Is strength training good for the heart?

We know from tons and tons of research that staying active is good for our hearts. Epidemiological evidence has mounted for years that aerobic activity, the kind that gets your heart rate up and makes you sweat, is associated with a lower risk for heart disease. This is why the American College of Cardiology and American Heart Association recommend 150 minutes of moderate intensity (or 75 minutes of vigorous intensity) aerobic physical activity per week for optimal heart health. Not infrequently, however, I get asked about what role resistance or strength training has for heart disease prevention. Should we be incorporating weight lifting into our exercise regimen for optimal heart health?

What is strength training?

In the literature, strength training is defined as a dedicated program of carefully chosen exercises performed over an extended period of time, designed to increase the ability to produce muscular force. It uses the concept of progressive overload, a steady increase in the applied stress via either incremental increases in weight, training frequency, or sets/repetitions.

What are the benefits of strength training?

The vast majority of the literature to date has focused on the benefits of weight lifting and other forms of resistance training on improving strength, body composition, and bone health. It is a powerful treatment for sarcopenia, muscle loss leading to frailty in elderly adults. Some studies have also seen improvements in anxiety, depression, and insomnia.

With regards to body composition, resistance training has been found to increase lean body mass and decrease total body fat, including visceral fat (which is highly linked to metabolic syndrome and increased cardiovascular risk). One study randomized 100 moderately obese individuals with metabolic syndrome to several different types of exercise programs in conjunction with low calorie diets. The group assigned to the high resistance-moderate endurance training lost the most visceral fat compared to the other groups (moderate resistance-moderate endurance and moderate resistance-high endurance), highlighting the impact high resistance training can have on body composition.

Resistance training has also been demonstrated to have important improvements in another cardiovascular risk factor, hypertension. A meta-analysis of 5 randomized controlled trials found that resistance training alone reduced systolic and diastolic blood pressure significantly (- 8 mmHg and -4 mmHg, respectively) in hypertensive and prehypertensive subjects. The blood pressure lowering effect of resistance training may even be distinct from that of aerobic training, as it appears that strength training may uniquely increase the ability of the blood vessels to dilate.

Strength training also has profound effects on insulin resistance and glucose regulation, with some evidence it may even be better than traditional aerobic activity for improving metabolic health. Strength training increases glucose uptake and oxidation in those with and without diabetes. One study found that just 10 weeks of resistance exercise resulted in improvements in HgbA1c in type 2 diabetics and was even associated with better glycemic control than treadmill exercise. Improvements have been seen in HgbA1c, fasting glucose, fasting insulin, and other measurements of insulin resistance.

Is there any evidence that strength training is beneficial for the heart?

Given the well demonstrated improvements in cardiometabolic risk factors with strength training for heart disease - visceral fat, blood pressure, and glycemic control - one would also anticipate a decrease in cardiovascular disease risk. The data is somewhat less robust here, but has recently been mounting.

There is a strong body of evidence demonstrating that physical strength is associated with reductions in risk of death, including cardiovascular death. Many studies have found that greater muscle strength, typically assessed by handgrip strength, is associated with reduced risk of death from any cause. Risk of death increases with poor handgrip strength on initial assessment as well those showing the greatest decline in strength over time. This, however, is somewhat indirect evidence as it doesn’t directly assess the effect of strength training per se.

One recent prospective study of over 12,000 previously healthy adults found that resistance training one to three times per week was associated with reduced risk of cardiovascular disease, independent of aerobic exercise. There were no additional benefits seen with increasing resistance training of 4 times per week or more. In another, men who lifted weights for 30 minutes or more per week had a 23% lower risk of heart disease compared to those who didn’t. This risk reduction was less than that seen for men who ran for an hour or more per week, but more than those who rowed for an hour per week or walked briskly for a half-hour a day.

So should we lift or just stick with the treadmill?

While the American College of Cardiology guidelines do not specifically prescribe a specific amount of resistance training given that it is not totally clear if it lowers the risk of heart disease, they do state that “resistance training should be encouraged.” Other organizations including the American Diabetes Association, American College of Sports Medicine, and the CDC include both aerobic and resistance training in their guidelines.

As a form of exercise, it confers the same benefit as any form of physical activity. Circuit training and other forms of active resistance training can certainly reach the same metabolic equivalent (METs) as other moderate or vigorous intensity physical activity (as a reminder, activities that are considered moderate intensity include brisk walking, active yoga, light biking and light swimming). In addition, there are benefits unique to resistance training including improvements in strength and decreased frailty. It also may be superior to traditional aerobic activity in those with metabolic syndrome or diabetes - and with cardiometabolic risk an increasingly prevalent risk factor for cardiac disease, this should certainly not be overlooked. Some studies have shown that improvements in cardiometabolic risk parameters may be superior in exercise programs that prescribe both aerobic and strength training, and so, as time permits, they are more than likely complementary.