Measuring Interval Intensity

You can use two methods to measure how hard you are working based on effort during an interval training session-- using a set scale or using your heart rate to determine your intensity.

By using a rating of perceived exertion (RPE) scale, you can rate your intensity and effort by the way it feels to you, assigning it a number. Some use a 15-point Borg scale with 6 representing no exertion and 20 representing maximal exertion . You can use a Category-Ratio scale, in which 0 is no effort at all and 12 is the absolute maximum.

However, I think it's easier to simplify things and rate effort on a 0 to 10 scale, where 0 is no effort and 10 is maximal effort. Then you can correlate these numbers to percentages and say that a 5 is 50 percent effort and a 10 is 100 percent effort (the point at which you can't do any more). You should be at 5 at the end of your warm-up, at 3 at the end of your cool-down, and at 9 or 10 (for advanced interval trainers) during the work portion of the workout. For example, a beginner should warm up to 5, work at 6 to 7, recover at 5 to 6, and cool down at 5 to 3. Intermediates should warm up to 5, work at 7 to 8, recover at 6 to 7, and cool down at 5 to 4. Advanced trainers can warm up to 5, work at 8 to 10, recover at 7 to 8, and cool down at 5 to 4.

Using your heart rate maximum (HRmax) to determine intensity is a little difficult and sometimes inaccurate, because heart rate doesn't always correlate with effort, but wearing a heart rate monitor will simplify things. For safety for beginners, using the age-predicted maximum heart rate formulas and a heart rate monitor to assess your intensity is essential. To determine what heart rate to work at for your intense work sessions, calculate your age-predicted maximum heart rate (APHRmax) and multiply it by the appropriate intensity percentage. The American College of Sports Medicine (ACSM) recommends an intensity percentage between 60 and 90 percent for work sessions. For a beginner, work ratio intensities should be between 60 to 80 percent and then can progress up to 85 to 90 percent as you become more acclimated to interval training. Here's an example for a 30-year-old female beginner who wants a 70 percent intensity work bout:

APHRmax = 220 - age (220 - 30) = 190 × .70 = 133

You can also arrange the heart rate percentage to reflect your selected recovery heart rate. Let's say that our 30-year-old beginner wanted to recover at 60 percent of her APHRmax:

APHRmax = 220 - age (220 - 30) = 190 × .60 = 114

Then she wouldn't begin her next interval work repetition until her heart rate had recovered to 114 beats per minute.

The first time that you try interval training instead of your usual cardio program, you'll be pleasantly surprised at how difficult it is. If you are in the gym using cardio equipment that is computerized, record the METs (metabolic equivalents, based on a method of measuring energy expenditure in relation to the resting metabolic rate), miles, number of steps climbed, and so forth for your typical endurance session and compare it to your interval session. You will find that you are actually working harder for longer, but in a shorter overall period of time. Don't we want the biggest bang for our buck-he best workout in the shortest time period so that we can get on with our lives? Interval training can deliver that and more. The following are two interval workouts you can incorporate into your cardio program:

Stadium intervals-You can use stadium bleachers found on high school or college campuses, or you can use regular steps or stairs for this interval workout. Your work is walking or running up the steps, and your recovery is walking or running down the steps. Beginners should start by walking one step at a time with their arms at their sides, then move, when ready, to walking with arms overhead. Progress to running, then to taking two steps at a time, for a more intense work bout. Always begin with a five-minute warm-up and end with a five-minute cool-down. Gauge your work and recovery ratios by either the heart rate method or rating of perceived exertion (RPE) method (detailed in the following section).

Bicycle or treadmill intervals-You can also simply use an interval program or hill program on the standard computerized bicycles found in most gyms for an interval workout. The resistance you have to pedal against on the bicycle will increase during the work bout while you try to maintain a high RPM and will decrease during the recovery bout. Of course, you can also control the program manually if you prefer to control your work-to-rest ratio. Another way to intensify the work bout is to crank it up to the highest level of tension and then stand up and ride the bike (without your bottom touching the seat), while still trying to maintain the same RPM. Does this sound like one of those indoor cycling classes? Most of these classes do incorporate intervals. Some treadmills are also programmable, and some require a manual adjustment. You can choose a walk-jog, walk-run, walk-sprint, or jog-sprint, run-sprint WRR, depending on your level of fitness. Adjusting the incline on the treadmill is also a nice way to progress the intensity of the work session.