Supplementation Protocols and Effects on Muscle Creatine Stores
Various supplementation protocols have been suggested to be efficacious in increasing muscle stores of creatine. The amount of increase in muscle storage depends on the levels of creatine in the muscle prior to supplementation. Those who have lower muscle creatine stores, such as those who eat little meat or fish, are more likely to experience muscle storage increases of 20–40%, whereas those with relatively high muscle stores may only increase stores by 10–20% [19]. The magnitude of the increase in skeletal muscle creatine content is important because studies have reported performance changes to be correlated to this increase [20,21].
The supplementation protocol most often described in the literature is referred to as the "loading" protocol. This protocol is characterized by ingesting approximately 0.3 grams/kg/day of CM for 5 – 7 days (e.g., ≃5 grams taken four times per day) and 3–5 grams/day thereafter [18,22]. Research has shown a 10–40% increase in muscle creatine and PCr stores using this protocol [10,22]. Additional research has reported that the loading protocol may only need to be 2–3 days in length to be beneficial, particularly if the ingestion coincides with protein and/or carbohydrate [23,24]. Furthermore, supplementing with 0.25 grams/kg-fat free mass/day of CM may be an alternative dosage sufficient to increase muscle creatine stores [25].
Other suggested supplementation protocols utilized include those with no loading phase as well as "cycling" strategies. A few studies have reported protocols with no loading period to be sufficient for increasing muscle creatine (3 g/d for 28 days) [15] as well as muscle size and strength (6 g/d for 12 weeks) [26,27]. These protocols seems to be equally effective in increasing muscular stores of creatine, but the increase is more gradual and thus the ergogenic effect does not occur as quickly. Cycling protocols involve the consumption of "loading" doses for 3–5 days every 3 to 4 weeks [18,22]. These cycling protocols appear to be effective in increasing and maintaining muscle creatine content before a drop to baseline values, which occurs at about 4–6 weeks [28,29].
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