Journal Title (Medline/Pubmed accepted abbreviation): Serbian J. Sports Sci.
Page numbers: 99-105
Summary of background and research design:
Background: Because of its ability to increase the efficiency of ATP (energy) production, creatine aids in the increase of lean muscle mass in conjunction with an exercise routine. It is believed that chronic (daily) consumption of creatine is best, as opposed to single doses of creatine. However, it is unknown exactly how many days of creatine supplementation are required before one can make maximal gains.
Hypothesis/Purpose of study: The purpose of this study was to evaluate the effects of 3, 5, or 7 days of creatine loading (at 20 g/day) would affect strength gains and body composition during resistance training.
Subjects: Twenty men, age about 19-22 yrs. The subjects were randomized to either a creatine group (n = 10) or placebo group (n = 10).
Experimental design: Independent groups
Creatine: 20 g/day of creatine monohydrate – 5 g dissolved in 300 mL grape juice four times per day
Placebo: 20 g/day of dextrose (sugar), prepared same as above.
Protocal : First, the participants were familiarized with the testing procedure which included strength, power, agility, sprinting, and muscle size. At least 24 hrs later baseline testing values were obtained and the participants began taking their assigned supplement. On days 3, 5, and 7 they participated in resistance training. The training included 3 sets of 10 repetitions of 9 exercises at 75-85% of their one-repetition maximum (1RM). On days 4, 6, and 8 they underwent testing.
Summary of research findings:
- There were no significant differences between the baseline and any of the subsequent time points for the placebo for any of the test exercises.
- Creatine showed a benefit between baseline and 3 days creatine supplementation for bench press strength, back squat strength, arm curl strength, and standing long jump distance.
- Creatine showed a benefit between baseline and 5 days creatine supplementation for 45 m sprint time and body mass (increased).
- Creatine showed a benefit between baseline and 7 days creatine supplementation for 4 x 9 m shuttle run time, arm cross sectional area, and thigh cross sectional area.
- For several endpoints (back squat, arm curl, long jump, sprint, and body mass), both the 5 and 7 day results were significantly improved compared with the 3 day loading (there were no differences between 5 and 7 days loading).
- For the shuttle run and arm cross sectional area, the 7 day loading period was significantly improved compared with the 3 or 5 day loading (there were no differences between 3 and 5 day loading)
- Body fat percentage did not change for either group.
Key practice applications:
With a very short, 7 day intervention, creatine supplementation led to significantly improved performance metrics. While the placebo group showed slight improvements, differences were not statistically significant. Daily creatine supplementation led to greater gains than acute supplementation. It appeared from this study that, on the whole, the 7 day creatine loading period was associated with greater benefits.
The small sample size and short duration of this study are limitations and the subjects were recreational, as opposed to elite or competitive, athletes.