The principle of the test is to gradually increase the resistance to the pedaling following a standardized protocol while keeping the rate of pedaling constant, hereby controlling the workload the patient is performing.

Depending on the patient's condition one can start with a load of 50 W (normal) or 25 W (modified).

Every 3 min the workload is increased 50 W in the normal protocol or 25 W in the modified protocol. It takes about 1-2 min for the cardiovascular system to adjust and stabilize HR and BP at each new workload. HR, BP and ECG are noted at the end of each 3 min stage.

HR, BP and ECG are also registered every 3 min during recovery.

The tracer is injected at the discretion of the monitoring physician and the exercise continues at the same or ½ speed for 60 sec. There is no reason for increasing the speed after the injection; the continuation of the exercise after the tracer injection is done to insure blood clearance of the tracer. With an extraction coefficient of 65% (Tc-tracers) or 85% (Tl-201) it only takes a few circulation to clear the blood. The circulation time at rest is about 15 sec, and much shorter during exercise. It usually takes much longer for induced ischemia to resolve than for the tracer to clear the blood. The tracer uptake thus reflect myocardial perfusion at the moment of injection: peak Stress