The effects of arginine/lysine supplementation and resistance training on glucose tolerance and glomerular filtration rate: Relationship with alterations in selected hormonal parameters.

Abstract

The purposes of this study were to evaluate and compare the independent and combined effects of arginine/lysine (AL) supplementation and resistance training (RT) on glucose tolerance and golmerular filtration rate, and to determine whether or not alterations were associated with changes in selected hormonal parameters. The study involved 30 physically active college males, ages 20-30 years, randomly assigned to one of four groups: Placebo/Control (P/C, n = 7), P/RT (n = 8), AL/C (n = 7), or AL/RT (n = 8). During the 10-week program, exercise subjects participated in a progressive resistance training program stressing all major muscle groups. An arginine/lysine supplement at a dosage of 132 mg/kg fat-free body (FFB) or placebo was administered to controls and training groups. Oral glucose tolerance (OGT) tests were performed on each subject before and after the 10-week intervention in order to evaluate resting levels of plasma insulin-like growth factor-1 (IGF-1), as well as resting levels and responses of glucose, insulin and glucagon for 180 minutes following an oral glucose challenge. Glomerular filtration rate (GFR) was determined from creatinine clearance (C(Cr)) as calculated from plasma creatinine, urine creatinine and urine flow. Significant increases in strength, and fat-free body (FFB) weight were seen in both resistance trained groups compared to controls, while supplement status had no apparent effect. Glucose tolerance parameters which significantly increased following the 10-week intervention included resting insulin for P/RT and glucagon area under the curve (AUC) for P/C, AL/C, and P/RT. While IGF-1 did not significantly increase within groups, a significant post-treatment difference was seen between P/RT (0.93 ± 0.10 U/ml) and AL/RT (0.60 ± 0.08 u/ml); percent carbohydrate in diet and absolute change in FFB were significant predictors of the absolute change in IGF-1, accounting for 22.0% (p < 0.01) and 20.8% (p < 0.01) of the variability, respectively. It was concluded that AL supplementation for 10 weeks had no significant effect on strength, FFB, OGT or GFR, while RT increased both strength and FFB with no significant effect on OGT or GFR.