The rate of muscle oxidative ATP production during exercise and the rate of PCr recovery after exercise both increase in subjects supplemented for 15 days with citrulline/malate. (NOTE: This is an ingredient in Annabolic Innovations product EXCELL):

Citrulline/malate promotes aerobic energy production in human exercising muscle -- Bendahan et al. 36 (4): 282 -- British Journal of Sports Medicine