horse needs
to reduce his forward momentum. He
raises his head, often quite sharply, to aid in this. The non-leading leg lands first, followed very
quickly by the leading leg. Both front
legs then actually push upwards and backwards to counteract the force of the
body coming over. If they did not do
this, the horse would somersault over the front end. The hind legs rotate forward, and the front end
needs to get out of the way as the hind feet touch down.
Okay,
so now we understand what horses’ bodies go through to get over jumps. How does our position on their back affect
them? That depends a lot on what we do
with our own bodies.
Let’s
start with the takeoff phase. I rode
equitation and hunters as a kid, so I learned, like most still do, to put my
body forward onto the horse’s neck in order to get off his back. Sound familiar? But think about it – the horse’s center of
gravity is essentially right below the saddle.
Adding weight over that area is easy for him to handle. Adding 100 or 150 or 200 lb up onto his neck
– which, remember, he’s trying to shorten in order to get off the ground –
makes the rotation of his shoulder more difficult, and reduces the ability of
the hind legs to get underneath the body to develop the proper coil.
Once
the horse gets off the ground, well, now if I’m your average equitation rider
I’m going to be putting my knuckles on his neck and resting my body weight over
my knuckles. There is nothing at all
wrong with a crest release – but the release needs to come from the shoulder
and arm, not from the whole torso.
Remember, your hands weigh next to nothing; but your body from the hips
forward? Not as easy. As a result, the horse has to stiffen his
neck to brace against the added weight, rather than being able to stretch it
out and down as a balance arm. Now, the
long muscles of the topline are stiffened and he can’t crack his back into a
proper bascule. So, he has to crank
his forearms and his hind legs up higher in order to clear the jump. This is do-able for most horses over smaller
jumps, but you start getting to the 3'6" to 4' level, or higher, and it takes a
truly special athlete to be able to do it.
Now, what
about landing? It’s very difficult, when
you are pivoting on your knee and dropping your upper body forward and your
heels are swinging up, to then fully correct that when you are landing, as now
you essentially need to throw yourself backward. Some people manage this – but often punish
the horse in the mouth or the back as they over compensate. Other people stay on the horse’s forehand,
leading to some ugly landings. Remember,
the horse has to both bring his head upwards and use his front legs to push
upward and backward as he lands, in order to keep from somersaulting. If you’re falling forward on his neck, it
just makes his job that much harder.
Another
way to think about this is to imagine an airplane. In order to take off, the airplane needs to
be able to lift the nose in the air, and in order to land, it actually rocks
back a little bit, to keep the nose from smashing into the ground. If all the passengers, engine, and equipment
were packed into the nose of the airplane, rather than distributed evenly over
the body, how safely do you think that plane could take off, fly, and
land? Not very safely at all, and it
likely would not even make it off the ground.
To
finish up, here is a photo of a winning hunter:
This
is a beautiful horse, but I want you to notice a couple of things. First of all, look at where the bulk of the
rider’s weight is. Her entire body from
the knee up is forward of the center of this horse’s balance. See how the horse holds his neck. While his nose is poking forward and his
rider is not hitting him in the mouth, the neck is stiff and straight. He is not lifted through the shoulders or the
withers, and is clearing the jump primarily because his knees are up and he is
tight below. Notice that his back is a
little bit hollow behind the withers (yes, the saddle obstructs this some, but
you can tell because the bottom of his chest is dropped below his elbow). He has just pushed off from the ground, so
his hind legs are close to fully extended, as expected. Now, draw the arc his
body is taking. You will see he will
have to really hike his stifles and hocks to clear this relatively low jump
with his back end. As a last point, note
that her heel has slipped up and back and her spur is digging into his
flank. He must be a good-natured horse.
Now,
look at this picture of an event horse and rider:
 |
| Dom Schramm on Cold Harbor |
Notice where this rider’s body is. He is balanced directly over his foot, which
is essentially lined up with the horse’s center of gravity. This horse is making a beautiful effort over
this jump. The neck is long, arched
along the top, and stretched fully. He
is round from nose to tail – note that the underside of his trunk is slightly
above his elbows, indicating an ability to engage his abs and crack his
back. And look at how easily he can flex
and tuck his hind end! Look at this
rider’s release. He is utilizing an
automatic release, which means he is not dependent upon the horse’s neck to
maintain his balance. Rather than
resting on the neck, the hands are maintaining a following contact with the
horse’s mouth, which makes it easier to make adjustments on landing. However, the issue is not crest release vs.
automatic release – both can be appropriate in this situation; the goal is to
have the rider’s body as easy for the horse to carry as possible. From there,
riders can use whatever release they want.
Think about
how much harder to ride the bigger jump is, but note how balanced the rider
is. Who is likely to stay better
balanced on landing? Which of these
riders would be more able to help their horse prepare for the next jump? If the horse should stumble on landing, who
would be better able physically to help prevent a fall? Understanding biomechanics over fences can
save your life, and that of your equine partner.
Thank you to Cindy Lawler, Dom Schramm, Denny Emerson,
Daryl Kinney and Bob Haarmans for the use of their photos
