Treadmill test (exercise ECG) has the objective of studying the ECG and the patient during exercise. The idea is to increase the product of heart rate and systolic blood pressure (double product) to maximal for the age and surface area of the individual. Maximal double product of a person is available by nomgrams. Some people do not go to the maximum but to 85% of the predicted maximal especially if the patient has significant disability due to suspected cardiac ailment. For a diagnostic study it is always recommended to stop heart rate lowering agents so that the heart rate increases adequately. If the patient is taking beta blockers (like atenolol) for hypertension, the medication is changed to an agent, which has no effect on heart rate. If the ECG shows ischemic changes at a relatively lower heart rate the likelihood of severe coronary artery disease becomes very high and such patients need to have a coronary angiography.
If the purpose is to evaluate the effect of treatment then the drugs are given to the desired dose and then the TMT test is done. It would show how significant is the response to treatment. The effort tolerance will increase in cases of angina as compared to the baseline test done without drugs.