Changes in cardiac tone regulation with fatigue after supra-maximal running exercise.
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 400 m long sprint event and a 300 m with the same 400 m 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 7 min period immediately following exercise. Biochemical parameters (blood lactate, pH, PO₂, PCO₂, SaO₂, and HCO₃⁻) were measured at 1, 4 and 7 min after exercise. Time to perform 300 m was not significantly different between both running trials. HHRτ measured after the 400 m running exercise was longer compared to 300 m 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 400 m compared to the 300 m trial (P < 0.05). No correlation was found between biochemical and cardiac recovery responses except for the PO₂ values which were significantly correlated with HF levels measured 4 min after both bouts. Thus, it appears that fatigue rather than metabolic stresses occurring during a supramaximal exercise could explain the delayed postexercise parasympathetic reactivation in longer sprint runs.
Laboratoire de Recherche Adaptations Physiologiques à l'Exercice et Réadaptations à l'Effort, EA 3300, UFR-STAPS, Université de Picardie Jules Verne, 80025 Amiens Cedex 1, France. pierre-marie.lepretre@u-picardie.fr
Pierre-Marie
PM
Leprêtre
Philippe
P
Lopes
Claire
C
Thomas
Christine
C
Hanon
D000293:Adolescent; D000328:Adult; D005221:Fatigue; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D009129:Muscle Tonus; D012420:Running; D055815:Young Adult