Force Plate Data and Plotting Anatomical Markers

Question 1

state 4 facts about the sampling rate required when using a force plate

Answer 1

1) need a higher frequency than the frequency of the movement
2) 1000 Hz for most so you don’t miss key information
3) can get away with 500 Hz for walking and balancing trials as you want increased sensitivity for lower forces

4) choose an appropriate sample duration (time)
- usually 10-15 seconds

Question 2

how, and why, do you edit the ‘amplifier ranges’ ?

Answer 2

1) click set-up
- click devise set-up
- click properties
- click ‘edit ranges’ (bottom left)

2) sheer ranges (non-vertical forces being applied to the plate)
- leave as it is (approx. 2538)

3) vertical range
- higher values for larger movements which create larger vertical forces, but loses sensitivity for lower forces
- change to lower values for balance movements (e.g. - one value down)

Question 3

what considerations need to be made when starting the trial ? (5 points)

Answer 3

1) explain the move to the participant - ask them if they need a practice
2) participant not to stand on the platform or surrounding set-up
3) press ‘start’ to zero the platform
4) for moves beginning on the platform, ask your participant to now step on the platform
5) press ‘ok’ to start the sample

Question 4

state 3 facts about data analysis

Answer 4

1) press F3 for summary statistics
2) hold the right curser to zoom over key information
3) vertical threshold bars can be moved to hone in on specific information

Question 5

explain how you would instruct the participant through the following movement - ‘countermovement jump’

Answer 5

• ask the participant to stand on the force plate and hold still for accurate body weight reading
• once you feel they are still, press ‘ok’ to start collecting your trial
• wait a couple of seconds and then give them a ‘3-2-1’ countdown before the participant performs their jump
• upon landing, ask the participant to remain on the platform until the timer ends

Question 6

explain how you would instruct the participant through the following movement - ‘squat jump’

Answer 6

• ask the participant to stand still on the platform for an accurate body weight reading
• once you feel they are still, press ‘ok’ to start collecting your trial
• wait a couple of seconds, and them ask themselves to lower themselves into the squat position and hold still
• once you feel they are still, give them a ‘3-2-1’ countdown before the participant performs their trial
• upon landing, ask the participant to remain on the platform until the trial is over

Question 7

explain how you would instruct the participant through the following movement - ‘drop jump’

Answer 7

• once the plate has been zeroed, ask the participant to stand on the platform and press ok to begin the trial
• once settled, give them a ‘3-2-1’ countdown for them to step off the box and perform a drop jump and have as quick a changeover as possible
• upon landing, ask them to remain on the platform until the end of the trial for accurate body weight measurements

Question 8

explain how you would instruct the participant through the following movement - ‘double/single leg hopping’

Answer 8

• ask the participant to stand on the platform and hold still to get an accurate body weight measurement
• once you feel they are still, press ‘ok’ to start the trial
• wait a coupe of seconds, and then give them a ‘3-2-1’ countdown before the participant completes 10 hops
• once completed, ask them to remain on the platform until the end of the trial

Question 9

explain how you would instruct the participant through the following movement - ‘walking/jogging/running’

Answer 9

• once the platform has been zeroed, make sure the participant is ready
• give them a ‘3-2-1’ countdown for them to start their trial
• press ‘ok’ as they approach the platform s there is enough ‘quiet time’ before the data is loaded

Question 10

explain the anteroposterior reading from ‘walking/jogging/running’

Answer 10

• Fnet x does not include the weight force as that only acts vertically
• first part of contact phase, magnitude increases below zero as the horizontal component is acting against the COM –> a breaking force
• then becomes positive after mid stance as the vector points upwards and forwards causing acceleration –> propulsive phase

Question 11

what is the purpose of the amplifier ranges ?

Answer 11

changing the amplifier ranges adjusts the sensitivity of the force plate