The thought of interval training may be scary, especially if you’re considering the latest version of it. After all, HIIT is the acronym for “high-intensity interval training,” and the high-intensity part sounds like it could be difficult. With images of formats such as CrossFit and Insanity™ burned into one’s mind, interval training may appear to be fit for only the fittest.
Interval training comes in as many different forms as there are exercises themselves, and many people may benefit from it. Specifically, interval training is when you switch between periods of high-intensity exercise and recovery periods of lower intensity exercise.
You can turn nearly any activity into an interval session: walking and/or jogging outdoors or on a treadmill, bike riding—outdoors or stationary, a gym workout with free weights and other equipment, or at home with just your body weight.
The benefits of interval training
If you’re still unsure, consider this: Interval training may be an effective and accessible way to help you get fit compared with continuous moderate exercise without rest periods. Because of the built-in breaks, interval training may help you work out with more intensity and reap the benefits.
HIIT produces physiological, metabolic, and physical changes in the body. The good news is the harder you push—the greater your intensity of effort—the more calories you torch during your workout. This in turn causes your body to burn more calories post-workout.
Energy is needed to return the body to its pre-exercise state, and the more intense the training session, the longer it takes for the body to do this and the more energy is required to make it happen. This process is known as EPOC: excess post-exercise oxygen consumption. Cutting to the chase, your body will burn up to 15 percent more calories in the couple of hours after HIIT compared to a steady-pace session, where you exercise at the same intensity during the entire workout.
Aside from the obvious potential weight-loss benefits, research has shown, according to the American College of Sports Medicine, that interval training offers up some serious health advantages of boosting both aerobic and anaerobic fitness, improving cholesterol profiles and insulin sensitivity, reducing blood pressure, and burning up abdominal fat while maintaining muscle mass. (Abdominal fat includes visceral fat surrounding internal organs that has been linked to health problems like heart disease, type 2 diabetes, high blood pressure, abnormal cholesterol, and breathing problems.) Research indicates that HIIT may also help you burn subcutaneous fat—the stuff just under the skin.
Interval training may even help slow the progression of, and in some cases even prevent, muscle loss as you grow older. A 2017 study published in Cell Metabolism found that HIIT improved age-related decline in muscle mitochondria, the power generators of muscle cells. Researchers have also found that HIIT may help control blood glucose levels in people with type 2 diabetes and improve their cardiovascular health. And HIIT may also help improve your cognitive functioning, as a study published last year found.
Interval training tips for beginners
Use these guidelines to approach interval workouts safely and with confidence:
Consult with your physician before beginning a new exercise program, especially an interval training program.
Take things slowly at first, and see how you feel. You can push harder on subsequent sessions and gradually build to harder efforts. This includes increasing your speed and range of motion as you feel more comfortable.
How hard you work is up to you. You can adjust intensity by the exercises you choose and the length of your intervals. Keep in mind, however, that the higher the intensity, the shorter the work interval. For example, a tuck jump is a very high-intensity plyometric exercise that should be done for a relatively shorter amount of time than, say, jumping jacks. Also, the more intense the interval, the longer you should take to recover.
Use a consistent work-to-rest ratio, meaning the length of your work and recovery periods. For example, 30 seconds of work followed by 15 seconds of rest, which means the ratio is 2:1. You may choose whatever ratio you wish, just keep with it throughout the course of your workout session.
Recovery breaks can be low-intensity exercises or the time when you catch your breath as you prepare for the next working set. To begin, use the rest time to sip some water and prepare for what’s next. As you build endurance and strength, include balance exercises during recovery segments, such as standing on one foot or doing heel raises.
Never sit during the recovery period.
Move slower if you feel like you’re not recovering between the high-intensity sets. If that doesn’t work, extend the rest intervals by five seconds at a time until you feel you’re ready for the next round.
Hard breathing, rapid heart rate, and burning muscles are acceptable measures of pushing your body through intervals. Joint and back pain, lightheadedness, and the inability to catch your breath indicate a need to slow down and take longer breaks between sets.
Use a timer or timer app—the Seconds Pro interval timer app, the Tabata Pro app, and the Gymboss Interval Timer app —to guide you through the sequences.
We recommend doing HIIT training no more than twice per week, with at least 48 hours between workouts.