Deceleration Mechanics: Knee Injury Prevention

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Deceleration Mechanics Knee Injury Prevention

• Jason Riddell MS, CSCS, USAW
• Head Strength Conditioning Coach
• American University

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The Stoppie, Nose Wheelie or Endo

• Not the kind of Deceleration Mechanics I was
  talking about but cool none the less!!!
  
• No, I dont do this on my motorcycle because it
  is dangerous! Shhhhhhh that is what I tell my
  fiancé!

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Deceleration Mechanics

• The ability of an athlete to decelerate their
  body weight with proper biomechanics, then use
  that potential energy and translate it back into
  kinetic energy efficiently accelerating out of a
  jump or turn.
• Go G-men!!!!!!! I miss Tiki already!

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Good Mechanics Efficient Change of Direction
(COD)

• One of the best ever when comes to COD.

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Bad Mechanics Inefficiency and Possible Injury

• Commonly, the athlete runs, suddenly stops, and
  then turns, thereby causing a deceleration of the
  lower limb, a forced hyperextension of the knee,
  or a forced tibial rotation, resulting in injury
  to the ACL (3).

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Sports with the highest occurrence of ACL
injuries

• FEMALE
• Gymnastics
• Soccer
• Basketball
• Field Hockey
• Volleyball
• Lacrosse
• Softball

• MALE
• Football
• Wrestling

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Women are 2 to 8 times more likely to have an ACL
injury than men

• Intrinsic factors
• hormonal influences
• intercondylar notch width
• joint laxity
• limb alignment
• muscle strength
• neuromuscular activation
• ligament size

• Extrinsic factors
• excessive shoe-surface interface friction
• sports activity
• training/conditioning level
• equipment

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What factors are in your control as strength
conditioning coaches?

• lower limb alignment
• muscle strength
• neuromuscular activation
• training/conditioning level
• More on this later

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What typically happens with poor mechanics?

• Typical Scenario
• An athlete jumps and they land on the balls of
  their feet and end up with their knees out over
  their toes, then jump back up or turn rapidly.
  This lends to the majority of the work
  concentrated on the quads and not letting their
  hamstrings, gluteus and hips take the majority of
  the impact force.
• In simplest terms they dont sit back when
  landing, and that leads to big problems down the
  road.

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Knee Anatomy
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Knee Injury Biomechanics

• . It is the synergistic relationship between the
  ACL and the hamstrings that activates to decrease
  the shear forces at the knee during pivoting and
  jumping motions (5).
• In contrast, the quadriceps acts
  antagonistically to the ACL, encouraging forward
  displacement of the tibia relative to the femur.
  The contraction force produced by the quadriceps
  can produce forces in excess of what the ligament
  can handle, predisposing a person to ligament
  tensile failure (1).

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Knee Injury Biomechanics (visual)
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2 Major Problems

• Posterior Kinetic Chain Strength Deficiencies
• Poor Deceleration Mechanics
• By addressing these problems we can lower the
  injury rate and keep your athletes on the field
  and out of the athletic training room. In doing
  so, you make yourself invaluable to your sport
  coaches and look like a damn genius to your AD!
  We all know that nothing but good can come of
  that!
• Lets come back to those factors mentioned
  earlier that we can control.

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1) Lower Limb Alignment

• Can be worked on every time you squat, dead,
  lunge, clean, snatch or jerk.
  
• Remember that the key is to tell your athletes to
  let your hips, hamstrings and glutes do the work.
  Which joint can hold more weight, your hip or
  knee?
• Make sure that during squats they have proper
  foot placement and on the concentric portion
  there is no valgus stress on the knee.
  
• Cues Insteps off, Spread the floor, Push
  your feet out the side of your shoes, Drive
  through the heel.
  

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Tom Platzs Legs
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1) Lower Limb Alignment

• With lunges, step-ups, Bulgarian split squats or
  any other unilateral movement the key is to watch
  the knee angle.
  
• To be safe I am always saying I want a 90 degree
  angle at the back of the knee with the top of the
  thigh parallel in the bottom. If I dont see it,
  my athletes go right back to body weight only
  until they get it right.
• With the Olympic lifts the key is to watch the
  catch in whatever lift you might be performing.
  They must catch everything with their heels down
  and their feet the proper width or you are
  setting them up for problems.

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1) Lower Limb Alignment

• The primary goal of Olympic lifting is to
  increase rate of force development and power
  output not coordination.
  
• Coordination is a nice by-product but not the
  primary reason for using them.
  
• If your athletes cant do full cleans and
  snatches correctly then take them back to
  explosive pulls and they will still make
  tremendous progress.

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2) Muscular Strength

• Posterior chain (lower)- Hamstrings, Gluteus,
  Spinal Erectors.
  
• Ronnie Coleman is pharmaceutically enhanced but
  jacked and strong none the less!!!
  

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2) Muscular Strength

• The show muscles are in the front and the go
  muscles are in the back! Jason Beaulieu Head
  Strength Conditioning Coach at U of Delaware.
  
• DLs, Glute/Hams, GMs, RDLs and Rev Hypers.
• Iso-Dumbell and Barbell RDLs and Iso Hamstring
  bridges for time. Stabilizer work

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3) Neuromuscular Activation

• Bouncing not Sticking
• During natural movements, the primary
  requirement for a proper motion pattern is not to
  resist the external force and decrease the bodys
  kinetic energy but to increase the potential for
  the ensuing takeoff (Zatsiorsky, 158.)
• When it comes to jumping and landing you want
  your athletes to focus on landing soft and
  making as little sound as possible.
  
• During soft landing by experienced athletes,
  only 0.5 of the bodys kinetic energy is spent
  to deform body tissues (bone, cartilage, spine).
  During a stiff landing, the deformation energy
  amounts to 75 of the bodys mechanical energy.
  The difference is 150 fold! (Zatsiorsky, 178)

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3) Neuromuscular ActivationProper
Jumping/Landing Mechanics

• Use box jumps for practicing soft landings before
  incorporating traditional plyometrics.
  
• Set yourself down on the box and absorb the
  impact by sitting back and letting the
  hamstrings/posterior chain do the work.
  
• The position that you jump in, is the position
  you land in.
  
• The less noise made on impact the better the
  jump.
  

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3) Neuromuscular ActivationProper Turning
Mechanics

• Short Shuttle/5-10-5/Pro Agility Procedures
• Athlete begins in a 3 point stance, facing timer,
  with hand on start line and one foot on each side
  of the start line.
  
• Athlete starts after being instructed "You may
  go."
  
• Run directly to the right 5 yards and touch line
  with right hand.
  
• Reverse direction and run directly to the left
  for 10 yards and touch line with left hand.
  
• Reverse direction again and run 5 yards through
  the start/finish line.
  
• Each athlete performs the short shuttle run
  twice, once to the left and once to the right.
  

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3) Neuromuscular ActivationProper Turning
Mechanics

• 3 Cone Drill Procedures
• Athlete begins in 3 point stance with hand on
  start'/finish line.
  
• Run forward 5 yards and touch top line with right
  hand.
  
• Turn back and touch start/finish line with right
  hand.
  
• Turn back again and run around top of second
  cone.
  
• Weave underneath and around third cone.
• Run around outside of second cone back through
  start/finish line.
  
• Each athlete performs the 3 cone drill twice.
• Both times are recorded and the best time is used
  for scoring purposes.

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3) Neuromuscular ActivationTurning Mechanics
Keys

• If an athlete can turn quickly and change
  direction without dissipating a lot of energy
  they tend to be successful on the field.
  
• Turns are all about fluidity mentally picture
  smooth, flowing movements. SmoothFast,
  ChoppySlow
  
• Try to lose as little speed and momentum as
  possible when turning.
  
• Reducing the risk of knee injury is best
  accomplished by having the athlete get use to
  firing the hamstrings first and not the
  quadriceps to decelerate themselves.
• This is accomplished by touching the ground with
  legs extended and feet plantar-flexed, and
  immediately after ground contact, avoid a stiff
  landing by flexing the knees and lowering their
  center of gravity (Zatsiorsky, 178).
• Once again, you must decelerate by lowering the
  center of gravity by dropping the hips in the
  turn.
  

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4) Training/Conditioning Level

• Its easy to stop by landing on your toes when
  fatigue begins to set in.
  
• Athletes will go to the old, easy default setting
  if they are not conditioned to use the proper
  mechanics all the time.
  
• You as a coach must stress proper mechanics all
  the time and especially when your athletes are
  tired.

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4) Training/Conditioning Level

• Jumping/Landing Mechanics
• Variations of the repetition method.
• Using a light weight for sets of 30, 40 and 50 in
  all forms of the squat or deadlift are not easy
  but elicit the ability to fire the proper motor
  pattern repeatedly.
• Remember you are looking for the athlete to
  perform these actions without conscious thought
  and acquire muscle memory.
  
• You are only limited by your imagination.

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4) Training/Conditioning Level

• Turning Mechanics (COD)
• Continuous pattern agilities.
• Examples- Snake, zig-zag, wheel patterns and
  shuttles.
  
• The key is to stress proper turning mechanics
  even when fatigue starts to take hold.
  
• The bonus to these types of patterns is energy
  system development. Continuous pattern running
  closely simulates most court and field sports
  metabolic demands as compared to straight ahead
  speed and distance runs.

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Summary

• I feel that as strength professionals if we can
  focus a little more on limb alignment, muscular
  strength, neuromuscular activation and
  conditioning this will help alleviate the rampant
  problem of knee/ACL injuries we see in athletics
  today.

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Summary

• We all know that it isnt completely unavoidable
  and injuries will occur but by reducing injury
  rates and decreasing recovery times we will make
  a stronger, more durable, more productive athlete
  for the future.

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References

• 1) Huston, L.J., and E.M. Wojtys. Neuromuscular
  performance characteristics in elite female
  athletes. Am. J. Sports Med. 24(4)427-435.
  1996.
• 2) Ireland, M.L. Anterior cruciate ligament
  injury in female athletes Epidemiology. J.
  Athletic Training. 34(2)150-154. 1999.
  
• 3) Loudon, J.K., W. Jenkins, and K.L. Loudon. The
  relationship between static posture and ACL
  injury in female athletes. J. Sports Phys. Ther.
  24(2)91-97. 1996.
• 4) Pettineo, S.J., K. Jestes and M. Lehr. Female
  ACL injury prevention with a functional
  integration exercise model. Strength
  Conditioning Journal. 26(1)28-33. 2004.
• 5) Rosene, J.M., and T.D. Fogarty. Anterior
  tibial translation in college athletes with
  normal ACL integrity. J. Athletic Training.
  34(2)93-98. 1999.
• 6) Zatsiorsky, V.M., Science and Practice of
  Strength Training. Human Kinetics, Champaign, IL.
  1995.
  
• (VISUAL) All photos are courtesy of Google Images
  or T-Nation.