1. Clinical Exercise Physiology
V. Froelicher, MD
Professor of Medicine
Stanford University
VA Palo Alto HCS

2. Advances in Clinical Exercise Testing Physiology
Manual SBP measurement (not automated) most important for safety
No Age predicted Heart Rate Targets
The BORG Scale of Perceived Exertion
METs not Minutes
Fit protocol to patient (RAMP)
Expired Gas Analysis - ready for clinical use
Avoid HV and cool down walk
Use standard Exercise ECG analysis
Heart rate recovery

3. Types of Exercise Isometric (Static) weight-lifting
pressure work for heart, limited cardiac output, proportional to effort
Isotonic (Dynamic)
walking, running, swimming, cycling
Flow work for heart, proportional to external work
Mixed

4. Oxygen Consumption During Dynamic Exercise Testing
There are Two Types to Consider:
Myocardial (MO2)
Internal, Cardiac
Ventilatory (VO2)
External, Total Body

5. Myocardial (MO2) Coronary Flow x Coronary a - VO2 difference
Wall Tension (Pressure x Volume, Contractility, Stroke Work, HR)
Systolic Blood Pressure x HR
Angina and ST Depression usually occurs at same Double Product in an individual ** Direct relationship to VO2 is altered by beta-blockers, training,...

6. Problems with Age-Predicted Maximal Heart Rate
Which Regression Formula? (2YY - .Y x Age)
Big scatter around the regression line
poor correlation [-0.4 to -0.6]
One SD is plus/minus 12 bpm
Confounded by Beta Blockers
A percent value target will be maximal for some and sub-max for others
Borg scale is better for evaluating Effort
Do Not Use Target Heart Rate to Terminate the Test or as the Only Indicator of Effort or adequacy of test

7. Symptom-Sign Limited Testing Endpoints
Dyspnea, fatigue, chest pain
Systolic blood pressure drop
ECG--ST changes, arrhythmias
Physician Assessment
Borg Scale

8. Myocardial (MO2) Systolic Blood Pressure x HR
SBP should rise > 40 mmHg
Drops are ominous (Exertional Hypotension)
Diastolic BP should decline

9. Ventilatory (VO2)
Cardiac Output x a-VO2 Difference
VE x (% Inspired Air Oxygen Content - Expired Air Oxygen Content)
External Work Performed
****Direct relationship with Myocardial O2 demand and Work is altered by beta-blockers, training,...

10. VO2 = C.O. x C(a-v)O2 C(a-v)O2 ~ k VO2 THE FICK EQUATION
then, VO2 ~ C.O.

11. VO2 vs. EF% Poor correlation EF % between VO2 (~CO)
and Ejection Fraction
VO2 = C.O.
= HR x SV
= HR x EDV x EF
Froelicher et al. Exercise and the Heart (74)
VO2 MAX
EF %

12. What is a MET? Metabolic Equivalent Term
1 MET = "Basal" aerobic oxygen consumption to stay alive = 3.5 ml O2 /Kg/min
Actually differs with thyroid status, post exercise, obesity, disease states
But by convention just divide ml O2/Kg/min by 3.5

13. Key MET Values (part 1) 1 MET = "Basal" = 3.5 ml O2 /Kg/min
2 METs = 2 mph on level
4 METs = 4 mph on level
< 5METs = Poor prognosis if < 65;
limit immediate post MI;
cost of basic activities of daily living

14. Key MET Values (part 2)
10 METs = As good a prognosis with medical therapy as CABS
13 METs = Excellent prognosis, regardless of other exercise responses
16 METs = Aerobic master athlete
20 METs = Aerobic athlete

15. Calculation of METs on the Treadmill
METs = Speed x [0.1 + (Grade x 1.8)]
Calculated automatically by Device!
Note: Speed in meters/minute
conversion = MPH x 26.8
Grade expressed as a fraction

16. METs---not Minutes (Report Exercise Capacity in METs)
Can compare results from any mode or Testing Protocol
Can Optimize Test by Individualizing for Patient
Can adjust test to 8-10 minute duration (aerobic capacity--not endurance)
Can use prognostic power of METs

19. Estimated vs Measured METs
All Clinical Applications based on Estimated
Estimated Affected by:
Habituation (Serial Testing)
Holding on
Deconditioning and Disease State
Measured Requires a Mouthpiece and Delicate Equipment
Measured More Accurate and Permits measurement of Gas Exchange Anaerobic Threshold and Other Ventilatory Factors
Prognostic in CHF and Transplantation

20. MAXIMAL TREADMILL TIME (min)
METS
* Froelicher et al. Chest 1975 (68: 331).
VO2max
ml/kg
(METS)
30%
random
error in
Estimated
METS 70 60 50 40 30 25
MAXIMAL TREADMILL TIME (min)

21. WHY USE A BIKE ERGOMETER?
WORK
TREADMILL
RAMP
WHY USE A BIKE ERGOMETER?
1. Accurate measurement of POWER.
2. Ramping protocols allow for assessment of physiologic function across all work levels. Staged protocols only assess partial physiologic function.
3. Independent of patient’s weight (Treadmill results are influenced by weight).
4. Less danger of fall and injury to patient.
5. Easier to take accurate B/P at high work rates (Patient arm is steady and there is far less noise - no treadmill motor).
6. Patient can stop at anytime.
7. Holding handle bars does not effect test (Holding treadmill handrails can significantly effect results).
8. Fits into smaller space and is portable.
9. Patients with knee or hip problems tend to perform better and report being more comfortable on the bike.
10. Bike ramp protocols are designed to last 6-10 minutes, resulting in less fatigue (yet peak work is maximized).
11. HR, Work, and VO2 (Cardiac Output) are linearly related. Bike ramp protocols produce linear increases in Work, thereby mimicking the expected physiologic response in health and disease.
12. Determination of the Anaerobic Threshold (AT) by the most popular methods (V-slope and VE/VO2 nadir) were developed and proven through the use of bike ramp protocols. To use another method means to lose AT detection accuracy.
13. Bike ramp protocols are used by many of the leading clinical and research cardiopulmonary exercise testing labs (UCLA, Duke, Mayo, Stanford, Bowman-Gray, Johns Hopkins, UAB, Temple to name a few). Recently, treadmills capable of performing ramp protocols have been developed.
WORK
WORK
TIME
TIME

22. NO
LOAD
REST
C.O.
VO2
WORK
BEGIN
EXERCISE
6 min
10 min

23. METS* MEASURED VO2 (METS) PREDICTED VO2 (METS) UNITY RAMP-CHF
* Myers et al. JACC; 1991 (17: 1334).
MEASURED
VO2
(METS)
overestimation
of METS
UNITY
RAMP-CHF
BRUCE-CHF
PREDICTED VO2 (METS)

24. Why Ramp?
Started with Research for AT and ST/HR but clinically helpful
Individualized test Using Prior Test, history or Questionnaire
Linear increase in heart rate
Improved prediction of METs
Nine-minute duration for most patients
Requires special Treadmill controller or manual control by operator

25. Should Heart Rate Drop in Recovery be added to ET?
Long known as a indicator of fitness: perhaps better for assessing physical activity than METs
Recently found to be a predictor of prognosis after clinical treadmill testing
Does not predict angiographic CAD
Studies to date have used all-cause mortality and failed to censor

26. Heart Rate Drop in Recovery
Probably not more predictive than Duke Treadmill Score or METs
Studies including censoring and CV mortality needed
Should be calculated along with Scores as part of all treadmill tests

27. Heart Rate Drop in Recovery vs METs
10 to 15% increase in survival per MET
Can be increased by 25% by a training program
What about Heart Rate Recovery???

28. For CV Health Benefits
Training or Activity?

29. Highest exercise level
Baseline risk
Physical activity
Risk Reduction
Physical fitness
Williams, Meta-analysis, MSSE 2001:754
8 fitness cohorts (317,908 person-yrs fu)
30 activity cohorts (>2 million person-yrs fu)
Percentile activity/fitness level
Highest exercise level

30. Prescription for CV Training
Mode: Dynamic
Duration: 30 mins
Intensity: HR, AT, BORG
Frequency: 3/week