Strength training and cardio are two types of exercise that trigger different adaptations and changes to our bodies. Right? Strength training makes us stronger and leads to muscle growth while aerobic exercise improves another important muscle – our heart. No argument here – but does strength training also enhance cardiovascular fitness?
Resistance Training: Does It Offer Cardiovascular Benefits?
Some types of resistance training offer more cardiovascular benefits than others. Circuit training, where you quickly move from resistance exercise to resistance exercise with little or no rest between sets, elevates your heart rate enough to give you cardiovascular benefits, assuming you’re doing it properly. That’s the benefits of circuit training – it’s a time expedient way to work out when your goal is general fitness – but can circuit training improve your aerobic capacity? Let’s see what research shows.
In one study, participants did a circuit training workout consisting of 10 reps of 10 different resistance training exercises. The weight they used was rather light around 40% of their one-rep max, which is appropriate for a circuit workout since you’re not giving your muscles a chance to recover. The participants moved quickly from exercise to exercise. When researchers measured parameters like how much oxygen they consumed and how much their heart rate increased, it WAS enough to offer cardiovascular benefits.
So, resistance training using lighter weights in a circuit-style manner DOES elevate your heart rate and oxygen consumption enough to make your cardiovascular system more efficient. However, strength and hypertrophy training are different animals. When you lift loads of 65 to 80% of your one-rep max (hypertrophy) or 80 to 90% of your one-rep max (strength), you have to rest long enough between sets to give your muscles time to recover. For a hypertrophy workout, you might rest for a minute or two and a strength workout from 2 minutes to as long as 5 minutes between sets. During the time between, your heart rate can come down.
Strength Training for Heart Health
Although there’s not a lot of experimental research looking at whether non-circuit style resistance training has cardiovascular benefits, the authors of a paper published in the Journal of Exercise Physiology believe that intense resistance training likely DOES offer cardiovascular benefits – but how?
Aerobic exercise like running, cycling, and interval training improve cardiovascular health and exercise endurance in a number of ways. In response to an aerobic workout, your heart becomes a more efficient pump, capable of delivering more blood to the body with each beat. At the level of the muscle, more oxygen gets to muscle tissue to sustain ATP production. Changes even take place inside muscle cells. Mitochondria, the ATP energy producers of cells, become more efficient at producing ATP. In response to exercise, the number of mitochondria increase and the number of enzymes involved in making ATP rise, all for the purpose of making more of the energy source muscle cells use for contraction – ATP.
According to the Journal of Exercise Physiology article, an intense resistance training workout also has the potential to expand the number of mitochondria inside muscle cells and increase mitochondrial enzymes that make ATP. Therefore, high-intensity resistance training could potentially enhance aerobic endurance. In reality, this is more of a theory than a proven fact.
Another reason you might think intense resistance training benefits the heart is because your heart rate rises when you train hard. The rise in heart rate you get with resistance training is due to activation of the sympathetic, or “fight or flight” portion of your nervous system. On the other hand, strength training doesn’t increase the stroke volume or the amount of blood your heart can pump with each beat as aerobic exercise does.
How Aerobic and Resistance Exercise Affect Blood Vessels
According to a study from 2010, resistance training and aerobic exercise have different effects on the heart and blood vessels, but each may ultimately offer cardiovascular benefits. When you do an aerobic workout, blood vessels called arteries open up and become less stiff. In contrast, resistance exercise increases blood flow to the muscles being worked but also slightly increases arterial stiffness.
At the same time, resistance exercise also leads to a more sustained drop in blood pressure after exercise relative to an aerobic workout. Keep in mind that DURING heavy resistance training, you may experience a temporary rise in blood pressure, which is why you should consult your doctor before strength training if your blood pressure isn’t well controlled.
Researchers point to the fact that resistance exercise increases blood flow to the working muscles as being favorable for cardiovascular health. The drop in blood pressure after resistance training doesn’t hurt either. In addition, some research shows regular resistance training leads to a decrease in heart rate by as much as 11%, suggesting the heart is becoming a more efficient pump, just as it does with aerobic exercise.
In terms of long-term cardiovascular health, strength training improves a variety of markers for heart health, including the way cells respond to glucose and insulin. As such, regular resistance training helps prevent insulin resistance and the harmful effects of metabolic syndrome, a condition linked with a greater risk for type 2 diabetes and heart disease. Some, but not all studies, show strength training is associated with a more favorable lipid profile.
What Does This Mean?
Resistance training improves heart health, although it’s not clear whether it actually enhances aerobic endurance. If it does, the effect is probably slight. However, as one study showed, it does lower risk factors for heart disease by reducing blood pressure longer term and by improving insulin sensitivity.
The bottom line? If you’re concerned about the health of your heart, don’t give up aerobic exercise completely. If you don’t enjoy it, shorten your sessions by doing HIIT training. You will likely get some improvements in how efficiently your heart functions if you do more compound resistance exercises that work large muscle groups and if you do circuit training where you’re moving quickly from exercise to exercise. However, include some cardio in your routine for good measure. After all, your heart is the hardest working muscle in your body and it never goes on vacation. Give it the support it needs for good health.
References:
IDEA Health and Fitness Association. “New Insights Into Circuit Training”
“New Insights into Circuit Training” Len Kravitz Ph.D.
Journal of Exercise Physiology. 2012 Jun;15(3).
Pain Science. “Brief, intense muscular training for cardiovascular fitness” June 28, 2015.
Gatorade Sports Science Institute. “SSE #54: Muscle Adaptations to Aerobic Training”
Medical News Today. “Weight Training Has Unique Heart Benefits, Study Suggests”
Resistance Training: Adaptations and Health Implications. Len Kravitz, Ph.D.
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