Assessing Hair Cortisol as Biomarker to Prevent Over-Training

Abstract

Overtraining is primarily related to chronic stress caused by sustained high load training, and often coupled with other stressors. However, a diagnostic tool that monitors chronic stress has yet to be developed. Recently, hair cortisol concentrations （HCC） has been increasingly gaining attention as a novel biomarker of chronic stress, and we hypothesize that HCC could be a useful biomarker for preventing overtraining. To determine this hypothesis, we investigate the relationships between HCC and aerobic performance such as the peak oxygen uptake （V･O2peak） and oxygen transport ability for 41 young male adults （Age: 19.7±1.5yr, Height: 171.7±5.2cm, Weight: 58.2±5.3kg）．HCC, blood cortisol, red blood cells （RBC）， hemoglobin concentrations （Hb）， were measured once per month at June and July. 27 subjects without big sports events in June and July measured V･O2peak. HCC was measured by the enzyme-linked immunosorbent assay （ELISA） in the most proximal 1cm of hair. The results showed that HCC and V･O2peak increased in July. Although, there was no significant negative correlation between HCC and V･O2peak, there were significant negative correlation between HCC and RBC （June: r=-0.309, p<0.05; July: r=-0.384, p<0.05）．Moreover, there were significant negative correlation between HCC and The POMS category vigor in July （r=-0.341, P<0.05） .These results suggest that HCC associated with declining oxygen transport ability and mood. Chronic stress of athletes may cause declining endurance performance and mood and as a result may be related to overtraining syndrome.