With carbs:
Green, A. L., Simpson, E. J., Littlewood, J. J., Macdonald, I. A., & Greenhaff, P. L. (1996). Carbohydrate ingestion augments creatine retention during creatine feeding in humans. Acta Physiol Scand, 158, 195-202.
Insulin increases creatine uptake:
Haugland, R. B., & Chang, D. T. (1975). Insulin effect on creatine transport in skelatal muscle. Proc.Soc Exp.Biol Med, 148, 1-4.
Steenge, G. R., Lambourne, J., Casey, A., Macdonald, I. A., & Greenhaff, P. L. (1998). Stimulatory effect of insulin on creatine accumulation in human skeletal muscle. Am. J. Physiol.-Endocrinol. Metab., 38(6), E974-E979.
With alpha lipoic acid:
Burke, D. G., Chilibeck, P. D., Parise, G., Tarnopolsky, M. A., & Candow, D. G. (2003). Effect of alpha-lipoic acid combined with creatine monohydrate on human skeletal muscle creatine and phosphagen concentration. Int J Sport Nutr Exerc Metab, 13(3), 294-302.
When you want greater glycogen levels:
Green, A. L., Sewell, D. A., Simpson, L., Hultman, E., Macdonald, I. A., & Greenhaff, P. L. (1996). Creatine ingestion augments muscle creatine uptake and glycogen synthesis during carbohydrate feeding in man. J.Physiol.Lond., 491, 63P-64P.
Muscle contraction (exercise) increases creatine uptake:
Harris, R. C., Söderlund, K., & Hultman, E. (1992). Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin. Sci.(Colch). 83, 367-374.
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