reply posted on 16-5-2004 @ 12:20 PM by Shoktek
Long-term creatine supplementation does not significantly affect clinical markers of health in athletes.
Kreider RB, Melton C, Rasmussen CJ, Greenwood M, Lancaster S, Cantler EC, Milnor P, Almada AL.
Exercise and Sport Nutrition Laboratory, Department of Human Movement Sciences and Education, The University of Memphis, Memphis, TN, USA.
Creatine has been reported to be an effective ergogenic aid for athletes. However, concerns have been raised regarding the long-term safety of
creatine supplementation. This study examined the effects of long-term creatine supplementation on a 69-item panel of serum, whole blood, and urinary
markers of clinical health status in athletes. Over a 21-month period, 98 Division IA college football players were administered in an open label
manner creatine or non-creatine containing supplements following training sessions. Subjects who ingested creatine were administered 15.75 g/day of
creatine monohydrate for 5 days and an average of 5 g/day thereafter in 5-10 g/day doses. Fasting blood and 24-h urine samples were collected at 0, 1,
1.5, 4, 6, 10, 12, 17, and 21 months of training. A comprehensive quantitative clinical chemistry panel was determined on serum and whole blood
samples (metabolic markers, muscle and liver enzymes, electrolytes, lipid profiles, hematological markers, and lymphocytes). In addition, urine
samples were quantitatively and qualitative analyzed to assess clinical status and renal function. At the end of the study, subjects were categorized
into groups that did not take creatine (n = 44) and subjects who took creatine for 0-6 months (mean 4.4 +/- 1.8 months, n = 12), 7-12 months (mean 9.3
+/- 2.0 months, n = 25), and 12-21 months (mean 19.3 +/- 2.4 months, n = 17). Baseline and the subjects' final blood and urine samples were analyzed
by MANOVA and 2 x 2 repeated measures ANOVA univariate tests. MANOVA revealed no significant differences (p = 0.51) among groups in the 54-item panel
of quantitative blood and urine markers assessed. Univariate analysis revealed no clinically significant interactions among groups in markers of
clinical status. In addition, no apparent differences were observed among groups in the 15-item panel of qualitative urine markers. Results indicate
that long-term creatine supplementation (up to 21-months) does not appear to adversely effect markers of health status in athletes undergoing intense
training in comparison to athletes who do not take creatine.
Effects of long-term creatine supplementation on liver and kidney functions in American college football players.
Mayhew DL, Mayhew JL, Ware JS.
Exercise Science Program, Truman State University, Kirksville, MO 63501, USA.
The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function.
Twenty-three members of an NCAA Division II American football team (ages = 19-24 years) with at least 2 years of strength training experience were
divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which
they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20 g (mean SD = 13.9 5.8 g) for 0.25 to 5.6 years
(2.9 1.8 years). Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea,
and creatinine produced no significant differences between groups. Creatinine clearance was estimated from serum creatinine and was not significantly
different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were
nonsignificant. Therefore, it appears that oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly
trained college athletes in the absence of other nutritional supplements.
Creatine supplementation in young soccer players.
Exercise and Sport Nutrition Laboratory, O.C.A. Sports Medicine Institute, Kikindska 13/11, Pancevo 26000, Yugoslavia.
The purpose of this study was to examine the effects of acute creatine-monohydrate supplementation on soccer-specific performance in young soccer
players. Twenty young male soccer players (16.6 +/- 1.9 years) participated in the study and were matched and allocated to 2 randomly assigned trials:
ingesting creatine-monohydrate supplement (3 x 10-g doses) or placebo for 7 days. Before and after the supplementation protocol, each subject
underwent a series of soccer-specific skill tests: dribble test, sprint-power test, endurance test, and vertical jump test. Specific dribble test
times improved significantly in the creatine group (13.0 +/- 1.5 vs. 10.2 +/- 1.8 s; p < .05) after supplementation protocol. Sprint-power test times
were significantly improved after creatine-monohydrate supplementation (2.7 +/- 0.4 vs. 2.2 +/- 0.5 s; p < .05) as well as vertical jump height (49.2
+/- 5.9 vs. 55.1 +/- 6.3 cm; p < .05) in creatine trial. Furthermore, dribble and power test times, along with vertical jump height, were superior in
creatine versus placebo trial (p < .05) at post-supplementation performance. There were no changes in specific endurance test results within or
between trials (p > .05). There were no between-trial differences in the placebo trial (p > .05). The main finding of the present study indicates that
supplementation with creatine in young soccer players improved soccer-specific skill performance compared with ingestion of placebo.