Julie Hartman

Importance of resistance training for patients after a cardiac event.

After a myocardial infarction (MI), percutaneous coronary intervention, or angina pectoris, patients receive conflicting advice from physicians about the level of activity that is acceptable. Most are told that they should not lift anything >5 pounds. When we conducted an informal survey of 28 patients from the Cardiac Rehabilitation Department at the Baylor Jack and Jane Hamilton Heart and Vascular Hospital, patients also recollected advice such as not to lift >10 pounds “for a while,” not to lift anything for a week, not to drive more than 30 minutes, not to “get exhausted” for a month, not to exercise for a few weeks, and not to lift >25 pounds for a period of time—or ever. These guidelines are not only confusing but can also promote fear and inactivity. Further complicating the scenario is that while physicians typically prescribe aerobic exercise—and particularly walking—for the purpose of avoiding further heart complications, patients are more interested in being able to return to activities of daily living, such as mowing the lawn, lifting grandchildren, or vacuuming. The resistance training that would lead to that outcome is rarely prescribed. Exercise physiologists, cardiac rehabilitation professionals, and personal trainers focus on three principles in training. One such principle is specificity. This principle indicates that the training effect is limited to the muscle fibers involved in the activity. For example, mitochondria adapt to endurance training, and contractile proteins adapt to resistance training. It is not reasonable to expect the arms to become trained during a 10-weekjogging program, for example(1). When the specificity principle was applied to football, coaches moved from mile runs for training to 100-yard runs, simulating the longest distance a player would run in competition. The other two principles of fitness training are overload, which states that for a training effect to occur, a tissue must be challenged with an intensity, duration, or frequency to which it is not accustomed; and reversibility, which states that training gains are quickly lost when the overload is removed (1). Over time, positive gains have been made in motivating patients to become more active following MI. Just 40 years ago, patients were put on bedrest for 4 to 6 weeks after an MI. Since then, it has been shown that after just a few days or weeks of bedrest, the patient experiences decreased cardiorespiratory fitness, strength, and flexibility (2). While physicians now acknowledge the value of exercise in cardiac rehabilitation, they have been hesitant to allow resistance training. Part of the problem is the existing guidelines (Table ​(Table11). In our opinion, these guidelines not only delay resistance training unnecessarily but also prescribe weight amounts that are below what patients need for even the most basic activities of daily living. We argue that resistance training should be promoted following the principle of specificity—that is, based on the fact that most patients set goals not to run a 10-kilometer race or to go mountain biking but rather to rise from the bathtub or mow the lawn. The constraints faced in cardiac rehabilitation, from physician prescriptions and from the guidelines, are particularly worrisome, since in society today we seem to place more importance on specifically training athletes (cyclists, marathon runners, football players) than we do on appropriately preparing patients to safely perform everyday activities. This limitation has become particularly obvious as cardiac rehabilitation patients have become younger. Some of these patients need to return to firefighting, police work, or other physically stressful jobs. Table 1 Cardiac rehabilitation resistance training guidelines by diagnosis∗ Our reasons for promoting resistance training are presented below.

Exercise tolerance testing in a cardiac rehabilitation setting: an exploratory study of its safety and practicality for exercise prescription and outcome data collection.

An exercise test is a valuable tool that should be a part of every patients assessment before beginning cardiac rehabilitation. We analyzed data from one exercise tolerance test used in a cardiac rehabilitation program among 103 subjects: 65 men with a mean age of 60.5 years and 38 women with a mean age of 62.4 years. Results indicated that, after cardiac rehabilitation, subjects had significant improvement in maximum metabolic equivalents (an increase of 0.9, P < 0.0001), which indicates functional capacity, and an improvement in rate of perceived exertion (decrease of 1 point; not statistically significant), which indicates more tolerance at the same work level. In general, men showed more improvement than women on the various outcome measures. Further, the testing protocol was shown to be safe. Blood pressure values did not exceed 188/86 mm Hg, and maximum heart rate did not exceed 165 beats per minute. The increased practice of exercise testing before and after cardiac rehabilitation may help expedite the development of a standardized exercise tolerance protocol to optimize patient rehabilitation and recovery and document outcomes for both individual patients and the rehabilitation program as a whole.

A randomized controlled trial of a controlled breathing protocol on heart rate variability following myocardial infarction or coronary artery bypass graft surgery

Objectives: To determine whether a controlled breathing programme increases heart rate variability following an acute myocardial infarction and/or coronary artery bypass graft surgery. Rationale: Heart rate variability is reduced following a myocardial infarction, and low heart rate variability is associated with a high mortality risk. By changing tidal volume and rate of breathing, individuals can alter beat-to-beat heart rate variability. It is hypothesized that heart rate increases with inspiration and decreases with exhalation, and that deep slow breathing enhances respiratory sinus arrhythmia, increasing heart rate variability. Design: Randomized controlled trial. Setting: Cardiac rehabilitation programme at a large academic medical centre in North Texas. Subjects: From 2001 to 2005, 44 patients, age 46—65 years, who had a myocardial infarction and/or undergone coronary artery bypass graft surgery 1—8 weeks previously and were referred to the Cardiac Rehabilitation Program. Intervention: Patients were randomized to either usual cardiac rehabilitation or cardiac rehabilitation with controlled breathing (6 breaths/min for 10 minutes twice daily during the eight-week treatment period). Main measures: Weekly measurements of total power and standard deviation of the mean normal to normal RR interval (SDNN), and fortnightly measurements of respiratory sinus arrhythmia were taken using Biocom Technologies Heart Rhythm Scanner and Tracker software. Results: No significant difference in change were seen between groups in SDNN (P = 0.3984), baseline respiratory sinus arrhythmia (P = 0.6556) or total power (P = 0.6184). Conclusion: Results suggest participation in the controlled breathing programme offered no additional benefit in increasing heart rate variability following myocardial infarction or coronary artery bypass graft surgery. However, 77% of study patients were on heart rate-lowering medications, which may have masked changes in heart rate variability.

Risk Factor Outcome Comparison Between Exercise-Based Cardiac Rehabilitation, Traditional Care, and an Educational Workshop

BACKGROUND This study examined risk factor outcomes among patients who attended cardiac rehabilitation sessions, those who received traditional care, and those who attended Leap for Life workshops. METHODS A non-equivalent, three-group design was used in this observational study. Baseline and 12-month measurements were collected for 217 participants. Analysis of covariance was performed to determine differences between groups on outcome variables. RESULTS The only significant finding was in participants with an initial high-density lipoprotein value of less than 40. High-density lipoprotein levels increased more in the cardiac rehabilitation group than in the traditional care group (30.54 to 37.48 versus 30.17 to 33.67 [F= 4.577, p = .035]). CONCLUSIONS Based on these findings, a strong case can be made for the transition to more individually intense and focused risk factor modification strategies for patients in cardiac rehabilitation programs.

Myocardial work during endurance training and resistance training: a daily comparison, from workout session 1 through completion of cardiac rehabilitation

Patients in cardiac rehabilitation are typically advised to complete a period of supervised endurance training before beginning resistance training. In this study, however, we compared the peak rate-pressure product (RPP, a calculated indicator of myocardial work) of patients during two types of exercise—treadmill walking and chest press—from workout session 1 through completion of cardiac rehabilitation. Twenty-one patients (4 women and 17 men, aged 35 to 70 years) were enrolled in the study; they were referred for cardiac rehabilitation after myocardial infarction, percutaneous coronary intervention, or both. The participants did treadmill walking and chest press exercises during each workout session. Peak values for heart rate (HR) and systolic blood pressure (SBP) were recorded, and the peak RPP was calculated (peak HR x peak SBP). Paired t tests were used to compare the data collected during the two types of exercise across 19 workout sessions. The mean peak values for HR, SBP, and RPP were lower during resistance training than during endurance training; the differences were statistically significant (P < 0.05), with only one exception (the SBP for session 1). Across all 19 workout sessions, the participants performed more myocardial work, as indicated by the peak RPP, during treadmill walking than during the chest press.