Figure 2.

Importance of individualizing the clinical exercise test. Schematic illustrating for a typical stable patient following a spontaneous coronary artery dissection on optimal pharmacological rate-limiting therapy how differences in clinical exercise testing protocols can affect stage-to-stage increases in systolic blood pressure (SBP) relative to the level of metabolic equivalent of task (METS) performed. In the absence of cardiopulmonary exercise testing which is the preferred clinical test, but less readily available than exercise stress testing, METS achieved in this example are estimated using the FRIEND⁷³ equation relying on treadmill belt velocity and grade. The first 3 min is pre-test for both protocols at an estimated 1.5 METS and SBP of 115 mmHg. The Bruce protocol consists of 3-min length stages where treadmill belt velocity and grade both change each stage. The starting treadmill belt velocity is 1.7 mph at a grade of 10%. Alternatively, the individualized protocol consists of an initial 3-min ‘warm-in’ phase at 1.0 mph and grade of 0.0%; thereafter including 2-min length stages where velocity remains constant at 2.0 mph while grade progressively increases beginning at the second stage. The horizontal dotted line is set at SBP = 150 mmHg and represents the upper level which should not be surpassed while performing continuous duration aerobic exercise training on a routine basis. The figure illustrates that by having patients participate in the conventional Bruce protocol, they would achieve the threshold SBP within 3 min at an estimated MET level of 4.2. Conventional exercise training criteria based on the conventional use of the Bruce protocol would recommend patients perform aerobic exercise training at intensities no greater than the first stage of the Bruce protocol, possibly explaining why patients might express frustration and feel discouraged in maintaining a routine.