I don’t use a power tap since I really don’t want to spend the money on it.  I’d love to have one, but just tough to drop that kind of coin.    After reading both Friel and Carmicheal, I learned another way to track workload.  Here is what they suggest:  Multiply the HR Zone by the number of minutes your in that zone, then add those numbers together. 

Example:
HR Zone 1: 10 minutes = 10
HR Zone 2: 5 minutes = 10
HR Zone 3: 10 minutes = 30
HR Zone 4: 20 minutes = 80
HR Zone 5: 10 minutes = 50
Total Workload = 180

Since using this method, I’ve found the intensity of my workouts increasing.  Based on the workout I’m doing, I can set a workload goal since I know how much recovery time and how much interval time I will have.  Initially I found my actual workload coming in much lower even though I felt like I was pushing hard.  My intensity has increased as I strive to reach my goal.  I find it to be a great training tool when not using a power tap.