Changes in inflammatory activity, heart rate variability, and biochemical indices in young athletes during the annual training cycle

Inflammatory activity, heart rate variability (HRV), and biochemical and functional indices were assessed in young ski racers during the preparation, competition, and recovery periods of an annual training cycle. During the preparation period, autohemodilution (decreased red blood cell count (RBC) and hematocrit (Ht) levels) and a decrease in the systemic inflammatory activity (C-reactive protein) occurred, without significant differences in the HRV or serum protein and lipid profile. During the competition period, the systemic inflammatory activity increased by 50% ( p = 0.047), eliminating differences from the control group, and the HRV indices (SDNN, HF, TP, and IT) decreased ( p ≤ 0.013), indicating an increase in the sympathetic effects on the HRV. During the recovery period, hematological indices (Ht and RBC), inflammatory activity, and fibrinogen levels decreased, and the parasympathetic effects on the heart increased. These findings allowed us to conclude that mental and physical activation led to a moderate increase in the systemic inflammatory activity and a shift in the sympathovagal balance towards increased sympathetic activity, providing a nonspecific contribution to the physiological regulation of biochemical (lipoproteins and immunoglobulins) and hematological indices in the athletes. However, similar changes in many biochemical and hematological indices in both groups during the year indicated the important role of a common, probably seasonal, factor in the regulation.