From enhancing endurance to boosting metabolism and blasting fat, high-intensity interval training (HIIT) comes with some substantial health benefits. Defined by periods of hard effort followed by short rests, the idea behind HIIT is fairly straightforward.
And whipping up a HIIT routine is super easy too — you don't need any special equipment (or even a gym for that matter) to do intervals of jumping jacks, push-ups and mountain climbers. That said, there are also a ton of ways to mess up and sabotage your results.
1. You Do HIIT Every Day
"Over training is a real thing," says Summers. "If you do HIIT every day, your body will start to break down." It's true. Over time, if you work out too intensely on most days, you're likely to experience overuse injuries like tendinitis or stress fractures, according to the Mayo Clinic.
Plus, the stress that overtraining causes to your body is associated with hormonal imbalances that result in chronic fatigue, according to a February 2013 review in the Journal of Novel Physiotherapies.
Instead, aim for about two to three HIIT sessions a week (no more than four), always giving your body at least a full day in between to rest. You don't have to take those days totally off of exercise altogether, though, you can try low-impact, cross-training workouts like swimming, walking, cycling, hiking or yoga.
2. You Don’t Push Yourself Hard Enough
"HIIT training is not meant to be short and sweet; it's meant to be quick and dirty," says Summers. Meaning, since HIIT workouts can be as brief as 10 to 20 minutes, they're supposed to be intense (hence the name). You'll gulp in air, your muscles will burn and your heart will hammer against your chest — that's the point. On a scale of perceived exertion, where the max is 10, you should be at an eight or a nine.
If you don't go beast mode during work intervals, you won't reap the fat-burning, metabolism-boosting benefits. So don't hold back and conserve your energy like you might for a longer workout — give it all you got.
3. You Go Too Hard, Too Quickly
That said, if you're a HIIT newbie, doing too much too quickly can backfire. For example, when you push too hard during the first work interval, you might not have enough gas in the tank for the last. Or worse, you might injure yourself.
So, what can you do? Consider how many intervals you'll be doing ahead of time and strategize how to pace yourself, says Summers. The idea is to start at a moderately high level of intensity and then ramp it up a notch with each successive interval. That way, you're working hard from the get-go without using up all your energy in one fell swoop.
Also, you might want to start with a shorter workout, say eight-minutes long, so you can maintain your intensity for the duration of the routine. Then, gradually progress to something longer as you get stronger.
4. You Rest Too Long Between Sets
Anyone who does HIIT lives for those little breathers between work intervals. Indeed, short recovery periods are necessary when you're gunning at your max, as they give you the oomph you need to maintain your intensity. Just make sure you're not resting too long.
HIIT is an intentionally timed workout, so sticking with a work-to-rest ratio like 2:1 is essential for fitness gains, says Summers. That means if your work intervals are 30-seconds long, you should recover for 15 seconds. Ideally, you want a rest time that helps you catch your breath but that's also short enough to keep your heart rate up.
5. Your Intervals Are Too Long
When it comes to HIIT, less is more, says Summer. For HIIT to be effective, it needs to be quick and intense. Matter of fact, if you're really pushing with maximum effort, odds are you won't be able to maintain the same vigor for very long.
That's because when you do a too-lengthy HIIT routine, your body won't be working as efficiently — you'll either hold back to preserve your energy, peter out halfway through or hurt yourself. That's why most fitness experts suggest capping HIIT routines at 30 minutes, tops.
6. Your Form Is Off
"Since HIIT is a quick workout, many people rush each exercise," says Summers. The issue? When you breeze through a movement, you don't pay attention to proper form or exert appropriate control over the move.
When your form suffers, you put stress on your body — especially your joints — and increase your risk for injury. To ensure good form, pick simple moves you can perform well. Better to do fewer reps with perfect form than more with crappy technique. And always master the body-weight version of an exercise before adding any weight.
7. You Skip Your Warm-Up or Cooldown
"A car can't go from zero to 100 mph without warming up, and the body is the same," says Summers. HIIT is demanding as it involves high impact moves like jumping, which can be hard on the joints.