Biomechanics and Gait Analysis Flashcards
the study of the mechanics of a living body, especially of the forces exerted by muscles and gravity on the skeletal structure
biomechanics
applied physics do not want to change the center of gravity of the animal
law 1 - change requires force
law 2 - force must be enough to accelerate the mass
law 3 - the ground must resist the push
simplified explanation of the complexity of the horses back
bow and string theory
the abdominal muscles contracting allow the back to lift
bow and string theory
E. J. Slijper in 1946
bow and string theory
bow and string model
by pulling on the string - tightening the abdominal muscles the back is able to flex and the hind legs can step under further resulting in lifted front end and lowered head and neck
The extensors of the spine must be RELAXED to allow stretch and flexion
bow and string
Richard Tucker 1964
expanded on the bow and string theory
longissimus dorsi - fascicles insert obliquely, down and forward
multifidus - oblique, down and backward
these muscles allow for forward transmission of horizontal forces by compression
forward motion - Richard Tucker 1964
vertical transmission of forces through rotary motion (resistance to gravity, balance control)
Tucker 1964
demonstrated that the muscles are mirrored to each other and have to act in concert
James Rooney 1969
the rider has a direct influence on the muscle groups activated
encouraged neutral balance
pilates idea - balance the work of the abdominal and back muscles to straighten the spine
james rooney 1969
strength of riders core versus horses core
James Rooney 1969
The creation of upward vertical forces through the spine was coordinated by muscles WITHOUT much movement of the vertebrae
increased stiffness of the muscles
decreased ROM of vertebral units
James Rooney
Demonstrated that the abdominal muscles aren’t strong enough to influence the huge back muscles
James Rooney
Function of the back muscles is to stabilize the vertebral column
Hans Carlson 1976
Rather than increasing ROM, they function to prevent excessive ROM
Hans Carlson 1976
confirmed and furthered by Leo Jeffcott in 1980
measured actual ROM of the joints in the vertebral column
Hans Carlson 1976
Demonstrated that lateral bending was each vertebrae rotating around each other
Jean Marie Denoix 1999
Researched the effect of the lowered neck on mobility of the spine
lowered neck results in stiffening of the lumbar vertebrae
Jean Marie Denoix
lowered neck creates a stiff back
Jean Marie Denoix
lumbar stiffness - increased work of the iliopsoas
iliopsoas muscle
creates the illusion of lumbosacral mobility
increases injury risk - iliopsoas mm damage, lumbosacral damage, SI damage
lumbar stiffness
transmission of horizontal forces results in
increased back mm tension
lowering of neck/head increases
lumbar tension
lateral bending is the result of
coordinated rotation of vertebrae
absorption of impact (vertical forces) also results in
increased back mm tension
equine design of potential, elastic, and kinetic energy - by having the majority of mass near the body (no mm distal to hock/carpus)
increases ROM
increases elastic potential of ligaments/tendons
elastic potential of rib cage
equine design increases stride length without increasing
effort
hairtie - stretches, holds the force and then contracts back together from stored energy
elastic energy
assists the horse in overcoming gravity
elastic energy
the potential energy stored when an object is stretched
elastic energy
tendons can recoil faster than muscles can contract - allowing for higher jumping
elastic
when a horse lands, full extension of fetlock - suspensory ligament acts as a cup so when it drops it creates the elastic recoil to not have the horse expend more energy
loading
___ of horses weight is in the head/neck
10%
eases teh work of the upper neck muscls
nuchal ligament
nuchal ligament effore to keep neck in it’s position
___ at the walk
___ at the trot and canter
55%
32%-36%
goals of the athlete
move weight bearing from front to rear
rear has more pushing power
change the rear from braking to pushing
travels through the thoracolumbar spine
if the back muscles do not act to absorb this thrust, the front legs are loaded
hindleg thrust
increase duration of supporting phase
step further under the body
increased duration of deceleration
increased absorption forces on the joitns
hindleg thrust
the movements of the back directly influence the
head and neck position
With a high head and neck position, the stride length and extension of the back are
significantly reduced
downward/upward force is actually what maintains forward movement
propulsion
why transitions strengthen
they require more push
increasing speed requires more push
the rest is downward force pushing up maintaining momentum forward - why impulsion is so important
The forelegs produce the greatest percentage of upward vertical forces.
__ of the vertical impulse is produced by the forelegs
__ is produced by the hind legs
57%
43%
causes of increased back stiffness
increased speed
pushing on the bit
rider’s weight
lowered head/neck
rider in propulsion adds increased pressure to the
extensor muscles
breathing changes when under tension
lack of abdominal effort
increased ribcage and diaphragm breathing
abdominal muscles
