Igor Hisashi Murai

Does long-term creatine supplementation impair kidney function in resistance-trained individuals consuming a high-protein diet?

BackgroundThe aim of this study was to determine the effects of creatine supplementation on kidney function in resistance-trained individuals ingesting a high-protein diet.MethodsA randomized, double-blind, placebo-controlled trial was performed. The participants were randomly allocated to receive either creatine (20 g/d for 5 d followed by 5 g/d throughout the trial) or placebo for 12 weeks. All of the participants were engaged in resistance training and consumed a high-protein diet (i.e., ≥ 1.2 g/Kg/d). Subjects were assessed at baseline (Pre) and after 12 weeks (Post). Glomerular filtration rate was measured by 51Cr-EDTA clearance. Additionally, blood samples and a 24-h urine collection were obtained for other kidney function assessments.ResultsNo significant differences were observed for 51Cr-EDTA clearance throughout the trial (Creatine: Pre 101.42 ± 13.11, Post 108.78 ± 14.41 mL/min/1.73m2; Placebo: Pre 103.29 ± 17.64, Post 106.68 ± 16.05 mL/min/1.73m2; group x time interaction: F = 0.21, p = 0.64). Creatinine clearance, serum and urinary urea, electrolytes, proteinuria, and albuminuria remained virtually unchanged.ConclusionsA 12-week creatine supplementation protocol did not affect kidney function in resistance-trained healthy individuals consuming a high-protein diet; thus reinforcing the safety of this dietary supplement.Trial registrationClinicalTrials.gov NCT01817673

No effect of creatine supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats.

BackgroundExacerbated oxidative stress is thought to be a mediator of arterial hypertension. It has been postulated that creatine (Cr) could act as an antioxidant agent preventing increased oxidative stress. The aim of this study was to investigate the effects of nine weeks of Cr or placebo supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats (SHR).FindingsLipid hydroperoxidation, one important oxidative stress marker, remained unchanged in the coronary artery (Cr: 12.6 ± 1.5 vs. Pl: 12.2 ± 1.7 nmol·mg-1; p = 0.87), heart (Cr: 11.5 ± 1.8 vs. Pl: 14.6 ± 1.1 nmol·mg-1; p = 0.15), plasma (Cr: 67.7 ± 9.1 vs. Pl: 56.0 ± 3.2 nmol·mg-1; p = 0.19), plantaris (Cr: 10.0 ± 0.8 vs. Pl: 9.0 ± 0.8 nmol·mg-1; p = 0.40), and EDL muscle (Cr: 14.9 ± 1.4 vs. Pl: 17.2 ± 1.5 nmol·mg-1; p = 0.30). Additionally, Cr supplementation affected neither arterial blood pressure nor heart structure in SHR (p > 0.05).ConclusionsUsing a well-known experimental model of systemic arterial hypertension, this study did not confirm the possible therapeutic effects of Cr supplementation on oxidative stress and cardiovascular dysfunction associated with arterial hypertension.

Can creatine supplementation form carcinogenic heterocyclic amines in humans

There is a long‐standing concern that creatine supplementation could be associated with cancer, possibly by facilitating the formation of carcinogenic heterocyclic amines (HCAs). This study provides compelling evidence that both low and high doses of creatine supplementation, given either acutely or chronically, does not cause a significant increase in HCA formation. HCAs detection was unrelated to creatine supplementation. Diet was likely to be the main factor responsible for HCAs formation after either placebo (n = 6) or creatine supplementation (n = 3). These results directly challenge the recently suggested biological plausibility for the association between creatine use and risk of testicular germ cell cancer.

GLUT4 translocation is not impaired after acute exercise in skeletal muscle of women with obesity and polycystic ovary syndrome

The aim of this study was to examine the effects of acute exercise on insulin signaling in skeletal muscle of women with polycystic ovary syndrome (PCOS) and controls (CTRL).

Performance Enhancement Drugs and Sports Supplements for Resistance Training

In general, nutritional sports ergogenics are designed to enhance energy production and/or improve body composition, promoting muscle growth and decreasing body fat. Many nutritional supplements and pharmacological substances have been used during resistance training without knowledge of the effects on human metabolism caused by their chronic administration. Before the utilization or prescription of any ergogenic aid, it is important to consider some questions about that substance: Is it effective? Is it safe? Is it legal and ethical? In this chapter we discuss the most widely utilized drugs and supplements among individuals engaged in resistance training—testosterone, creatine, beta-hydroxy beta-methylbutyrate (HMB) and caffeine—focusing on their effects on strength and body composition, the safety of their utilization, and their mechanisms of action.

Influência da suplementação de creatina sobre a massa óssea de ratos espontaneamente hipertensos

INTRODUCTION Recent evidence has suggested that creatine supplementation (Cr) can increase the bone mineral density (BMD) of the femur in healthy growing rats. Nevertheless, studies assessing the efficacy of the Cr supplementation in conditions characterized by bone mass loss are scarce. OBJECTIVE To investigate the effect of Cr supplementation on BMD and bone mineral content (BMC) in spontaneously hypertensive rats (SHRs), an experimental model of osteoporosis. MATERIALS AND METHODS Sixteen 8-month-old male SHRs were randomly allocated into two groups matched by body weight: 1) Pl group: SHRs treated with placebo (distilled water; n = 8); and 2) Cr group: SHRs treated with Cr (n = 8). After nine weeks of supplementation, the animals were euthanized and their femur and spine (L1-L4) were analyzed by use of densitometry (Dual Energy X-Ray Absorptiometry). RESULTS No significant difference was observed between the groups regarding either the spine or the total femur measures as follows: spine - BMD (Pl = 0.249 ± 0.003 g/cm² vs. Cr = 0.249 ± 0.004 g/cm²; P = 0.95) and BMC (Pl = 0.509 ± 0.150 g vs. Cr = 0.509 ± 0.017 g; P > 0.99); and total femur - BMD (Pl = 0.210 ± 0.004 g/cm² vs. Cr = 0.206 ± 0.004 g/cm²; P > 0.49) and BMC (Pl = 0.407 ± 0.021 g vs. Cr = 0.385 ± 0.021 g; P > 0.46). CONCLUSION In this study, using the experimental model of osteoporosis, Cr supplementation had no effect on bone mass.

Acute exercise elicits differential expression of insulin resistance genes in the skeletal muscle of patients with polycystic ovary syndrome.

This study aimed to explore the role of acute exercise on skeletal muscle gene expression related to insulin resistance in patients with polycystic ovary syndrome (PCOS) and controls.

Reversal of Improved Endothelial Function After Bariatric Surgery Is Mitigated by Exercise Training

Flow-mediated dilation (FMD) is a marker of endothelial function and a strong independent predictor of cardiovascular events, constituting a valid prognostic tool beyond traditional cardiovascular risk factors [(1)][1]. Bariatric surgery elicits short-term improvements in FMD [(2)][2], but