There always seems to be confusion about the activity levels so I hope this post helps.
Physical Activity Factor and Grams of Protein per Pound of Lean Body Mass
Light activity (e.g., walking); .6
Moderate activity (1.5 hours per week); .7
Active (1.5 to 2.5 hours per week) .8
Very active (greater than 2.5 hours per week); .9
Elite athlete (or weight training five times per week); 1.0
Dr. Sears says on pg. 10 of "MTZ" "Keep in mind that people tend to overestimate their physical activity, just as they underestimate how much they actually eat. So here are some guidelines. If you walk 30 minutes a day seven times a week, then consider this light activity. If you work out three days a week for about 30 minutes a day, this would constitute moderate activity (this is about 1.5 hours per week of formal exercise). If you are working out five times a week for about 30 minutes (or about 2.5 hours per week), consider yourself active. If you do weight training at least three times a week in addition to working out for more than 2.5 hours per week, you are in the very active category. And finally, if you work out intensely twice a day, consider yourself an elite athlete".
The active category can be 1.5 hours of weight training up to and including 2.5 hours of weight training a week or working out 5x a week for about 30 minutes doing formal exercise.
When I initially began the Zone lifestyle, I wanted to know what the difference was between "very active" and "elite" because I was certainly doing enough exercise to qualify as an "elite athlete". I e-mailed Cara Hogue, a Zone trainer on the Zoneperfect site and she advised me that "the jump from very active to elite has to do solely with hours of weight training (60% or more of one rep max), not other activities." Cara Hogue also advised me in another e-mail that "the workouts you count to calculate protein needs are the weight workouts, not Tae-bo or yoga workouts".
She also said "use very active for weight training 2.5 hours per week, and elite for 3.5 or more hours per week (2.5 - 3.3 is generally very active)". So if I had increased my weight training and kept my other activities the same I could have moved up a category.
I also asked Cara Hogue about extra blocks for aerobics. She said "adding one block 1/2 hour before and/or 1/2 hour after intense aerobics exercise (depending on your eating schedule) or between exercise types will help stabilize your blood sugar and hormones, but will not throw off your eating".
I searched more of Cara Hogue's material on the Zone Perfect site and concluded from her posts that to get the extra block and not count it, one must be doing 45 minutes of intense aerobic exercise. Also, if doing weight training 5 times a week, you automatically get an extra block and you don't have to count it.
P.S. I know that this will not cover off everyone's individual activities so my suggestion is when trying to find the appropriate level pick a category that best suits you individually. Eat that number of blocks for a couple of weeks and monitor how you feel (ie are you tired, fatigued etc). Keep checking your measurements and muscle and fat on the body fat calculator to see if you need to increase a block (because you are losing LBM) or you need to decrease a block (because you have gained fat). The activity levels are all a fine-tuning process, just like adjusting carbs and fat are in the Zone. Not everybody's biochemistry is the same. Remember, that you don't want to overeat protein. Dr. Sears says "never consume any more protein than your body needs to maintain your lean body mass, but never eat less. Eating too little is to subject yourself to protein malnutrition".