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chapter 4

chapter 4. chapter. 4. Assessing Cardiorespiratory Fitness. Author name here for Edited books. Chapter Objectives. Differentiate between VO 2 max and VO 2 peak Differentiate between relative and absolute VO 2 Understand general exercise testing guidelines

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chapter 4

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  1. chapter4 chapter 4 Assessing Cardiorespiratory Fitness Author name here for Edited books

  2. Chapter Objectives . . . • Differentiate between VO2max and VO2peak • Differentiate between relative and absolute VO2 • Understand general exercise testing guidelines • Understand similarities and differences between maximal and submaximal exertion testing • Understand exercise testing assessments for children and older adults • Convert units of measure and perform metabolic calculations

  3. Cardiorespiratory Endurance • Ability to perform dynamic exercise involving large muscle groups at moderate-to-high intensity for prolonged periods (ACSM 2000) • Criterion measure is VO2max . (continued)

  4. Cardiorespiratory Endurance (continued) . • VO2max is the most valid measure of the cardiorespiratory system’s functional capacity. • VO2max reflects • maximal ability of cardiorespiratory system to deliver O2 and nutrients to muscles and • ability of muscles to use them. .

  5. . . VO2peak Versus VO2 max • Peak criteria: • HR fails to increase with increasing workload • Blood Hla- 8 mmol/L • RER  1.15 • RPE  17 on Borg 6 to 20 scale • Max criteria: • All of the above plus • 50 ml/min change with increasing workload (plateau attained)

  6. . Absolute VO2 • A discrete volume of O2 consumption in reference to time • Expressed in L/min or ml/min • Used for nonweight-bearing modalities • Directly related to body weight

  7. . Relative VO2 • A volume of O2 consumption relative to unit of body mass and time • Expressed as ml/kg/min • Used for weight-bearing modalities • Best for comparing people of different body size • Can express as ml/kgFFM/min to look at O2 consumption of muscle mass

  8. . Gross Versus Net VO2 • Not synonymous terms • Gross VO2 = caloric cost of exercise and rest (Gross = exercise + rest) • Net VO2 = caloric cost of exercise only (Net = Gross – rest) • Express in either absolute or relative terms • Rest is 3.5 ml/kg/min or 1 MET . .

  9. Graded Exercise Testing • Objective assessment of functional capacity • Can use maximal or submaximal tests • Can observe and compare numerous variables from baseline testing to follow-up testing • Instrumental for exercise programming and goal setting (continued)

  10. Graded Exercise Testing (continued) • ACSM recommends maximal exercise testing prior to start of vigorous exercise program for older, moderate-risk, or high-risk individuals. • Vigorous is >60% VO2max, or >6 METs. . (continued)

  11. Graded Exercise Testing (continued) • ACSM recommends submaximal testing for low- or moderate-risk individuals prior to starting a moderate-intensity exercise program • Moderate intensity is 40% to 60% VO2max, or 3 to 6 METs. .

  12. GXT Guidelines • Review contraindications to exercise testing. • Use maximal or submaximal GXT as appropriate. • If goal is diagnosing CAD, use max GXT. • Little difference exists in danger levels (max v. submax). • Use multiple stages (hence “graded”). • For non-ramp protocols, stages usually last 2 to 3 minutes each. • Know GXT termination criteria.

  13. . . VO2 peak Versus VO2 max . • Peak criteria are similar to criteria for VO2 max except RER is <1.15 and no plateau is attained. • Children, older adults, sedentary people, and those with known disease are likely to attain VO2 peak, but not max. .

  14. Procedures for Conducting GXTs • Pretest instructions • Paperwork • Resting baseline data (HR, BP, EKG) • Instructions and warm-up stage • Periodic (and continual) monitoring • Stage changes (depend on protocol) • Termination (criteria depend on protocol, client, S/S) • Cool-down (recovery)

  15. Rating of Perceived Exertion (RPE) • Original 6 to 20 scale was revised to 0 to 10 scale. • Both highly related to HR and VO2 • Subjective scales of overall exertion • Moderate intensity is 12 to 14 on original scale and 6 on revised scale. • OMNI pictorial scales may also be used for children through adult age groups. .

  16. Maximal Exertion Protocols • Choose protocol and modality wisely! • Individualized protocol is best • Highest VO2 is with uphill running; lowest is with arm ergometry • Usually lasts 8 to 12 minutes long • Can be a continuous or discontinuous protocol • Discontinuous protocols take longer .

  17. Submaximal Exertion Protocols • Choose protocol and modality wisely! • Similar to maximal exertion GXTs • May or may not involve stage change(s) • Monitor constantly for S/S and proper hemodynamic response • Generally terminated based on predetermined criteria (e.g.,: 85% age-predicted maximal HR) • Results can be used to estimate exercise tolerance

  18. Treadmill Protocols • Manipulate workload via speed (mph) and grade (%). • ACSM’s TM walking and running equations estimate metabolic cost of exercise (energy expenditure). • Assume steady state stages (overestimates if not) • Cannot account for anaerobic component • Walking equation better if walking with incline • Use running equation for speeds >5mph or slow jog (3mph) (continued)

  19. Treadmill Protocols (continued) • Many treadmill protocols exist. • Choose best one for your client. • Many have their own equation to calculate VO2. • Some use nomograms. .

  20. . Calculating VO2 • 70 kg woman walks at 3.5 mph at no grade • VO2 = Horizontal + Vertical + Rest • VO2 = (speed x 0.1) + 0 + 3.5 ml/kg/min • VO2 = [(3.5mph x 26.8m/mi) x 0.1] + 0 + 3.5 • VO2 = (93.8 m/min x 0.1) + 0 + 3.5 ml/kg/min • VO2 = 9.38 + 0 + 3.5 ml/kg/min • VO2 = 12.88 ml/kg/min . . . . . .

  21. 12.88 ml 0.005 kcal kg*min 1 ml 4.508 kcal 1 min 560 kcal X min 560 4.508 = = 124 min What’s the Energy Cost? • 70 kg woman walks at 3.5 mph at no grade • VO2 = 12.88 ml/kg/min • Kcal/min = . 70 kg = 4.508 kcal/min How long must she walk to expend 560 kcal?

  22. Second Stage of Bruce Protocol . • 90 kg man walks at 3.4 mph at 14% grade • VO2 = Horizontal + Vertical + Rest • VO2 = (speed x 0.1) + (speed x grade x 1.8) + 3.5 • VO2 = [(3.4mph x 26.8m/mi) x 0.1] + (speed x grade x 1.8) + 3.5 • VO2 = (91.12 m/min x 0.1) + (91.12 x .14 x 1.8) + 3.5 • VO2 = 9.11 + 22.96 + 3.5 ml/kg/min • VO2 = 35.57 ml/kg/min . . . . .

  23. Individualized Protocol . • 60 kg man running at 7 mph at 14% grade • VO2 = Horizontal + Vertical + Rest • VO2 = (speed x 0.2) + (speed x grade x 0.9) + 3.5 • VO2 = [(7mph x 26.8m/mi) x 0.2] + (speed x grade x 0.9) + 3.5 • VO2 = (187.60 m/min x 0.2) + (187.6 x .14 x 0.9) + 3.5 • VO2 = 37.52 + 23.64 + 3.5 ml/kg/min • VO2 = 64.66 ml/kg/min . . . . .

  24. Another Individualized Protocol • 60 kg woman jogging at 3.2 mph at 2% grade • VO2 = Horizontal + Vertical + Rest • VO2 = (speed x 0.2) + (speed x grade x 0.9) + 3.5 • VO2 = [(3.2mph x 26.8m/mi) x 0.2] + (speed x grade x 0.9) + 3.5 • VO2 = (85.76 m/min x 0.2) + (85.76 x .02 x 0.9) + 3.5 • VO2 = 17.15 + 1.54 + 3.5 ml/kg/min • VO2 = 22.19 ml/kg/min . . . . . .

  25. 22.19 ml 0.005 kcal kg*min-1 1 ml 6.66 kcal 1 min 560 kcal x min 560 6.66 = = 84 min What’s the Energy Expenditure? • 60 kg woman walks at 3.2 mph at 2% grade • VO2 = 22.19 ml/kg/min • Kcal/min = . 60 kg = 6.66 kcal/min How long must she walk to expend 560 kcal?

  26. Cycle Ergometer Protocols • Manipulate workload through cadence (rpm) and resistance (kp, W). • ACSM leg ergometry equations estimate metabolic cost of exercise (energy expenditure). • Power = force x distance/time • Power expressed as kpm/min or W. • Distance is 6 m for Monark and Bodyguard ergometers. (continued)

  27. Cycle Ergometer Protocols (continued) • Electrically braked ergometers allow variable cadences for any workload. • Mechanically braked ergometers require close monitoring of cadence. • Cadence based on client fitness level and cycling experience. • 60 rpm produces highest VO2 max compared to other specific cadences. .

  28. What’s the Energy Expenditure? . • 80 kg man cycling at 100 W • VO2 = Resistance pedaling + Unloaded pedaling + Rest • VO2 = [(100W / 80kg)x 10.8] + 3.5 + 3.5 ml/kg/min • VO2 = (1.25 x 10.8) + 3.5 + 3.5 • VO2 = (13.5) + 3.5 + 3.5 ml/kg/min • VO2 = 13.5 + 7ml/kg/min • VO2 = 20.5 ml/kg/min . . . . . (continued)

  29. What’s the Energy Expenditure? (continued) . • 60 kg woman cycling at 2 kp with cadence of 60 rpm • VO2 = Resistance pedaling + Unloaded pedaling + Rest • Power output = 2kp/min * 6m/rev * 60 rpm = 720 kpm/min • VO2 = [((720/6) / 60kg)] x 10.8] + 3.5 + 3.5 ml/kg/min • VO2 = [((120/60) x 10.8)] + 3.5 + 3.5 • VO2 = (21.6) + 3.5 + 3.5 ml/kg/min • VO2 = 21.6 + 7ml/kg/min • VO2 = 28.6 ml/kg/min . . . . .

  30. Tips for Using Ergometer Protocols • For GXTs, confirm steady state HR attained prior to stage change. • If half of terminal stage is not completed, use resistance and cadence (power output) from prior stage for VO2 calculations. .

  31. Other Testing Protocols . • Step tests: Several exist; require use of metronome; VO2 calculations are based on step height and cadence. • Recumbent stepper: Alternative for testing those with neuromuscular conditions affecting gait, coordination, and balance. • Stair stepper: Good for aerobic step practitioners. • Rowing ergometer: One exists for noncompetitive or unskilled rowers.

  32. Submaximal Protocols • Not direct assessments of cardiorespiratory capacity • May be more practical than maximal exertion protocols • Can be performed on many modalities • Can involve multiple stages or just one • Can determine VO2 via calculations or nomograms • Rely on underlying assumptions .

  33. Submaximal Assumptions • Steady-state HR is achieved and is consistent for work rate. • Relationship between HR and VO2 is linear for HRs between 110 and 150 bpm. • Mechanical efficiency is the same for all tested. • HRmax is similar for all of same age. .

  34. Field Tests • Practical • Inexpensive • Expedient • Easy to administer • Good for assessing numerous people simultaneously • Suitable for a variety of settings • Generally based on postexertion HR measures • Least desirable manner of assessing cardiorespiratory fitness • Not for diagnosing CHD

  35. Testing Children • Treadmills are a better modality than cycles. • ACSM recommends modified Balke or modified Bruce protocols with 2-minute stages. • Field tests may be used.

  36. Testing Older Adults • Use an extended warm-up at a low exertion starting stage. • Be ready to adjust treadmill speed for client safety. • May need to adjust grade and not speed. • Target a total test time of 8 to 12 minutes. • Extend stage duration to allow steady-state HR achievement. • Cycle ergometry may be preferable for client safety and comfort. • Field tests are also a possibility.

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