High-intensity strength training of patients enrolled in an outpatient cardiac rehabilitation program

Abstract

Purpose: This randomized controlled study assessed whether adding a program of high-intensity strength training (80% of maximum) to an outpatient cardiac rehabilitation program would be a safe and effective means of improving muscle strength and body composition.

Methods: Thirty-eight cardiac patient volunteers (29 men and 9 women) were randomized to either high-intensity strength training or flexibility training added concurrently to a 12-week outpatient cardiac rehabilitation aerobic exercise program. Muscle strength, local muscle endurance, joint flexibility, maximum treadmill tolerance time, and body composition were measured before and after completion of the training.

Results: The strength-trained patients (n = 18) had greater increases in mean strength (90 +/- 19% versus 9 +/- 4%, P < 0.0001) and local muscle endurance (20 versus 6 times, P < 0.0001), and decreases in mean perceived exertion for lifting the initial one repetition maximum load (11 +/- 1 versus 15 +/- 1, P < 0.0001) when compared with flexibility-trained patients (n = 16). The strength group lost more body fat (2.8 +/- 2.0 versus 1.3 +/- 2.0 kg, P < 0.01), tended to gain more lean tissue (1.5 +/- 2.3 versus 0.5 +/- 1.2 kg, P < 0.10), and had greater improvements in treadmill time (2.3 +/- 1.3 versus 1.2 +/- 1.0 minute, P < 0.02) than did the flexibility group. Improvements in joint flexibility were similar for each group. None of the subjects had evidence of cardiac ischemia or arrhythmia during the training sessions.

Conclusions: Medically supervised high-intensity strength training is well tolerated when added to the aerobic training of cardiac rehabilitation programs and allows patients to aggressively gain the strength and endurance they will need to complete daily living tasks at lower perceived efforts. Strength training also reduces cardiac risk factors by improving body composition and maximum treadmill exercise time.