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标题：VENTILATORY THRESHOLD IN ENDURANCE CYCLISTS AND RECREATIONALLY ACTIVE SUBJECTS: EFFECT OF CHRONIC ENDURANCE TRAINING
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作者：Zübeyde AslanKESER ; Şükrü Serdar BALCI
期刊名称：International Journal of Sport, Exercise and Training Sciences
电子版ISSN：2149-8229
出版年度：2017
卷号：3
语种：English
出版社：Balikesir University
摘要：Maximal oxygen consumption (VO2max) and anaerobic threshold (AT) are physiological evaluations about endurance performance. Anaerobic threshold can be determined by lactate or ventilatory responses during an incremental exercise. Ventilatory threshold (VT) is noninvasive method depends on gas exchange. The anaerobic threshold responses differ by trained and untrained subjects. PURPOSE: The purpose of this study was to compare the VT responses between endurance trained and untrained individuals. Method: 10 well-trained and 10 recreationally active young men volunteered to participate in this study. Maximal oxygen consumption (VO2max) test was applied by breath- by- breath gas exchange measures (Cosmed K4 portable telemetry system,Italy) using a cycle ergometer (Monark,839-E). The control subjects warmed up 50 W-3 min and the load was increased 25W in every 2 min. Athletes subjects warmed up 100 W-3 min and the load was increased 25 W in every 2 min. Maximal oxygen consumption was assessed by the attainment of the following criteria: a plateau in VO2 with increases in external work,maximal respiratory exchange ratio (RER) > 1.1,and maximal HR within 10 b/min of the age-predicted maximum (220 – age)( Noakes 1998). The ventilatory threshold was determined using the criteria of an increase in both ventilatory equivalent of oxygen (VE/VO2) and end-tidal pressure of oxygen (PETO2) with no concomitant increase in ventilatory equivalent of carbon dioxide (VE/VCO2) and the R value having been flat or rising slowly (Beaver et al.,1986). Unpaired t test was used to compare mean values between trained and control subjects. Statistical significance was set at a level of p < 0.05,and data were expressed as the means ± standard deviation of the mean. Results: VO2max,VT load and VT time were different between the groups (p<0.01). Trained subjects had higher VO2max (4,35 L;3,11 L trained and untrained respectively) and workloads (189 W;100 W in trained and untrained subjects respectively) at VT. Also,time to VT (9,2 min;6,4 min in trained and untrained subjects respectively) were higher in trained than untrained group. DISCUSSION: During any incremental exercise,peripheral metabolic end-productions increase. At the first ventilator threshold measured this study,ventilation and VCO2 increase as parallel as the exercise intensity. Above VT,increased hydrogen ions and increased PCO2 stimulate ventilation via chemoreceptors. The correlation between endurance capacity and VT is reported by several studies. Physiological adaptations may affect a variety of mechanism influencing the ventilatory responses to exercise. After chronic endurance training loads,high aerobic capacity can cause postpone of the anaerobic threshold. References:Noakes TD. Maximal oxygen uptake: “classical” versus “contemporary” viewpoints: a rebuttal. Med SciSports Exerc 1998;30:1381- 98.Beaver WL,Wasserman K,Whipp BJ (1986) A new method for detecting anaerobic threshold by gasexchange. J Appl Physiol 60:2020-2027.