I would keep it under 50 mg per dose, that is the amount in the Cliff bars (peanut toffee buzz) I've been using. The caffeine in it comes from a green tea extract. Ive also used the Hammer gel product with 25 mg with no ill effect. Cant stress enough to try it in training first.
By the way a cup of coffee has about 90- 150 mg (unless my wife made the coffee then it has 3000). If you can't get a product like the one i mentioned try using your regular rehydration drink and then eat some dark chocolate. The whole idea is to keep your body processing what your drinking and eating. The harder your working and the hotter your body gets the more of a problem it becomes.
Remember you only really need to use a rehydration drink if your event goes past the 1 hour to 1.5 hour mark, other wise just drink water.
P.s. when i think "energy drink i think red bull, monster, rock star,et all... thats not what i am talking about when i say rehydration drink. Im talking about Gatoraide , Acceleraide, Hammer nutrion and the sort. I have never had an energy drink, other than coffee. Sorry if i was not clear.
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