International Society of Sports Nutrition position stand: energy drinks - Campbell, B.; Wilborn, C.; La Bounty, P.; Taylor, L.; Nelson, M. T.; Greenwood, M.; Ziegenfuss, T. N.; Lopez, H. L.; Hoffman, J. R.; Stout, J. R.; Schmitz, S.; Collins, R.; et al. (Journal of the International Society of Sports Nutrition, 2013)