HIIT Prescriptions

In my last post I discussed high-intensity interval training and its benefits, but didn't provide a lot of practical information in terms of incorporating it into your own program. Today I'll be covering some basic HIIT prescription and expanding upon why high intensity exercise is so beneficial.

Before getting into the nitty gritty science and research bits, let's look at a couple of very simple ways you could incorporate HIIT into your exercise regime.

Depending upon the volume of resistance training you do (or don't do, but you should!) 1-3x per week is probably going to be plenty in terms of HIIT frequency. When done properly, HIIT should be taxing and requires a bit of time to recover from, so generally it's best to perform it on non-consecutive days. HIIT can be done on a day of its own, or thrown in after your resistance training session. The beauty of HIIT is how brief your cardiovascular exercise can be. A good bout of HIIT is probably going to last between about 10-25 minutes of actual work, with only a fraction of that being at a high intensity.

A couple protocols that I like are 15/45 and 15/75. That'd be 15 seconds of max effort work followed by 45 or 75 seconds respectively of a recovery pace. Max effort means you go as fast as you possibly can. Recovery pace should be fairly easy and the goal is to be prepared for the next max effort interval. Try not to kill yourself during the recovery period, go easy and get ready. This sequence would be performed 10-15 times total in a workout.

The entire thing, using 15/45 as an example, would look like this:

Warm-up - ~5 minutes of gradually increasing intensity, but nothing too strenuous
Intervals - 15 seconds max effort, 45 seconds recovery, repeated for a total of 10-15 times (10-15 minutes total in this case)
Cooldown - ~3-5 minutes of gradually decreasing intensity as heart rate begins to return to normal

As you can see, total time, including warm-up AND cooldown is at most 25 minutes for this example.

Intervals that are of short duration, such as 10-30 seconds, are best performed on pieces of equipment that allow you to rapidly change your speed and intensity. Rowing machines are fantastic, spin bikes and ellipticals work as well, as does running on a track or outside. Treadmills are not optimal for this kind of interval because it takes an extended period of time to increase and decrease speed.

Intervals of a longer duration can also be performed, and it's nice to get a mix in once in a while. When doing longer intervals, you can either base them on distance or time. For example, you might do 4-6 sets of 400m on the treadmill/track or 500m on the rowing machine with 1-4 minutes of rest in between them. Try to finish each interval as quickly as possible. Instead of distance you could perform 1-2 minute intervals. The distance or time for each interval does not really matter, as long as they are relatively brief (no more than a few minutes) and performed at a high intensity with recovery in between.

You can abstract this concept to any number of other workout formulations. For example, you may try to see how many times you can sprint 50-100m in 15-20 minutes or you can randomly intersperse bursts of intensity into an otherwise relatively steady state workout. If you're a particularly sick person you can do fun things like find a hill that takes 15-30 seconds to sprint up and see how many times you can repeat that in 15-20 minutes or how long it takes you to perform 10-20 sprints up it. Stairs work in a similar fashion.

High intensity training methods are so effective because they result in a physiological condition called EPOC (excess post-exercise oxygen consumption). What exactly contributes to the EPOC effect physiologically is not completely clear, but the basic premise of it is that after exercising at a high intensity, your metabolism is elevated for a period of time afterwards. When the body is at rest, it burns more calories from fat, so an elevated metabolism at rest is great for fat loss. The duration of EPOC depends upon the intensity and duration of exercise and appears to be longer when resistance training is involved.

I don't think you should go and replace every single episode of your traditional cardiovascular work with HIIT, but if you are short on time and can only pick one, go with something that is higher intensity. Ideally a blend of HIIT and more sustained cardiovascular conditioning should be performed to achieve the best of both worlds, especially if you enjoy doing long slow distance cardio.

My next post will continue our high intensity trend and discuss what happens when we introduce the resistance training variable into high intensity conditioning methods (and thus why our kettlebell bootcamps are so awesome for fat loss and improving conditioning!).

In essence: HIIT alternates periods of high and low intensity. The lengths of the high intensity interval doesn't have to be super specific, but it needs to be relatively short so that it can be approached with a max effort. I like work/rest ratios of 15/45 and 15/75 on equipment like rowing machines, bikes, ellipticals, or running on a track or outside. You can also have longer intervals based on time or distance. Repeats of 400m runs or 500m rows with a couple minutes rest in between are great. If you're masochistic, you can see how many times you can run up a fairly steep, short-moderate distance hill in 15 or 20 minutes. Stairs work too. Max effort means WORKING AS HARD AS POSSIBLE! Recovery/rest means just that, let yourself recover for the next interval. High intensity training methods elevate your metabolism via EPOC. A blend of HIIT and longer duration cardiovascular exercise is probably optimal compared to picking one or the other, but if you're short on time, do HIIT.

- Jonathan