Measurement Of Strength & Power Using Various Techniques Flashcards
Three factors affecting muscle strength and power?
- Muscle structure
- Joint position
- Joint velocity
Physiological and Mechanical factors affecting muscle structure
Fibre type E → Innervation ration
Arichitecture → CSA & pennation
Physiological and Mechanical factors affecting Joint position
Moment arm
Muscle length → Force length
Physiological and Mechanical factors affecting Joint velocity
Force velocity → Eccentric/Isometric/Concentric
Purpose of strength assessments
- Ability to distinguish between athletes at different levels
- Indicator of ‘good’ athletic performance
- Correlation with athletic performance
- Sensitivity to training adaptations
- Availability of normative data for comparison
- Injury prevention
Strength assessment: Specificity
- Testing conditions should imitatethe movement/activity &training conditions
- Violation of the following specific conditions will result in data which cannot describe an individual’s specific strength/power profile and/or specific training adaptations
Things to consider: •Type of movement (movement pattern) •Velocity of movement (joint velocity) •Posture •Joint position •Bilateral–Unilateral use of limbs (Bilateral deficit/bilateral facilitation)
Anisometric (Isotonic) strength testing
•Isotonic: ‘equal + tension’
•Anisometric: ‘non + equal + length’
–constant load
–variable speed/variable resistance
•Equipment:
–free weights, resistance machines
–1RM, 3RM, 5RM…
“For” Anisometric (Isotonic) testing
- Execution of a similar movement to the one performed during the sporting activity
- Maximal and submaximal tests
- Some quantification during submaximal lab-based tests
- Suitable communication to coaches and athletes
“Against” Anisometric (Isotonic) testing
- Some quantification techniques are not as accurate as lab based tests (e.g. Myotest)
- Issues with accuracy and reliability
- The resistance is equal to the amount of torque developed by the weakest joint position (max loading only at specific angles)
- Inability to test specific muscle groups (e.g. stronger muscles work for weaker muscles)
Isometric strength testing
- Isometric: ‘equal + length’
- Isometric: fixed load –fixed speed (0°/s) → fixed resistance
- Equipment: commercial dynamometers, custom made devices (incorporating force sensors)
“For” Isometric strength testing
- Muscle group isolation
- Accurate and reliable
- Quantification and detailed biomechanical analysis
- Allows collection of accurate and reliable EMG data
- Availability of normative data for comparisons
“Against” Isometric strength testing
- Specific joint position strength
* Difficulty to elicit an MVC (maximum voluntary contraction)
Isometric pre-testing considerations
- Develop Protocol (single/multi joint, bi-/unilateral, posture, joint angle…)
- Familiarisation (2+ sessions)
- Establish intra-subject stability (no of trials)
- Establish intra-subject reliability (no of sessions)
Isometric testing considerations
- Calibration
- Equipment settings (sampling rate)
- Warm-up
- Instructions (Max force/torque –Rapid force/torque)
- Live feedback(?) –Post-trial feedback
Isokinetic strength testing
- Isometric: ‘equal + movement speed’
- Isokinetic: variable load –fixed speed (> 0 °/s) → variable resistance
- Equipment: isokinetic dynamometers (30 –+500°/s)
