Week 9 Lecture: Strength and Power Assessment 1 PDF

Week 9 lecture: Strength and Power Assessment 1 Strength Testing (Part 1) Content Strength & Strength Endurance Assessment - National Sports Science Quality Assurance program - NSSQA protocols Validity & Reliability Norms Predictive equations Scaling Why Is Assessing Strength Im...

Week 9 lecture: Strength and Power Assessment 1 Strength Testing (Part 1) Content Strength & Strength Endurance Assessment - National Sports Science Quality Assurance program - NSSQA protocols Validity & Reliability Norms Predictive equations Scaling Why Is Assessing Strength Important? Measures of strength strongly correlated with athletic performance Discriminator of performance level in multiple sports Optimise program design Protective effect Assess effectiveness of training program Consider - absolute vs relative strength - Contraction mode specificity - maximal strength v power Discriminator of Performance Level Strength Training for Endurance? - Assessing strength can also be useful for endurance type shit Strength Testing (Part 2) Testing - consistent Time of day Pre test training Pre test nutrition & hydration Exercise order - Explosive before max strength Validity Reliability Calibration Reporting Force-Velocity-Power Type of test? High force – low velocity E.g., ??? Low force – high velocity E.g., ??? Moderate force – moderate velocity E.g., ??? Specificity – What are you testing? SAID Principle – Specific Adaptations to Imposed Demands Monitoring impact of training Relative Strength In Different Movements Validity and Reliability Vital for data interpretation  Simple concepts, should be clearly understood Validity How is it assessed? Compared to a ‘gold standard’. Beep test example Reliability How is it assessed? Multiple, repeat tests in the same condition - Same day – intra-day reliability - Different day – inter-day reliability Example of magnetic stimulation to the femoral nerve Test Validity: Military Example – Jobs? Infantry - Packs often > 40 kg - Marching with packs often > 5 km Tank Crew - Frequent shell loading - ~20 kg per shell Clerk - Frequent desk operations Military Example – continued. Biased toward lighter individuals No ‘strength’ assessment Scaled for age and sex Every job, same tests Military Example – new, proposed tests Basic level for all soldiers - Clerks may need to be deployed Assess key capacities - E.g., strength No scaling “Level” based on job demand Strength Testing (Part 3) What are we testing? Maximum Dynamic Strength: Maximum force that can be generated in a single effort against an external resistance Can be assessed in a number of ways Types of Strength Testing Maximum Dynamic Strength - Isokinetic - Isometric - Isoinertial Origins: - ísos = ‘equal’ - kinetikos = ‘to move’. - metricos = ‘measure’ - inertia = ‘resistance of physical object’ Why not isotonic? What is it? ísos = ‘equal’ tonic = ‘tension’ But: Tension = changes through ROM isoinertial = more accurate Equipment Isometric testing - Force plate & immovable bar - Other measurement device Isokinetic testing - Dynamometer Isoinertial testing - Barbell/db - Weight plates Isokinetic Dynamometry Constant angular velocity Peak/average force Popular clinically Used in research Assess asymmetry Criticised for lack of performance specificity but may be useful  Ham/Quad Ratio… Isometric Assessment Characterised by muscle actions that result in no change in joint angle Assess peak force & RFD Require subjects to produce max force against - Strain gauge - Cable tensiometer - Force platform - Load cells Isometric mid-thigh pull: A popular test Conducting an IMTP Test Other Isometric Tests Hip abduction & adduction Shoulder (ASH/IR/ER) Back extension Grip strength Groin Squeeze Iso Push Up Isoinertial Testing Constant gravitational load throughout the movement Repetition Maximum (RM) testing: generally involve large muscle mass movements for a specified number of repetitions Requires ability to handle maximal loads Strength Testing (Part 4) Strength Testing Guidelines General warm up/Stretch?? Specific warm up - 40-60% specified RM for up to 10 reps - Minimum 2 min recovery - 60-80% specified RM for max 5 reps - Minimum 2 min recovery - 90% specified RM for max 3 reps - 5 minute rest - Test sets Other considerations: Experience Strength - E.g., Lifter who squats 200 kg Strength Testing Guidelines Technical errors Lowering and lifting in a continuous manner No > 3s pause between reps Max 5 min recovery between sets Minimum weight increments dictated by - Equipment availability - Test movement - TE/CV% Strength Testing Challenges Questions you should ask yourself: Where do you start? - E.g., Specific loads? Exercises? Safety? - Are they ready for this? Why are you testing? - What’s the goal? - Is it actually necessary? What movements? Bench press  Bench pull Chin ups/Lat pulldown Incline leg press Single leg press Squat Others? Max Strength Reliability Determining Change From previous: What degree of change is required to be practically important? - Individually - Group Need to make an assessment of the magnitude of change and consider the “noise” in the test Test Sensitivity Ability of a test to detect smallest practically important change Smallest worthwhile change calculated as: - 0.5 CV% or 0.2 x between subj SD Individual Comparisons Example 1RM Squat - CV:3.5% Strength Testing (Part 5) Prediction Equations Not all subjects are capable of performing 1RM testing Prediction equations allow estimation of 1RM from submaximal repetitions Numerous population specific equations Multiple ways to predict Repetition Max Calculation - PLENTY OF THINGS ON THIS IN PREVIOUS LECTURES Reps to fatigue Velocity-based predictions Using barbell velocity to: - Predict 1RM - Measuring barbell velocity during concentric phase of movement Limitations with Velocity Tests? Not all the research ends up with the same results Relationship post-training intervention Stable following training: Muscular Endurance Some sports require high force production for long durations Generally: - Low load/No load (BW) - Absolute / Relative strength endurance - Multi-joint movements e.g., Chins, Leg Press, etc. Issues? Strength Testing (Part 6) Big V Small Body Weight Considerations Important issue in max strength assessment If not taken into account then there can be an over or underestimation of max strength depending on the lift - External load favours heavier athletes - Body weight movements favour lighter athletes Scaling relative to body weight (strength/body mass) common but result may not be equal for lifters of different mass (Cleather 2006)  Other scales have been developed “Wilks” formula used in Powerlifting - Lift weight x body weight conversion factor - E.g. 69.3 kg male conversion factor is 0.7552 “Siff” formula for Olympic and other lifts “Sinclair” formula used in Weightlifting and adjusted every Olympic year based on World Record totals over previous years From Previous - smaller guy stronger Allometric Scaling Scaling according to body mass attempts to account for influence of muscle mass on performance Known as “ratio” scaling (i.e. strength/BM) Assumes a linear relationship between BM and performance Allometric scaling involves raising BM to the power of 0.67 (BM0.67) Based on theory that force & power increase with BM to the power of 2/3