Gold Standard for Muscle Recovery. Recover Faster. Rebuild Muscle Protein. Reduce Muscle Soreness. Come Back Stronger. 4:1 Carbohydrate Protein Formula. All Natural. The Gold Standard for Muscle Recovery. Developed by leading exercise physiologists Endurox R4, with its patented ratio of carbohydrates to protein, is proven to speed muscle recovery and reduce muscle damage following exercise. No product can help you recover faster, recover better and come back stronger in your next workout. Performance by the Numbers: 18 peer reviewed studies have shown Endurox R4 delivers: 128% greater replenishment of muscle glycogen than a carbohydrate sports drink. 38% more muscle protein synthesis than a protein drink. 36% reduction in post-exercise muscle damage. 55% greater endurance in a subsequent workout.