Improving Cardiac Rehabilitation Exercise Using Target Heart Rate Trial

This study aims to conduct a practical two-arm, parallel-group, open-label, efficacy randomized trial comparing Graded Exercise Testing+ Target Heart Rate Range (GXT-THRR) vs. Usual Care (UC) on changes in fitness (as measured by 6MWT, exercise training METs, handgrip strength and Short Physical Performance Battery [SPPB]) and PA behavior among 320 patients enrolled in CR. The investigators will recruit older adults (age ≥ 60 years) attending outpatient CR from two complementary but different CR centers. The investigators will compare changes in fear and self-efficacy between these two groups and measure long-term clinical outcomes. The investigators have designed the study to be as generalizable as possible, so most CR programs can immediately apply the results in clinical practice.

Eligible patients who are willing to participate will complete written informed consent. Baseline demographics, comorbidities, and prescribed medications and doses (including beta-blockers) will be collected.

Patients will then undergo a baseline assessment. This will include a 6MWT and SPPB using standard guideline procedures. During this time period, patients will also be fitted with an accelerometer to wear for 7 days (Actigraph, CenterPoint, Pensacola, FL) to assess time spent in moderate to vigorous PA (MVPA). The investigators have significant experience assessing PA, 6MWT, and SPPB, and anticipate few issues in making these measurements. Patients will also complete the following psychological assessments:

• Multidimensional Self-Efficacy for Exercise Scale. Self- efficacy is a robust predictor of exercise and PA behavior and may be influenced by exercise prescription method (GXT-THRR or UC). This validated tool will assess three dimensions of self-efficacy: task efficacy (confidence in performing the elemental aspects of exercise), coping efficacy (confidence in exercising under challenging circumstances), and scheduling efficacy (confidence in being able to schedule regular exercise into one's lifestyle).
• Exercise Sensitivity Questionnaire (ESQ). The ESQ is an 18-item self-report measure developed by Dr. Farris that conceptualizes exercise anxiety as worry and fear about the physical sensations of exercise. The ESQ has two dimensions: (1) anxiety about cardiopulmonary sensations during exercise (i.e., blurry vision, chest pain/tightness, difficulty breathing) and (2) anxiety about pain/weakness sensations during exercise (i.e., joint/back/body pain, aches, soreness).
• Exercise Perception Questionnaire. This survey uses relevant subscales of the Intrinsic Motivation Inventory and will assess patient interest/enjoyment, as well as perceived choice, competence, pressure/tension, and effort.
• Preference for and Tolerance of Exercise Intensity Questionnaire (PRETIE-Q). This validated tool reflects a patient's general attitude towards and tolerance for higher-intensity exercise. We have included this survey as an important baseline measure, which may predict exercise gains and PA patterns.
• 36 Item Short Form Survey (SF-36). This well-validated general QOL survey has been used extensively in CR and provides a useful measure of a patient's overall physical, emotional, and social QOL.
• Fried Frailty Phenotype. This assesses physical frailty through five criteria: unintentional weight loss; weakness or poor handgrip strength; self-reported exhaustion; slow walking speed; and low physical activity.
• International Physical Activity Questionnaire-Elderly. This well-validated survey will assess levels of physical activity (moderate, moderate-vigorous, vigorous) and sedentary activity.

During the time between informed consent and randomization, patients will continue to undergo CR using UC to guide intensity. This allows for exercise-related baseline measurements to be taken, including the exercise training METs on the 3rd session of CR, as suggested by AACVPR performance measures. It also allows measurement of baseline resting HR, exercise HR, and exercise RPE.

After completing all baseline assessments (including 3 sessions of CR), patients will be randomized (1:1) to either GXT-THRR or UC. Randomization will be stratified based on age, recent cardiac surgery, and site (Baystate vs. Henry Ford.) This will be done because age may have a differential impact on exercise gains; cardiac surgery can limit the available exercise training modalities (i.e., no upper body exercises); and CR site may influence the outcome in unanticipated ways. The investigators will randomize patients through use of the Research Electronic Database Capture (REDCap) software randomization module which allows secure, sequential, and concealed group allocation, as was done in the pilot. REDCap will also be used by both sites to allow uniform data collection, capture, and entry.