Lecture 1- Intro/Athlete Evaluation Flashcards
Why do we do fitness testing?
- assess current physical fitness and work capacity
- establishing a baseline (reference point) to track performance improvements or decrements that may be related to issues such as injury or overtraining
- identify strengths and weaknesses in order to develop a program to address them
- tracking changes in performance
- goal setting and planning
Keys to a “good” fitness test
1) reliable
- ability to be able to count on something consistently
2) valid
- obtaining correct and believable info
- measures what it is designed to measure
- example: strength test- are results a true indicator of what we’re trying to evaluate?
3) Practical
- cost, time, facilities
4) suitable
- appropriate and relevant to athlete/client activities
5) ethical
- safe, informed, protected
Reliability - what is it?
- refers to the extent a measurement is consistent and free from error
what is variance?
- measure of the variability or differences among test scores
- example: measuring blood pressure every minute for 5 minutes
sources of measurement error: the tester
- the individual taking the measurement
sources of measurement error: the measurement instrument
- the more complex, the greater the chance of more variability
sources of measurement error: variability of the characteristic being measured
- blood pressure, blood glucose
test-retest reliability
- measures the consistency of a measuring instrument (equipment or person)
- most studies usually involves the person operating the. instrument (strength testing machines, questionnaires, those tools have variability to them but on top of that, there is variability with the person using the tool)
why is test-retest reliability important?
- physical ability improvement or deterioration during rehab or training –> you want it to be a result as a true effect, not due to variability or errors in measurement
example for test-retest reliability- how can physical activity be measured?
example; HIIT, does it work?
- in order to track improvement in aerobic capacity, we need to establish a baseline (VO2Max pre-test)
- it’s important that the pre and post-test are the same–> pre test done on a treadmill than the post test is too.
- different modes of assessment= measurement error because you cannot compare them
test-retest reliability- STUDY: how can strength be measured?? isokinetic dynamometry
- isokinetic dynamometry; computer controlled device that provides very objective measure of muscle strength using
- constant velocity, maximal-effort muscle contractions
- torque increases, hits a maximum and then decreases.
- with these measurements we can come up with indicators of strength
peak torque
- peak torque is the single highest torque value that the person is able to generate just past the mid-range of knee motion
average torque
- average of all torque values
angular work
- area under the curve, it is a product of torque and angular displacement
is isokinetic dynamometry for quads and hammys strength and endurance reliable??- study- methods
- 21 healthy young adults (10 males, 11 females)
- evaluated for max strength
- muscle fatigue also evaluated
2 different tests (measured 2 times) - 1 week apart
is isokinetic dynamometry for quads and hammys strength and endurance reliable??- results/coefficients
- very high reliability values
- intra-class correlation coefficients (0-1.0)
- values above 0.8 are considered very high reliability indicators
- notable exception: peak torque to body weight; this means we can expect more test-retest error when evaluating strength capability of the knee extensor muscle group when it is corrected to body weight
Factors Affecting Test-retest Reliability: testing effects
- influence of one test on subsequent tests
- learning effect: becoming familiar with the test, you can provide better results
- better scores with better practice
- OR worse scores due to boredom (questionnaires or surveys)
Factors Affecting Test-retest Reliability: rater bias
- same rater or tester involved in both trials
- tester may unconsciously (or consciously) desire a certain outcome (biased)
- tester may alter procedures to get the desired results
Factors Affecting Test-retest Reliability: test-retest intervals
- period of time in between two tests
- too short: fatigue or learning effect (strength)
- too long: physiological or biomechanical changes in athletes/clients (training, injury, disuse)
- important to understand what activities your client engaged in prior to carrying out a subsequent fitness test
- desired length: enough time to eliminate fatigue (physiological mechanisms)
to maximize test reliability
- minimize measurement errors- carried out by; tester becoming more confident and familiar with the test)
- tester AND athlete/client must practice test
- replicate near-identical testing scenarios- using the same equipment to measure
- be objective
- understand the purpose of the test - strength? agility? power?
How can reliability be quantified?
- X= T +/- E
- X= observed score (blood pressure measurement or how much strength can be lifted)
- T= true score (diastolic/systolic “physiology”)
- E= error (recording the reading, slipping of BP cuff from being too big, or small fluctuations in BP)
Measurement error: systematic error
- predictable errors of measurement- if we can predict, we can correct for them
- one direction (positive or negative)
- problem: threatens the validity of the measurement
example: - recalibration instrumentation (computer based device)
- checking properly functioning measurement instrument, if device is not calibrated than results can drift in either a positive or negative direction)
Measurement error: random error
- errors due to chance (unpredictable)
- not following procedures properly
- variability in research participants day to day (experience physical, psychological deviations day to day)
validity
- concerns the extent to which an instrument measures what it is intended to measure
- determines believability of results
- an instrument may be reliable, but may not give you what you are intending on measuring
- it can give consistent reading but test itself may not give you what you intend on measuring
internal validity
- deals with factors within the study (or within fitness test)
- did the treatment in a study actually cause the effects?
example; is a new training program actually responsible for an increase in strength or was it due to learning response?
external validity
- to what extent can the results of a study be generalized to a population or setting
- generalizing results may be affected by the experimental sessions or environment
example: subject anxiety during the test that would effect both validities
face validity
- a testing instrument appears to be valid
- is it testing that it is supposed to test?
- least rigorous method of establishing internal validity
- judged to be valid subjectively, not compared to a known standard
- examples; muscle strength, balance, ROM- testers observations carrying out the test can affect face validity
content validity
- defines the validity of the items selected to represent an adequate portion of all possible items
- “can’t test everything”
- must select certain items that will represent an overall profile
- not influenced by factors not associated with the test
questionnaires, surveys
content validity example
- measuring pain
- VAS; visual analog scale
problem: obtaining only 1 general aspect of pain perceived by a person; content validity is questionable in this case
example; measuring pain - McGill pain questionnaire
- McGill pain questionnaire allows you to determine where (location) and nature of the pain
- more comprehensive; provides a better indication
criterion-related validity
- indicates that the outcome of one instrument, the target test, can be used as a substitute measure for an established reference standard criterion test
- comparing one test to a “gold standard” for ease of use in the future
two types:
- concurrent validity
- predicted validity
concurrent validity
- occurs when the measurement to be validated and the criterion measure are taken at relatively the same time
- example; measuring body comp
- under water weighing- gold standard
- skinfolds; more efficient and easier, but more variable
predictive validity
- establishes that a measure will be a valid predictor of some future criterion score
- goal: take physical fitness measure to predict future performance, behaviour or outcome
example; functional movement screen
- battery of physical tests that is intended to provide an overall understanding of a person’s ability to have a functional ROM
predictive validity of FMS - study; FMS predicting 10m sprint times
- 10 m sprite tiem is criterion variable
- x axis- predictor variable (on the right; 1RM/Body mass)
- can the measurement predict the 10m sprint time?
- want to see inverse relation
- lower body strength is related to a greater ability to move through 10m
- this is correlation not cause and effect
- on the left; FMS predicting 10m sprint
- very low correlation, the FMS does not have any type of correlation or predictive validity for this test
- lower body strength has a good predictive validity for 10m sprint time
construct validity
- refers to the ability to measure a concept, not an operational definition
- measuring functional outcome with a questionnaire
- the actual function of the person is not measured, just the concept
example;
- WOMAC - western Ontario and McMaster universities osteoarthritis index
