High intensity interval training (HIIT) improved peak oxygen intake (VO2peak), left ventricle ejection fraction (LVEF), and health-related quality of life (HRQoL) in those with heart failure (HF), showing superiority to medium chain triacylglycerol, used to improve endurance performance for athletes, and the usual care, according to results of a systematic review published in Heart & Lung.
In the review, the authors stated that cardiac rehabilitation is an important intervention for the “secondary prevention of cardiovascular disease” (CVD). This can include education, lifestyle behavioral changes, psychological support, and exercise, the latter being a low-cost intervention. One interest for cardiac fitness includes HIIT, which as been proven to be safe and effective in coronary artery disease and HF, according to the study authors.
Investigators aimed to review the physiological and psychological outcomes of HIIT in patients with HF when compared to medium chain triacylglycerol and the usual care. Meta-analyses were also conducted by investigators to determine changes following HIIT with clinical minimally important differences, according to the study authors.
3 Key Takeaways
- High Intensity Interval Training (HIIT) demonstrated superior improvements in peak oxygen intake (VO2peak), left ventricle ejection fraction (LVEF), and health-related quality of life (HRQoL) compared to both medium chain triacylglycerol and usual care in patients with heart failure (HF).
- SThe systematic review included 16 studies with a total of 482 individuals undergoing HIIT, 266 on medium chain triacylglycerol, and 346 receiving usual care.
- While the results indicate positive outcomes for HIIT in HF patients, the study authors cautioned about the limitations, including the low confidence rate in the GRADE assessment due to small study effects and the heterogeneity of included studies.
The study authors said they included a total of 16 studies, which included 482 individuals for HIIT, 266 for medium chain triacylglycerol, and 346 for the usual care. Approximately 65% were male, according to the results. For HIIT training, 9 studies used a bike, 2 used a treadmill, 1 used a bike or treadmill, 3 used aerobics, and 1 did not report what was used. For medium chain triacylglycerol, 6 studies used a bike, 2 used a treadmill, and 1 used a bike or treadmill.
Additionally, intensity was determined by VO2peak in 5 studies, percentage peak heart rate in 5, percentage max workload per rate and percentage of peak power output in 3, Borg scale in 2, and percentage of heart rate reserve in 1. The median length for both programs was 12 weeks across all studies and the median number of sessions per week was 3 for both studies, according to the study authors.
Investigators said the non-controlled effects size had low or very low confidence due to imprecision, inconsistency, and evidence of small-study effects, according to the analysis. Controlled studies had higher confidence, according to the study authors.
The results indicated that, out of the 12 controlled studies, there were improvements in VO2peak for those who participated in HIIT compared to the usual care and medium chain triacylglycerol. In a combined analysis, the study authors reported that this superiority was likely closer to the usual care than medium chain triacylglycerol. Improvements to LVEF indicated superiority of HIIT compared to both the usual care and medium chain triacylglycerol, but the authors also reported substantive uncertainty with the estimates, according to results from 10 studies.
Data from 8 studies showed that absolute improvements in quality of life from the Minnesota Living With Heart Failure Questionnaire was superior with HIT compared to both medium chain triacylglycerol and the usual care. The combined analysis also revealed that the improvement with HIIT was more likely to be relative to the usual care, according to the study authors.
The study authors did caution against limitations of the study, specifically following the low confidence rate in the GRADE assessment. They said this was due to small study effects and pooling results from heterogeneous studies.
Reference
Callum K, Swinton P, Gorely T, Crabtree D, Leslie S. Physiological and psychological outcomes of high intensity interval training in patients with heart failure compared to moderate continuous training and usual care: a systematic review with meta analysis. Heart Lung. 2023. doi:10.1016/j.hrtlng.2023.12.002
