Proprioception: Real World Applications

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Proprioception Real World Applications

• Eric Cressey
• www.EricCressey.com
• October 31, 2006

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What is unstable surface training (UST)?

• Unstable training surfaces which may include
  half-dome stability balls, wobble boards, foam
  pads, and balance discs reduce (or altogether
  eliminate, depending on the exercise) an
  individual's points of contact with solid ground.
  

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Why has UST become so popular?

• Proponents "functional balance training" will
  improve four components of "body equilibrium"
  balance, kinesthetic sense, proprioception, and
  gradation of force.
• Complex movement schemes require a combination of
  stability and mobility it may be valuable to
  train these two qualities simultaneously with a
  greater challenge to stability.
• Afferent vs. Efferent Training

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Functional Ankle Instability

• Following acute lateral
• (inversion) ankle sprains,
• chronic lateral instability
• develops in 20-30 of patients.
• Increased risk of sprain recurrence
• due to a delayed proprioceptive response of
• the peroneals.

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Functional Ankle Instability Rehabilitation

• One must retrain altered
• afferent neuromuscular
• pathways to eliminate this
• deficit and restore normal
• reflex joint stabilization and
• force absorption patterns.
• Favorable UST Clinical Outcomes
• Wester et al. (1996)
• Sheth et al. (1997)
• Osbourne et al. (2001)

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So what is the problem?

• There is considerable opposition to the
  utilization of UST outside of rehabilitation
  settings. UST may
• undermine specificity in programming
• lead to unfavorable biomechanical compensations
• actually impair the development of athletic
  qualities.
• No studies to-date have examined the effects of
  UST on improving sport performance in healthy,
  trained individuals with no recent history of
  injuryUNTIL NOW!

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The Science of Stability and Balance

• Hall (2003)
• Stability - "resistance to both angular
• and linear acceleration, or resistance
• to disruption of equilibrium
• Balance - "the ability to control
• equilibrium or the process of
• maintaining the center of gravity
• within the bodys base of support within a given
• sensory environment

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The Science of Stability and Balance

• Neural factors such as
• muscular strength, kinesthetic
• awareness, coordination, and
• proprioception all contribute to
• ones balancing proficiency.
• These factors interact with non-
• neural (positional/environmental)
• Factors that change under different
• circumstances this interaction
• determines ones stability.

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Non-Neural Factors Affecting Stability

• Amount of body mass more mass more stable
• Friction between the surface and the body in
  contact with it Increased friction increased
  stability.
• Size of the base of support (BOS) Generally
  refers to the positioning of the feet. Normally,
  a wide stance improves stability. The size and
  direction of the BOS must be appropriate in light
  of the direction of the external force acting on
  an object.
• Horizontal positioning of the center of gravity
  (COG) For maximum stability, the COG should be
  on the edge of the BOS at which an external force
  is acting.
• Vertical position of the COG lower COG more
  stable

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The Science of Stability and Balance

• Technical training, manipulation of body mass,
  and equipment can change these structural and
  positional factors.
• Development of the aforementioned neural
  qualities can markedly influence ones balance
  and, in turn, stability in a given situation.
• Training initiatives to enhance balance serve as
  one approach to enhance performance.

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The Afferent System

• Three sources of feedback comprise the afferent
  pool.
• Exteroceptive - info related to external
  environment (vision, hearing)
• Interoceptive - info processed within the body
  (pain, hunger)
• Proprioceptive information related to
  perception of position and movement of limbs with
  reference to both the entire body and single
  limbs
• While the three sources
• interact with each other
• extensively, UST mainly
• focuses on proprioception.

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The Proprioceptive System

• Perception and transmission of sensory
  information related to position sense
• Interpretation of this information in order to
  respond to a given stimulus with alterations to
  posture and movement.
• Adequate peripheral feedback is
• imperative for maintenance of both
• static and dynamic postural stability.
• Comprised of three senses
• The position sense
• The movement sense
• The force sense

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Proprioception and Athletic Performance

• The importance of proprioception to everyday
  human
• function cannot be overstated. Insufficient
  proprioceptive input
• negatively impacts interjoint coordination.
• Proprioception is both a constant source of
• feedback and a key factor in CNS processing
• of voluntary movements.
• Take-home message Improved
• proprioception stiffens joint complexes to
• reduce injury risk, enhance RFD, and minimize the
  SSC
• amortization phase (which is dependent on reflex
  response).

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Afferent Efficiency and RFD

• Proprioception is a key component of optimal
• excitation of the neuromuscular system.
• Optimization includes faster input faster
• input gathering, transmission, and processing.
• RFD is not dependent on muscle cross sectional
  area
• it is enhanced through purely
• neural mechanisms.

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Purpose

• The purpose of this study was to determine the
  effects of 10 weeks of lower-body unstable
  surface training on performance indices of the
  short and long stretch-shortening cycle,
  sprinting speed, and agility in elite collegiate
  soccer players.

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Subjects

• 19 members of a NCAA Division I collegiate mens
  soccer team
• Ages 18-23
• Minimum six months resistance training
  experience,
• No UST involvement or ankle sprains in previous
  six months. 

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Study Design

• Pre-test, post-test control group design
• Subjects were matched for age and position
  (goalkeeper, defender, midfielder, and forward
  in order to account for varying activity levels
  during training and competition)
• Each subject was randomly assigned into either
  the experimental (10 subjects) or control (9
  subjects) group 

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Pre-Testing

• Bounce Drop Jump (BDJ)
• Countermovement Jump (CMJ)
• 40-yard Sprint
• 10-yard split
• T-Test (agility)
• Prior to testing, each participants
  fully-clothed body weight was recorded.
• As a general warm-up, participants jogged lightly
  for five minutes and then participated in a team
  dynamic warm-up directed by their strength and
  conditioning coach.

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Training Intervention

• Participants completed their normal spring SC
  program, but the experimental group performed the
  UST intervention for one exercise in each
  resistance-training session.
• 10 training week (plus a one-week break after
  week 4)
• 27 total UST sessions. 
•  

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Results Bounce Drop Jump

• No significant pre-intervention differences
  between groups
• Stable (ST) group improved significantly over
  baseline, unstable (US) did not

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Results Countermovement Jump

• No significant pre-intervention differences
  between groups
• ST group improved significantly over baseline, US
  did not

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Results 40-Yard Sprint

• No significant pre-intervention differences
  between groups
• Both groups improved significantly over baseline
• ST improved significantly more than US in 40-yard
  time

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Results 10-yard Split

• No significant pre-intervention differences
  between groups
• Both groups improved significantly over baseline
• ST showed a trend (p.06) toward significantly
  greater improvement than US

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Results T-Test (Agility)

• No significant pre-intervention differences
  between groups
• Both groups improved significantly over baseline
• No significantly different improvements between
  groups

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A Watered Down Interpretation

• Stretch-shortening cycle function is likely
  negatively affected with chronic UST use.
• There may be unfavorable biomechanical
  consequences related to this altered SSC function
  (overpronation, increased antagonist activation).
• Impaired strength gains likely
• Interference with specificity
• Confused motor programming learning different
  non-specific skills

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UST and the Stretch-Shortening Cycle

• Komi (2003) three fundamental conditions for
  effective SSC action
• a well-timed preactivation of the muscles before
  the eccentric phase
• a short and fast eccentric phase
• immediate transition (short delay) between
  stretch and shortening (concentric) phases.
• A Tentative Athlete?

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Practical Applications

• The vast majority of athletic endeavors involve
  stable surfaces where instability is applied
  further up the kinetic chain. 
• Instability at the foot vs. instability at the
  torso and arms. 

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Practical Applications

• More useful in measures aimed at training the
  core and upper body musculature. 
• Impose instability in a more sport-specific
  contexts.

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What is Sport-Specific Instability Training?

• Instability may also be imposed through the use
  of destabilizing torques.
• Unilateral training, lifts performed with
  non-symmetrical objects, and uneven loading
• Behm et al. (2005) unilateral shoulder and chest
  dumbbell presses increased activation of the
  lumbo-sacral and upper lumbar erector spinae.
  Destabilizing torques must be offset by
  contralateral limb musculature action.

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The Science of Stability and Balance

• Non-Neuromuscular Factors Affecting Stability
• Amount of body mass more mass more stable
• Friction between the surface and the body in
  contact with it Increased friction increased
  stability.
• Size of the base of support (BOS) In athletics,
  this generally refers to foot positioning.
• Horizontal positioning of the center of gravity
  (COG) For maximum stability, the COG should be
  on the edge of the BOS at which an external force
  is acting.
• Vertical position of the COG The lower the COG,
  the more stable the object.

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Instability Training

• Unilateral Movements
• progressively limit base of support
• Move toward rapid shifts in center of gravity
  (change of direction work)
• Move from dumbbells to various barbells (raise
  center of gravity to increase difficulty)
• Incorporate asymmetrical/ awkward/unpredictable
  loading, uneven loading, kettlebells, kegs

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Instability Training

• Classic agility drills require rapid shifts in
  center of gravity and repositioning of base of
  support
• Teach positioning low COG, wide BOS
• Anticipate horizontal positioning of COG

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But

• As we do these exercises, we need to recognize
  that stability and mobility are joint-specific.
• We require a balance of the two, but the
  contribution of each is dependent on the joint
  this affects how we should train people for
  health and performance!!!

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The Ideal Body
Joints that needMOBILITY Thoracic
Spine Hips Ankles
Joints that needStability Lumbar Spine Knees
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Enter Mobility/Activation Work
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Why Dynamic Flexibility?

• Improves performance and dynamic range of motion,
  and reduces injury rates when compared to a
  static stretching program
• Passive vs. Active Flexibility
• Neural Control
• Stability within a given ROM
• Excessive Passive ROM is actually an injury risk
  (e.g. gymnastics, ballet)
• Simultaneous Activation Work
• Some Static Stretching is a good thing.

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Some Examples

• Thoracic Mobility
• Side-Lying Extension/Rotation
• Quadruped Extension/Rotation
• Split-Stance Broomstick Pec Mobilizations
• Hips
• Overhead Lunge Walk
• Cradle Walks
• Pull-Back Buttkicks
• Walking Spidermans

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Some Examples

• Hips continued
• Supine Leg Whips
• Squat-to-Stand
• Ankles
• Wall Ankle Mobilizations
• Quadruped Ankle Mobilizations
• Knee Breaks

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Thank You!

• For more information
• www.EricCressey.com
• www.ExcelStrength.com
• EC_at_EricCressey.com