How the test is performed:
The treadmill test starts at a relatively slow "warm-up" speed. The treadmill speed and it's slope or inclination are increased every three minutes according to a preprogrammed protocol (Bruce is the commonest protocol in the USA, but several other protocols are perfectly acceptable). The protocol dictates the precise speed and slope. Each three minute interval is known as a Stage (Stage 1, Stage 2, Stage 3, etc. Thus a patient completing Stage 3 has exercised for 3 x 3 = 9 minutes). The patient's blood pressure is usually recorded during the second minute of each Stage. However, it may be recorded more frequently if the readings are too high or too low.
An EKG is constantly displayed on the monitor. The physician pays particular attention to the heart rate, blood pressure, changes in the EKG pattern, irregular heart rhythm, and the patient's appearance and symptoms. The treadmill is stopped when the patient achieves a target heart rate (this is 90% of the maximal heart rate predicted for the patient's age). However, if the patient is doing extremely well at peak exercise, the treadmill test may be continued further. The test may be stopped prior to achievement of the target heart rate if the patient develops significant chest discomfort, shortness of breath, dizziness, unsteady gait, etc., or if the EKG shows alarming changes or serious irregular heart beats. It may also be stopped if the blood pressure (BP) rises or falls beyond acceptable limits. Please note that the systolic BP (upper number) may normally rise to 200 at peak exercise. At the same time, the diastolic BP (lower number) remains unchanged or falls to a slight degree. In contrast, the BP of patients with hypertension or high BP will show a rise of both systolic and diastolic readings. The latter may rise above 90 - 100.
Preparing for the regular stress test:
How safe is a regular treadmill stress test?
The risk of the stress portion of the test is very small and similar to what you would expect from any strenuous form of exercise (jogging in your neighborhood, running up a flight of stairs, etc.). Experienced medical staff is in attendance to manage the rare complications like sustained irregular heart beats, unrelieved chest pain or even a heart attack.