WTake a spoonful of white powder, mix it in a couple ounces of water, drink and wait for the body to tingle, heart rate to spike, energy to explode and muscles to swell.

These are not side effects of the latest street drug. They are bodily reactions to a more than $28 billion industry of pre-workout supplements being sold on shelves across America, which claim certain results often supported by athletes, bodybuilders and gym rats who contend the experience of unparalleled workout boosts.