Limitations to high intensity exercise prescription in chronic heart failure patients

Cardiorespiratory Improvements Achieved by American College of Sports Medicine's Exercise Prescription Implemented on a Mobile App

Background

Strong evidence shows that an increase in cardiorespiratory fitness (CRF) and physical activity (PA) reduces cardiovascular disease risk.

Objective

To test whether a scientifically endorsed program to increase CRF and PA, implemented on an easy-to-use, always-accessible mobile app would be effective in improving CRF.

Methods

Of 63 healthy volunteers participating, 18 tested the user interface of the Cardio-Fitness App (CF-App); and 45 underwent a 2-week intervention period, of whom 33 eventually concluded it. These were assigned into three groups. The Step-based App (Step-App) group (n=8), followed 10,000 steps/day prescription, the CF-App group (n=13), and the Supervised Cardio-Fitness (Super-CF) group (n=12), both followed a heart rate (HR)-based program according to American College of Sports Medicine (ACSM) guidelines, but either implemented on the app, or at the gym, respectively. Participants were tested for CRF, PA, resting systolic and diastolic blood pressures (SBP, DBP), resting, exercise, and recovery HR.

Results

CRF increased in all groups (+4.9%; P<.001). SBP decreased in all groups (-2.6 mm Hg; P=.03). DBP decrease was higher in the Super-CF group (-3.5 mm Hg) than in the Step-App group (-2.1 mm Hg; P<.001). Posttest exercise HR decreased in all groups (-3.4 bpm; P=.02). Posttest recovery HR was lower in the Super-CF group (-10.1 bpm) than in the other two groups (CF-App: -4.9 bpm, Step-App: -3.3 bpm; P<.001). The CF-App group, however, achieved these improvements with more training heart beats (P<.01).

Conclusions

A 10,000 steps/day target-based app improved CRF similar to an ACSM guideline-based program whether it was implemented on a mobile app or in supervised gym sessions.

High-intensity aerobic interval exercise in chronic heart failure

Aerobic exercise training is strongly recommended in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF) to improve symptoms and quality of life. Moderate-intensity aerobic continuous exercise (MICE) is the best established training modality in HF patients. For about a decade, however, another training modality, high-intensity aerobic interval exercise (HIIE), has aroused considerable interest in cardiac rehabilitation. Originally used by athletes, HIIE consists of repeated bouts of high-intensity exercise interspersed with recovery periods. The rationale for its use is to increase exercise time spent in high-intensity zones, thereby increasing the training stimulus. Several studies have demonstrated that HIIE is more effective than MICE, notably for improving exercise capacity in patients with HF. The aim of the present review is to describe the general principles of HIIE prescription, the acute physiological effects, the longer-term training effects, and finally the future perspectives of HIIE in patients with HF.

High-intensity interval training in cardiac rehabilitation

High-intensity interval training (HIIT) is frequently used in sports training. The effects on cardiorespiratory and muscle systems have led scientists to consider its application in the field of cardiovascular diseases. The objective of this review is to report the effects and interest of HIIT in patients with coronary artery disease (CAD) and heart failure (HF), as well as in persons with high cardiovascular risk. A non-systematic review of the literature in the MEDLINE database using keywords 'exercise', 'high-intensity interval training', 'interval training', 'coronary artery disease', 'coronary heart disease', 'chronic heart failure' and 'metabolic syndrome' was performed. We selected articles concerning basic science research, physiological research, and randomized or non-randomized interventional clinical trials published in English. To summarize, HIIT appears safe and better tolerated by patients than moderate-intensity continuous exercise (MICE). HIIT gives rise to many short- and long-term central and peripheral adaptations in these populations. In stable and selected patients, it induces substantial clinical improvements, superior to those achieved by MICE, including beneficial effects on several important prognostic factors (peak oxygen uptake, ventricular function, endothelial function), as well as improving quality of life. HIIT appears to be a safe and effective alternative for the rehabilitation of patients with CAD and HF. It may also assist in improving adherence to exercise training. Larger randomized interventional studies are now necessary to improve the indications for this therapy in different populations.

High-Intensity Interval Training

High-intensity interval training (HIT) is characterized by intermittent periods of work and rest and may include work bouts lasting seconds to minutes. HIT has typically been applied to older, diseased, and at-risk populations using longer work intervals (2-4 minutes), whereas more recent definitions of HIT include work intervals of 30 to 60 s. Both traditional endurance training (TET) and HIT exert a peripheral affect increasing the capacity of muscle cells to oxidize substrate via signaling cascades that support the activation of transcription factors that orchestrate the coexpression of nuclear and mitochondrial genes, with HIT triggering these benefits following minutes of training. With 1 exception, reports of central adaptations (eg, increased stroke volume) have been based on longer work intervals (eg, 4 minutes). Recent investigations have tied HIT to increased lipolysis and enhanced insulin sensitivity. HIT favors the activation of oxidative as opposed to hypertrophic pathways. Although the length of the work interval may need to be adjusted to fit the needs and capacity of the participant, HIT should be considered as an alternative to TET for older adults with the expectation that it requires less time to execute, yet promotes peripheral and perhaps central adaptations.

High-intensity interval exercise in chronic heart failure: protocol optimization

BACKGROUND

There are little data on the optimization of high-intensity aerobic interval exercise (HIIE) protocols in patients with chronic heart failure (CHF). Therefore, we compared acute cardiopulmonary responses to 4 different HIIE protocols to identify the optimal one.

METHODS AND RESULTS

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 VO(2peak) 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 ± 347 s; C: 1,574 ± 382 s) compared with protocols with active recovery intervals (B: 986 ± 542 s; D: 961 ± 556 s). All protocols appeared to be safe, with exercise tolerance being superior during protocol A.

CONCLUSION

Among the 4 HIIE protocols tested, protocol A with short intervals and passive recovery appeared to be superior.