Chapter 20 Laboratory Assessment of Human Performance

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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
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Factors That Contribute to Physical Performance
Figure 20.1
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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

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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

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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 athletes sport
• Exercise test protocol
• Should use large muscle groups
• Optimal test length 10-12 minutes
• Start with 35 minute warm-up
• Increase work rate to near maximal load
• Increase load stepwise every 14 minutes until
  subject cannot maintain desired work rate

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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 gt8 mmolesL-1
• Respiratory exchange ratio ?1.15
• HR in last stage ?10 beatsmin-1 of HRmax

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Determining VO2 Max
Figure 20.2
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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 5060 of peak VO2
• Limits muscular fatigue early in test

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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 gt5 sec

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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)
• 25 minute warm-up
• Stepwise increases in work rate every 13 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

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Lactate Threshold
Figure 20.3
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Ventilatory Threshold
Figure 20.4
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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 3060 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 3100
  min
• Highly correlated with high VO2max and LT

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Concept of Critical Power
Figure 20.6
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Measurement of Peak Running Velocity

• Predictor of performance in endurance events
  lasting lt20 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

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Relationship Between Running Velocity and 5 km
Race Performance
Figure 20.5
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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

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The Oxygen Cost of Running
Figure 20.7
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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 mmin-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 mlkg-1min-1
• VO2 of 40 mlkg-1min-1 running speed of 200
  mmin-1
• Estimated 10,000 m running time

10,000m ? 205 mmin-1 48.78 min
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Running Economy and LT Results From Incremental
Exercise Test
Figure 20.8
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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

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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 200800 m
• Sport-specific tests

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Energy System Contribution During Maximal Exercise
Figure 20.9
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Series of 40-yard Dashes to Test Anaerobic Power
Figure 20.10
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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

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