Zipvit Sport L-Arginine is a high strength formulation. In recent studies by researchers at the University of Exeter it was discovered that supplementing with L-Arginine improved levels of Nitric Oxide in endurance athletes which may increase stamina levels REFERENCE: Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Jones AM.Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise toleranceJ Appl Physiol