RealAge Workout Scale
From "RealAge Workout: Maximum Health, Minimum Work"
To help you gauge your level of intensity, I have developed a scale from 1 to 10. (You need to reach at least 6, and preferably 7, to be at the heart rate that gives you the most benefits form stamina activities.)
1. Effortless. How you might feel when reclining to watch television. There is no elevation in your breathing.
2. Very light effort. How you might feel brushing your teeth, shaving, or putting on makeup. There is no noticeable elevation in your breathing.
3. Light effort. You might experience this level while walking around the house. There is a slight elevation in your breathing, but you are probably not aware of it.
4. Light to moderate effort. When you go for a leisurely stroll, you may reach this level. Your breathing is noticeably elevated but still relatively slow and comfortable.
5. Moderate effort. You are on a brisk walk. You can still easily carry on a conversation, but you are aware that you are working. Your breathing rate and depth are increased.
6. Moderately heavy effort. You walk as quickly as possible. You know you are breathing harder, but at the same time you know you can continue at this pace for a while. You begin to perspire lightly.
7. Heavy effort. You are breathing faster and deeper, and you are perspiring. You could still carry on a conversation, but you'd rather not. This is likely where you will spend much of your stamina-exercising time.
8. Very heavy effort. You are exercising so vigorously that you are not sure you can keep up this pace for the next 15 minutes. You can converse only in short phrases. You have a feeling of discomfort (but not necessarily of a negative sort).
9. Extreme effort. You are exercising at your peak, and must concentrate to keep up this intensity. You feel you cannot do it for long. Many professional athletes train in this range, but it is unnecessary for the rest of us.
10. Maximum effort. Most exercisers never reach this level, and it is not advisable to try to do so.
Source: Dr. Michael F. Roizen