Twenty men with stable systolic CHF performed 4 different randomly ordered single HIIE sessions with measurement of gas exchange. For all protocols (A, B, C, and D) exercise intensity was set at 100 % of peak power output (PPO). Interval duration was 30 seconds (A and B) or 90 seconds (C?and D), and recovery was passive (A and C) or active (50 % of PPO in B and D). Time spent above 85 % of VO2peak and time above the ventilatory threshold were similar across all 4 HIIE protocols. Total exercise time was significantly longer in protocols with passive recovery intervals (A:?1,651 ¡À 347 s; C:?1,574?¡À 382 s) compared with protocols with active recovery intervals (B:?986?¡À 542 s; D: 961 ¡À 556 s). All protocols appeared to be safe, with exercise tolerance being superior during protocol A.
Among the 4 HIIE protocols tested, protocol A with short intervals and passive recovery appeared to be superior.