Central nervous system fatigue after VO2max test in triathletes

Abstract

Introduction: Several authors have studied the influence of exercise on the nervous system and cognitive functioning in untrained subjects and different types of efforts using the Flicker Fusion Threshold (FFT). However, the effect on the central nervous system (CNS) of maximum aerobic stimuli is not well studied. The purpose of this study was to examine changes in FFT before and after perform an incremental VO2max running test as a means to evaluate the CNS fatigue. Methods: 9 male trained triathletes (26±6.7 years; 173.3±5.9 cm; 66.4±5.9 kg; VO2max: 59.5±5.1 ml/kg/min) were tested in an incremental treadmill maximal running test (starting at 10 km/h during 5 min and with 1km/h increments every 1 min until complete fatigue). Before and after the maximal test the subject performed ascending and descending test, 3 times and average value was analysed. FFT ascendent (FFTa) and descendent (FFTd), the subjective test (ST) and sensory sensitivity (SS) was recorded by Lafayette Instrument Flicker Fusion Control Unit. The flicker frequency increment (2Hz/sec) changed in 2 ways: from 10 to 100 Hz and from 60 to 0 Hz in ascending and descending test respectively. Cortical Activation was measure through the Critical Flicker Fusion Thresholds (CFFT). The data were analyzed with SPSS 20.0 software. Shapiro-Wilk normality test was used to check homogeneity and then Friedman test was performed. The level of significance was p<0.05. Results: FFTa increased (2.2 %) from basal (35.2±2.3) to after the test (36±2.2). FFTd basal values were higher (0.2 %) than after the test (38.5±7.1 to 38.4±6.8). ST increased (74 %) after the VO2max test (-3.2±6.9 to -2.4±6.1). Finally, CS decreased significantly (p<0.01) after the trial (36.8±3.9 to 35.3±2.1 or 4.2%). Discussion: The results showed no changes in CFFT, thus, there was not decrease in sensorial sensibility or increase in cortical activity. In this sense, the decrease in CFFT is related to fatigue of CNS and also to decrease in processing information. VO2max test did not result in symptoms of fatigue in CNS in triathletes, as the results in CCFT showed. Therefore, the fatigue in this type of effort may due to muscle fatigue than CNS factors2 . The significant decrease in CS values were not in accordance with the results obtained in stressful situation as VO2max and submaximal test. SS values were maintained, according to the results obtained after a submaximal effort.DANI: el resumen de este poster está publicado en la revista Cultura, Ciencia y Deporte que si tiene FI en SJR. Pero la cita la he hecho sobre el congreso en el que fue presentado y por tanto no he puesto el FI (he estado viendo ejemplos de poster en Abacus)y por eso he decidido hacerlo así.