analyzing human movement: four examples Flashcards
walking and stability
to prevent a fall, a toddler takes short steps forward with feet flat and a wide stance
pointing the toes outward
the wide stance increases the width of his base of support and therefore increases his stability
walking and principle 4
over time, a child acquires a more mature proficient walking pattern
characterized by an increased stride length
the increased stride length allows a greater application of force by the foot against the ground at push-off
walking and principle 5
as the child gains greater control of their balance, out-toeing is reduced and the base of support narrows
this allows more force to be applied in a forward-backward direction
eventually, the child will grow up and demonstrate the mature, proficient walking pattern of a young adult
forces involved in a soccer kick
from the moment the ball leaves the toe of a soccer player, gravity acts on the ball’s mass, giving it weight and resisting its upward motion
wind is another external force that can act upon the ball as it hurtles toward the goal
pushing down on the ground with the non-kicking foot generates ground reaction force, which helps the soccer player impart force to the ball
analyzing a soccer kick qualitatively
the player’s running approach toward the ball creates momentum and permits a long angular swing of their kicking leg toward the ball
the kicking leg acts as a third-class lever in propelling the ball forward toward the goal
maximum velocity is imparted to the ball as a result of sequenced movements
as the kicking leg swings to kick the ball, the player moves their arms in an effort to keep their centre of mass positioned over the supporting leg
wrist shot and levers
the pull of the top hand on the stick provides the effort force
the push represents the load
the fulcrum exists at the location of the player’s bottom hand, which grips the stick about mid-way down the shaft
ground reaction force and principle 1
pushes backward with their back foot to create a ground reaction force
directs their body and the puck in a forward direction
their front foot, in turn, plants and their arms swing around his body, in an effort to keep their centre of mass over this new base of support and to maintain his balance
friction, gravity, and momentum
as the puck slides across the surface, a frictional force arises between the puck and the surface, opposing the puck’s forward motion
whether or not the puck enters the goal cage in the air or along the ground depends on the angle at which it leaves the stick, as well as the amount of momentum that is imparted to the puck by the shooter
wrist shot and the impulse-momentum relationship
impulse is increased by starting the shot from a position behind the body, stepping into the shot, and applying a force as the stick moves forward until the point of release
wrist shot and maximizing effort
the amount of force applied to the puck is increased by the use of leg drive, and by sequencing the use of all the necessary muscles and joints in the arm
the wrist shot relies on the sequenced use of the muscles and joints of the upper arm followed by those in the forearm, finishing with a rapid extension of the wrist
computerized motion analysis
the process of videorecording the movements of objects or people
analyzing a jump shot in basketball
broken down into 9 separate actions or phases
viewing each phase separately can reveal where an athlete is making one or more errors in executing a shot
when the errors are corrected, the player’s shooting performance will improve
