Week 2 Flashcards
Acceleration Characteristics
- forward lean around 45 degrees
- parallel shins and body
- toe up
- low ground clearance
- head down
- big arms
- less GCT
Impulse/Momentum Equations
- force x time = impulse
- mass x velocity = momentum
- impulse = change in momentum
think about what two things can increase it (magnitude and time?)
How to achieve max horizontal impulse in minimal time
increased…
- force applied
- duration of force application
How to increase acceleration
- create as much horizontal impulse
- longer contact times
- concentric muscle actions
- increase force production
How to increase max velocity
- create as much vertical force to overcome gravity and maintain forward velocity
- shorter contact times
- minimal joint movements during GCT
- increase SSC
Step Frequency/Length Training Considerations
- step frequency = neural activation and quick turnover of legs
- step length = maintain strength and flexibility
Good and Bad Frontside Lift
- Good = attack from above and more furce during first half of GC
- Bad = increasing braking forces and placing strain on hamstrings
powerful hip drive, stiff ankle contact and elastic energt recoiling
Hip Extensor Hypothesis
gluteus is the muscle that generates force (hip extension important in running speed)
pefs
4 Factos Affecting Long Distance Running Technique
- Pacing
- Economy of locomotion
- Foot strike pattern
- Step length vs frequency
Performance Time (Tp) Equation
C (RE) x d (distance of race)
DIVIDED BY
F (fraction of max O2 sustained) x VO2 Max
Factors affect RE during Marathons
WKFTRBB
- Weight (higher BF = more energy needed)
- Knee extension (straight knee produces resistance)
- Foot strike (overstriding = braking)
- Trial foot height (close to ground for energy conservation)
- Rear foot action (avoid outward swing)
- Body angle (slight lean and relax posture to conserve energy)
- Bounding (avoid too much vertical displacement)
motor units? what muscles?
Muscle Fibre Recruitment for RE
- increased number and quicker recruitment and activation prior and during braking motions e.g. gastrocnemius, rectus femoris and hamstrings
motor units?
Strength for RE
- Fewer muscle fibres recruited for necessary force allowing energy conservation
Muscle Tendon Unit Elasticity for RE
- legs compress during breaking and release during propulsion (stiffer spring = greater elasticity)
Foot Pronation
foot rolls inwards to absorb impact
Foot Supination
foot rolls outwards to propel forwards
Stance Phase of Running Gait
- impulse moving forward
- hip flexion during impact
- hip extension during swing (glute mx and hamstring concentric)
Swing Phase of Running Gait
- foot clearance and reposition ASAP over COM
- hip flexion during swing (RF and iliopsoas)
think about length and frequency
Step Velocity and Running Velocity
lower running velocity = step length increase
max running velocity = step length or frequency increase
Why Forefoot could be more efficient than Rearfoot?
- liberation of elastic energy via Achilles Tendon
- heel strikes provide braking force and energy needed to overcome braking force
Arm Actions in Running
- movement counteracts angular momentum of lower limbs through Newton’s 3rd Law
- prevent external rotation and maintains stability of upper body
Trunk Lean Considerations
- Slight lean = more activation of hip muscles during sagittal movements, takese stress away from ankles
- need torso strength and mobility to improve performance
wbgsf
Components of Runing Shoes
- weight
- breathability
- ground contact
- stable midfoot
- flkexible midfoot
Foot Orthodics Belief
- correct misalignments and improper movements to minimize injury risk
