The acute effects of thermogenic fitness drink formulas containing 140 mg and 100 mg of caffeine on energy expenditure and fat metabolism at rest and during exercise - Clark, Nicolas W; Wells, Adam J; Coker, Nicholas A; Goldstein, Erica R; Herring, Chad H; Starling-Smith, Tristan M; Varanoske, Alyssa N; Panissa, Valéria L. G; Stout, Jeffrey R; Fukuda, David H (Journal of the International Society of Sports Nutrition, 2020)