In order to have a valid test, your heart rate should go above 85% of your maximal predicted. This is calculated as (220-age) x 85%.
You will need to come in your exercise gear. That is, a pair of comfortable shorts and sneakers. You don’t need to have any period of training before coming for this test.
This is an example of treadmill stress ECG. The top panel below shows the ECG at rest. The arrows denote the portion of the ECG called ‘ST segment’. The bottom panel shows a positive test. The ‘ST segment’ is depressed compared to baseline (Pink arrow). This indicates the presence of blocked arteries.