Training Load Control During Training Camp Using Hematological Biomarkers and Digital Training Data

This study examined hematological and cytokine responses during a supervised 10-day triathlon training camp with individualized, lactate-threshold–based intensity prescription in amateur athletes. Eighty-four participants were enrolled, and a biomarker subcohort (n = 59) underwent serial blood sampling at baseline, day 5, and day 10. Training load was managed using individualized heart rate, power, and pace targets, digital training data aggregated in TrainingPeaks, session-RPE, coach observations, and interim complete blood count monitoring. Cytokine profiling was performed post hoc and did not influence real-time training decisions. Despite a twofold increase in cycling session duration on the corresponding sampling days, perceived exertion remained stable. Individual load modifications were made when signs of disproportionate physiological stress were identified. Complete blood count showed moderate increases in leukocytes and neutrophils, with transient lymphocyte redistribution, while all values remained within reference ranges. Cytokine profiling showed reduced CXCL10/IP-10 and interleukin-8 concentrations, alongside increased interleukin-1 receptor antagonist and selected growth-factor– and platelet-associated mediators. Overall, the findings support the feasibility of combining threshold-based prescription, digital training records, and interim hematological monitoring for practical load supervision during intensified triathlon training in heterogeneous amateur athletes.