2) Running Gait Cycle and Athletic Shoe Evaluation Flashcards
Running
- Most popular recreational sport
- Biomechanics differ from walking
- Responsible for many lower extremity injuries
Stride
- Foot strike to ipsilateral foot strike
Step
- Foot strike to contralateral foot strike
Speed
- Stride length + stride cadence
Forces
- 3 – 4x body weight at contact
Kinetics vs. kinematics
- Kinetics = causes
- Kinematics = effects
Pelvis and running
- Function: maintain balance and keep center of gravity over support leg
- Pelvic motion is the key to postural control
Support phase
- Contact phase, 20 – 35 %
- Foot strike
- Midsupport
- Propulsion
Non-support phase
- Forward recovery phase, 65 – 80 %
- Follow through
- Forward swing
- Foot descent
Foot strike (0-25%)
- Ankle dorsiflexed, knee flexed, lower extremity inverted
- Toe strike: (sprinters) Midtarsal joint provides control
- Midfoot strike: most runners
- Heel strike: “normal”; long distance runners
Midsupport (35-40%)
- Knee flexion and subtalar joint pronation are maximal (shock absorption)
- Patellar cross: as one legs passes the other
Propulsion (70-90%)
- Begins with foot lift and ends with toe lift
- Active subtalar and midtarsal joint supination
Non-support phase (forward recovery phase)
- Majority of the running gait cycle
- Involves a change in direction twice (more energy expenditure than in support phase ?)
Follow through
- From toe lift until leg velocity = 0
- Continued extension of the hip with rapid flexion of the knee and ankle
Forward swing
- Transference of angular momentum: hip flexors allow the leg to move faster than the body
- Forward movement of the leg
Foot descent
- Begins with hip and knee extension and ends with foot contact
Double float phase
- One foot in follow through and the other in foot descent
- Neither foot is in contact with the ground
Running compared with walking
- Less time in the support phase
- Double float phase
- Decreased angle of gait
- Decreased base of gait
- Increased limb varus
- Increased velocity of stj / mtj pronation
- Increased ankle joint dorsiflexion at foot contact
Running vs. walking
- Greater ROM and force generated at the first MTPJ in walking vs. running
- Slower running associated with a greater overuse injury rate vs. faster running
Running shoe construction
- Last: board, slip or combination
- Outersole: carbon rubber, tire rubber, blown rubber, gum rubber
- Midsole: Ethyl vinyl acetate (EVA) or polyurethane foam
- Upper: leather, canvas or Gortex
Running specific shoes
- Extra heel cushioning
- Low – cut to allow for ankle motion
- Minimal lateral stability
Basketball specific shoe
- ¾ - top construction for lateral stability
- Firm upper for torsional stability
- No additional heel cushioning
Cross-trainers
- Ok if doing a little of everything and < 10 miles / week running
Running specific shoe exception
- Ok for walking
- A walking shoe has a more rocker sole configuration which better approximates walking, though
Shoe flexibility
- Forefoot (toe box) should be flexible
- Midfoot (shank) should be stable (not flexible)
- Rearfoot should be firm
Problems / solutions
- Hallux limitus: a more rigid toe box would be desirable
- Rigid toe box: may contribute to anterior tibial shin splints
- Flexible shank: notorious for causing plantar fasciitis
Last construction
- Slip (sock – type, one piece construction)
- Board (fiber board skeleton, most anti-pronation shoes)
- Combination (most shoes)
Last shape
- Straight (rectus foot; anti-pronation)
- Curved (cavus foot)
- Semi-curved (most shoes)
Running shoe categories
- Neutral cushioning
- Neutral cushioning with midtarsal joint control (pronation)
- Stability cushioning: Subtalar and Midtarsal joint control
- Motion (pronation) control: subtalar and midtarsal joint
- Motion control: global
Motion (pronation) control (midsole modifications)
- Higher durometer EVA or polyurethane
- External plastic bars or cups
Cushioning (midsole modifications)
- Specialized EVA
- Gel components
- Compressed freon gas (Nike)
Running shoe styles
- Standard training shoes
- Lyte training
- Racing flats
- Trail shoes
Minimalist/other shoes
- Nike “Free”
- Vibram “five-finger”
- Newton shoe
- The best advice: they are not for everyone !
Rocker shoes
- Stable (hard / firm heel)
- Unstable (soft heel)
- Unstable rockers require a stable knee
- Useful for a variety of problems
Barefoot running
- Recent popularity
- Experienced runner
- Gradual introduction
- Compact sand / turf surfaces initially
Shoe weight
- NOT a good way to select an appropriate athletic shoe
- A light shoe is not necessarily desirable
Fit (feel)
- Subjective
- “If it feels right, it probably is” (assuming that the other criteria have been met)
Running shoe replacement time frame
- Running shoes should be replaced every 200 – 400 miles
- For those who run every day: buy two pairs and rotate them
Patient Rx: shoe selection
- Sport specific
- Trainer / trail / racing flat
- Motion / cushioning needs : biomechanically correct shoe
- Check flexibility: toe box
- Price: > $ 85.00
- Fit (feel): Their call !
- Weight: Forget about it
- Proper size: Thumb width
Excessive pronator shoe prescription
- Some degree of motion control shoe (usually 3 levels available)
Excessive supinator shoe presecription
- Cushion with stability
- Currently no reverse-density midsole available ( other than custom, Bart Hersey shoes)
Sock influences
- Blister formation (friction)
- Perspiration
- Comfort (hot / cold)
- Tinea pedis / onychomycosis
- Acrylic / CoolMax fibers reduce blister formation and “breath” better than cotton socks !!
Eliminating perspiration: the wicking effect (from best to worst)
- CoolMax
- Acrylic
- Polypropylene
- Wool
- Cotton
Sock fiber type –> Sport
- Acrylic –> Golf, tennis, hiking
- Acrylic / wool –> Outdoor – cold
- Acrylic / Thermax –> Outdoor – cold
- Acrylic / CoolMax –> Outdoor – warm
- CoolMax –> Running, cycling
