Lecture 3 - Biomechanics

Question 1

define the difference between discrete, serial, and continuous skills…

Answer 1

discrete - defined beginning and end
serial - series of discrete skills linked together
continuous - no defined beginning or ending

Question 2

define between an open and closed skill….

Answer 2

open is performed in a unpredictable/ variable environment; closed is in a stable/able to recreate environment

Question 3

correct biomechanics reduce….

Answer 3

resistance and risk of injury

Question 4

what is the order of force transfer for throwing from the bottom up?

Answer 4

legs, hip & trunk, shoulder & scapula, elbow & forearm, object

Question 5

what are the 4 phases of throwing?

Answer 5

wind up/ prep
cocking (combined with step 1 = 80%)
acceleration (2%)
deceleration (18%)

Question 6

what happens with the body segments during the wind up phase?

Answer 6

body winds up 90 degrees to target
lower half produces force for forward controlled falling
upper half is INACTIVE
(rhythm set)

Question 7

what happens with the body segments during the cocking phase?

Answer 7

arms ABD and ER (elastic recoil)
trunk, abs and hips start contributing to propulsion
lead leg plants
(optimal body position and projectile propulsion is set)

Question 8

what happens with the body segments during the acceleration phase?

Answer 8

elastic recoil and IR generate force
ant chest and spine contribute
(explosive/unstable phase)

Question 9

what happens with the body segments during the deceleration phase?

Answer 9

momentum travels from shoulder and elbow to object
shoulder continues to experience stress/instability
torso contributes to force transfer with rotation
(force generation phase)

Question 10

what does the gait cycle include?

Answer 10

one foot experiencing stance phase (60%) and one swing phase (40%)

Question 11

define ‘step length’

Answer 11

longitudinal distance between 2 feet (35-41 cm)

Question 12

define ‘stride’

Answer 12

advancement of both feet (one step by each leg)

Question 13

define ‘stride length’

Answer 13

distance covered during 1 cycle (2 step lengths = 70-82 cm)

Question 14

what are the A-G phases of a gait cycle?

Answer 14

a- heel strike
b- loading response
c- midstance
d- terminal stance
e- preswing
f- initial and mid swing
g- terminal swing

Question 15

what is the ‘stance phase’ and what occurs during it?

Answer 15

occurs when foot is on ground and bearing weight

• initial contact (heel strike)
• load response (foot flat)
• mid stance (single leg stance)
• terminal swing (heel off)
• pre swing (toe off)

Question 16

what is the ‘swing phase’ and what occurs during it?

Answer 16

occurs when foot is non-weight bearing and moving forward

• initial swing
• mid swing
• terminal swing

Question 17

what is the importance of lateral pelvic shift/pelvic list?

Answer 17

maintains center of gravity (side to side movement of pelvis - 2.5-5cm)

Question 18

what is the importance of vertical pelvic shift?

Answer 18

maintain smooth pattern of gait as body advances (vertical movement of sacrum to keep COG)

Question 19

what is the importance of pelvic rotation?

Answer 19

allow for step length (rotates 40 degrees during SWING PHASE)