Cardiovascular Benefits of Strength Training

Article by Ed McNeely

Performance benefits usually dominate discussions on strength training. Though this type of training can induce significant increases in strength, power, and speed of movement, we give little attention to the resulting health benefits. This Series of articles examines those benefits.

           

Weight training is generally believed to be of little benefit in modifying the risk factors of cardiovascular disease. This opinion, however, is slowly changing as more research reveals that the heart, like other muscles, adapts to the stress of weight training. Specifically, the left ventricular (LV) wall thickens to adapt to the stress. The left ventricle is the part of the heart that circulates blood to the muscles and organs of the body other than the lungs. An increase in wall thickness is presumed to allow the heart muscle to contract more forcefully. Several studies have shown that with as little as eight weeks of strength training LV wall thickness can increase as much as 10%.

 

Increases in LV mass appear to be a function of exercise intensity. High intensity strength training increases blood pressure during exercise. The increase in blood pressure is the stimulus for increased heart muscle size.  This is not only true for exercise researchers have found that elevated blood pressure increases LV mass and thickens the LV wall in people with hypertension.

 

An increase in chamber size is one of the heart adaptations often attributed to aerobic exercise (this idea has recently been challenged). Although, most types of strength training do not appear to affect the size of the heart chamber some types of high volume bodybuilding programs may increase the chamber’s size. This can result in an increase in stroke volume, the amount of blood circulated with each beat of the heart. This means the heart can beat less often and still provide the same amount of blood flow to the rest of the body.

 

Though strength training does not produce the same cardiac functional improvements gained from aerobic training, it is becoming more popular as a rehabilitation tool with individuals who have had heart problems.  If you want to improve heart function while doing your strength training consider the following:

 

 

Circuit training not only provides a strength training stimulus but the continuous nature of the activity has been shown to increase aerobic fitness. Circuit training can also be a time saving method of doing a strength workout.

 

 

The vasalva manoeuvre occurs when you hold your breath while lifting. It significantly increases both systolic and diastolic blood pressure and can result in dizziness or lightheadedness. Though performing the manoeuvre is not a major problem for healthy individuals, and can even benefit strength performance by increasing intrabdominal pressure, it can be dangerous for people with cardiac problems.  

 

 

Training to failure is unnecessary to achieve improvements in strength. There is no advantage to training to failure and several possible disadvantages. The highest blood pressure readings occur at or near the failure point. A study done at McMaster University in Hamilton, Ontario noted that exercising to exhaustion using large muscle masses could increase blood pressure to as high as 400/300 mm Hg. While this is transient and probably not dangerous to a young health individual the researches suggested that it may be a cause for concern in older people or those with a history of cardiovascular problems.

 

 

In strength training intensity is expressed as a percentage of the maximum amount of weight that you can lift (%1RM). Intensities below 60%1RM do not increase strength. Circuit training is most effective with intensities in the 60-75% 1RM range.