An excerpt from Death of the Diet:
“Interval training is an advanced, highly effective form of cardiovascular training. It involves brief bursts of higher-intensity work – anywhere from 15 to 60 seconds – followed by a recovery period. A classic example is to run or walk quickly for 30 seconds, then walk more slowly for 60 seconds, and repeat. The amount of time spent resting between high-intensity bursts usually starts at two or three times the length of the burst, like in the example above, but advanced exercisers can reduce rest periods until they’re equal to or even shorter than the work phase.
Studies have shown that these brief bursts of activity boost your metabolism and may burn more total fat than the “low and slow” cardio that most people consider to be aerobic exercise—and it’s over faster! On top of that, interval training can provide many of the same benefits as resistance and neuromuscular training.”
While interval training will not prepare you for a marathon, interval training is a great option for those people who want to burn calories, fast. The main concern with interval training, however, is that the harder we push our bodies, the greater the risk of injury. To maximize results while minimizing injury risk, follow these three tips:
Use an Honest Rate of Perceived Exertion (RPE) Intensity
A low-tech, but effective method for measuring interval intensity is rating of perceived exertion (RPE). Use RPE to estimate how hard you’re working, and progress yourself gradually. This is how it works:
Imagine a scale of 1 to 10, where 1 is the easiest activity ever and you could do it forever. 10 is the hardest, most challenging intensity and you feel like you’re going to collapse. After self-myofascial release and movement preparation, an interval training warm-up (five minutes or so) should have you around a 4 to 5. When you get into the interval, you should be pushing yourself anywhere from a 6 to a 9, depending on your experience with training and intervals.
If you’re newer to intervals, aim for closer to a 6 to 7. If you’re more experienced, you can push towards an 8 to 9. Then recover at a rate of about 3 – easier than the warm-up. Repeat this anywhere from six to twelve times, depending on the duration of your interval. For example, a 1-minute “on” and 2-minute “off” interval can be done six times in 18 minutes, while a 30-second “on” and 60-second “off” is performed twelve times in the same period.
Even if you’re experienced with exercise, keep in mind that interval training is a new stress on the body, so it may take some time to adapt so be honest with how hard you’re working. There’s no point in calling something “easy” if it gets you injured.
Use Familiar Movements and Equipment
The great thing about interval training is that you can use a variety of tools – cardio machines, bodyweight exercises such as squats or pushups, jumping jacks, jump rope, kettlebells, and more. Because you will be performing movements at a greater intensity and higher fatigue points, any poor form or compensations will be magnified. The key to interval training is pushing yourself in good form for a brief period.
Therefore, be sure to choose exercises that you are extremely familiar with and you have confidence you can do properly, even when fatigued. Choose the exercise or cardio machine you’ve been using for a long time, not the one you just started last week. Learn the correct form for any exercise before you push the intensity level. Additionally, consider the potential of joint impact – for example, elliptical may be better for those who can’t tolerate the impact of lots of running at high speeds.
Everything in Moderation: Progress Gradually
As mentioned earlier, if you’re new to interval training, keep your intervals at the lower end of the range, around a 6 or 7. As you get better, you can eventually increase that towards an 8 or 9. As you get even better you can start increasing the work rate and reducing the rest time.
When progressing yourself, however, change only one variable at a time. For example, don’t increase intensity via RPE or interval length and also decrease rest time on the same day. I often give clients a little more rest time on days when I progress their intensity. Then we focus on reducing rest time in future sessions.
If you enjoy intervals, slowly work up to no more than two or three interval training sessions per week and supplement with other forms of exercise or physical activity. Performing interval training too often keeps your body from recovering properly and increases your injury risk.