High-intensity interval training seems all the rage these days, as both anecdotal information and scientific evidence support its claims to be an efficient and effective form of exercise. The intensity is thought to facilitate muscle growth and better body composition, while also keeping the heart rate at an elevated level to increase cardiovascular health and performance. However, many experts are concerned that deconditioned clients may think the programming is too tough. Is there a way to facilitate HIIT sessions that doesn't leave novice exercisers feeling overwhelmed? A new study says yes.
To begin with, what is HIIT? HIIT, or high-intensity interval training, is a training technique in which you give all-out, one hundred percent effort through quick, intense bursts of exercise, followed by short, sometimes active, recovery periods. This type of training gets and keeps your heart rate up and burns more fat in less time. "A high-intensity workout increases the body's need for oxygen during the effort and creates an oxygen shortage, causing your body to ask for more oxygen during recovery," says Eric Salvador, NASM, NSCA, head instructor at The Fitting Room in New York City. This afterburn effect is referred to as Excess Post-Exercise Oxygen Consumption (EPOC) and is the reason why intense exercise will help burn more fat and calories than regular aerobic and steady-state workouts.
Reported in Medicine & Science in Sports & Exercise, the study included 20 overweight and deconditioned people around 22 years of age. Participants completed several types of high-intensity training. The first was a 20-minute continuous workout without a rest. The other three workouts lasted 24 minutes each and featured a 1:1 work-to-rest ratio of 30 seconds, 60 seconds and 120 seconds, respectively. The goal was to determine perceived exertion ratings (RPE) for all four workouts.
Before the training began, participants anticipated that the 120-second protocol would require the greatest exertion. During all workouts, RPE increased from beginning to end. The highest overall perceived exertion resulted from the continuous workout, followed by the 120-second protocol. The 30-second protocol produced the lowest RPE of the interval scenarios, despite producing the same volume of work as the other protocols.
The authors believe that these findings may be beneficial in attracting more people to participate in and benefit from HIIT. These findings suggest that 30-[second HIIT] protocols limit the perceptual drift that occurs during exercise, in comparison to [heavy continuous] exercise, they explained. Moreover, performing more intervals of shorter durations appears to produce lower post exercise RPE values than performing fewer intervals of longer duration and equal intensity. Because effort perception may influence behavior, these results could have implications for the prescription of interval training in overweight sedentary adults.