5 Ways High-Intensity Interval Training (HiiT) Improves the Health of Your Heart

5 Ways High-Intensity Interval Training (HiiT) Improves the Health of Your Heart

HIIT training is all the rage these days. How can you beat a workout that’s effective, possibly more so than steady-state training, and that takes less time? With high-intensity interval training, the intensity level is more important than time. With a typical HIIT session, you alternate periods of very high-intensity exercise with periods of rest. The rest periods allow partial, but not complete, recovery before tackling the next active interval.

HIIT training is versatile too. Since you’re not restricted to a single type of exercise during the active intervals. You have your choice of movements – sprints, jumping jacks, squat jumps, cycling against resistance, or everyone’s favorite – burpees. You can also alternate between exercises. The key is keeping the intensity level high. For maximal intensity, shoot for 90% of your maximal aerobic capacity or greater during the active intervals. That’s a challenging pace!

HIIT training has benefits that go beyond fat loss. You already know exercise is good for your heart and HIIT training is no exception. In fact, preliminary studies show high-intensity exercise may be better for heart health than moderate intensity workouts. Good news if you like time-expedient workouts! Here are five ways HIIT training improves heart health and lowers your risk for cardiovascular disease.

HIIT Training Will Enhance Your Aerobic Capacity

Aerobic capacity, also referred to as V02 max, is a measure of the maximal amount of oxygen your body is able to use per minute. V02 max has a genetic component but is also impacted by how you train. Your V02 max, which can be measured at some sports centers, says something about your endurance level and your risk for heart disease. In one study, researchers did physical exams on more than 33,000 men and women, finding a low V02 max, or aerobic capacity was linked with a higher risk of cardiovascular death.

How does this tie in with HIIT training? Vigorous exercise increases aerobic capacity, or V02 max, AND anaerobic capacity. Moderate-intensity exercise only improves aerobic capacity or endurance. Plus, HIIT training enhances aerobic capacity more quickly than long periods of moderate-intensity exercise. It does this in a number of ways. For one, it increases the amount of blood your heart pumps with each beat, leading to better oxygen delivery to tissues.  That’s important for your overall health.

HIIT Training Improves Cholesterol

Most people focus on keeping their cholesterol down, but one form of cholesterol, called HDL, is cardioprotective. This desirable form of cholesterol-carrying protein helps prevent damage to the inner walls of your arteries. It does this by removing cholesterol and transporting it back to your liver. High-intensity interval training raises levels of this “good” form of cholesterol with as little as 8 weeks of training.

High-Intensity Interval Training Improves Insulin Sensitivity

Insulin sensitivity is an important marker for metabolic health. Poor insulin sensitivity is associated with high blood pressure, heart disease, and type 2 diabetes. Fortunately, exercise, especially vigorous exercise, can enhance insulin sensitivity by as much as 58%. High-intensity interval training is a good prescription for people with type 2-diabetes since it helps with blood glucose control. When you work out at a vigorous pace, it increases the capacity of muscle cells to take up glucose. This bodes well for blood sugar control and metabolic health.

Need another reason to do HIIT training? Insulin sensitivity declines with age. The age-related drop in insulin sensitivity partially explains why both men and women tend to gain belly fat after menopause and are at greater risk for type 2 diabetes.

Vigorous Exercise Lowers Blood Pressure

High blood pressure is a risk factor for heart disease and stroke. HIIT training improves the way blood vessels function and can lower your blood pressure, although it may take up to 12 weeks of training to see a significant change. If you have mild high blood pressure, exercise alone may be enough to keep it controlled, but you should talk to your doctor before beginning an exercise program if you have poorly controlled high blood pressure. In fact, research shows exercise helps prevent the onset of hypertension with age.

Improvements in Body Weight

Obesity is a strong risk factor for heart disease, and HIIT training is a time-expedient strategy for fat loss. When you do high-intensity exercise, it’s a catalyst for the release of fat-burning hormones like epinephrine and growth hormone. The intensity of HIIT training primes your body for fat loss, unlike moderate-intensity exercise that your body quickly adapts to. Plus, you get the “after-burn” effect as your body expends extra energy to recover from the stress of vigorous exercise. So many people are interested in increasing their metabolism – HIIT does it for at least a few hours after you finish. Take advantage of it!

Some studies also suggest that high-intensity exercise is more effective for reducing a particularly unhealthy type of belly fat called visceral fat. This type of deep belly fat linked with health problems like metabolic syndrome, type 2 diabetes, and heart disease. Visceral belly fat increases in women after menopause as hormonal changes cause a reduction in insulin sensitivity. HIIT training is your best defense.

The Bottom Line

You’re probably doing high-intensity interval training to lose body fat or because you need a fast and effective way to stay in shape, but when you do this style of vigorous workout, you lower your risk for heart disease as well. It’s not necessary to train at this intensity every day, in fact, you shouldn’t. Doing a workout this intense every day will leave you exhausted if you’re doing it at the recommended intensity. Aim for 2 or 3 times a week of high-intensity training. Vary the exercises you do during the active intervals so you’re working your muscle groups differently. This will lower your risk for injury and add variety to your workouts. Keep your body guessing – and most importantly – have fun!



HIIT vs Continuous Endurance Training: Battle of the Aerobic Titans. Micah Zuhl, Ph.D. and Len Kravitz, Ph.D.

Metabolic Effects of HIIT Training. Len Kravitz, Ph.D.

J Physiol. 2010 Aug 1; 588(Pt 15): 2961-2972.

Diabetes Metab Syndr Obes. 2013; 6: 113-122.Published online 2013 Feb 27. doi:  10.2147/DMSO.S29222

Medscape Multispecialty. “Physically Active Avoid Hypertension, But Only if Fitness Is High” June 8, 2010.


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High-Intensity Interval Training: How Intense Does It Have to Be?

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Related Cathe Friedrich Workout DVDs:

HiiT and Interval Workout DVDs



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