Is High-Intensity Interval Training Right For You?

There's no question it's a great way to smash calories, but is high-intensity interval training (HIIT) actually good for you? Take a look at what the science says about this popular method of getting in your cardio.

Defining HIIT

High-intensity interval training (also known as sprint interval training or high-intensity intermittent exercise) is a form of cardiovascular exercise in which short intense periods of activity are separated by intervals of rest. Associated with increased calorie burn, HIIT promotes fat loss and builds lean muscle mass. Intervals are typically about 20 seconds long, with 40- to 60-second rest periods, for a 1:2 or 1:3 work-to-rest ratio.

Explosive movement requires too much energy for aerobic pathways alone, so the body relies on anaerobic ones, which don't use oxygen, for energy. This generates energy more quickly but is difficult to sustain. Because of the demanding nature of HIIT, optimal workouts typically last 20 to 30 minutes.

Benefits

HIIT challenges your body, pushing your muscles to their limit before giving them full recovery, as opposed to typical exercise, in which you conserve energy to perform a movement for a longer period. The benefits of pushing your body in this way are impressive: increased speed, metabolism (for up to 48 hours), V02 Max (better use of oxygen) and improved explosive performance, insulin sensitivity, blood pressure and cardiovascular function. Significant excess post-exercise oxygen consumption (EPOC) supports weight loss and gets you the best bang for your buck in terms of total calorie burn per minute of work.

Risks

Anyone new to exercise or unsure how to safely perform HIIT should not engage in it until they are thoroughly educated on the method. Due to its explosive nature, HIIT can cause muscle, joint or tendon injury, particularly if you're not able to maintain proper form. (Using body-weight exercises instead of those that use equipment can minimize risk.) Diving into HIIT without a proper HIIT warm-up, which is more intense than a usual one, can also lead to strained or pulled muscles. Pushing too hard, too long or too often can be overwhelming both mentally and physically, leading to injury, dizziness, pain and unsustainable practices.

It's always advisable to talk to your doctor before starting any new workout program, particularly one as intensive as this. HIIT may not be recommended if you are: pregnant or three to six months postpartum; injured, immunosuppressed or ill; have a heart condition or recent history of cardiac surgery, osteopenia, osteoporosis, pelvic floor weakness or prolapse.

HIIT modifications

It's important to realize many "HIIT workouts" aren't actually HIIT, but are rather cardio interval workouts that don't require pushing to your max every circuit. If your doctor deems you healthy and your joints don't mind, an interval workout should be okay. Plus, even "modified HIIT" still produces cardiovascular, muscle endurance and strength benefits. Modified HIIT may be the safer and better option for the average person, but your doctor may have an opinion on this.

True HIIT may not be right for you. What's safe for one person may not be for another, even the same age, gender, athletic ability, etc. Even experienced athletes should keep in mind that not giving yourself time to recover can result in burnout and decreased performance over time.

Safely incorporating HIIT into your life

Do your research, understand the technique and make sure you maintain form. Don't engage in HIIT more than twice a week and make sure to schedule rest days in between. If you prefer exercising daily, go for long walks or engage in a gentle yoga session so your "off days" still provide movement.