The effects of creatine supplementation on thermoregulation and physical (cognitive) performance: a review and future prospects

Abstract

Creatine (Cr) is produced endogenously in the liver or obtained exogenously from foods such as meat and fish.In the human body, 95% of Cr is located in the cytoplasm of skeletal muscle either in a phosphorylated (PCr) or free form (Cr). PCr is essential for the immediate rephosphorylation of adenosine di-phosphate (ADP) to adenosine tri-phosphate (ATP). PCr is rapidly degraded at the onset of maximal exercise at a rate that results in muscle PCr reservoirs being substantially depleted. A well-established strategy followed to increase muscle total Cr content is to increase exogenous intake by supplementation with chemically pure synthetic Cr.

International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine

“…Watson and colleagues [117] reported that short-term creatine supplementation (21.6 g/day for 7 days) did not increase the incidence of symptoms or compromise hydration status or thermoregulation in dehydrated (−2%), trained men exercising in the heat. Similar findings were observed by several other groups [118, 119, 127, 128] leading researchers to add creatine to glycerol as a highly effective hyper-hydrating strategy to help athletes better tolerate exercise in the heat [116, 120–122, 125, 126]. These findings provide strong evidence that creatine supplementation (with or without glycerol) may serve as an effective nutritional hyper-hydration strategy for athletes engaged in intense exercise in hot and humid environments thereby reducing risk to heat related-illness [5, 129].…”

Creatine: a miserable life without it

“…However, additional creatine supplementation may be indicated for athletes to achieve further improvement in performance. Creatine supplementation (3-4 g/day is shown not only to improve muscle mass and performance, both short term high-intensity and endurance, but also to improve recovery after heavy exercise and avoid muscle soreness and injury (see Roberts et al 2016;Twycross Lewis et al 2016).…”

“…A detailed review of the ergogenic benefits to athletes of creatine elevation in muscle is presented in Twycross Lewis et al (2016). Based initially on studies of Harris et al (1992), supplementation with 20 g per day of creatine monohydrate for 5-10 days was advocated, achieving a 25-30 % increase in muscle TCr, that was then followed by a maintenance dose of 3 g per day.…”

“…In this alternative model, the primary role of PCr in exercising muscle is in preventing the accumulation of ADP triggering the onset of adenine nucleotide degradation via myokinase/AMP deaminase to IMP, and subsequently to hypoxanthine, a role which fits with the relative properties of the PCr-CK system compared with other members of the phosphorylguanidino family (Ellington 1989). Twycross Lewis et al (2016) raise the additional possibility that the increase in water retention in muscle with Cr supplementation, possibly associated with increased muscle glycogen storage (Fernández-Elías et al 2015), may help in the maintenance of total body hydration and fatigue resistance when exercising under hot ambient conditions likely to contribute to dehydration and thermal stress. This, together with the documented ergogenic effects of muscle creatine elevation, would be important to athletes performing in endurance events, especially in hot climates, as well as to military personnel operating in desert conditions.…”

Changing to a vegetarian diet reduces the body creatine pool in omnivorous women, but appears not to affect carnitine and carnosine homeostasis: a randomised trial

“…Carnosine has a wide spectrum of bioactive properties such as pH buffering, Ca 2+ regulation, anti-glycation and antioxidant activity (9) . Numerous studies in the literature demonstrated the beneficial effects of creatine, carnitine (combined with carbohydrates) or β-alanine (precursor amino-acid of carnosine) supplementation on exercise performance in athletes (10)(11)(12) , and therapeutic potential towards certain disorders in which muscle function is a key component (5,13,14) .…”