High Intensity Interval Training in Patients With Cardiovascular Disease: A Brief Review of Physiologic Adaptations and Suggestions for Future Research

Exercise-Based Cardiac Rehabilitation Programs in Heart Failure Patients

Exercise training is recommended for patients with heart failure by major societies' guidelines. It improves exercise capacity and quality of life, reduces symptoms of depression, can improve survival, and reduce the risk for hospitalizations. Exercise-based cardiac rehabilitation can be offered with different modalities, such as continuous or interval aerobic training, resistance, and inspiratory muscle training. The intervention must follow an accurate evaluation of the patient's cardiovascular conditions and functional capacity. Despite the multiple benefits of exercise training, there is a lack of adherence to exercise-based programs, due to socioeconomic factors, patients' characteristics, and lack of referral.

Exercise Training Workloads Upon Exit From Cardiac Rehabilitation in Men and Women: THE HENRY FORD HOSPITAL EXPERIENCE

PURPOSE

To describe exercise training workloads, estimated as metabolic equivalents of task (METs) both upon exit from cardiac rehabilitation (CR) and as the change in MET level following CR, stratified by age, sex, initial MET level, number of sessions completed, and qualifying event at entry into CR.

METHODS

A retrospective study involving 8319 (31% female) patients who completed ≥9 exercise training sessions in the early outpatient CR program at Henry Ford Hospital. Exercise training MET levels achieved during CR were estimated on the basis of the speed and grade recorded from a treadmill. Exercise training METs at the start of CR were defined as the average of the second and third sessions, whereas MET level upon exit from CR was determined from the average of the last 2 patient encounters.

RESULTS

The overall mean MET level while training just prior to exit from CR was 3.9 ± 1.4 (4.1 ± 1.4 and 3.3 ± 1.0 in men and women, respectively). The mean change in METs after CR was 1.3 ± 1.1 (+45% ± 37%) and 0.9 ± 0.7 (+40% ± 32%) in men and women, respectively.

CONCLUSIONS

In a large and demographically diverse cohort of patients who participated in CR, increases in mean workload (ie, METs) during exercise training were observed that approximated 45% in men and 40% in women. These data could be considered when establishing benchmarks for program-related performance outcome measures.

Aquatic High Intensity Interval Training for Cardiometabolic Health: Benefits and Training Design

High-intensity interval training (HIIT) has emerged as an attractive alternative to traditional continuous exercise training (CT) programs for clinical and healthy populations who find that they can achieve equal or greater fitness benefits in less time. Land-based HIIT may not be an appropriate choice for some participants. Few studies have explored the acute responses and chronic adaptations of HIIT in an aquatic environment, and no study has compared the cardiometabolic responses of an aquatic-based program to a land-based HIIT program. Shallow-water aquatic exercise (AE) programs utilizing HIIT have elicited comparable and, in some cases, greater physiological responses compared with constant-intensity or continuous AE regimens. Factors that may explain why HIIT routines evoke greater cardiometabolic responses than CT protocols may be based on the types of exercises and how they are cued to effectively manipulate hydrodynamic properties for greater intensities. Favorable aquatic HIIT protocols such as the S.W.E.A.T. system may serve as a beneficial alternative to land-based HIIT programs for clinical, and athletic populations, potentially reducing the likelihood of associated musculoskeletal and orthopedic complications. Hence, the purpose of this review is to examine the role of AE as an alternative safe and effective HIIT modality.

Incorporating patients with chronic heart failure into outpatient cardiac rehabilitation: practical recommendations for exercise and self-care counseling-a clinical review

PURPOSE

A recent policy change from the Centers for Medicare and Medicaid Services includes coverage of cardiac rehabilitation (CR) for patients with chronic heart failure (CHF) with reduced ejection fraction. This article provides a framework by which CR programs can incorporate disease-specific services for patients with CHF who participate in CR.

DISCUSSION

Cardiac rehabilitation should include self-care counseling that targets improved education and skill development (eg, medication compliance, monitoring/management of body weight). Various tools are available for assessing exercise tolerance (eg, stress test with gas exchange and 6-minute walk), health-related quality of life, and other outcome-related parameters. Exercise should be prescribed in a manner that progressively increases intensity, duration, and frequency, to a volume of exercise equivalent to 3 to 7 metabolic equivalent task (MET)-hr per week. The benefits of exercise training are limited by patient adherence; therefore, CR providers need to identify the adherence challenges unique to each patient and address each accordingly. To optimize the referral of patients with CHF to CR, program staff should develop strategies to raise both health care provider and patient awareness about the benefits of CR, as well as work collaboratively to set up system-based approaches to CR referral.

CONCLUSIONS

The referral of patients with CHF to CR will increase in 2014 and beyond, due partly to a policy change from the Centers for Medicare and Medicaid Services that allows coverage for CR. These patients should be integrated into existing programs, with the intent of providing both standard CR services and CHF-specific education and disease management activities that target improved outcomes.

Greater improvement in cardiorespiratory fitness using higher-intensity interval training in the standard cardiac rehabilitation setting

PURPOSE

We tested the hypothesis that higher-intensity interval training (HIIT) could be deployed into a standard cardiac rehabilitation (CR) setting and would result in a greater increase in cardiorespiratory fitness (ie, peak oxygen uptake, (·)VO₂) versus moderate-intensity continuous training (MCT).

METHODS

Thirty-nine patients participating in a standard phase 2 CR program were randomized to HIIT or MCT; 15 patients and 13 patients in the HIIT and MCT groups, respectively, completed CR and baseline and followup cardiopulmonary exercise testing.

RESULTS

No patients in either study group experienced an event that required hospitalization during or within 3 hours after exercise. The changes in resting heart rate and blood pressure at followup testing were similar for both HIIT and MCT. (·)VO₂ at ventilatory-derived anaerobic threshold increased more (P < .05) with HIIT (3.0 ± 2.8 mL·kg⁻¹·min⁻¹) versus MCT (0.7 ± 2.2 mL·kg⁻¹·min⁻¹). During followup testing, submaximal heart rate at the end of stage 2 of the exercise test was significantly lower within both the HIIT and MCT groups, with no difference noted between groups. Peak (·)VO₂ improved more after CR in patients in HIIT versus MCT (3.6 ± 3.1 mL·kg⁻¹·min⁻¹ vs 1.7 ± 1.7 mL·kg⁻¹·min⁻¹; P < .05).

CONCLUSIONS

Among patients with stable coronary heart disease on evidence-based therapy, HIIT was successfully integrated into a standard CR setting and, when compared to MCT, resulted in greater improvement in peak exercise capacity and submaximal endurance.

Energy expenditure, cardiorespiratory, and perceptual responses to shallow-water aquatic exercise in young adult women

INTRODUCTION

Aquatic exercise (AE) is a popular form of physical activity, yet few studies have assessed the individual's energy expenditure (EE) associated with a continuous bout of AE. Studies using indirect calorimetry to measure EE have reported limitations associated with test methodology and the ability to control individual's exercise intensity or tempo.

PURPOSE

To evaluate EE and cardiorespiratory (CR) responses during a 40-minute shallow-water AE session in young adult women.

METHODS

Twenty-one healthy women (aged 21.7 ± 3.4 years) completed an orientation practice session and a 40-minute shallow-water AE session using a traditional exercise class format and the SWEAT video-based instructional cuing program. The high-intensity interval format included the following segments: 1) warm-up (3 minutes); 2) CR segment ( 22 minutes); 3) muscular endurance segment (ME; 10 minutes); and 4) cool-down (5 minutes). Subject oxygen consumption (VO2; mL/kg/min), heart rate (HR) and OMNI overall ratings of perceived exertion (RPE-O) were assessed each minute. Average kcal/min1, metabolic equivalents (METs; 1 MET = 3.5 mL/kg/min), and total kcals per segment and for the overall session were calculated.

RESULTS

The total subject EE throughout the 40-minute trial (including warm-up and cool-down segments) was 264 kcals, with an overall average of 6.3 kcals/min (5.6 METs).The average kcals/min expended throughout CR segments 2 through 6 was 8.05 (7.1 METs), with the Hoverjog segment producing the greatest average kcals/min at 8.3 (7.3 METs). The CR portion (22 min) contributed 65% of the total EE (171 kcals) of the 40-minute AE trial. For the overall AE trial, the highest and average subject VO2 achieved were 33.3 and 19.7 mL/kg/min, respectively. The average highest subject heart rate achieved was 177 beats per minute (bpm), equivalent to 90% of the participant's age-predicted HRmax.

CONCLUSION

Energy expenditure during a 40-minute AE session met national recommendations for a daily moderate-to-vigorous bout of physical activity offering a viable alternative to land-based exercise. Because AE serves as a partial-weight bearing modality, future studies are needed to clarify the EE of shallow-water AE in apparently healthy and clinical populations.