Biomarkers in endurance exercise - Individualized regulation and predictive value

Abstract Objectives The high inter-individual variability of exercise response complicates the efficient use of blood-based biomarkers in sports. To address the problem, a useful algorithm to characterize the individual regulation and predictive value of different candidate markers will be developed.Methods Forty-nine participants completed two identical exercise trials. Blood samples were collected before, immediately after, 3 hours after and 24 hours after completion of exercise. Plasma concentrations of interleukin (IL-) 1RA, IL-8, IL-15, IL-10, CK, CRP, LDH, cortisol and thiobarbituric acid reactive substances (TBARS) were measured. Individualized regulation was analyzed using k-means clustering and a Group Assignment Quality Score (GAQ). Regression trees with a bootstrapped-aggregated approach were used to assess the predictive qualities of the markers.Results For most of the markers studied, a distinction can be made between individuals who show a stronger or weaker response to a particular endurance training program. The regulation for IL-10, IL-6, IL-8 and CK exhibited a high degree of stability within the individuals. Regarding the predictive power of the markers, for all dependent variables, the most accurate predictions were obtained for cortisol and IL-8 based on the baseline value. For CK, a good prediction of recovery of maximal strength and subjective feeling of exhaustion can be made. For IL-1RA and TBARS, especially their re-regulation can be predicted if the baseline level is known.Perspectives Focusing individual variations in biomarker responses, our results suggest the combined use of IL-6, IL-8, IL-10, and CK for the personalized management of stress and recovery cycles following endurance exercise.