To investigate the effect of low-dose supplementation of creatine monohydrate without the use of the saturation phase, 36 male university students engaged in resistance training (age 22.5 ± 4.3 years, height 1.76 ± 0.08 m, weight 77.0 ± 11.0 kg, and body mass index 24.6 ± 2.5 kg/m 2 ) were randomly divided into three groups: group placebo (GP), group supplemented with creatine 3 g/day (3G), and group supplemented with 5 g/day creatine (5G). The subjects were tested for maximum muscle strength (1RM), upper body muscle endurance (MPU), and abdominal muscle endurance (MSU) before and after 7, 14, 21, 28, and 35 days of creatine supplementation or placebo and performing standardized resistance training. After 35 days of supplementation and training, all groups showed a significant improvement in the 1RM test; however, the percentages of strength increase were significantly higher (P < 0.05) in the groups supplemented with creatine (G3, ∆% 1RM = 20.0 ± 4.0; G5, ∆% 1RM = 19.9 ± 1.5) than in the placebo group (GP, ∆% 1RM = 10.3 ± 1.9). Upper limb muscle endurance showed a significant improvement only in 5G, ranging from 39.9 ± 7.9 MPU/min to 50.7 ± 11.0 MPU/min after 35 days of supplementation. Interestingly, abdominal muscle endurance showed no increase in any of the groups (GP, P > 0.528; G3, P > 0.076; G5, P > 0.148). These results support a number of earlier studies that demonstrated that creatine supplementation at low doses and without the use of the loading phase are effective for increasing maximal strength and endurance of upper limbs.
AbstractThe aim of this study was to evaluate the impact of creatine supplementation (CS) on renal function in young, healthy, and active subjects. We used a randomized, double-blind, placebo-controlled clinical trial as the study design. Thirty-six healthy male university students were recruited and divided into three groups: group placebo, group G3 (3 g/day of CS), and group G5 (5 g/day of CS). To assess renal function, new kidney biomarkers, kidney injury molecule-1 (KIM-1) and monocyte chemoattractant protein-1 (MCP-1), were quantified. Serum albumin, serum creatinine, serum urea, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria were also measured. All groups were evaluated at two times: prior CS or placebo (pre) and after 35 days on CS or placebo (post). After 35 days of intervention, all characteristics were maintained without significant difference (P > 0.05) between the groups, including serum creatinine, eGFR, and more sensitive kidney biomarker concentrations (KIM-1 and MCP-1). The paired analysis showed that the supplemented groups (G3 and 5G) had increased serum creatinine and decreased eGFR levels (P < 0.05). However, the values were still within the normal reference range. In conclusion, the results of renal function evaluation did not show any difference between the evaluated groups. Increased serum creatinine and decreased eGFR levels in CS groups can be explained by increased creatine stores and metabolism, since creatinine is a by-product of creatine metabolism. These findings indicate that the use of CS at doses of 3 g and 5 g/day for a short period (35 days) is safe and did not impair the kidneys or renal function in young healthy subjects.
The aim of this study was to evaluate the hypothalamic-pituitary-gonadal axis functionality on a bodybuilding competitioner before, during and after the use of anabolic-androgenic steroids. A young healthy man was followed up for 4 months. The subject reported his drug administration protocol through periodic interviews and performed laboratory tests to monitor the function of his hypothalamic-pituitary-gonadal axis. Time 1 (before the steroids use) shows all hormones levels (follicle-stimulating hormone = 4,2 mUI/ml, luteinising hormone = 3,7 mUI/ml and total testosterone = 5,7 ng/ml) within reference values. In Time 2, after 8 weeks on steroids abuse, a complete hypothalamic-pituitary-gonadal axis derangement is evident with noticeable negative feedback (follicle-stimulating hormone = 1,47 mUI/ml, luteinising hormone = 0,1 mUI/ml and total testosterone = 1,47 ng/ml). At the third moment (40 days after Time 2), we can see a tendency to recovery, however, the serum levels of the investigated hormones were still considerably lower than the baseline values. At the end, we could conclude that the use of anabolic-androgenic steroids, at supraphysiological dosages, even for a short time (8 weeks), causes severe disorder in the hypothalamic-pituitary-gonadal axis. The endogenous testosterone synthesis was severely compromised by important decline in serum luteinising hormone levels.
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