Effects of relaxation intervention in phase II cardiac rehabilitation: replication and extension.

OBJECTIVES

To examine the effects of progressive muscle relaxation and guided imagery on psychological and physiologic outcomes in adults with cardiovascular disease who were participating in a phase II cardiac rehabilitation program. To examine tension levels, practice patterns, and perceived helpfulness of the intervention reported by subjects.

DESIGN

Prospective, quasi-experimental, with random group assignment within sites. Independent replication and extension of a study by Bohachik (1984).

SETTING

Four midwestern hospital-based phase II cardiac rehabilitation programs.

PATIENTS

Fifty patients who within the preceding 12 weeks had had acute myocardial infarction or coronary artery bypass surgery or both, studied during 6 weeks of participation in a phase II cardiac rehabilitation program.

OUTCOME MEASURES

Psychological measures included state and trait anxiety scores on the State-Trait Anxiety Inventory and reported symptoms on the Symptom Checklist-90-Revised. Physiologic measures were resting heart rate and blood pressure. Subjective tension levels before and after home practice, practice patterns, and perceived helpfulness of the intervention were examined.

INTERVENTION

Individual instruction session in progressive muscle relaxation and guided imagery at the phase II cardiac rehabilitation program, followed by daily home practice with audiotape instructions over a 6-week period.

RESULTS

No statistical differences at the p < or = 0.05 level were found in state anxiety scores or reported symptoms at study exit. However, reductions in mean subscale scores for interpersonal sensitivity (t [19] = 2.11, p < or = 0.05) and depression (t [19] = 2.07, p < or = 0.05) by paired t tests were found for the relaxation group (RG). The two groups differed at study exit in resting heart rate (t [42] = -2.02, p < or = 0.05) by independent t tests and in systolic blood pressure (F [1,42] = 5.13, p < or = 0.05) by analysis of covariance. The RG had a mean resting heart rate 8.6 beats/min lower than that of the control group (CG) and also had within-group reductions in mean heart rate (t [19] = 2.09, p < or = 0.05) by paired t tests. Contrary to expectation, the CG had a 3.5 mm Hg lower mean systolic blood pressure and within-group reductions in systolic (t [22] = 3.02, p < 0.01) and diastolic (t [22] = 3.83, p < 0.01) blood pressure by paired t tests. CG subjects had a greater number of dose increases in cardiac medications and fewer dose reductions than did RG subjects, who also had a higher number of dose reductions. RG subjects reported frequent practice of the technique, rated it as helpful, and reported lower subjective tension levels after practice.

CONCLUSIONS

Findings in this study did not support those of Bohachik (who reported lowered state anxiety and fewer somatization, interpersonal sensitivity, and depression symptoms). More instruction sessions on the relaxation method may have resulted in more positive outcomes. However, the within-group scores for interpersonal sensitivity and depression, the reduction in heart rate, and the receptivity of subjects to this intervention suggest that it may be a feasible and helpful adjunctive therapy for participants in a phase II cardiac rehabilitation program.