High-intensity interval training (or HIIT) appeared for the first time in the American College of Sports Medicine’s list of top 20 fitness trends for 2014, and it snagged the top spot. This past year’s predictions had it ranked second only to body weight training. This “trend,” however, has been around for much longer than two years. HIIT actually comes from the Tabata Protocol, researched in Japan in response to their national skating team’s unique training regimen in the ’90s: 20 seconds of high-intensity activity alternated with 10 seconds of rest. Many routines involve a few repetitions to create a workout that lasts 8 to 10 minutes excluding warm-up and cool-down. The key is to choose an uncomplicated activity that allows you to really push yourself as hard as you can for those 20 seconds. It’s not supposed to be easy. It’s supposed to be effective. You can find a routine online that was created by Dr. Izumi Tabata himself. HIIT evolved from Tabata and is not always as rigid. Intervals don’t need to be a certain length, and intensity may not necessarily need to be as high. Still, the goal remains the same: Push yourself really hard for a period of time, let your heart rate come down briefly, and then bring it back up by pushing yourself again. Sounds simple enough, right? Simplicity isn’t the only reason people love it. Here are some more.
THE PROS:
SHORTER WORKOUTS. Did you know that federal guidelines for physical activity recommend a minimum of one hour of exercise every week? That number is higher for children, adolescents, and anyone interested in weight loss. Many people find it hard to meet those guidelines. HIIT means you get in and out of your workout faster. MORE EFFECTIVE WORKOUTS. When done properly, HIIT can be just as effective as–if not more effective than–training longer at a lower but steady intensity. This is because the periods of really high intensity can help your body burn more calories even after the workout has ended. HIIT has also been shown to improve fitness levels, blood pressure, cholesterol levels and heart health, insulin sensitivity, and preservation of muscle mass during weight loss. Shorter workouts, greater gains in fitness and health…what’s the catch?
THE CONS:
EFFECTIVENESS. I know, I know: How can effectiveness be a pro and a con? To reap all of the benefits I just mentioned, you have to push yourself to high intensity. Everyone’s high intensity is different, but too often what is meant to be a vigorous interval winds up being moderate or lighter. Without getting to at least 80% of your maximal effort, you won’t have a shorter, more effective workout. You will just have a shorter workout. SAFETY. HIIT is, well, intense, and people all over are getting hurt by jumping in too quickly. Individuals are pushing themselves too hard and too often, winding up with injuries or worse. Exertional rhabdomyolysis (“rhabdo”) is a condition marked by muscle breakdown so great that it can cause kidney damage. The most severe cases are, in fact, fatal. During my dietetic internship clinical rotation, I saw young patients hospitalized for this condition, all because they went too far during a workout. HIIT may be effective if you push yourself hard, but only if your body is ready to take that kind of push.
THE BOTTOM LINE: FIT OR FLOP?
FIT, if we are careful. Here are my top five tips for using HIIT safely: 1) Always get a doctor’s clearance to exercise, especially if you have a medical condition (but even if you don’t). 2) If you’re new to exercise (or a bit rusty!), start with longer rest periods and less intense, shorter work intervals. As your fitness improves, your rests can shorten, and your intensity during the activity portion can increase. 3) Give your body time to recover. Start with just one or two sessions a week. Even at your peak fitness level, space HIIT out with other training techniques. 4) Always, always warm up and cool down. I know it seems silly to spend five minutes warming up for a 10-minute workout, but it’s crucial to avoiding injury. And yes, you do need to stretch afterward. 5) Consider employing the help of an experienced personal trainer, who can watch out for any muscle imbalances you may have and design an effective program tailored specifically to you. And last but certainly not least, remember to find a routine that you enjoy. The most effective program in the world isn’t worth it if you dread your sessions, so keep trying new things. It won’t be long before you discover a program that makes you feel truly, vibrantly, and powerfully alive.
