Acute physiological responses to high-intensity interval exercise in patients with coronary artery disease

Purpose Time spent closer to maximal effort during exercise is a potent stimulus for cardiorespiratory adaptations. The primary purpose was to determine which high-intensity interval exercise (HIIE) protocol provided the greatest physiological stimulus by comparing time spent >= 90% peak oxygen consumption (V?O(2)peak) and heart rate reserve (HRR) in patients with coronary artery disease (CAD) in response to 3 HIIE protocols and the exercise standard of care, moderate-intensity continuous exercise (MICE). A secondary purpose was to assess protocol preference. Methods Fifteen patients with CAD (6 females, 67 +/- 6 years) underwent measurements of V?O-2 and heart rate during MICE and three HIIE protocols all performed on a treadmill. The HIIE protocols included one with long intervals (4 x 4-min), short intervals (10 x 1-min), and an adapted version of the 4 x 4 [Toronto Rehabilitation Institute Protocol, (TRIP)]. Time spent >= 90% V?O(2)peak and HRR were compared. Results Time spent >= 90% V?O(2)peak was higher during 4 x 4 (6.3 +/- 8.4 min) vs. MICE (1.7 +/- 3.9 min; P = 0.001), while time spent >= 90% HRR was higher during 4 x 4 (6.0 +/- 5.3 min) vs. MICE (0.1 +/- 0.2 min; P < 0.001) and 10 x 1 (0.7 +/- 0.8 min; P = 0.016). TRIP had similar responses as 10 x 1 and MICE. The 10 x 1 was the most preferred protocol and the 4 x 4 was the least preferred protocol. Conclusion Longer intervals (4 x 4) provided the greatest physiological stimulus compared to the exercise standard of care and shorter intervals. However, this protocol was least preferred which may impact exercise adherence. Although the physiological stimulus is important to maximize training adaptations, exercise preferences and attitudes should be considered.

Automated summary

The study aimed to compare the physiological stimulus of different high-intensity interval exercise (HIIE) protocols in patients with coronary artery disease (CAD), and assess the preference of the protocols. The results showed that longer intervals (4x4) provided the greatest physiological stimulus, but this protocol was least preferred, which may impact exercise adherence.