If the idea of exercising for cardiovascular health makes you think of spin class, it’s time to shift that thinking. In addition to traditional “cardio” regimens such as biking, running and high-intensity interval training, there is another kind of workout that benefits your heart: strength training.
Although the primary benefits of strength training have been seen as musculoskeletal, and it has been especially recommended for older adults to maintain bone mass and prevent falls and injury, newer research shows that weight training reduces your risk of diabetes, stroke and heart disease.
What research tell us
Multiple studies have found an inverse relationship between strength training and heart disease. A study published in 2017 in Medicine and Science in Sports and Exercise (MSSE) analysed data from more than 35,000 women for more than a decade. Researchers found that those who performed resistance training had a 30 percent lower chance of being diagnosed with Type 2 diabetes than those who did not.
Meanwhile, women who performed any amount of resistance training reduced their risk of cardiovascular disease (including heart attack, stroke, coronary artery bypass graft surgery, an angioplasty or death from cardiovascular disease) by 17 percent.
Similarly, a 2019 study (also published in MSSE) found that weight training was associated with decreased cardiovascular disease, including heart attack and stroke, and increased longevity. According to that study, which included nearly 13,000 people, performing resistance training for less than an hour per week was associated with roughly 40 to 70 percent decreased risk of cardiovascular disease and all-cause mortality - independent of any aerobic exercise.
More isn’t necessarily better, though. Researchers found that those who engaged in more than one hour of strength training per week experienced no additional reduction in the risk of cardiovascular disease or mortality.
Finally, a 2019 study in JAMA Cardiology concluded that obese, sedentary adults who strength trained experienced different outcomes than those who performed aerobic exercise. Both groups experienced decreases in epicardial adipose tissue (one of two kinds of fat deposits surrounding the heart). However, the resistance-training group also saw a 32 percent reduction in pericardial adipose tissue (the other kind of fat deposit) while the aerobic exercise group saw no change in that tissue.
Pericardial adipose tissue, “the fat that’s right in the heart sack,” is most likely to increase your risk of heart disease and stroke. The strength-training cohort performed only three 45-minute sessions per week.
Why resistance training works
Science has yet to determine the exact cardiovascular mechanism by which weight training helps prevent diabetes. But according to Eric Shiroma, a scientist at the National Institute on Aging who co-authored the 2017 study mentioned above, “we know that it makes bigger muscles, and we know that, in general, muscle is good for [preventing] diabetes.”
When you have Type 2 diabetes, your body cannot regulate blood sugar. Normally, when your blood sugar rises, typically after you eat, your pancreas releases insulin, a hormone that serves as the “key” to “unlock” your cells, allowing blood sugar to enter and be stored. However, to regulate chronically elevated blood sugar, your pancreas goes into overdrive, which isn’t sustainable. Gradually, your body becomes insulin-resistant, leading to Type 2 diabetes.
As Brad Schoenfeld, associate professor of exercise science at Lehman College in New York, explains: “You have insulin circulating, but you don’t have the entry into the cells. . . . The doors are locked.” The “locked doors” that characterise Type 2 diabetes make it difficult for the insulin in your bloodstream to turn glucose into energy. This results in excess glucose in the bloodstream, which can lead to a number of health conditions, including heart disease and stroke.
Increased muscle mass can help you process blood sugar, decreasing your risk of Type 2 diabetes and the cascade of diagnoses it can set into motion, including heart attack and stroke. Schoenfeld uses an analogy to explain what your biceps have to do with your blood sugar. “Think of muscle as a storage bin for glucose. Glucose is glycogen, which is the stored form of sugar,” he says. “Let’s say you want to store your sweaters. If you have a small storage bin, it’s only going to store a certain amount of sweaters,” while a larger bin fits more sweaters. “If you have small amounts of muscle, your bin for storing glucose is small, and you can end up having issues,” particularly as your muscles naturally atrophy with age.
By building muscle mass, resistance training gives you “larger bins” with “greater storage capacity” to help prevent insulin resistance, Schoenfeld explains. In other words, the larger your muscles, the greater your body’s capacity for glucose uptake, Oja says. Increased muscle mass “drives down the blood sugar circulating through your body.”
This could explain why a 2019 study in the Journal of Epidemiology and Community Health found an inverse relationship between skeletal muscle mass and cardiovascular disease.
How to train
Your ideal training plan depends on myriad factors, including goals, genetics and lifestyle. “Strength training is so personalised,” Shiroma says.
That said, we know that even a minimalist approach to strength training can pay dividends for your long-term health. Based on the results of the study that Shiroma co-authored, he says: “Anything seems to be better than nothing, and you really should do more than just the treadmill.”
By building muscle mass, resistance training gives you “larger bins” with “greater storage capacity” to help prevent insulin resistance.
For general long-term health, aim for three 30-minute strength sessions per week. Complete at least one set of exercises targeting each major muscle group. Because the optimum number of repetitions and sets is unique to each individual, focus on perceived exertion: making sure you’re fatigued by the end of each set.
Schoenfeld explains: “If you can do 15 push-ups and you stop at eight, you’re not really going to reap those rewards.” Says Oja: “It really isn’t about what you do. It’s about how you’re responding to it.”
If you don’t have heavy weights, don’t sweat it. Schoenfeld, who has a history as a competitive bodybuilder, says the resistance bands and adjustable dumbbells in his home gym are sufficient. Body-weight exercises are also effective. For an extra challenge, most exercises can be upgraded, according to Schoenfeld, who says there’s no shortage of how-to videos online. Household items can also make your workouts spicier.
Should I stop aerobic exercise?
Don’t toss your sneakers just yet. According to Schoenfeld, a “synergy” between aerobic exercise and resistance training supports optimal health. Although strength training changes your muscle physiology, it can’t necessarily help “pump your blood more efficiently or [help you] breathe more efficiently,” Shiroma says.
If getting sweaty doesn’t sound like fun, aim for 10,000 steps’ worth of Non-Exercise Activity Thermogenesis (NEAT) per day instead. NEAT includes the activities of daily living, such as walking, laundry and grocery shopping. “Every minute counts, and every activity counts,” Shiroma says.
So does the intensity. The Centers for Disease Control and Prevention recommends a minimum of 150 minutes of moderate activity or 75 minutes of vigorous activity per week. According to Shiroma, whether you walk two miles or run two miles, you’re getting an equivalent benefit; although the walk is less intense, it also requires more time.
Resistance training, on the other hand, should always be performed with enough effort to induce muscle fatigue. Although you don’t need a bodybuilder physique to see the benefits, you do need to be intentional when you lift. As you get stronger, your workouts will get easier, so adjust accordingly to keep building muscle mass. “You always have to be doing something a little bit harder,” Shiroma says.
Moore is a freelance writer, speaker, marathoner, Ironman triathlete and fitness instructor.