Hickey M S, Costill D L, Vukovich M D, Kryzmenski K, Widrick J J
Human Performance Laboratory, Ball State University, Muncie, IN 47306.
Eur J Appl Physiol Occup Physiol. 1993;67(2):159-63. doi: 10.1007/BF00376660.
To investigate the influence of time of day on sympathoadrenal and pressor reactivity during exercise, eight trained men [age, mean (SD), 24 (0.5) years; maximal oxygen uptake (VO2max), 4.7 l.min-1] performed bouts of static (ST) and dynamic (DYN) exercise at 0600-0800 hours (AM) and at 1600-1800 hours (PM). The ST protocol utilized a two-leg isometric contraction at 30% maximum voluntary contraction until failure, and was monitored by a strain gauge interfaced from a leg extension apparatus to a computer. Heart rate (fc) and blood pressure (Pa) responses were recorded at rest, after 1 and 2 min of exercise, and at failure. Epinephrine (EPI) and norepinephrine (NE) levels were recorded before exercise, and after 2 min of exercise. The DYN exercise protocol involved stationary cycling for consecutive 6-min periods at 60% and 80% VO2max. fc, Pa, EPI, and NE were recorded before exercise and at each workload. No differences were observed in preexercise or exercise fc under any condition. Preexercise Pa did not differ under any condition. The Pa response to DYN was significantly higher at 80% VO2max during PM only. Pa was significantly higher in ST-PM at 1 min, 2 min, and failure. Elevations in both systolic and diastolic Pa contributed to this difference. Preexercise EPI-ST-AM was significantly elevated vs PM, but no other preexercise data were significantly different. Absolute exercise levels were significantly higher for EPI-ST-PM vs AM only, but the percentage change from baseline was significantly (P < 0.01) higher in ST-PM for EPI (+231% PM vs +32% AM) and NE (+352% PM vs +216% AM).(ABSTRACT TRUNCATED AT 250 WORDS)
为研究一天中的不同时间对运动期间交感肾上腺系统及升压反应性的影响，八名训练有素的男性[年龄，均值（标准差），24（0.5）岁；最大摄氧量（VO2max），4.7升·分钟-1]于上午0600 - 0800时（AM）和下午1600 - 1800时（PM）进行了静态（ST）和动态（DYN）运动。ST方案采用双腿等长收缩，强度为最大自主收缩的30%，直至疲劳，通过连接腿部伸展器械和计算机的应变仪进行监测。在静息状态、运动1分钟和2分钟后以及疲劳时记录心率（fc）和血压（Pa）反应。在运动前及运动2分钟后记录肾上腺素（EPI）和去甲肾上腺素（NE）水平。DYN运动方案包括在60%和80% VO2max下连续进行6分钟的固定自行车运动。在运动前及每个工作负荷下记录fc、Pa、EPI和NE。在任何条件下，运动前或运动时的fc均未观察到差异。在任何条件下，运动前的Pa也无差异。仅在下午，DYN运动在80% VO2max时的Pa反应显著更高。在ST - PM中，1分钟、2分钟和疲劳时的Pa显著更高。收缩压和舒张压的升高均导致了这一差异。运动前EPI - ST - AM与PM相比显著升高，但其他运动前数据无显著差异。仅EPI - ST - PM的绝对运动水平显著高于AM，但EPI（下午+231% 对比上午+32%）和NE（下午+352% 对比上午+216%）从基线的百分比变化在ST - PM中显著更高（P < 0.01）。（摘要截断于250字）
