measurement exam -red

Question 1

state the two types of 2D Kinematics

Answer 1

1. Linear kinematics

2. Angular kinematics

Question 2

State the Frame (sample) rate calculation.

Answer 2

The sample rate is based upon velocity data for walking and running.

With the use of an onlin vision research tool we identify a suitable frame rate.

Question 3

Why is the sample frame rate information important?

Answer 3

It helps in the process of research protocol. First we calculate the appropriate frame rates. This then allows us to set up the data collection area (according to those measures). Set up cameras and collect test data.

The sampling frequency or sampling rate, fs, is the average number of samples obtained in one second (samples per second), thus fs = 1/T.

Question 4

state performance variation

Answer 4

‘repetition without repetition’ (Bernstein, 1967). Implies
that a repeat performances will never be the same

These are the implications of visual identification of image data points.

Question 5

State the Frame (sample) rate calculation.

Answer 5

The sample rate is based upon velocity data for walking and running.

With the use of an online vision research tool we identify a suitable frame rate.

Question 6

what does the term coplanar mean

Answer 6

within the same plane

Question 7

when is 2D a suitable option for data collection.

Answer 7

Two-dimensional filming / analysis is suitable for position estimates of objects on
a plane or movements occurring in a plane.
– Examples: ball-surface impacts, straight line running, etc.
• Predicated on the assumption of coplanarity

Question 8

state and explain 4 camera based measurement tools

Answer 8

Stereophotogrammetry
• 3D motion capture
• Depth-cameras (show and tell)
• Synchronicity

Question 9

state, explain and evaluate sensor based measurement

Answer 9

IMUs

Question 10

explain the different 3D motion capture.

Answer 10

passive, multiple.

Question 11

what is a gyroscope

Answer 11

A gyroscope is a device that uses Earth’s gravity to help determine orientation.

Question 12

explain traumatic injuries and human impacts

Answer 12

Blunt force trauma; infrequent, high-force impact
– E.g. Commotio cordis in baseball
– Highlights requirement of personal protective equipment (PPE) in sport

Question 13

explain chronic/ overuse injuries and human impacts

Answer 13

Chronic, repetitive loading; accumulation of low-force impact (cp. bone tolerance)
– E.g. Medial tibial stress syndrome in running
– Highlights need to understand biomechanics of running

Question 14

name some human impact measurement devices

Answer 14

Measurement devices capable of directlymeasuring force
• Force platform and load cells (force applied at a point)
• Pressure platform (force applied over an area)
• *Isokinetic dynamometer (joint forces; not used in impact assessment)
– Measurement devices capable of indirectlymeasuring force
• Accelerometer (a = F / m)

Question 15

How are impacts interpreted?

Answer 15

Vector quantities such as magnitude and direction.

Question 16

State the mechanical derivatives that can also provide other ways of characterising impacts.

Answer 16

Acceleration- e.g. in tennis by measuring the impact acceleration that the racket endures this can help to identify the rackets sweet spot. This impact will be shown through vibrations. So we can use an accelerometer as an indirect measure of force to understand the impact force produced.

another example is zepp tennis which is a triaxial gyroscope and dual accelerometer.

Acceleration can also be used as a mechanical derivative to characterise head impacts. Such as the head impacts of CTD headform. This impact acceleration can then be used to design/re-design the properties of helmets. e.g. head impact crtierion HIC.

velocity, momentum, impulse
energy, power.

Question 17

Name a device that uses the mechanical derivative acceleration to characterise equipment impacts.

Answer 17

Accelerometers. (This can be an indirect measure for force as well).

Question 18

Explain the use of the mechanical derivative acceleration to characterise head impacts.

Answer 18

Head impact (CTD headform)
• Measuring impact acceleration experienced by the head can help assess
protective properties of helmets etc. (e.g. Head Impact Crtierion (HIC))

Question 19

Define Newtons law of gravitation

Answer 19

‘particles’ are attracted to other ‘particles’

Question 20

state the properties of attraction or force

Answer 20

• Directly proportional to product of masses

- Inversely proportional to distance between centres

Question 21

What are the units of pressure

Answer 21

Pressure is typically measured in units of force (N) per unit of surface area (m2^)
• SI unit: Pascal (Pa) which is equal to 1 N/m2 or kg·m-1
·s-2.

Question 22

how do we quantify variance

Answer 22

Mean and standard deviation of the differences or errors (e.g. systematic and random errors)
– Coefficient of variation: standardised measure of error distribution (e.g. precision)
• Given as: Cv(%) = (standard deviation ÷ mean) × 100

Question 23

What are the requisites of data captured in sport and exercise?

Answer 23

Accuracy
– Validity
– Precision or reliability
– Objectivity
– Minimal error propagation, i.e. during subsequent calculations
– Comprehensibility
• List selected from Mullineaux et al. (2001) and Mullineaux and Bartlett (1997)

Question 24

how do you calibrate and verify gas analysis measurements

Answer 24

calibration curves. gold standards

Question 25

what is the best way to verify a gas.

Answer 25

compare against the gold standard

Question 26

define cross validation

Answer 26

The same measurements are made on a smaller sample taken from the original population to check whether the prediction is accurate

Question 27

define precision

Answer 27

“precision” and “trueness” to describe the accuracy of a measurement method.
so precision refers to the closeness of agreement between test results.

Question 28

define trueness

Answer 28

“precision” and “trueness” to describe the accuracy of a measurement method.

Question 29

Name two types of team positioning systems

Answer 29

1. Vision-based positioning technologies

2. Player-worn technologies (wearables)

Question 30

what are the pros and cons of GPS and LPS.

Answer 30

GPS sensors are simpler to setup (just require sensor) but do not function indoors
– LPS sensors are more complex to setup (require multiple base stations around pitch) but do function
indoors
– Validity of position measurement for both systems are affected by player movements such as running,
sprinting and changes of direction

Question 31

what are criterion measures

Answer 31

Criterion validity (or criterion-related validity) measures how well one measure predicts an outcome for another measure. A test has this type of validity if it is useful for predicting performance or behaviour in another situation (past, present, or future).

Question 32

define sample rate

Answer 32

In audio production, a sample rate (or “sampling rate”) defines how many times per second a sound is sampled. Technically speaking, it is the frequency of samples used in a digital recording.

Question 33

advanced image measurement

Answer 33

this is the complex use of photography in order to derive measurements via multiple images.