Natural, Mixes Instantly, Tastes Great. Supports Muscle Production. No Artificial Sweeteners. NOW Arginine Power Super Stack is the ultimate energy sports supplement that also supports optimal performance. Arginine Power Super Stack has Creatine, a well-studied sports supplement, for its ability to support lean muscle production and muscle cell fuel availability. Yerba Mate and Guarana enhance alertness, while Rhodiola supports the body’s balanced response to stress. Green Tea Extract (GTE) quenches the free radicals formed during intense exercise; GTE has also been shown to support heart health.