Running biomechanics
- double-leg float or flight phase
- stance makes up 40% of running and swing makes up 60% (opposite of walking)
3 Phases of Stance Phase during Running
- Initial contact
- Midstance
- Toe-off
Initial contact in Running
Decelerates the forward-swinging leg and passively absorbs the shock of ground reaction forces
Midstance in running
Foot in full contact with ground and body weight shifts from the rear to the front
Toe off in running
Relative lengthening of LE with concentric muscle contraction of the hip and knee extensors in preparing for the foot to push off
“Spring mass system”
- Energy absorption- joints of LE lower the COM and absorb energy during early stance (spring compressing)
- Energy generation - LE moves into extension allowing for propulsion (spring recoiling)
Hip joint angular kinematics running vs. walking
- greater amount of ROM in sagittal plain (mainly flexion)
- less extension during toe-off
Knee joint angular kinematics running vs. walking
- greater amount of motion throughout cycle
- 20 to 30 degrees of flexion at initial contact
- 80 to 110 degrees during swing phase depending on speed
Ankle joint angular kinematics running vs. walking
-up to 20 degrees of DF at initial contact with rapid change over to PF up to 30 degrees during toe off
How would a mid foot or fore-foot strike pattern affect stride length vs. rear-foot strike pattern?
- shorter stride length which reduces ground reaction forces
- results in increased cadence
- increased cadence=shortened stride length=decreased forces through the knee
Benefits of higher cadence
Runners decrease:
- ground contact time (stance)
- flight time
- stride duration
- step (stride) length
- vertical excursion of COM
- braking and impact transient forces
Added energy cost of increased cadence?
-increased step rate of 10% did not alter metabolic cost
