Chapter 20 Laboratory Assessment of Human Performance

1. Chapter 20Laboratory Assessment of Human Performance EXERCISE PHYSIOLOGY Theory and Application to Fitness and Performance, 6th edition Scott K. Powers & Edward T. Howley Presentation revised and updated by Brian B. Parr, Ph.D. University of South Carolina Aiken

2. Factors That Contribute to Physical Performance Figure 20.1

3. What the Athlete Gains From Physiological Testing • Benefits • Information regarding strengths and weaknesses • Can serve as baseline data to plan training programs • Feedback regarding effectiveness of training program • Understanding about the physiology of exercise • What physiological testing will not do: • Accurately predict performance from single battery of tests

4. Effective Physiological Testing • Physiological variables tested should be relevant to the sport • Tests should be valid and reliable • Tests should be sport-specific • Tests should be repeated at regular intervals • Testing procedures should be carefully controlled • Test results should be interpreted to the coach and athlete

5. Direct Testing of Maximal Aerobic Power • VO2max is considered the best test for predicting success in endurance events • Other factors are also important • Specificity of testing • Should be specific to athlete’s sport • Exercise test protocol • Should use large muscle groups • Optimal test length 10-12 minutes • Start with 3–5 minute warm-up • Increase work rate to near maximal load • Increase load stepwise every 1–4 minutes until subject cannot maintain desired work rate

6. Direct Testing of Maximal Aerobic Power • Criteria for VO2max • Plateau in VO2 with increasing work rate • Rarely observed in incremental tests • Blood lactate concentration of >8 mmoles•L-1 • Respiratory exchange ratio 1.15 • HR in last stage 10 beats•min-1 of HRmax

7. Determining VO2 Max Figure 20.2

8. Determination of Peak VO2 in Paraplegic Athletes • Paraplegic athletes can be tested using arm exercise • Arm ergometers • Wheelchair ergometers • Highest VO2 measured during arm exercise is not considered VO2max • Called “peak VO2” • Higher peak VO2 using accelerated protocol • Test starts at 50–60% of peak VO2 • Limits muscular fatigue early in test

9. Laboratory Tests to Predict Endurance Performance • Lactate threshold • Exercise intensity at which blood lactic acid begins to systematically increase • Critical power • Speed at which running speed/time curve reaches plateau • Peak running velocity • Highest speed that can be maintained for >5 sec

10. Use of the Lactate Threshold to Evaluate Performance • Lactate threshold estimates maximal steady-state running speed • Predictor of success in distance running events • Direct determination of lactate threshold (LT) • 2–5 minute warm-up • Stepwise increases in work rate every 1–3 min • Measure blood lactate at each work rate • LT is the breakpoint in the lactate/VO2 graph • Prediction of the LT by ventilatory alterations • Ventilatory threshold (Tvent) • Point at which there is a sudden increase in ventilation • Used as an estimate of LT

11. Lactate Threshold Figure 20.3

12. Ventilatory Threshold Figure 20.4

13. Measurement of Critical Power • Critical power • Running speed at which running speed/time curve reaches a plateau • Power output that can be maintained indefinitely • However, most athletes fatigue in 30–60 min when exercising at critical power • Measurement of critical power • Subjects perform series of timed exercise trials to exhaustion • Prediction of performance in events lasting 3–100 min • Highly correlated with high VO2max and LT

14. Concept of Critical Power Figure 20.6

15. Measurement of Peak Running Velocity • Predictor of performance in endurance events lasting <20 minutes • High correlation between peak running velocity and 5 km race time • Measurement of peak running velocity • Progressively increasing speed on treadmill • Highest speed that can be maintained for more than five seconds

16. Relationship Between Running Velocity and 5 km Race Performance Figure 20.5

17. Tests to Determine Running Economy • Higher economy means that less energy is expended to maintain a given speed • Runner with higher running economy should defeat uneconomical runner in a race • Measurement of the oxygen cost of running at various speeds • Plot oxygen requirement as a function of running speed • Greater running economy reflected in lower oxygen cost

18. The Oxygen Cost of Running Figure 20.7

19. Estimating Distance Running Success Using LT and Running Economy • Close relationship between LT and maximal pace in 10,000 m race • Race pace at 5 m•min-1 above LT • Predicting performance in a 10,000 m race • Measure VO2max • Plot VO2 vs. running speed • Determine lactate threshold • Plot blood lactate vs. VO2 • VO2 at LT = 40 ml•kg-1•min-1 • VO2 of 40 ml•kg-1•min-1 = running speed of 200 m•min-1 • Estimated 10,000 m running time 10,000m  205 m•min-1 = 48.78 min

20. Running Economy and LT Results From Incremental Exercise Test Figure 20.8

21. Determination of Maximal Anaerobic Power • Tests of ultra short-term anaerobic power • Tests ATP-PC system • Jumping power tests • Running power tests • American football • Series of 40-yard dashes with brief recovery between • Soccer • Intermittent shuttle tests • Cycling power tests • Quebec 10 second test

22. Determination of Maximal Anaerobic Power • Tests of short-term anaerobic power • Tests anaerobic glycolysis • Cycling tests • Wingate test • Subject pedals as rapidly as possible for 30 seconds against predetermined load (based on body weight) • Peak power indicative of ATP-PC system • Percentage of peak power decline is an index of ATP-PC system and glycolysis • Running tests • Maximal runs of 200–800 m • Sport-specific tests

23. Energy System Contribution During Maximal Exercise Figure 20.9

24. Series of 40-yard Dashes to Test Anaerobic Power Figure 20.10

25. Evaluation of Muscular Strength • Muscular strength • Maximal force that can be generated by a muscle or muscle group • Isometric measurement • Static force of muscle using tensiometer • Free weight testing • Weight (dumbbell or barbell) remains constant • 1 RM lift, handgrip dynamometer • Isokinetic measurement • Variable resistance at constant speed • Variable resistance devices • Variable resistance over range of motion

26. Printout From Isokinetic Dynamometer During a Maximal-Effort Knee Extension Figure 20.14