Redox Physiology of Elite Endurance Athletes

As participation in sports and physical activity continues to thrive around the globe and athletes continue to push their limits to compete at the highest level, sport related injury and illness have become a concern. It is well known that illness and injury increase with athlete training load, however, so does performance. That leaves athletes and their support team constantly trying to find the edge of their physical and physiological training tolerance - especially elite and professional athletes. Despite great advances in science and technology, training load is still primarily managed via trial and error and subjective athlete feedback measures such as self-perception of mood, fatigue, soreness, and exertion. Because biomarkers of redox balance in the peripheral blood supply have shown early promise as a quantitative measure to assess the physiological response to training and competition, we sought to determine the effects of semi-acute physiological stressors on point-of-care (PoC) biomarkers of redox balance in a sample of elite endurance track athletes and compare those values to reported clinical values. The aims of this dissertation were divided into four hypotheses. First, despite extensive training, PoC redox biomarkers will reveal significantly lower oxidative stress in elite endurance track athletes relative to published values associated with clinical (disease) states. Second, because relative training load is typically the highest during pre-season training of endurance track athletes, (general preparation periodization phase), PoC redox biomarkers will show significantly higher oxidative stress during pre-season training relative to other training phases throughout the year. Third, periods of altitude training will be associated with significantly higher oxidative stress than sea level training. And finally, mRNA COVID-19 vaccination (SPIKEVAX™ (mRNA-1273), Moderna Co., Cambridge, MA, USA) will be associated with a significant but transient increase of oxidative stress and inflammation [i.e, high sensitivity C-Reactive Protein (hsCRP)]. To test the first hypothesis, PoC redox biomarker values collected from 24 elite endurance track athletes over a 5-year period were analyzed by athlete and compared to published data on independent samples involving clinical conditions. To test the second hypothesis, the PoC redox biomarker values collected from 24 elite endurance track athletes over a 5-year period were analyzed by month over the course of the competitive year to evaluate alterations in redox balance relative to time-in-season. To test the third hypothesis, PoC redox samples collected for eight elite endurance track athletes throughout the course of an altitude training camp were analyzed for alterations after 5, 12, 19 and 26 days at altitude relative to athlete specific sea-level baseline values. To test the fourth hypothesis, PoC redox biomarkers as well as hsCRP samples collected for nine elite endurance track athletes prior to and throughout the course of mRNA vaccination were analyzed for alterations in redox balance. In support of our first hypothesis, it was found that mean oxidative stress levels in elite endurance track athletes were lower than reported values for clinical states, but not significantly different than healthy controls or most other characterized athletic populations. Additionally, when alterations in athlete redox balance exceeded clinically relevant levels, the response was predominantly dynamic, quickly returning to within normal ranges. In support of our second hypothesis, it was observed that oxidative stress (i.e., OSI) was elevated during pre-season training of elite endurance track athletes, particularly in December (i.e., General Preparatory training period). This alteration in redox balance was primarily driven by a decrease in anti-oxidative capacity (i.e., FORD). Contrary to our third hypothesis, no significant alteration in redox balance was detected over 26 days of training at altitude in our sample of athletes. And in support of our final hypothesis, it was observed that COVID-19 mRNA vaccination transiently increased oxidative stress (i.e., OSI) 6 days after the first vaccine dose, with a reduction in anti-oxidative capacity (i.e., FORD) that persisted throughout the inter-dose period. Additionally, a stark but transient rise in hsCRP was detected in the first 6 days after the first COVID-19 mRNA vaccine dose in some by not all athletes. From these results, we conclude that PoC redox biomarkers are a valuable objective means to monitor the physiological condition and resilience of athletes, especially for high level programs where professional longevity depends on continued health, minute fluxuations in athlete performance are meaningful, and sport scientists are available to interpret the data from this pioneering bio-analytical method.