Introduction to exercise testing

Exercise testing lecture for Physiotherapy students

1. Introduction to Exercise Testing Dr Anwar Hasan Siddiqui

2. What is Exercise testing? Exercise testing elicits the body’s reaction to measured increases in acute exercise. The changes in heart rate, blood pressure, respiration and perceived level of exercise provide data that permit quantitative estimation of cardiovascular conditioning and function. Exercise tests provide an opportunity to observe a person during exercise. By measuring and monitoring heart rate and blood pressure, one can detect changes in the hemodynamic and ischemic results due to exercise.

3. E xercise testing - assessment of the integrative exercise responses involving pulmonary, cardiovascular, haematopoietic, neuropsychological, and skeletal muscle systems

4. Indications of Exercise testing Diagnosis Unexplained dyspnea Exercise limitation Exercise induced asthma Heart failure Assessment of functional Exercise capacity Disability evaluation Preoperative evaluation Prognosis in heart or pulmonary disease

5. Exercise prescription Pulmonary or cardiac rehabilitation Health maintainance or athlete training Assessing response to therapies

6. Contraindication Acute Ishchemic changes on ECG Uncontrolled CHF Uncontrolled arrythmia Uncontrolled hypertension 3rd degree Heart block Thrombosis in lower extremeties Uncontrolled asthma Pulmonary oedema O2 saturation less than 85% in room air Advanced or complicated pregnancy

7. The Fick equation Fick equation states that oxygen uptake (VO2) equals cardiac output times the arterial minus mixed venous oxygen content: VO2 = (SV x HR) x (CaO2 - CvO2) Where , SV is the stroke volume, HR is the heart rate, CaO2 is the arterial oxygen content, and CvO2 is the mixed venous oxygen content. Oxygen uptake is often normalised for body weight and expressed in units of ml O2/kg/min.

8. One metabolic equivalent (MET) is the resting oxygen uptake in a sitting position and equals 3.5 ml/kg/min. At maximal exercise, the Fick equation is expressed as follows: VO2max = ( SVmax x HRmax ) x (CaO2max - CvO2max)

9. VO2 max It is capacity of an individuals body to transport and utilize oxygen during incremental exercise. It reflect physical fitness of the individual. It determine athlete capacity to perform sustained exercise. Normal VO2 max = 0.25-4 l/min (3.6ml/kg/min) Highest = 60-70ml/kg (in athlete)

10. Factor affecting VO2 max Genetic factors Age Gender Altitude

11. Muscle blood flow during exercise Resting blood 3.6ml/100g muscles/min Can increase to 50-100 ml/100gm/min Stroke volume at rest 75ml/beat Heart rate at rest 75 beats/min

12. Equipment

13. Equipment for airflow and gas measurement Airflow or volume transducers Pneumotachograph Mass flow sensor Pitot tube flowmeter Turbine volume transducer Gas Analyzer Mass spectrometer: measure O2, CO2, N2 Separate analyzer for O2, CO2

14. Exercise Testing Protocols Maximal incremental cycle ergometry protocols Maximal incremental treadmill protocols Constant work rate protocol

15. Maximal incremental cycle ergometry protocols IET protocol 3 minutes of rest, then 3 minutes of unloaded pedalling then the incremental phase of exercise every minute (5 to 25 W/minute) until the patient reaches volitional exhaustion or the test is terminated by the medical monitor Ramp protocol increase the work rate continuously, usually every 1 to 2 seconds in a ramplike fashion Standardized exponential exercise protocol work rate is increased exponentially by 15% of the previous workload every minute

16. Maximal incremental treadmill protocols Bruce protocol: the starting point ( ie , stage 1) is 1.7 mph at a 10% grade (5 METs). Stage 2 is 2.5 mph at a 12% grade (7 METs). Stage 3 is 3.4 mph at a 14% grade (9 METs). This protocol includes 3-minute periods to allow achievement of a steady state before workload is increased. Modified Bruce protocol 2 warm up stages, each lasting 3 minutes. The first is at 1.7 mph and a 0% grade, the second is at 1.7 mph and a 5% grade

17. Constant work rate protocol Treadmill or cycle ergometry exercise at levels approximating the subject’s usual daily activities (e.g., up to 3.0 mph on a treadmill, or up to 50 W on a cycle ergometer ). This test should involve at least 6 minutes of continuous exercise.