WEEK 12

Question 1

what are the 2 factors at which an athlete runs in order to create a running stance

Answer 1

1) the distance covered with each stride taken (stride length)

2) the number of strides taken in a given time ( stride frequency)

Question 2

how do you calculate stride frequency

Answer 2

1 (stride) / stride time (s)

Question 3

describe stride versus step (x2)

Answer 3

• one complete cycle of walking = stride
• one half cycle of walking = step

Question 4

describe “stride” track and field (x2)

Answer 4

one half cycle of running (from touch down of one foot to touch down of the next foot)

one stride = one step everywhere else.

Question 5

define stride length

Answer 5

horizontal distance between touch down of one foot to the touch down position of the next foot.

Question 6

what is the calculation for running speed

Answer 6

stride length x stride frequency

Question 7

describe foot strike patterns

Answer 7

the running foot strike position can be either through the heel, through the mid foot or forefoot. at low running speeds, people generally have a heel striking pattern, whereas when sprinting it is usually an “active” forefoot striking pattern.

Question 8

describe “braking “ during the contact phase

Answer 8

from foot strike to mid support the runner controls his motion by creating a horizontal braking. this slows the foot motion down, giving the runner stability whilst the body rotates about the foot.

Question 9

describe propulsion during the contact phase

Answer 9

from mid support to take off the runner creates a horizontal propulsion (a positive force). this provides the runner with energy (momentum) for the next stride.

Question 10

describe the elastic energy contribution

Answer 10

the achilles tendon is stretched at foot strike during which time it stores elastic energy. this energy is released when it contracts to raise the heel and propel the body forward.

Question 11

describe the active foot strike

Answer 11

mid foot to forefoot position= is when the ground reaction force is close to the centre of gravity (COG) of the body, which reduces the braking forces and increase propulsion during ground contact.

Question 12

describe the foot strike during pronation

Answer 12

the foot strike occurs slightly on the lateral side of the foot when running

Question 13

describe the mid stance during pronation

Answer 13

the subtler joint pronates for approx 70% of total ground contact time with peak pronation occurring at 40% of gct

Question 14

describe the toe off during supination

Answer 14

the sub taller joint then supinates for the final 30%

Question 15

describe the recover phase during knee flexion

Answer 15

• speed of the swinging leg is increased through knee flexion
• increased drive ( forward swing) is achieved through increased hip flexion (to raise the knee) and fast extension of the knee.

Question 16

describe hip extension during the recovery phase of running

Answer 16

rotating the lower leg backwards quickly and driving the trail (opposite) hit forwards then enables the body to be in a good position for an “active” foot plant.

Question 17

define a bunches start before a sprint

Answer 17

the interlock spacing of 30cm or less. during the bunch start the toes of the rear foot are approx. level with the heel of the front foot. this brings the CG closer to the start line.

Question 18

define a medium start before a sprint

Answer 18

the interlock spacing is between 30-50cm.

theories suggest that the front block should be placed form the start line at a distance equal to 60% of the athletes leg length and a distance of 45% leg length for the interlock spacing.

Question 19

define an elongated start before a sprint

Answer 19

interlock spacing= greater than 50cm

theories suggested that the front block should be placed form the start line at a distance equal to 60% of the athletes leg length.

Question 20

describe the start time of a swim phase

Answer 20

traditionally defined as the time from the starting signal until the swimmer begins kicking or stroking the water.

Question 21

what are the 3 factors that start time include when swimming

Answer 21

1) the time from the starting signal until the feet leave the block ( block time)

2) the time from the feet leaving the block until the first contact with the water ( flight time)

3) the time from first contact with the water until the swimmer starts stroking ( glide time)

Question 22

define stroke length in swimming

Answer 22

the average horizontal distance travelled during one complete cycle of the swimmers arm.

Question 23

what is the calculation for stroke length in swimming

Answer 23

SL = distance stroked/ number of complete arm cycles

Question 24

define stroke frequency in swimming

Answer 24

the average number of complete arm cycles in each time

Question 25

what is the calculation for stroke frequency

Answer 25

SF = number of complete arm cycles/ time spent stroking

Question 26

what is the calculation for stroke velocity

Answer 26

stroke length x stroke frequency

Question 27

describe propulsive and resistive forces in swimming

Answer 27

propulsive = drive the swimmer forward through the water in reaction to the movements by the swimmer makes resistive= oppose the swimmers motion and are exerted by the water.

Question 28

describe the stroke phase and drag

Answer 28

- flexed hips and knees in recovery phase of breastroke = 226 newtons of drag - dropped hips in pre thrust phase of breastroke = 217 newtons of drag

Question 29

describe the swimming lifting forces of the hands

Answer 29

- the hand is foil shaped when swimming - the action of the hand creates a lift and drag force the outward and inward movements keep the swimmer at the surface of the pool when sculling as it maximises lift and minimises drag.

Question 30

describe swimming lift forces

Answer 30

similarly, the outward and inward movement of the hand in breastroke produces a lift forces in the forward direction generating propulsion

Question 31

describe freestyle propulsion (x3)

Answer 31

- the mechanisms behind propulsion during freestyle swimming still remain unclear - may be a contribution of drag and lift that is responsible for creating propulsion during freestyle swimming - approx. 80% arms , 20% leg contribution

Question 32

describe the freestyle arm action ( x3)

Answer 32

s shaped hand path= longer distance travelled by the hand which creates a greater propulsive impulse - propulsive lift force are primarily used with the s shaped pull back because there is a pressure difference which creates an upward lift - laminar versus turbulent water which helps with lift

Question 33

describe the pull phase and recovery phase during swimming

Answer 33

- pull phase= begins as the hand enters the water and ends as it leaves - the recovery phase = when the hand moves forward above the water in preparation for the next pull phase.