Random Running Facts

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

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• 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