Best Practice Protocols for Physique Assessment in Sport by Patria A. Hume Deborah A. Kerr & Timothy R. Ackland

Author:Patria A. Hume, Deborah A. Kerr & Timothy R. Ackland
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

The second principle is the rate of isotope loss in relation to carbon dioxide production. The rate at which the isotopes of hydrogen and oxygen leave the body is related to the rate of production of carbon dioxide. This can be converted to a measure of the number of calories consumed over 14 days.

10.3.2 Measurement of the Isotopes in Body Fluid

The measurement of any biomarker requires that the amount of biomarker added is able to be detected with adequate precision so as to detect small changes. The most sensitive means of measuring the isotopes of deuterium and oxygen-18 is by isotope ratio mass spectroscopy. The use of this measurement technique reduces the amount of dose required but is expensive in terms of the equipment, sample processing and time for an expert to measure the samples. The isotope ratio mass spectroscopy instrumentation determines the ratio of numbers of heavy to light isotopes of a gaseous element. The sample must be processed first so that a gas is formed and then, when accelerated through an energy field, the isotopes will behave differently according to mass, which allows the ratio to be determined. Fourier transform infrared spectroscopy can be used to measure deuterium in saliva and plasma but requires much larger doses as it relies on the properties of the spectrum of infrared light relative to a standard. Relatively few laboratories are able to undertake these analyses with the required precision and reliability; therefore, it is prudent to get quotes for both the labelled isotopes and the analysis, as well as information about the laboratory’s quality control measures before undertaking or proposing a doubly labelled water study.

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