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