Final answer:
The correct answer is C) The development of horizontal or downsloping ST-segment depression of 1 mm or more at 80 ms after the J point. This indicates potential myocardial ischemia during an exercise stress test, a key diagnostic criterion for coronary artery disease.
Step-by-step explanation:
The standard minimum criterion for a positive exercise test is C) The development of horizontal or downsloping ST-segment depression of 1 mm or more at 80 ms after the J point. This is considered a sign of myocardial ischemia during an exercise stress test, which is used to diagnose the presence of coronary artery disease. A positive exercise test does not refer to achieving a maximum heart rate, maximum workload, or completing a specific duration of exercise. The significance of the test lies in the ability to detect cardiac function abnormalities under stress.
During exercise, the heart rate (HR) of healthy individuals may increase, and their stroke volume (SV) can also rise due to increased strength of contraction, thereby increasing cardiac output (CO) significantly above resting levels. This is particularly true for cardiovascular athletes. The ability of the heart to increase output during exercise is referred to as the cardiac reserve, which is an important measure of heart health and efficiency.