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  1. 1. Assessing Cardiorespiratory Endurance A Fitness Indicator
  2. 2. Determination of Fitness Level <ul><li>Everyone possesses some degree of cardiorespiratory endurance (CRE) </li></ul><ul><li>CRE=a health associated component that relates to the ability of circulatory and respiratory systems to supply fuel during sustained physical activity and to eliminate fatigue products after supplying fuel. </li></ul>
  3. 3. VO 2 max <ul><li>VO 2 max is the most commonly used index to assess CRE </li></ul><ul><li>Definition - The largest amount of oxygen that an individual can utilize during strenuous exercise to complete exhaustion </li></ul><ul><li>Has become the accepted measure of CRE </li></ul>
  8. 8. VO 2 max <ul><li>Units </li></ul><ul><ul><li>liters/minute or ml/minute (absolute) </li></ul></ul><ul><ul><li>ml/kg/min (relative to body weight) </li></ul></ul><ul><ul><li>ml/kg of FFM/min (relative to FFM) </li></ul></ul><ul><li>Range 15 (sedentary with disease) to 75 (young endurance runner) ml/kg/min </li></ul><ul><li>Women about 10-20% lower than men </li></ul>
  9. 9. Methods of Determining VO 2 max <ul><li>Submaximally </li></ul><ul><li>Maximally </li></ul>
  10. 10. GXT <ul><li>Graded Exercise Testing - GXT (incremental increases in workload) </li></ul><ul><li>General Guidelines </li></ul><ul><ul><li>measure the subject’s HR and BP and RPE at regular intervals (near the end of each stage [HR, BP, RPE] or every minute [HR]) </li></ul></ul><ul><ul><li>if HR does not reach steady state during the stage extend stage 1 minute </li></ul></ul>
  11. 11. GXT <ul><li>General Guidelines </li></ul><ul><ul><li>All testing begins with a 2-3 min warm-up </li></ul></ul><ul><ul><li>Cool- down at a low intensity for at least 4 minutes - continue measuring HR, BP and RPE </li></ul></ul><ul><ul><li>increase intensity in .5-2 MET increments </li></ul></ul><ul><ul><li>closely observe subject for contraindications </li></ul></ul>
  12. 12. Submaximal Assumptions <ul><li>1. A steady-state HR is obtained for each exercise work rate </li></ul><ul><li>2. A maximal HR for a given age is uniform (220-age) </li></ul>
  13. 13. Assumptions <ul><li>3. Mechanical efficiency (ie. VO 2 at a given work rate) is the same for everyone. </li></ul><ul><ul><li>This may not be true and it has been suggested that submaximal exercise testing underestimates VO 2max in the untrained and overestimates in the trained </li></ul></ul>
  14. 14. Submaximal Assumptions <ul><li>4. There is a linear relationship between HR and Workload </li></ul><ul><li>5. HR will vary depending on fitness level between subjects at any given workload </li></ul>
  15. 15. Age vs. HR
  16. 16. Submaximal Protocols <ul><li>Oxygen consumption for any given WL does not vary between subjects </li></ul><ul><li>The slope of the line is about the same for any two given subjects </li></ul><ul><li>The rate of increase in O2 consumption with increasing WL does not vary between subjects </li></ul>
  18. 18. Submax Protocols <ul><li>HR does vary between subjects </li></ul><ul><li>rate of increase in HR depends on fitness level </li></ul><ul><li>The more fit you are the lower your HR at any given WL </li></ul><ul><li>An untrained person will reach their HR max at a lower WL vs. a trained person of the same age. </li></ul>
  21. 21. HR vs. Workload
  23. 23. HR vs. WL and VO 2
  24. 24. Submaximal Protocols <ul><li>1. YMCA - bike </li></ul><ul><li>2. Astrand Rhyming – bike </li></ul><ul><li>3. ACSM - bike </li></ul><ul><li>4. Bruce Protocol - treadmill </li></ul><ul><li>5. McCardles Step Test </li></ul>
  25. 25. YMCA <ul><li>Multi-stage protocol </li></ul><ul><li>3-4 consecutive 3 minute stages </li></ul><ul><li>HR between 110-150 bpm (the HR range at which the relationship between VO 2 and WL is most linear) </li></ul>
  26. 26. YMCA Procedures <ul><li>1. Adjust seat height (legs nearly straight when extended - 5º bend) </li></ul><ul><li>2. Measure pre-exercise BP and HR with subject seated on bike </li></ul><ul><li>3. Pedal at 50 rpm (if using a metronome - 100x/minute) </li></ul><ul><li>4. Warm-up, zero resistance for 2-3 minute </li></ul>
  27. 27. YMCA Protocol <ul><li>5. Stage 1 </li></ul><ul><ul><li>.5 kp for 3 minutes </li></ul></ul><ul><ul><li>at every stage measure BP at 2.0 min (more often if hypertensive) </li></ul></ul><ul><ul><li>at every stage measure HR during last half of minutes 2 and 3 </li></ul></ul><ul><ul><li>if HR at 2 and 3 minutes differ by more than 6 bpm extend the stage for 1 min </li></ul></ul>
  28. 28. YMCA Protocol <ul><li>6. Stage 2 </li></ul><ul><ul><li>Workload in this stage and successive stages depends on HR during stage 1 (p 75 guidelines) </li></ul></ul><ul><li>7. Continue test until HR recorded at two successive WL are between 110 and 150 bpm (for many this occurs during 2nd and 3rd WL) </li></ul>
  29. 29. YMCA Protocol <ul><li>8. Note that if HR is greater than 110 at end of 1st stage then only one more stage is necessary </li></ul><ul><li>9. At completion of test reduce resistance to .5kp and allow subject to pedal for at least 4 minutes or until HR falls below 100 bpm and BP stabilizes. </li></ul>
  30. 30. YMCA Protocol <ul><li>10. The HR measured during the last minute of each stage is plotted against workload. </li></ul><ul><li>11. The line generated from the plotted points is extrapolated to the age-predicted HR max </li></ul><ul><li>12. A perpendicular line is dropped to the x-axis to estimate the work rate this person would achieve if taken to max. </li></ul>
  31. 32. ACSM Bike Test <ul><li>1. 2-3 minute warm-up </li></ul><ul><li>2. Take HR twice during each stage (3 minute stages) and RPE/BP once (similar to YMCA) </li></ul><ul><li>3. If HRs are greater than 110, steady state should be reached (HRs within 6bpm) before increasing the workload </li></ul>
  32. 33. ACSM <ul><li>Protocol A B C (kgm/min) </li></ul><ul><li>Stage 1 150 150 300 </li></ul><ul><li>Stage 2 300 300 600 </li></ul><ul><li>Stage 3 450 600 900 </li></ul><ul><li>Stage 4 600 900 1200 </li></ul>
  33. 34. ACSM <ul><li>Protocol Selection </li></ul><ul><li>BW Very Active </li></ul><ul><li>(kg) No Yes </li></ul><ul><li><73 A A </li></ul><ul><li>74-90 A B </li></ul><ul><li>>91 B C </li></ul><ul><ul><li>*very active is defined as aerobic exercise 20 minutes, 3 days/week </li></ul></ul>
  34. 35. ACSM <ul><li>5. Terminate test when HR reaches 85% of age-predicted max HR or 70% of HR reserve </li></ul><ul><li>6. Recovery at workload equal to the 1 st stage or less for at least 4 minutes with HR, BP, and RPE monitored. </li></ul>
  35. 36. ACSM <ul><li>Plot HRs from last two stages to determine VO2max much like YMCA. </li></ul>
  36. 37. Astrand Rhyming <ul><li>Single-stage test (VO2 max is determined using 1 submaximal data point-HR) </li></ul><ul><li>Duration of test is 6 minutes </li></ul>
  37. 38. Astrand Rhyming <ul><li>1. Adjust seat height (legs nearly straight when extended - 5º bend) </li></ul><ul><li>2. Measure pre-exercise BP and HR with subject seated on bike </li></ul><ul><li>3. Pedal at 50 rpm (if using a metronome - 100x/minute) </li></ul><ul><li>4. Warm-up, zero resistance for 2-3 minute </li></ul>
  38. 39. Astrand Rhyming <ul><li>5. Pedal rate is 50 rpm </li></ul><ul><li>6. Determine Workload </li></ul><ul><ul><li>unconditioned males - 300 or 600 kgm/min </li></ul></ul><ul><ul><li>conditioned males - 600 or 900 kgm/min </li></ul></ul><ul><ul><li>unconditioned females - 300-450 kgm/min </li></ul></ul><ul><ul><li>conditioned females - 450 or 600 kgm/min </li></ul></ul><ul><li>7. 6 minute test </li></ul>
  39. 40. Astrand Rhyming <ul><li>8. At end of 2nd minute of pedaling take HR (BP at 1.25-1.5 min) </li></ul><ul><ul><li>want the HR to be between 125-170bpm </li></ul></ul><ul><ul><li>if less than 125 increase resistance by 1 kp for men and 1/2 kp for women </li></ul></ul><ul><ul><li>if greater than 170 bpm decrease resistance by 1 kp </li></ul></ul><ul><ul><li>continue to monitor HR every minute until HR exceeds 125 </li></ul></ul>
  40. 41. Astrand Rhyming <ul><li>9. At the end of the 5th and 6th minute take HR and average the two values (make sure values are within + 6bpm to assure a steady state HR was obtained) </li></ul><ul><li>10. BP at 4:30 and 5:30 </li></ul><ul><li>11. Reduce resistance and cool-down for 4 minutes. </li></ul>
  41. 42. Astrand Rhyming <ul><li>10. Determine VO 2 from nomogram (p. 73 guidelines, p.69 Heyward) </li></ul><ul><li>11. Age-correction factor (p. 74 guidelines, p.72 heyward) </li></ul><ul><li>12. Convert to relative value </li></ul>
  42. 43. Treadmill Tests <ul><li>Bruce Protocol </li></ul><ul><li>Balke </li></ul><ul><li>Ellestad </li></ul><ul><li>Others………. </li></ul>
  43. 44. Treadmill Protocols <ul><li>Bruce and Ellestad </li></ul><ul><ul><li>larger increments </li></ul></ul><ul><ul><li>use on younger and/or more physically active </li></ul></ul><ul><li>Balke-Ware </li></ul><ul><ul><li>smaller increments (1MET/stage or lower) </li></ul></ul><ul><ul><li>use on older, deconditioned, and/or diseased subjects </li></ul></ul>
  44. 45. Treadmill Protocol <ul><li>Single-stage (using one data point) even though we may have more than one stage </li></ul><ul><li>May need to have a long accustomization period and explanation of procedures before beginning </li></ul>
  45. 46. Bruce Treadmill Protocol <ul><li>1. Measure resting BP and HR while standing on the belt of the treadmill </li></ul><ul><li>2. Ask subject to straddle the belt while starting treadmill at 1.7 mph and 0% grade </li></ul><ul><li>3. Ask subject to begin walking and when comfortable release handrails </li></ul><ul><li>4. This is a warm-up and should continue until subject is comfortable </li></ul>
  46. 47. Bruce Treadmill Protocol <ul><li>5. Stage 1 </li></ul><ul><ul><li>Increase grade to 10% </li></ul></ul><ul><ul><li>3 minutes long </li></ul></ul><ul><ul><li>Measure HR at end of each minute and BP at end of each stage </li></ul></ul>
  47. 48. Bruce Treadmill Protocol <ul><li>6. The objective is to reach a steady state HR between 115 and 155 bpm (usually occurs during the first 6 minutes of exercise or by the end of the 2nd stage) – Page 98 guidelines </li></ul><ul><li>7. Once subject reaches proper HR terminate the test at the end of that stage </li></ul>
  48. 49. Bruce Treadmill Protocol <ul><li>8. Reduce treadmill speed to 1.7mph and 5% grade and cool-down for 4 minutes. </li></ul><ul><li>9. VO2 is estimated from the last minute of a fully completed stage </li></ul>
  49. 50. Treadmill Protocol <ul><li>10. Calculate VO 2 from the gender specific equations </li></ul><ul><li>Males </li></ul><ul><ul><li>VO 2 =SM VO2 [(HR max -61)/(HR SM -61)] </li></ul></ul><ul><li>Females </li></ul><ul><ul><li>VO 2 =SM VO2 [(HR max -72)/(HR SM -72)] </li></ul></ul><ul><ul><li>SM VO2 = submaximal VO 2 from table or ACSM equations </li></ul></ul><ul><ul><li>HR SM = submax HR from test </li></ul></ul>
  50. 51. Modified Bruce Protocol <ul><li>Start at 1.7 mph, 0% grade or at 1.7 mph and 5% grade (used on diseased and elderly populations) </li></ul>
  51. 52. Treadmill Protocol <ul><li>Protocols should be individualized </li></ul><ul><li>Test time should ideally be 8-12min </li></ul><ul><li>Increments of 10-15 W/min or 1-3%/min grade can be used for the elderly </li></ul>
  52. 53. McCardle’s Step Test <ul><li>Bench ht. = 41.25 cm </li></ul><ul><li>Step Rate = 24 step/min (metronome = 96) for men and 22 step/min (metronome=88) for women </li></ul><ul><li>3 minutes of stepping </li></ul><ul><li>Record HR from the first 15seconds after the stepping has stopped </li></ul>
  53. 54. McCardle <ul><li>Men </li></ul><ul><ul><li>VO 2 = 111.33 - (0.42 x HRrec) </li></ul></ul><ul><li>Women </li></ul><ul><ul><li>VO 2 = 65.81 - (0.1847 x HRrec) </li></ul></ul><ul><ul><li>value is ml/kg/min </li></ul></ul>
  54. 55. Maximal Testing <ul><li>Assumption: The subject was highly motivated and gave a maximal effort. </li></ul>
  55. 56. Max Testing <ul><li>Laboratory Tests </li></ul><ul><li>1. Open Circuit Indirect Calorimetry </li></ul><ul><li>2. Cycle </li></ul><ul><li>3. Treadmill (Bruce) </li></ul>
  56. 57. Maximal Protocols <ul><li>Field Tests </li></ul><ul><li>4. 12 minute run </li></ul><ul><li>5. 1.5 mile run </li></ul><ul><li>6. Rockport Walking Test </li></ul>
  57. 58. Measuring Energy Costs of Exercise <ul><li>Direct calorimetry —measures the body's heat production to calculate energy expenditure. </li></ul><ul><li>Indirect calorimetry —calculates energy expenditure from the respiratory exchange ratio (RER) of CO 2 and O 2 . </li></ul>
  59. 60. Open Circuit Indirect Calorimetry (Gas Analysis)
  60. 61. Respiratory Exchange Ratio <ul><li>The ratio between CO 2 released (VCO 2 ) and oxygen consumed (VO 2 ) </li></ul><ul><li>RER = VCO 2 /VO 2 </li></ul><ul><li>The RER value at rest is usually 0.78 to 0.80 </li></ul>
  61. 62. RER <ul><li>Value ranges from .7-1.0 </li></ul><ul><li>0.7 mainly uses fats as an energy source </li></ul><ul><li>1.0 mainly uses carbohydrates as an energy source </li></ul><ul><li>Can exceed 1.0 during heavy non-steady state, maximal exercise, or when nervous due to hyperventilation (increased CO2) </li></ul>
  62. 63. KCALS <ul><li>(RER + 4) x (Liters of O 2 consumed per minute) = kcal/minute </li></ul><ul><li>For example: </li></ul><ul><ul><li>RER determined from gas analysis = .75 </li></ul></ul><ul><ul><li>4 + .75 = 4.75 </li></ul></ul><ul><ul><li>L of O 2 per minute = 3 liters </li></ul></ul><ul><ul><li>4.75 x 3 = 14.25 kcal/min </li></ul></ul><ul><ul><li>If exercised for 30 minutes = 427.5 kcals </li></ul></ul>
  63. 64. Cycle to Max <ul><li>15 W/min protocol </li></ul><ul><li>VO 2males =10.51 (power in W) + 6.35 (BW in kg) - 10.49 (age in y) + 519.3 </li></ul><ul><li>VO 2females =9.39 (power in W) + 7.7 (BW in kg) - 5.88 (age in y) + 136.7 </li></ul><ul><li>values are in ml/min - divide by BW in kg </li></ul>
  64. 65. Treadmill to Max (Bruce) <ul><li>VO 2 = 14.8 - 1.379 (time in min) + 0.451 (time 2 ) - 0.012 (time 3 ) </li></ul><ul><li>While holding handrail </li></ul><ul><li>VO 2 = 2.282 (time in min) + 8.545 </li></ul>
  65. 66. Population-specific Equations <ul><li>P. 61 Heyward </li></ul><ul><li>Active vs. Sedentary, Gender specific, Cardiac patients </li></ul>
  66. 67. 12 minute run
  67. 68. 12 minute run <ul><li>The further you can run in 12 minutes the higher your VO 2max </li></ul>
  68. 69. 1.5 mile run/Rockport Walking
  69. 70. 1.5 Mile Run/1 Mile Walk <ul><li>The faster you can run 1.5 miles or walk 1 mile the higher your VO 2max </li></ul>
  70. 71. Field Tests <ul><li>12 min run </li></ul><ul><ul><li>VO 2 = 3.126 (meters in 12 min) - 11.3 </li></ul></ul><ul><li>1.5 mile run </li></ul><ul><ul><li>VO 2 = 3.5 + 483/(time in minutes) </li></ul></ul><ul><li>Rockport Walking Test (1 mile walk) </li></ul><ul><ul><li>VO 2 = 132.853 - 0.1692 (BW in kg) - 0.3877 (age in y) + 6.315 (gender) - 3.2649 (time in min) - 0.1565 (HR) </li></ul></ul><ul><ul><li>0 for female; 1 for male; HR at end of walk </li></ul></ul>
  71. 72. Normal Responses to GXT <ul><li>1. Systolic BP increases in direct proportion to increasing WL </li></ul><ul><li>2. HR increases linearly with WL </li></ul><ul><li>3. Diastolic BP changes very little </li></ul><ul><li>4. Shortened QT Interval </li></ul><ul><li>5. Reduced R-wave amplitude </li></ul><ul><li>6. Positive upslope of ST segment </li></ul>
  72. 73. Abnormal responses to GXT <ul><li>1. ST segment depression </li></ul><ul><li>2. Increased R-wave amplitude </li></ul><ul><li>3. V-tach </li></ul><ul><li>4. Multiform PVC’s </li></ul><ul><li>5. Failure of HR to rise with WL </li></ul><ul><li>6. Failure of systolic to rise </li></ul><ul><li>7. Systolic and diastolic greater than 250 or 120 </li></ul>
  73. 74. Test Termination <ul><li>1. Have reached a pre-determined endpoint </li></ul><ul><li>Absolute </li></ul><ul><li>1. Suspicion of myocardial infarction </li></ul><ul><li>2. Moderate to severe angina </li></ul><ul><li>3. Drop in Systolic BP with increasing Workload (>20) </li></ul>
  74. 75. Absolute <ul><li>4. Arrhythmias </li></ul><ul><li>5. Pale or cold and clammy skin </li></ul><ul><li>6. Severe shortness of breath </li></ul><ul><li>7. Dizzy, blurred vision, or confusion </li></ul><ul><li>8. Patient requests stop </li></ul><ul><li>9. V-tach or multiform PVC’s </li></ul><ul><li>10. ST segment depression </li></ul>
  75. 76. Absolute <ul><li>11. Excessive rise in BP (systolic >250; diastolic >120) </li></ul><ul><li>12. Failure of HR to increase </li></ul>
  76. 77. Relative <ul><li>1. ECG changes from baseline </li></ul><ul><li>2. Chest pain that is increasing </li></ul><ul><li>3. Wheezing </li></ul><ul><li>4. Leg cramps </li></ul><ul><li>5. High Systolic/Diastolic </li></ul><ul><li>6. Less serious arrhythmias </li></ul><ul><li>7. Less severe shortness of breath </li></ul>
  77. 78. Advantages of Submaximal Testing <ul><li>1. Safer </li></ul><ul><li>2. Controlled pace (motivation not a factor) </li></ul><ul><li>3. Not population specific (no pacing advantage) </li></ul><ul><li>4. Quick assessment </li></ul><ul><li>5. Cost effective </li></ul>
  78. 79. Advantages of Submaximal Testing <ul><li>6. Don’t need highly trained personnel </li></ul><ul><li>7. Can do mass testing </li></ul><ul><li>8. No physician supervision required (if symptom and disease free) </li></ul>
  79. 80. Disadvantages of Submaximal Testing <ul><li>1. VO 2 max is not directly measured (error rate of 10-20%) </li></ul><ul><li>2. Don’t get a measure of true maximal HR </li></ul><ul><ul><li>estimates of max HR using 220-age can vary by + 15 bpm for individuals of the same age </li></ul></ul>
  80. 81. Advantages and Disadvantages of a Maximal Test <ul><li>Advantages </li></ul><ul><li>1. More accurate </li></ul><ul><li>Disadvantages </li></ul><ul><li>1. Motivation is a factor </li></ul><ul><li>2. More risk involved </li></ul><ul><li>3. Time </li></ul><ul><li>4. Cost of equipment (if using metabolic cart) </li></ul>
  81. 82. Walking/Running vs. Cycling/Stepping <ul><li>Walking/Running are the most natural forms of locomotion (most Americans are unaccustomed to cycling </li></ul><ul><li>In general, subjects reach higher VO2max values during treadmill tests </li></ul><ul><li>Treadmill are more expensive than cycles </li></ul><ul><li>Treadmill is less portable </li></ul>
  82. 83. Walking/Running vs. Cycling/Stepping <ul><li>Body weight has a much smaller effect on cycle ergometry versus treadmills </li></ul><ul><li>Treadmill more dangerous (greater risk of a fall </li></ul><ul><li>Measurement of HR is more difficult on a treadmill and while stepping </li></ul>