High-Intensity Interval Training in Patients With Heart Failure With Reduced Ejection Fraction

Figure 1.. Study enrollment, randomization, and follow-up. Enrollment was stopped when it was estimated that at least 200 patients would complete the 12-week assessments according to protocol. Two hundred fifteen patients came to follow-up assessments and were included in the intention-to-treat analysis; 207 of these were included in per-protocol analysis. Two hundred two patients came to the 52-week assessments and fulfilled the criterion of having completed either echocardiography or cardiopulmonary exercise testing. LVEF indicates left ventricular ejection fraction; and SAE, serious adverse event.

Figure 2.. Training intensity during the 12-week intervention. A, Heart rate during training. Average heart rate during the 12-week intervention, estimated as weekly mean (SD) during moderate continuous training (MCT) and during the last 2 minutes of high-intensity interval training (HIIT). Constant difference between groups: 16 bpm (10–22 bpm; P<0.001). B, Workload. Average workload estimated as for heart rate. Difference between groups: 33 W (24–42 W; P<0.001). C, Training intensity. Average relative training intensity (percentage of maximal heart rate) estimated as for heart rate: HIIT, 90% (88%–92%); MCT, 77% (74%–82%); difference, 10% (8%–13%; P<0.001). Some of the variability in estimated training intensity probably results from variation in maximal heart rate. Comparing baseline and follow-up assessments in individual patients revealed differences that seemed randomly distributed and independent of intervention group, center, and whether the patients had sinus rhythm or atrial fibrillation (data not shown). Shaded areas mark boundaries of prescribed training intensity: HIIT, 90% to 95%; MCT, 60% to 70%. D, Training intensity on target. Distribution of average training intensity…