The cientificWorldJOURNAL Research Article Changes in Cardiac Tone Regulation with Fatigue after Supra-Maximal Running Exercise

Copyright © 2012 Pierre-Marie Leprêtre et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To investigate the effects of fatigue and metabolite accumulation on the postexercicse parasympathetic reactivation, 11 long-sprint runners performed on an outdoor track an exhaustive 400m long sprint event and a 300m with the same 400m pacing strategy. Time constant of heart rate recovery (HRRτ), time (RMSSD), and frequency (HF, and LF) varying vagal-related heart rate variability indexes were assessed during the 7min period immediately following exercise. Biochemical parameters (blood lactate, pH, PO2, PCO2, SaO2, and HCO3−) were measured at 1, 4 and 7min after exercise. Time to perform 300m was not significantly different between both running trials. HHRτ measured after the 400m running exercise was longer compared to 300m running bouts (183.7 ± 11.6 versus 132.1 ± 9.8 s, P < 0.01). Absolute power density in the LF and HF bands was also lower after 400m compared to the 300m trial (P < 0.05). No correlation was found between biochemical and cardiac recovery responses except fo