Cycling studies ingestion

Animal studies have shown that most ingested uranium (99%) is not absorbed in rats, but is eliminated in the feces without being cycled through the bile. In rats, most of the absorbed uranium leaves the body within a few days in urine half is excreted in 2-6 days (Durbin and Wrenn 1975), and 98% within 7 days (Sullivan 1986). About 95% of the uranium in the kidneys of rats is excreted in urine within 1 week, and very little remains in any other organ (LaTouche et al. 1987 Sullivan 1980a, 1986). 

Although several mechanisms have been proposed to be responsible for causing CRS, none has been extensively studied. One hypothesis has been that the effects are due to an immediate hypersensitivity reaction. Since no IgE-mediated reaction has been documented, there is no direct evidence that this is the case. Another hypothesis is that vitamin Bg deficiency plays a role in the response because the symptoms were prevented by supplementing individuals with the vitamin. Since glutamate can be converted to acetylcholine by the tricarboxylic acid cycle, it has also been proposed that the effects are due to an increase in acetylcholine levels. It has been noted that after MSG ingestion, there is a decrease in cholinesterase levels. Due to inadequate investigations, it is not currently known if any or all of these mechanisms are responsible for CRS. The neurotoxicity of MSG, demonstrated after exposure... 

A), a "chemical biopsy" can be performed on animals or on human beings, who may ingest gram quantities of sodium phenylacetate without harm. The phenylacetate is converted to an amide with glutamine (phenylacetylglutamine) which is excreted in the urine, from which it can easily be recovered for analysis. "" This provides a non-invasive way of studying the operation of the citric acid cycle in the human body. Direct measurement on animal brains°T and on human limbs or brain has also been accomplished by NMR spectroscopy ) and may become more routine as instrumentation is improved. ... 

In this section, we will discuss the use of radionuclide tracers in a metabolic index study. This subject is related to the subjects discussed in our section on cycling (Section 10.2), which included ingestion, biological uptake and retention, and excretion. However, we included in that section references wherein the investigators were interested in a specific radionuclide or its stable isotope. We will consider here cases in which the specific tracer was not of concern, but rather was used as a means to an end. 

In contrast, the effect on performance of carbohydrate feeding 30 to 60 min before exercise is unclear. Although blood glucose concentrations increased after ingestion of carbohydrate, one study reported improved and othCTS - showed no effects on performance compared to controls. There was consensus of no adverse effects on performance. Sherman et al. reported a 15% improvement in cycling performance when cyclists consumed 300 g of carbohydrate 4 h before the performance test. Thus, exogenous carbohydrate fed before exercise may be beneficial to individuals who have low glycogen stores. 

---