3 Vivarin = 600mgs... that's a LOT of caffeine!
The only time I use caffeine is with ephedrine as a fat loss aid. Even then, I use it only sparingly (100mgs at a time).
If you need a "caffeine crutch" to get through your workouts, you probably need more sleep. I shoot for 7-8 hours per night.
Excessive "caffeination" causes bone loss, dehydration, dependence, insomnia, stomach problems, decreased insulin sensitivity, headaches and high blood pressure.
Be careful.