Assessing Cardiorespiratory Endurance A Fitness Indicator

Determination of Fitness Level n Everyone possesses some degree of cardiorespiratory endurance (CRE) n 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.

VO 2 max n VO 2 max is the most commonly used index to assess CRE n Definition - The largest amount of oxygen that an individual can utilize during strenuous exercise to complete exhaustion n Has become the accepted measure of CRE

VO 2 max n Units –liters/minute or ml/minute (absolute) –ml/kg/min (relative to body weight) –ml/kg of FFM/min (relative to FFM) n Range 15 (sedentary with disease) to 75 (young endurance runner) ml/kg/min n Women about 10-20% lower than men

Methods of Determining VO 2 max n Submaximally n Maximally

GXT n Graded Exercise Testing - GXT (incremental increases in workload) n General Guidelines –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]) –if HR does not reach steady state during the stage extend stage 1 minute

GXT n General Guidelines –All testing begins with a 2-3 min warm-up –Cool- down at a low intensity for at least 4 minutes - continue measuring HR, BP and RPE –increase intensity in.5-2 MET increments –closely observe subject for contraindications

Submaximal Protocols n Oxygen consumption for any given WL does not vary between subjects n The slope of the line is about the same for any two given subjects n The rate of increase in O2 consumption with increasing WL does not vary between subjects

Bruce Treadmill Protocol n 5. Stage 1 – Increase grade to 10% –3 minutes long –Measure HR at end of each minute and BP at end of each stage

Bruce Treadmill Protocol n 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 n 7. Once subject reaches proper HR terminate the test at the end of that stage

Bruce Treadmill Protocol n 8. Reduce treadmill speed to 1.7mph and 5% grade and cool-down for 4 minutes. n 9. VO2 is estimated from the last minute of a fully completed stage

Treadmill Protocol n 10. Calculate VO 2 from the gender specific equations n Males –VO 2 =SM VO2 [(HR max -61)/(HR SM -61)] n Females –VO 2 =SM VO2 [(HR max -72)/(HR SM -72)] –SM VO2 = submaximal VO 2 from table or ACSM equations –HR SM = submax HR from test

Modified Bruce Protocol n Start at 1.7 mph, 0% grade or at 1.7 mph and 5% grade (used on diseased and elderly populations)

Treadmill Protocol n Protocols should be individualized n Test time should ideally be 8-12min n Increments of W/min or 1-3%/min grade can be used for the elderly

Maximal Protocols n Field Tests n minute run n mile run n 6. Rockport Walking Test

Normal Responses to GXT n 1. Systolic BP increases in direct proportion to increasing WL n 2. HR increases linearly with WL n 3. Diastolic BP changes very little n 4. Shortened QT Interval n 5. Reduced R-wave amplitude n 6. Positive upslope of ST segment

Abnormal responses to GXT n 1. ST segment depression n 2. Increased R-wave amplitude n 3. V-tach n 4. Multiform PVC’s n 5. Failure of HR to rise with WL n 6. Failure of systolic to rise n 7. Systolic and diastolic greater than 250 or 120

Test Termination n 1. Have reached a pre-determined endpoint n Absolute n 1. Suspicion of myocardial infarction n 2. Moderate to severe angina n 3. Drop in Systolic BP with increasing Workload (>20)

Absolute n 4. Arrhythmias n 5. Pale or cold and clammy skin n 6. Severe shortness of breath n 7. Dizzy, blurred vision, or confusion n 8. Patient requests stop n 9. V-tach or multiform PVC’s n 10. ST segment depression

Absolute n 11. Excessive rise in BP (systolic >250; diastolic >120) n 12. Failure of HR to increase

Relative n 1. ECG changes from baseline n 2. Chest pain that is increasing n 3. Wheezing n 4. Leg cramps n 5. High Systolic/Diastolic n 6. Less serious arrhythmias n 7. Less severe shortness of breath

Advantages of Submaximal Testing n 1. Safer n 2. Controlled pace (motivation not a factor) n 3. Not population specific (no pacing advantage) n 4. Quick assessment n 5. Cost effective

Advantages of Submaximal Testing n 6. Don’t need highly trained personnel n 7. Can do mass testing n 8. No physician supervision required (if symptom and disease free)

Disadvantages of Submaximal Testing n 1. VO 2 max is not directly measured (error rate of 10-20%) n 2. Don’t get a measure of true maximal HR –estimates of max HR using 220-age can vary by +15 bpm for individuals of the same age

Advantages and Disadvantages of a Maximal Test n Advantages n 1. More accurate n Disadvantages n 1. Motivation is a factor n 2. More risk involved n 3. Time n 4. Cost of equipment (if using metabolic cart)