Many activities of daily living require significant amounts of muscular strength. Time lines for current strength training guidelines preclude many myocardial infarction patients from receiving strength training as part of their cardiac rehabilitation program. This study was designed to examine the effectiveness and safety of low-to-moderate level strength training in patients early after myocardial infarction.
Fifty-seven low-risk men (<61 years of age, 6-16 weeks post-infarction) were randomly assigned to a control group or one of three treatment groups. All groups trained aerobically, three times per week for 12 weeks. The three treatment groups performed additional strength exercises on each training day of the last 10 weeks. These groups differed in their strength training stimulus with Group 20 performing 20 reps of 20% of 1 repetition maximum (1 RM), Group 40 performing 10 repetitions of 40% of 1 RM, and Group 60 performing 7 repetitions of 60% of 1 RM.
Maximal strength remained unchanged in the control group (+0.5%), but increased in Groups 20, 40, and 60 by +10.5%, +11.9%, and +13.5%, respectively. The increases in strength in the treatment groups were all significantly different (P <.001) from the results of the control group, but were not significantly different from each other. For the three treatment groups, 30 of 42 subjects had one or more cardiovascular complication (arrhythmias, angina, ischemia, hypertension, hypotension) during the aerobic exercises as compared to only 1 subject with complications during the resistive exercises (P <.01).
In selected patients, low-to-moderate intensity strength training performed early after infarction is effective and may have lower rates of cardiovascular problems than aerobic exercise.
From the Northern Alberta Cardiac Rehabilitation Program, Glenrose Rehabilitation Hospital, Edmonton, Alberta.
Address for correspondence: William D. Daub, MSc, Northern Alberta Cardiac Rehabilitation Program, Glenrose Rehabilitation Hospital, 10230-111 Avenue, Edmonton, Alberta, T5G 0B7.