We all know Creatine as favoured supplement in the bodybuilding and strength sports worlds; but can games and team sports athlete reap benefits from adding this to their diet?
What is creatine?
Deemed ‘The most effective ergogenic nutritional supplement available to athlete’s’ when it comes to high intensity exercise capacity (Buford et al., 2007), creatine has received much attention in sports science and more recently medical research. Creatine’s place as an ergogenic aid in the form of creatine monohydrate, comes from its role in the resynthesis of PCr (phosphocreatine), following high intensity bursts of exercise. PCr is replenished via a process known as the Creatine Kinase reaction which (as the name suggests) requires creatine (Myers, 2000). During periods of high intensity exercise, the PCr system acts to provide a large amount of energy very quickly. Stored PCr is almost entirely used up within around 10 seconds of maximal sprinting (Forbes, Slade, & Meyer, 2008). As such increasing the capacity of these stores, means greater amounts of energy can be provided by the PCr system before becoming depleted (Buford et al., 2007). Normal baseline creatine level in humans is around 125 mmol per kg of dry mass. The consumption of creatine has been shown to boost this by around 20mmol per kg of dry mass, although due to differences between study participants, actual figures found in research are between 0 and 40 mmol per kg of dry mass (Harris, Söderlund, & Hultman, 1992).
Why supplement?
On ingestion creatine is carried in the blood then stored predominantly in skeletal muscle (Greenhaff, Bodin, Soderlund, & Hultman, 1994). Humans can obtain creatine in two ways. Firstly the body is able to produce creatine itself by combing the amino acids arginine, glycine and methionine through a process known as Endogenous synthesis (this process is inhibited if dietary consumption is high enough). This can only provide around half of creatine requirements, which leaves the rest to be obtained through exogenous sources (through dietary consumption) (Myers, 2000). Sources of dietary creatine include meat and fish, however large amounts of this need to be consumed to maximise creatine uptake, also certain populations such as vegans consume almost no dietary creatine due to a diet void in meat (Balsom et al., 1994). For these reasons, a very cheap and effective way to ensure optimum levels of creatine is to use a creatine monohydrate supplement (Buford et al., 2007).
Application to repeated sprints and team sports
As well as the obvious and well published benefits to strength and power sports,
creatine can have significant benefits to repeated sprint activities. PCr provides around 50% of repeat-sprint energy contribution even on the last sprint of a test (Bishop et al., 2011), as such, greater availability of PCr (phosphocreatine) will positively influence the ability to perform high intensity sprints more frequently (Forbes et al., 2009).
How it works
In terms of the physiological effects, which provide improved RSA performance, there are multiple contributions. The first and most important factor as previously discussed is the increased storage of PCr (Rawson & Persky, 2007). During a 6 second sprint 20% greater PCr stores is shown to provide 5% greater energy supply (Terjung et al., 2000). Another benefit of increased PCr stores during repeated-sprints is that there is less demand on anaerobic glycolysis (energy production from glycogen without oxygen), which means a reduced build up of metabolites such as H+ (hydrogen ions) and Lactate (Balsom et al., 1994). As most athletes and recreational exercisers alike know, when these metabolites begin to accumulate, it becomes much harder to achieve maximal speeds, so any delay in this is advantageous. Creatine ingestion can also boost glycogen loading ability since it increases water retention and cell volume, providing an additional advantage when carbohydrate loading before a game (Mesa et al., 2002).
Dosage and use
When it comes to dosage of creatine, there tends to be two camps. The most straight forward method is to take 3g everyday which has been shown to achieve full loading within 28 days (Hultman, Söderlund, Timmons, Cederblad, & Greenhaff, 1996). This gradual loading strategy is very simple albeit at a slow rate (Hultman et al., 1996). A much faster and more popular method for creatine loading is to consume 20g per day for 6 days, then maintain levels with 2g per day there after (Mujika et al., 2000).
To maximize uptake of creatine, Green et al., (1996) suggests consuming 93g of simply carbohydrates alongside. This showed greater uptake and reduced difference between individuals uptake.
Side effects and potential issues
Many myths and anecdotal reports exist around creatine. Over-consumption isn’t really an issue as the body will excrete excess creatine via urine in the form of creatinine (Volek & Rawson, 2004). Some reported side effects include stomach upsets and muscle cramps although this is not supported by scientific evidence. High blood pressure has also been reported however again no evidence exists to support this. A common belief is that creatine causes kidney problems, however this is based on a single reported incident in which an existing kidney issue was present. No long term health issues have been found with creatine use (Schilling et al., 2001).
In summary, creatine monohydrate supplementation is a safe, cost effective and proven way to improve PCr storage and boost repeated sprint performance, with the quickest improvements seen at a dosage of 20g per day for 6 days and 3g per day thereafter.
By Andy Kay
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References
Balsom, P. D., Söderlund, K., & Ekblom, B. (1994). Creatine in humans with special reference to creatine supplementation. Sports Medicine (Auckland, N.Z.), 18, 268–280.
Balsom, P. D., Söderlund, K., Sjödin, B., & Ekblom, B. (1995). Skeletal muscle metabolism during short duration high-intensity exercise: influence of creatine supplementation. Acta physiologica Scandinavica, 154, 303-310.
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