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Exposure related observations in humans: other data

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exposure-related observations in humans: other data
Type of information:
experimental study
Adequacy of study:
other information
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication which meets basic scientific principles

Data source

Reference Type:
Effect on creatine and beta-alanine supplementation on performance and endocrine responses in strength/power athletes
Hoffman J, Ratamess N, Kang J, Mangine G, Faingenbaum A, and Stout J
Bibliographic source:
International Journal of Sport Nutrition and Exercise Metabolism, 2006, 16:430-446.

Materials and methods

Endpoint addressed:
repeated dose toxicity: oral
Test guideline
no guideline followed
Principles of method if other than guideline:
The effects of creatine and creatine plus beta-alanine on strength, power, body composition, and endocrine changes were examined during a 10-week resistance training program in collegiate football players.
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
- Name of test material (as cited in study report): beta-alanine
- Analytical purity: no data


Ethical approval:
confirmed and informed consent free of coercion received
Details on study design:
33 male strength power athletes volunteered for this study. The Institutional Review Board of the College of New Jersey approved the research protocol. Subjects were not permitted to use any additional nutritional supplementation and did not consume anabolic steroids or any other anabolic agents known to increase performance. Screening for steroid use and additional supplementation was accomplished via a health questionnaire filled out during subject recruitment.

Details on exposure:
TYPE OF EXPOSURE: Oral. Subjects consumed either the supplement or placebo twice per day. The supplement and placebo were in powdered form and mixed with 8 to 10 ounces of water. Subjects consumed the drink every morning. On days that they performed their resistance training program, they consumed another drink within 1 hour of their workout. On the days that the subjects did not exercise, they consumed the supplement or placebo in the late afternoon or early evening.

TYPE OF EXPOSURE MEASUREMENT: Blood measurements / Biochemical and hormonal Analyses / Body composition/ strength measures / anaerobic power measured


DESCRIPTION / DELINEATION OF EXPOSURE GROUPS / CATEGORIES: Subjects were randomly assigned to one of three groups. The first group (CA) was provided with a daily creatine plus beta-alanine supplementation (10.5 g/d of creatine monohydrate and 3.2 g/d of beta-alanine), the second group (C) was provided with a daily creatine supplement only (10.5g/d of cratine monohydrate), while the third group (P) was given a placebo (10.5 g/dextrose). These dosages were similar to those used in previous studies examining both creatine and beta-alanine supplementation. All subjects were athletes from the college’s football team with at least 2 years of resistance training experience. The study followed a double blind format. All groups performed the same resistance training program for 10 weeks. The training program was a 4-day per week, split routine that was supervised by study personnel. All subjects completed a daily training log and turned it in at the end of each week.

Results and discussion

No significant differences in average daily caloric intake were seen between P (2991 ± 809 kcal), CA (3222 ± 856 kcal), and C (2999 ± 546 kcal). Analysis of dietary composition showed that the daily dietary intake for all groups was comprised of 59% carbohydrates, 26% fat, and 15% protein. No significant changes in body mass were seen from PRE to POST in either P (101.2 ± 14.0 kg and 103.2 ± 13.8 kg, respectively), CA (94.1 ± 16.4 kg and 95.7 ± 16.6 kg, respectively), or C (91.9 ± 21.7 kg and 92.5 ± 21.5 kg, respectively). In addition, no significant differences were seen in groups in Δ body mass. However, significant differences in Δ% body fat (-1.21 ± 1.12% versus 0.25 ± 1.53%, p < 0.05, ES=1.15) and Δ lean body mass (1.74 ± kg versus, -0.44 ± 1.62 kg, p < 0.05, ES=1.13) were seen between CA and P, respectively. Significant improvements from PRE 1-RM squat levels (159.4 ± 28.6 kg) were seen in all the three groups. However, Δ strength comparisons showed that subjects in CA and C had significantly greater improvement in 1-RM squat strength compared to P. In addition, significant improvements from PRE 1-RM (1-repetition maximum) bench press levels (115.9 ± 17.7 kg) were also seen in all three groups. When comparing Δ strength improvements in bench press a two-fold greater improvement (p< 0.05) was seen in CA compared to P, and a two and a half-fold greater improvement (p <0.05) was seen in C compared to P.
Subjects in both CA and C trained at significantly higher exercise intensity during the 10 wk training program than P. In addition, the average weekly volume of training in the squat exercise was significantly greater in CA in comparison to P.
No significant between group differences were seen when comparing the average training intensity for the bench press exercise. However, when comparing the average training volume for the bench press exercise a significant difference was seen between the groups.
No significant improvement was seen for any group in any of the performance measures assessed in the 20 jump or the Wingate Anaerobic Power tests. In addition, no significant differences between the groups were observed. Although no significant changes were seen in resting total testosterone concentrations in P and CA during the 10-wk study, a significant elevation in resting testosterone concentration was seen in C between PRE and POST. The differences between the groups though were not significant. In addition, the free testosterone index (FT index) calculated from the ratio of testosterone to SHBG (sex hormone binding globulin) demonstrated a trend (p=0.056, EF=0.53) towards an increase from PRE to POST in C. No other significant hormonal changes were seen, and no between group differences were noted.

Applicant's summary and conclusion

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