Green et al. [17] demonstrated that ingesting 5 g CrM followed by 93 g simple carbohydrate (glucose and simple sugars) resulted in an increase in muscle Cr content compared to CrM alone. Later investigations have shown that a lesser amount of carbohydrate (35 g) with each dose of CrM may promote greater adaptations than CrM alone. Based on these findings, it has been hypothesized that Cr retention during supplementation may be mediated in part by the insulin pathway. In support of this hypothesis, Steenge et al. [28] demonstrated that insulin can enhance muscle Cr BIBW2992 accumulation, but only when present at physiologically high or supraphysiological concentrations.
While co-ingesting large amounts of carbohydrate and/or protein with Cr have been MLN2238 solubility dmso reported to promote muscle Cr retention, some athletes or recreationally active individuals may be interested in lower-calorie strategies to improve Cr
uptake. Greenwood et al. [16] found that the co-ingestion of 1 g of D-Pinitol (a plant extract with insulin-like properties) per day with CrM (20 g/d) for 3 days significantly improved whole body Cr retention. While D-Pinitol provides a non-caloric substitute to other higher calorie nutrients, it is relatively expensive. Further, no other studies have demonstrated D-Pinitol to increase total muscle Cr. Extracts of RT have been purported to have anti-hyperglycemic effects. The effect of RT on carbohydrate metabolism is most noted in animal models. For instance, Ribnicky et al. [27] showed the ethanolic extract see more of RT to reduce insulin concentrations by 33% compared to 48% and 52% for the antidiabetic drugs troglitzaone and metformin, respectively. Further, this same research group has shown ethanolic RT to significantly lower blood glucose concentrations by 20% in streptozotocin-induced diabetic mice, compared to control. However, the dosage in that study was significantly Sitaxentan greater than the present study (500 mg/kg bodyweight). Further evidence of the anti-hyperglycemic effects of RT has been provided by Pischel et al. [29]. Using
the same aqueous extract of RT and dosage used in the current study, Pischel et al. [29] reported lower blood glucose levels in both animals and humans (albeit non-statistically) following ingestion. While the antidiabetic properties of RT are a relatively new discovery [30], current investigations are focusing on alterations in the insulin pathway. Given the purported role of insulin in enhanced muscle Cr accumulation, RT may serve as a means to augment Cr retention without the ingestion of carbohydrate and the resulting greater caloric intake. Jäger et al. [20] demonstrated a significant reduction in plasma Cr levels following ingestion of similar dose of RT followed by CrM compared with CrM alone.