668 MEP104 – Monitoring effects of non-functional overreaching and overtraining via responses of cardiac biomarkers in highly trained athletes: implications for prevention of overtraining syndrome

AbstractBackground Professional sports require significant training loads to evoke the desired training effects in athlete's body,but with an inadequate recovery non-functional overreaching(NFO) and then overtraining syndrome(OTS) may occur.It is important to study chronic effects of exercises via responses of biomarkers for understanding of muscle fatigue and cardiac damage to identify athletes at risk of poor adaptation to training.Objective To study effects of non-functional overreaching and overtraining on responses of biomarkers of cardiomyocyte damage and their role in OTS prevention.Design Observational follow-up study.Setting Sports Medicine Clinic.Participants In 348 high level male athletes(22±4,7y.o) 37 athletes with NFO and 6 with OTS were identified,based on the checklist of the European College of Sports Science and the American College of Sports Medicine consensus statement(2017–2022).Interventions In 43 NFO/OTS athletes and 40 age-matched controls,besides clinical assessment,electrocardiography and transthoracic echocardiography,pre-season serum creatine kinase myocardial band(CK-MB) and cardiac troponin I(cTnI) were measured,followed by in-season evaluation of their dynamics:24hrs before strenuous sport-specific exercise,immediately after,in 6,48,and 72hrs(Figure 1).Main Outcome Measurements The participants were followed prospectively until 2020 with respect to identification of NFO/OTS and until 2022 with respect to detection of dynamics of cardiac biomarkers.Results Similar rising trend of CK-MB and cTnI levels was observed immediately after exercise,reaching peak values after 6hrs in all athletes,though,significantly greater in NFO/OTS athletes than controls,slightly exceeding reference range of cTnI(Table 1).After 48hrs of recovery biomarkers in NFO/OTS athletes were significantly higher than on entry,showing slower recovery.Electrocardiography and echocardiography didn't reveal any sustained systolic and diastolic alterations or clinically threatening myocardial damage,only minor diastolic changes due to adaptation to the post-exercise haemodynamic in OTS athletes(E/A pre-exercise:1.47±0.25;post-exercise:in 6hrs 1.06±0.14;in 48hrs 1.40±0.09,p<0.05).Conclusions In our study,intensive exercise caused transient increase of cardiac biomarkers in NFO/OTS athletes,without irreversible pathophysiological and clinical consequences,suggesting mostly benign cardiac involvement.Monitoring responses via alterations of cardiac biomarkers can be helpful for guiding athletic training and preventing OTS. View this table:View inline View popup Download powerpoint Abstract 668 Table 1 Levels of cTnI (ng/ml) and CK-MB (U/I) in studied groups pre- and post-exercise (Mean±SD)Download figure Open in new tab Download powerpoint Abstract 668 Figure 1 Biomarker testing time points