Optimum Nutrition Amino Energy delivers 5g of essential amino acids plus 100mg of natural caffeine per serve to fuel your workouts and daily performance. Formulated with L-arginine, citrulline, and green tea extract, it supports energy, focus, and muscle recovery without the sugar—just 5–10 calories per serving. Perfect pre-workout or anytime you need sustained energy and mental clarity. Versatile, convenient, and designed for serious athletes and fitness enthusiasts.