Chapter 19: Speed & Agility Flashcards
Definitions: Speed, Change of Direction, Agility
“the skills and abilities needed to”
Speed: achieve high movement velocities
COD: explosively change movement direction, velocities, or modes
Agility: change direction, velocity, or mode in response to a stimulus
Definitions: rate of force development (RFD), impulse
RFD: the development of maximal force in minimal time, typically used as an index of explosive strength
Impulse: the product of the generated force and the time required for its production, which is measured as the area under the force-time curve. Impulse dictates the magnitude of change of momentum of an object.
Why is RFD more useful than maximal force production for measuring explosive ability?
Maximal force takes at least 300 ms to accomplish and many sporting activities occur in less than 200 ms
Training activities aimed at improving the stretch-shortening cycle (SSC) should fulfill which 2 criteria?
- Involve skillful, multijoint movements that transmit forces through the kinetic chain and exploit elastic-reflexive mechanisms
- Structured around brief work bouts separated by frequent pauses to manage fatigue and emphasize quality and technique
Definition: complex training
Pairing plyometrics with heavy resistance exercise—works thanks to postactivation potential
Why is high-velocity and high-force eccentric training important for agility?
The braking phase has much longer ground contact time than sprinting. Also, eccentric tracing effects are specific and recruit different motor units than concentric activities.
What separates elite and novice runners?
The amount of vertical force applied to the ground during the stance phase.
This translates to to longer and more frequent strides
How long does it take for a sprinter to go from leaning forward to upright?
About 20 m
Sprinting Error correction: hips too high in start of crouch
Instruct athlete to space feet by 1.5-2 foot lengths, drop shin of back leg to leg parallel to sprint surface
Sprinting error correction: athlete stepping out laterally during initial drive phase
Causes by improper force distribution: instruct athlete to push through the ground
Sprinting error correction: abnormally short and tight arm movement
Instruct athlete to: drive the elbow down and back, or pull the hands and back to simulate pulling on a rope. Cue athlete to allow hands to fully break the waist and allow arms to recover at midline of the body
Sprinting error correction: unnecessary tension in dorsal muscles and/or neck hyper extension
Keep head in line with spine - torso and head rise together
Sprinting error correction: athlete “jumps” first stride or steps over knee of stance leg
Causes by too steep of an upward thrust/push off angle. Instruct athlete to drive through the ground and allow swing leg to horizontally “cut” the stance shin. May also cue to keep swing leg foot close to the ground during acceleration.
Sprinting error correction: premature upright posture from starting point
Caused by inadequate push off force - instruct athlete to continue pushing into the ground while maintaining natural trunk lean and keep head in line with spine
Sprinting error correction: attempting to keep accelerating once shins are vertical
Once shins and hips come vertical, torso and head should, too. Feel for the rise in the hips so that the joints stay stacked
Sprinting error correction: insufficient height of swing knee
Encourage athlete to push off the ground, NOT to lift knee higher as this will not help and may change the mechanics
Sprinting error correction: Athlete is overstriding
Instruct athlete to “run in their lane” and maintain natural gait cycle. They need more push off to lengthen stride without disrupting mechanics
Sprinting error correction: chronic hamstring injury/pain
Often due to insufficient mobility or anterior pelvic tilt during sprint—mobilize hamstrings and stabilize pelvis
Sprinting error correction: athlete is “cycling” leg action, which causes increased time in swing phase—there will be a gap between knees in stance phase
Drive the foot down and back into the track, don’t “paw.” Athlete is overusing horizontal force application
Sprinting error correction: arm movement in transverse plane
Cue athlete to spring down and back while maintaining an upright torso and recover near midline of body
What are the five phases of sprinting gait?
Early flight, mid flight, late flight, early support, late support
Fundamental components of early flight phase of sprinting
eccentric flexion of hip and eccentric extension of knee (deceleration of of backward movement of leg)
Fundamental components of mid flight phase of sprinting
concentric hip flexion and eccentric knee extension -> flexion (accelerate thigh forward)
Fundamental components of late flight phase of sprinting
concentric hip extension and eccentric knee flexion (thigh back for foot contact, avoid knee hyperextension for landing)
