Long-term Exercise in Older Cardiac Patients

Assisting individuals to adopt and maintain lifestyle exercise after a cardiac event remains challenging. The purpose of this 3-group, randomized controlled trial was to test two theoretically distinct behavior change interventions against a usual care (UC) group to increase lifestyle exercise after a cardiac event. In a new intervention, SystemCHANGE (SC), based on process improvement and ecological theories, participants were taught to use a series of small self-designed experiments to change their daily routines associated with exercise. The emphasis was on changing systems in their lives rather than relying on motivation or memory. The second intervention, CHANGE+ (C+), based on cognitive behavioral theory, included contemporary approaches to increase self-efficacy, motivation, and problem-solving skills.

Sample

The sample consisted of a convenience sample of 379 individuals who were consecutively recruited from five Phase II cardiac rehabilitation programs (CRP) in the greater Cleveland, Ohio area. Forty percent of the participants approached agreed to participate and were randomized. Of the 406 subjects consented, 379 completed the study. Subjects were randomly assigned to one of three study arms: SystemCHANGE (process improvement model program of health behavior change), CHANGE+ (cognitive behavioral model program of health behavior change), or Usual Care. All subjects had a recent cardiac event (myocardial infarction, coronary artery bypass surgery and/or percutaneous coronary intervention) and were participating in a Phase II cardiac rehabilitation program. Subjects were recruited near the end of their program and followed for one year after cardiac rehabilitation. Subjects were included if they were greater than 55 years of age and able to read and speak English; they were excluded if they met criteria for being at high risk for safe exercise participation following a cardiac event (ejection fraction < 30%, decrease in systolic blood pressure of > 15 mmHg with exercise, serious arrhythmias at rest or exercise induced, and exercise induced ischemia indicated by angina > 2 mm ST segment depression on the electrocardiogram).

Intervention Protocols

Both the CHANGE+ and SystemCHANGE interventions consist of a series of five small-group (six to eight people) education sessions provided in three 1.5-hour sessions once a week during the last three weeks of the CRP and in two sessions held at one and two months following completion of their CRP. An experienced cardiac nurse or exercise physiologist trained in the intervention protocol taught each of the sessions. In a series of structured activities, participants were taught to use behavior change strategies consistent with the respective intervention models. A series of three monthly booster calls were made during months four, five and six following the last intervention class and individuals were coached in the use of strategies consistent with the respective interventions. Usual Care consisted of only the routine care provided at the CRP. All participants received the usual CRP prescribed structured exercise and individual and group classes (four) on diet modification and stress reduction that are part of routine care at the CRPs. At the end of the CRP, all individuals were given an exercise prescription that included their target heart rate and counseled to exercise at least five times a week for 30 minutes.

Measures

Three dimensions of exercise were measured: frequency, amount, and maintenance. Exercise frequency was the number of sessions exercised (of at least 10 minutes duration) over a given period of time. Exercise amount was the number of hours exercised and reflected both the frequency and the duration of each exercise session. Exercise was measured using portable wristwatch heart rate monitors (Polar RS400) and exercise diaries. Data from the monitors was used as the primary data source with diary data used as backup if data from the monitor were not available (i.e., forgot to put on the monitor, monitor malfunction). The heart rate (HR) monitor memory was programmed to record HR at 5-second intervals during an exercise session. Standardized, validated measures were also obtained at baseline, two, six, and twelve months of: system changes, social support for exercise, problem-solving skills, motivation, health beliefs, and exercise self-efficacy. Measures were also obtained on possible moderating and confounding variables: age, race, functional capacity, body fat, co-morbidity, muscle or joint pain, exercise experience, home and neighborhood environment, and depression.

Procedures

Individuals who met study inclusion criteria were enrolled during the sixth to eighth week of the CRP and written informed consent was obtained. Baseline measures were obtained in a private interview at the CRP center. The intervention began week ten of the subjects' CRP. At the end of their CRP, subjects were given HR monitors and exercise diaries and were directed to return mail them during each of the next twelve months. The number of hours exercised during exercise adoption (months one through three) and maintenance (months four through twelve) was calculated. Multiple linear regression was used to determine if study group membership predicted exercise adoption and maintenance. Mediation analysis was also conducted.