According to their book, “This workout is self-regulating and evolutionary. That means no matter what your present condition, you’re ready for the ‘20-minute Aerobics Solution’, and you can never outgrow it”. It uses what they call the “Intensity Index”. This is a scale that goes from level 1 to level 10. Level 1 would be sitting on the couch watching TV (requires no intensity) level 3 may be walking, level 5 may be a fast walk (moderate intensity) and level 10 would be an all-out 100% effort sprint (maximum intensity). These levels will differ from person to person as everyone's level of fitness is different,
How to do the 20-minute Aerobics Solution workout
To do this 20 minute workout simply choose an exercise you like doing, such as a treadmill, jogging or a spin bike (like I did). You start by doing a 2 minute set-up phase at a level 5 intensity. After 2 minutes, your level should increase to level 6 for 1 minute, then level 7 for 1 minute then level 8 for 1 minute then level 9 for 1 minute. After the level 9 it goes back down to level 6 and we repeat the cycle 3 times. On the last cycle (between the 18th and 19th minutes of this 20 minute workout), we try to push it to a level 10. Basically, this is putting in maximum effort for the minute. Then for the last minute it goes back down to a level 5 to cool down. The table below shows the time and the intensity levels:
If you haven’t been exercising much before, a small jog may be maximum effort. But as you get fitter, your speed will increase. When I do this on the spin bike I use the RPM as my guide for intensity level. When you are concentrating on what level you are doing, the 20 minutes goes by super fast.
I would encourage you to give this work out a go. Even if you already do cardio, try it and see what you think, then let me know. I would be interested to see your thoughts.
Body for Life, Bill Phillips, Harper Collins Publishers, 1999