Twice the results in half the time! Hyperbole-laden promises like those are usually the province of infomercial hucksters and diet supplement marketers. But when you start digging into the science of interval training, you find doctors and researchers making similar statements.
What is interval training? In broad terms, it’s any form of exercise you can only perform for short stretches, explains Todd Astorino, Ph.D., a professor of kinesiology at California State University, San Marcos. Think of sprinting as fast as you possibly can, or cycling so hard you feel like your legs will fall off.
While going for a five-mile jog or 30-minute bike ride might push your lungs and heart to work at around 50% of their maximum capacity, interval training asks you to push those organs up to or above 90% of their max for short stretches—usually 30 seconds to two minutes. These intense stretches are interspersed with longer periods of rest.
Why do this? Keep reading. You may never run or cycle the same way again.
TIME, SAME (OR BETTER) RESULTS
Compared to traditional cardio, interval training is more time efficient, Astorino says. By that he means your body experiences the types of endurance and metabolism benefits of a long workout session in a small fraction of the time.
How small? One recent study from Canada’s McMaster University found going “all-out” on a stationary bike for just three minutes a week was enough to trigger significant and beneficial health adaptations among a small group of overweight but otherwise healthy guys. Those three minutes were broken down into three 20-second, balls-to-the-wall pedaling stints with two minutes of recovery time in between.
Basically, one minute of really hard pedaling a day, three days a week, brought about the kind of heart and muscle benefits an untrained guy might get from moderate 30-minute-long rides, the study suggests.
CLIMBING ABOVE YOUR PLATEAU
Research involving interval training and experienced endurance athletes is even more compelling.
One study from Australia’s University of Queensland found that, if you’re a regular runner or cycler, going for your usual 10-mile jog or hour-long ride might not do much to increase your endurance. On the other hand, interval training improves measures of endurance and cardio-metabolic fitness—even among these highly trained athletes, the study shows.
MORE BANG FOR YOUR BUCK, LESS BOREDOM
Cardio workouts out can be tedious and time consuming. But because interval training is based on variability—very intense stretches broken up by rest periods—tedium tends not to be an issue, Astorino says. “Doing the same intensity is boring,” he adds. “People enjoy dynamic exercises that change up intensity and stimulus.” If you have problems committing to a regular workout routine, you may stick with interval training longer than you would with traditional cardio exercise, he suggests.
Astorino also says the “magnitude of adaptations” when it comes to your metabolic or cardiorespiratory fitness— your heart and lungs’ ability to handle physical activity—would be “at least” as great from interval training as from traditional cardio.
BLOOD SUGAR BENEFITS, AND FEW RISKS
Research has linked interval training with healthier blood sugar levels, Astorino says. Those sorts of blood changes could protect you from metabolic diseases like type-2 diabetes.
Interval training is also “well tolerated” by a wide range of people, Astorino says. Even if you’re out of shape, there’s little risk associated with pushing yourself hard for short stretches, he says.
HOW TO GET STARTED
Some of today’s most popular workouts—from P90x to CrossFit—employ aspects of interval training. But you don’t have to shell out cash or join an exclusive gym to experience the benefits.
Whether you’re pushing yourself to sprint for one block, then rest for two, or interspersing 45-second periods of all-out pedaling during your normal bike rides, there are lots of ways to incorporate interval training into your workouts.
If your training is high-impact—meaning lots of jumping, lifting, or things that put stress on your joints—you could experience some soreness or pain in the beginning, Astorino adds. But he calls this a “minor annoyance” compared to all the benefits.