1. Injury Prevention and The Off-Ice Edge™
2. The Physics of Jumping and The Off-Ice Edge™
Beyond being sports-specific and incorporating principles of
ballet, the most important characteristic of this training aid
is injury prevention.
It is well known, that following the drop of compulsories in
1990, the sport became increasingly acrobatic and subsequently,
the amount of injuries increased. The popular theory for this
increase dealt with the rigidity of the boot. Many claimed that
because the boot did not hinge at the ankle, the shock absorption
was insufficient, thus resulting in injury during the landing
phase.
While there is no doubt that increased mobility at the ankle
allows for more shock absorption during a land and optimal lower
extremity biomechanics, we believe that a huge component
to injury-provoking lands includes the ability to take-off effectively.
Essentially, if you do not have enough strength in your take
off, your land will inevitably be off-balance. Landing without
proper balance, will invariably provoke joints such as the knee,
hip and lower back. It is well known throughout orthopedic medicine,
that most articular (joint lining) injuries such as labral tears
in the hip, are created with a combination of compression and
excessive rotation. Training on the Off-Ice Edge™ directly
isolates the musculature for proper take off during a jump. Therefore,
the chances of landing incorrectly will be minimized.
Our clinical EMG study confirms that the appropriate musculature
is being activated while training on the Off-Ice Edge™.
According to recent statistics published by the United States
Figure Skating Association, the two most common sources of injury
are in the lower back and knee, accounting for 34% and 26% respectively.
Recent sports medicine literature links weakness in the hip/pelvic
girdle to both lower back and knee injuries in female athletes.
The Off-Ice Edge™ directly targets this musculature and
will quickly expose any weakness that a skater may have in the
hip or pelvic girdle. Because the Off-Ice Edge™ effectively
isolates the musculature in the hip and the pelvic girdle, the
risk of injury to the lower back and knee will be decreased.
Correlation between pelvic weakness and injuries to the lower
back and knee:
Medical literature link between pelvic weakness and lower
back injuries:
Nadler SF, Bartoli LA, Feinberg JH, et al: Hip muscle imbalance
and low back pain in athletes: Influence of core strengthening.
Med Sci Sports Exercise 34(1): 9-16, 2002
Nadler SF, Malanga GA, DePrince M, et al: The relationship between
lower extremity injury, low back pain, and hip muscle strength
in male and female collegiate athletes. Clin J Sport Med 10(2):
89-97, 2000
Nadler SF, Malanga GA, Feinberg JH, et al: Relationship between
hip muscle imbalance and occurrence of low back pain in college
athletes: a prospective study. Am J Phys Med Rehabilitation
80 (8): 572-577, 2001
Medical literature link between pelvic weakness and knee
injuries:
Ireland ML, et al: Hip strength in females with and without
patellofemoral pain. J Orthop Sports Phys Ther. 33(11): 671-675,
2003
Mascal CL,et al: Management of Patellofemoral pain targeting
hip, pelvis, and trunk muscle function: 2 case reports. J Orthop
Sports Phys Ther. 33(11): 647-660, 2003
Powers CM: The influence of altered lower-extremity kinematics
on patellofemoral joint dysfunction: a theoretical perspective.
J Orthop Sports Phys Ther. 33(11): 639-646, 2003
Ward SR, et al: The influence of medial femoral rotation of
lateral patellar tilt during weight bearing and no weight bearing
movements. Med Sci Sports Exerc. 34: S160, 2002
The two research articles that have gained the most recognition
thus far in jump mechanics have been published by King, Arnold
and Smith (1994) and Albert and Miller (1996). These studies
both agreed that a decrease in the moment of inertia prior to
take off and a decrease in the skater's forward speed by virtue
of enhanced "skid" patterns, were consistent findings
in skaters that successfully performed multi-revolution jumps.
The King,et.al (1994) study further concluded that the skater's
increased their number of revolutions by increasing their rotational
velocity and not by increasing their air time.
Their study stated that the skaters' who successfully achieved
a triple axel had a rotational velocity that was on average
70% faster than their single axels. They also found that the
skaters' who successfully completed a triple axel traveled horizontally
only 70% as far as their single axels.
Albert WJ, Miller DI: Takeoff Characteristics of Single and
Double Axel Figure Skating Jumps. Journal of Applied Biomechanics,12:
72-87, 1996.
King DL, Arnold AS, Smith SL: A kinematic comparison of single,
double, and triple axels. Journal of Applied Biomechanics,10:
51-56, 1994.
So, let's take a closer look at these findings……..Decreased
inertia can be easily explained. If there is less resistance
to motion, then the given motion will be more powerful. This
is the same reason why a skater will speed up a rotation by
pulling their arms in and slow down by allowing their arms to
unravel. But why is it that skaters would actually slow down
prior to take off?
The answer most likely resides in Ground Reaction Forces. According
to Newton's Third Law of Motion (Law of Reaction), for every
action, there is an equal and opposite reaction. Therefore,
if you step down hard on the ground, an equal and opposite force
will travel up your body in the form of kinetic energy that
is either absorbed by your body or released through a certain
human motion, such as rotation. The slower a figure skater enters
into a jump take off, the more potential he or she has in generating
ground reaction forces through their skate into the ice.
The reason why a skater slows down prior to take off is because
they are trying to maximize their ground reaction force. If
they go into the jump entry with too much speed, they will loose
the potential of fully pressing down into the ice prior to take
off.
In figure skaters, the energy is transferred from the ground
into their hips, which then makes the rotation of the hips and
trunk more powerful. The chain of events looks like this:
First:
The more force that is applied into the ground at a given point
in time, the more potential there is for an equal and opposite
force to move up through the foot, knee and into the hips and
trunk.
Second:
Because the hips and trunk are going to rotate, you are now
supplying this rotation with more force. Therefore, as the forces
increase into the hips and trunk, the velocity of rotation increases.
Third:
As your rotational velocity increases, so does the ability of
the skater to achieve more rotation over a fixed rate of time
in the air.
This theory of ground reaction force and how it applies to rotational
sports is nothing new. It has been thoroughly studied with all
sports that involve a rotational component. Tennis and golf
both serve as fine examples.
So, how does all of this apply to the Off-Ice Edge™?
Remember, for every action, there is an equal and opposite reaction.
The more force you put down into the ground prior to take off,
the more equal and opposite force will travel up through your
body. In turn, your body will have more energy / force to rotate
faster and ultimately with more revolutions. The Off-Ice Edge™
was designed to replicate the contraction patterns of the on-ice
muscles and centers for balance that are responsible for creating
ideal ground reaction forces. |
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