Cardiovascular: No limiting or unstable angina No myocardial infarction within the past 6 months No horizontal or downsloping ST segment depression greater than 0.2 mV and/or frequent or repetitive arrhythmias (defined as more than 10 premature ventricular contractions per minute) No hypertension that is uncontrolled by one blood pressure medication No prior arrhythmia or valvular disease requiring treatment