I used it for a couple of weeks. Getting up at 5am to workout is tough so I would take a Charge 30 min prior to working out. I found that my legs would shake a lot more than they nornally would lifting. At first I thought is was just my workout and then it happened the next three workouts. I stopped taking it and the shaking has stopped. I also stopped taking it b/c I started breaking out with zits...ugh!
Regardless. I did get a burst of energy which helped with my workout, however I did "crash" after a few hours. I only took the 1 capsule dosage. Guy friends of mine were taking 2 at a time and said after a few times they didn't feel anything.
Sorry I couldn't be of anymore help.
Have you tried it yet?