High Intensity Interval Training and Heart Health

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The number one reason people say they can't stick with an exercise regimen is that they're just too busy. Enter high-intensity interval training, or HIIT for short.

Research shows that bursts of high-intensity activity can get your heart and lungs just as fit in less time, compared with the traditional prescription of 30 minutes a day of moderate-intensity exercise five days a week.

That sounds great for younger athletes. Many older adults worry that this type of intense exercise will cause more health problems than it solves by putting their hearts at risk. But research on high-intensity interval training in older adults, including those with age-related illnesses like diabetes and heart disease, is encouraging.

HIIT Basics

High-intensity interval training involves short bouts of intense exercise interspersed with longer periods of slower activity as recovery time. Any aerobic exercise can become a HIIT workout when it incorporates periods of intense effort (like sprinting).

Runners may be familiar with Fartlek or "speed play" training, which originated in Scandinavia several decades ago, based on similar principles. Since then, researchers have tested different interval patterns, varying the intensity and duration of both the all-out and recovery stages.

Martin Gibala, chair of the kinesiology department at McMaster University in Hamilton, Canada, revived interest in interval training in the mid-2000s. His research demonstrated that interval training delivered the same fitness benefits as moderate-intensity exercise in just a fraction of the time.

Later, Gibala and his team tested HIIT in eight older adults with diabetes. Gibala's data suggest that high-intensity training can be safe, effective, and—perhaps equally important—efficient for adults battling significant health challenges.

The study subjects showed measurable, beneficial changes in glucose metabolism, cardiovascular fitness, and body composition after just two weeks (six sessions). "Our study was small, but the results suggest that HIIT has real potential for improving fitness in older adults, without a major time commitment," Gibala said.

Indeed, subsequent research by Gibala and others has continued to show the benefits of HIIT for people with diabetes, prediabetes, and other health conditions.

HIIT and the Heart Patient

While numerous studies have shown the benefits of exercise for adults with cardiovascular disease, much of the research has involved moderate-intensity activity. But researchers are now examining whether high-intensity intervals are safe for older adults with serious heart problems.

One study, for example, reviewed research on HIIT in heart patients and found evidence of its safety and efficacy. Other research has shown HIIT to be safe in patients with chronic stroke and in sedentary older men.

Likewise, researchers reviewed 10 studies on HIIT in older subjects with conditions including coronary artery disease, heart failure, hypertension, metabolic syndrome, and obesity. The meta-analysis revealed that subjects using HIIT regimens showed greater improvements in cardiorespiratory fitness than people following moderate-intensity exercise programs.

Cardiorespiratory fitness—assessed by measuring maximum lung capacity—is also a predictor of better longevity. Martin Gibala believes HIIT holds strong potential and offers a real exercise alternative for improving the health of older adults.

"We know there's much more research to be done on HIIT," he says. "The traditional model of exercise may be the 'drug of choice,' with lots of supporting data, but interval training has shown lots of promise."

Gibala continues: "We're not demonizing traditional cardio guidelines. We just want to say that if people are pressed for time, they can safely consider this different exercise model."

Getting Started With HIIT

The first step is to get a doctor's OK to embark on interval training. Then, ramp up slowly. You don't need to hit a target of 95% of your peak heart rate, says Gibala.

If your daily exercise consists of an after-dinner walk with your dog, for example, he suggests using landmarks like light posts to insert more intense periods into the activity.

"Just get out of your comfort zone a bit," he advises. "Say, 'for these next two lamp posts I'm going to walk a bit faster.' You get out of breath, then slow down. You get a slight peak and a slight valley. For some people, that's an interval."

"We tend to use cycling for interval training because it's easy to measure in the lab," Gibala notes. "But you can also use an elliptical machine, swimming, uphill walking; any approach that uses large muscles like those in the legs will work."

Over time—and quite quickly, according to the evidence—your fitness level will improve. You will be able to sustain a higher-intensity effort, and will be able to achieve more of these active intervals.

6 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Little JP, Gillen JB, Percival ME, et al. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol. 2011;111(6):1554-60. doi:10.1152/japplphysiol.00921.2011

  3. Rezkallah SS, Takla MK. Effects of different dosages of interval training on glycemic control in people with prediabetes: A randomized controlled trial. Diabetes Spectr. 2019;32(2):125-131. doi:10.2337/ds18-0024

  4. Ribeiro PAB, Boidin M, Juneau M, Nigam A, Gayda M. High-intensity interval training in patients with coronary heart disease: Prescription models and perspectives. Ann Phys Rehabil Med. 2017;60(1):50-57. doi:10.1016/j.rehab.2016.04.004

  5. Weston KS, Wisløff U, Coombes JS. High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis. Br J Sports Med. 2014;48(16):1227-34. doi:10.1136/bjsports-2013-092576

  6. Gibala MJ. Interval training for cardiometabolic health: Why such a HIIT?. Curr Sports Med Rep. 2018;17(5):148-150. doi:10.1249/JSR.0000000000000483.

Additional Reading

By Sharon Basaraba
Sharon Basaraba is an award-winning reporter and senior scientific communications advisor for Alberta Health Services in Alberta, Canada.