Abstract
The present study aimed to determine the day to day variability and reliability of several blood oxidative stress markers at rest in a healthy young cohort over a four-week period. Twelve apparently healthy resistance trained males (24.6 ± 3.0 yrs) were tested over 7 visits within 4 weeks with at least 72 hrs between visits at the same time of day. Subjects rested 30 minutes prior to blood being obtained by vacutainer. Results. The highest IntraClass correlations (ICC's) were obtained for protein carbonyls (PC) and oxygen radical absorbance capacity (ORAC) (PC = 0.785 and ORAC = 0.780). Cronbach's α reliability score for PC was 0.967 and for ORAC was 0.961. The ICC's for GSH, GSSG, and the GSSG/TGH ratio ICC were 0.600, 0.573, and 0.570, respectively, with Cronbach's α being 0.913, 0.904, and 0.903, respectively. Xanthine oxidase ICC was 0.163 and Cronbach's α was 0.538. Conclusions. PC and ORAC demonstrated good to excellent reliability while glutathione factors had poor to excellent reliability. Xanthine oxidase showed poor reliability and high variability. These results suggest that the PC and ORAC markers were the most stable and reliable oxidative stress markers in blood and that daily changes across visits should be considered when interpreting resting blood oxidative stress markers.
Highlights
Numerous studies have been published in the last several decades supporting the concept that certain diseases [1, 2], aging [3], and exercise of sufficient intensity and duration [4, 5] can result in oxidative stress
It is interesting to note that our study reported similar intraclass correlation coefficients (ICC) ratings for our oxidative stress markers (PC and oxygen radical absorbance capacity (ORAC)) compared to the F2 isoprostanes (F2-IsoP) results in urine
In summary our results indicate that there are day to day fluctuations in the blood of oxidative stress markers that we assessed over a 4-week period while controlling for time of day, diet, and physical activity and nutrition in apparently healthy resistance trained young men
Summary
Numerous studies have been published in the last several decades supporting the concept that certain diseases [1, 2], aging [3], and exercise of sufficient intensity and duration [4, 5] can result in oxidative stress. Oxidative stress has been suggested to occur by measuring several outcome markers that are observed to increase following an intervention or treatment These markers are from blood [6,7,8], saliva [6], plasma [9], urine [10], or within specific tissues [11, 12] and the results are compared to baseline values but these results are reported without concern for diurnal variations or day to day fluctuations. These approaches do not factor in the normal fluctuations that might occur within the subjects from day to day
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