Invigorate your workout with interval training

By:
Jonny Bowden

If you're ready to take the next step up in intensity, burn some more calories and inject some novelty into a stale routine, interval training might be just what you've been looking for.

The idea behind it is relatively simple: Take a ho-hum run-of-the-mill aerobic workout and spice it up with a tough but short period -- called, appropriately, an interval -- of challenging intensity. Then bring it back down for a "recovery period" and do it all again. This basic template can be modified for levels of fitness ranging from virtual beginner to professional athlete.

Although the basics may be simple, the execution can be as easy or as difficult as you want to make it. To illustrate, though, we need some tangible measure of intensity. Exercise physiologists like to talk about "percentage of V02 max," which is a basic measure of how much oxygen you are using and can be estimated from your heart rate. Too complicated. For our purposes, let's use a simple scale of 1-10, with 1 being so easy it's practically like staying in bed and 10 being the hardest effort you're capable of putting out, one you couldn't possibly sustain for long.

Now let's further assume you've just begun a fitness program and have worked up to a simple, brisk 20-minute walk. Let's say that you would rate that brisk walk as a 3 on the scale of 1-10. Great. A basic interval program for you might look like this: Walk for a while at 3; now break out at 4 1/2 or 5 for a short spurt; return to 3 while you catch your breath, and, when you're ready, do it all over again.

Douglas Brooks, in his book Program Design for Personal Trainers, calls this a "spontaneous" interval, or "speed play." You're basically having fun -- deciding when to push the gas pedal and for how long, doing it kind of by instinct. It's a great way to start, and you can vary the "gas pedal" interval by time, intensity or frequency at your own pleasure. The recommended ratio of interval to recovery time is 1:3. So if you pushed the gas for 20 seconds, you'd spend a minute (3 times 20 seconds) in recovery mode before doing it again. Of course, in the very beginning, you may want to vary that and only introduce one or two intervals into the day's workout. That's fine. You get to choose how many "spontaneous intervals" you'd like to do in any given workout.

Next up in the intensity sweepstakes is a more structured pattern. For general aerobic conditioning, Brooks suggests that you use a 1:1 effort-to-recovery ratio. The "effort" interval should remain moderate, since you're going to do it for longer. Both effort interval and recovery interval should be 3-5 minutes. So, for example, if you're walking at a 2-3 level of difficulty, you do your effort interval for 3 minutes at 4-6 and then return to 2-3 for the same amount of time (3 minutes). Alternating these three-minute intervals of hard and easy gives you a lot of additional calorie burn and increases your aerobic conditioning. The number of cycles you do depends on your own goals, time and conditioning level.

Very conditioned folks can try an even more challenging model of interval training. This time the effort-to-recovery ratio goes back to 1:3, like in the "easy" spontaneous model, but the training interval is an all-out, killer effort, more like 7-10. You get to go back to the 2-3 level for recovery for three times the amount of time you spent in all-out mode, but you'll need it. These "killer" intervals are called anaerobic, because they are more like sprints and can't be sustained for a great amount of time on the aerobic energy system.

All of these models are easily adaptable to machines such as treadmills and stationary bikes. All you have to do is go in manual mode and push the "level" button up to the desired level for the training interval and then back down for the recovery one. When you're outdoors, simply use your own internal "rating of perceived exertion" scale -- how hard is it on a scale of 1-10 -- to determine what's up.

Interval training is a wonderful way to vary your training, increase your results, get better conditioned and fend off boredom. You'll find it's a great way to test yourself against previous accomplishments and to keep track of progress. It can push you off a stubborn plateau and move you past points of complacency into the heady arena of "I didn't realize I could do that!" feelings.

And once you do that, you'll want to keep it on the fitness menu permanently.

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