JEFF CUBOS
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Making seemingly random connections across disciplines

Random Running Facts

3/17/2010

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Differences between walking and running
  • Transition of 2 m/s (running is more energy efficient)
  • Increased Ground Reaction Forces with running
  • Flight & Float phases only occur in running
  • Double support & stance phases only occur in running
  • Decreased stance phase and increased swing phase in running
  • Overlap of swing phase (vs stance phase)
  • Running requires greater eccentric contractility

In General...
  • Sprinters – are more often midfoot strikers
  • Endurance runners – are more often heel strikers

Running incorporates a double float phase
 (vs the double stance phase in walking)
  • Immediately after toe off and immediately before initial contact
  • At the beginning and end of the swing phase

Running Kinematics
  • Stride Length – distance between initial contact to next initial contact of same foot
  • Step Length – distance between initial contact to initial contact of opposite foot

Each stride consists of...
  • A Support Phase
  • A Recovery phase (Follow through, Forward acceleration, Foot descent)

Running Gait Cycle


  • Stance Phase
    • Initial Contact
      • Heel strikers absorb increased vertical Ground Reaction Forces (close to 2.2x BW)
      • These forces should normally be absorbed by the hip, knee, and ankle complexes

  • Heel-off
    • Ankle plantar flexion initiates propulsion, lengthens stance phases, and increases stride length of opposite foot
    • Supination of foot begins!
      • Transverse tarsal joint converges for rigidity
      • Due to external rotation of the tibia, gastroc contraction (attachment point), and the metatarsal break phenomenon
      • Metatarsal Break Phenomenon: Contributes due to extension of the Metatarsophalangeal joint
    • Windlass Effect due to extension of Metatarsophalangeal joint
      • Leads to tension in the Plantar Fascia
      • This also increases stability of transverse tarsal joint
    • Contraction of intrinsic muscles of the feet
    • Max Ground Reaction Forces occur when the foot pushes off the ground
      • 2.8x BW

  • Toe off
    • Posterior lower leg muscles shut off and anterior musculature kick in for foot clearance
    • Hamstring group changes from knee stabilizer to hip extensor
    • Knee extensor mechanisms begin to contract concentrically to maximize knee extension (for propulsion)

  • Swing Phase
    • 1st part - knee flexes
      • Resisted by eccentric contraction of knee extensor mechanism
      • However, Rectus Femoris complex also acts to flex hip
      • Therefore knee extensors become prone to injury! (as do other muscles that cross 2 joints)

  • After 1st Float Phase, opposite foot touches down
    • Hip ABDuctors contract to stabilize pelvis

  • As the leg swings through, pelvis rotates putting hip into ABDuction
    • External rotation of the hip helps prepare for supination
    • This is controlled by eccentric ADDuction/ADDuctors (which are active throughout the entire swing phase)

  • Anterior lower leg compartment again kicks in to dorsiflex the ankle

  • Terminal swing (2nd Double Float)
    • Hip flexion stops and posterior chain (glute/ham complex) initiates hip extension
    • Knee extension results due to rapid knee extensor mechanism contraction
​
  • Force couple of the anterior and posterior lower leg musculature dampen the foot initial contact

Upper Extremities
  • Angular momentum of the arms balance the rest of body
  • Therefore, relatively low total body angular momentum

GRF
  • Highest stress (GRF) occurs just at toe-off (2.8x BW)
  • 2 rearfoot spikes
    • 2nd peak is influenced by muscle activity during support
    • Midfoot strikers have a single peak
      • Decreased GRF!
      • Posterior lower leg, knee, and hip musculature act as shock absorbers - for Proximal Stability
      • They act as shocks AND springs

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I created this blog to share my thoughts with others. It is not intended to be used for medical diagnosis, medical treatment or to replace evaluation by a health practitioner. If you have an individual medical problem, you should seek medical advice from a professional in your community. Any of the images I do use in this blog I claim no ownership of.
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