High-intensity interval training (HIIT) is growing in popularity, and with good reason. It may be the most efficient way to work out, burning as many or more calories as traditional exercise in less time. With HIIT, you apply all-out, one hundred percent effort during short, intense bursts of exercise, followed by short recovery periods. These intervals are repeated, alternating “bursts” with “rests” over a designated period of time. HIIT training gets your heart rate up quickly and keeps it up, so you burn fat faster.
This fat-burning effect is due, in part, to HIITs beneficial effects on cortisol (aka your “stress hormone”). Cortisol is not all bad- it’s essential for regulating metabolism, blood sugar, sleep/wake cycles, and inflammation in the body. However, too much cortisol over time can cause weight gain (especially around the midsection), high blood sugar, high blood pressure, and lower immune function.
This is where long periods of intense cardio can become problematic. They put your body into “fight or flight” mode, resulting in elevated cortisol. Your body has the same response to different types of physical stress: it can’t distinguish whether you’re running because you enjoy it, or because you’re being chased by a tiger. This stress response gives you the opposite effect exercise is supposed to have, leaving you sluggish, achy, and more likely to gain weight.
The goal of HIIT exercise is to alternate intense periods where you spike your heart rate with enough rest in between to keep you from entering “fight or flight” mode. These intervals give your body the break it needs to recover and normalize cortisol, while still reaping the benefits of traditional cardio.
In addition to keeping cortisol in check, HIIT stimulates the production of human growth hormone (HGH) for up to 24 hours after your workout. HGH increases metabolism, boosts muscle growth and repair, and helps slow the aging process. Healthy levels of HGH may also improve brain function.
Along with its beneficial effects on hormones, HIIT is a great option for those with a busy schedule, since workouts are short and can be done anywhere. They can be done with or without equipment. You can use an elliptical, treadmill, bicycle, or simply your body. Aim for 3-4 days per week with rest days in between workouts. You do not want to do HIIT workouts every day, since they are (as the name implies) INTENSE!
Try the following beginner’s HIIT workout you can complete in just 20 minutes!
- Warm up for three minutes
- Go as fast and hard as you can for 30 seconds. You should feel like you can’t push any harder!
- Recover for 90 seconds (recovery should still be active- i.e. you should still be moving and putting some effort in to keep your heart rate up)
- Repeat the HIIT windows and recovery cycle 7 more times (8 total for each)