Ruby Nucklos, M.D.
Assistant Professor of Medicine
Medical University of Ohio

Since the 1950’s, strength training has been recognized for its positive benefits in rehabilitation programs, athletic performance, fitness programs, functional capacity and many health related issues (1). Although strength training, also known as resistance training, has many positive benefits, there has been concern expressed by several authors regarding its effects on blood pressure and left ventricular hypertrophy (2-6).

In a 1988 paper, Fleck reported that the resting heart rate of body builders was not significantly different from sedentary subjects. He concluded that resistance training does not affect resting blood pressure (2). This conclusion suggests that strength trained athletes have an average or lower than average resting blood pressure. The same point has also been stressed in a more recent report from this author as well as others (3,4).

These observations occur on the background that during performance of strength training, both heart rate and blood pressure can increase to dramatic levels (3,4). Fleck and Kraemer noted that blood pressure could reach levels as high as 320/250 mmHg and heart rates as fast as 170. Some authors indicate that there might be a protective effect from the increase in intrathoracic pressure that ensues when doing strength training (3.4). As the intrathoracic pressure increases, cerebral spinal fluid pressure rises in parallel, and thus reduces the difference between the pressure inside and outside of cerebral vessels. Although the exact mechanism for the high blood pressures during strength training are unknown, it is clear that performing a Valsalva maneuver during strength training can augment the increase in blood pressure substantially. One study demonstrated that the more trained an individual, the lower the pressor response to acute strength training (3).

Regarding effects on LV mass, the general consensus is that strength training does not result in significant LV mass increases when normalized for lean body mass. Haykonsky and colleagues, studying elderly subjects in particular, also came to this conclusion. In this recent study, they examined the effects of strength training on LV morphology and systolic function in 22 healthy elderly men before and after 16 weeks of strength training (5). They found that strength training was not associated with a change in the size of the left ventricle. Other studies have demonstrated that neither ejection fraction nor LV mass is affected by strength training (2,4).

These conclusions may not be applicable to non-healthy subjects, however. Effron notes that strength training in hypertensive patients with normal LV function increased LVMI without an adverse effect on either LV systolic or diastolic function. He also stressed that strength training can have adverse effects on LV systolic function if there is abnormal baseline LV systolic function (4).

In summary, strength training has many health benefits but can acutely elevate blood pressure and heart rate. Moreover, in patients with hypertension and abnormal LV systolic function, it apparently can worsen systolic function. Thus, it is my opinion that each person should undergo a thorough medical evaluation to assess any health risk to strength training before embarking on a strength-training regimen.

Bibliography

Feigenbaum MS, Pollock ML. Prescription of Resistance Training for Health and Disease. Medicine and Science in Sports and Exercise. 1999; 31:38-45.

Fleck SJ. Cardiovascular Adaptations to Resistance Training. Medicine and Science in Sports and Exercise. 1988; 20:S146-S151.

Fleck SJ, Kraemer WJ. Designing Resistance Training Programs, 2nd edition; 1997.

Effron MB. Effects of Resistive Training on Left Ventricular Function. Medicine and Science in Sports and Exercise. 1989; 26:694-697.

Haykonsky M, Humen D, Teo K, Quinney A, Souster M, Bell G, Taylor D. Effects of 16 Weeks of Resistance Training on Left Ventricular Morphology and Systolic Function in Healthy Men > 60 Years of Age. American Journal of Cardiology. 2000; 85:1002-1006.

Baechle TR, Earle RW. Essentials of Strength Training and Conditioning, 2nd Edition, 2000.