Critical difference and biological variation in biomarkers of oxidative stress and nutritional status in athletes
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Date
2016Author
Lewis, Nathan A.
Howatson, Glyn
Newell, John
Burden, Richard
Pedlar, Charles R.
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Show full item recordAbstract
The longitudinal monitoring of oxidative stress (OS) in athletes may enable the identification
of fatigued states and underperformance. The application of OS biomarker monitoring programs
in sport are hindered by reliability and repeatability of in-the-field testing tools, the
turnaround of results, and the understanding of biological variation (BV). Knowledge of BV
and critical difference values (CDV) may assist with data interpretation in the individual athlete.
Methods: We aimed firstly to assess the repeatability of the clinical point of care redox
test, Free Oxygen Radical Test (FORT) and the Free Oxygen Radical Defence (FORD) in
trained participants and elite athletes and secondly to calculate the analytical, BV, CDV and
index of individuality (II) for FORT, FORD, red blood cell glutathione, lutein, α and γ–tocopherol.
Part 1: Fifteen elite athletes were sampled in duplicate for calculation of the repeatability
of the FORT and FORD tests. Part 2: Twelve well-trained athletes had venous samples
drawn every 2 hours from 0800 to 1800 for calculation of BV, CDV, II for FORT, FORD,
RBC GSH, lutein, α-tocopherol and γ–tocopherol. Results: Repeatability of the FORT and
FORD assay was 3.9% and 3.7% respectively. Biomarker CDV ranged from 12.8% to 37%,
with a circadian effect for FORT, α-tocopherol and γ-tocopherol (p<0.01), with all biomarker
indices of individuality < 0.8 arbitrary units. Conclusion:We report that the use of the novel
redox test in athletes is practical, and the generation of BV and CDV for biomarkers of OS
enhances the interpretation of physiologically meaningful changes in individuals above the
use of clinical reference ranges alone