Subjects sat on upright bicycles for preexercise symptoms, respiratory gases, EKG, and vital sign measurements.
Submaximal exercise began at low resistance with increases every 30 to 60 seconds until 70% predicted heart rate was reached by 5 minutes. Subjects maintained their pace until 25 minutes, then resistance was increased incrementally to increase to 85% predicted heart rate (approximately sufficient to reach anaerobic threshold).
Symptoms, respiratory gases, EKG, and vital signs were measured every 5 minutes, at peak of exercise, and 5 minute intervals after exercise.
The identical exercise protocol was used approximately 24 hr later. Secondary outcomes were assessed by comparisons from before exercise to after the second bicycle exercise stress test.
