Kenny G P, Denis P M, Proulx C E, Giesbrecht G G
University of Ottawa, School of Human Kinetics, Ontario, Canada.
Eur J Appl Physiol Occup Physiol. 1999 May;79(6):495-9. doi: 10.1007/s004210050543.
The purpose of this study was to evaluate the effect of exercise on the subsequent post-exercise thresholds for vasoconstriction and shivering measured during water immersion. On 2 separate days, seven subjects (six males and one female) were immersed in water (37.5 degrees C) that was subsequently cooled at a constant rate of approximately 6.5 degrees C x h(-1) until the thresholds for vasoconstriction and shivering were clearly established. Water temperature was then increased to 37.5 degrees C. Subjects remained immersed for approximately 20 min, after which they exited the water, were towel-dried and sat in room air (22 degrees C) until both esophageal temperature and mean skin temperature (Tsk) returned to near-baseline values. Subjects then either performed 15 min of cycle ergometry (at 65% maximal oxygen consumption) followed by 30 min of recovery (Exercise), or remained seated with no exercise for 45 min (Control). Subjects were then cooled again. The core temperature thresholds for both vasoconstriction and shivering increased significantly by 0.2 degrees C Post-Exercise (P < 0.05). Because the Tsk at the onset of vasoconstriction and shivering was different during Pre- and Post-Exercise Cooling, we compensated mathematically for changes in skin temperatures using the established linear cutaneous contribution of skin to the control of vasoconstriction and shivering (20%). The calculated core temperature threshold (at a designated skin temperature of 32.0 degrees C) for vasoconstriction increased significantly from 37.1 (0.3) degrees C to 37.5 ( 0.3) degrees C post-exercise (P < 0.05). Likewise, the shivering threshold increased from 36.2 (0.3) degrees C to 36.5 (0.3) degrees C post-exercise (P < 0.05). In contrast to the post-exercise increase in cold thermal response thresholds, sequential measurements demonstrated a time-dependent similarity in the Pre- and Post-Control thresholds for vasoconstriction and shivering. These data indicate that exercise has a prolonged effect on the post-exercise thresholds for both cold thermoregulatory responses.
本研究的目的是评估运动对随后在水浸过程中测量的运动后血管收缩和寒战阈值的影响。在两个不同的日子里，七名受试者（六名男性和一名女性）被浸入水中（37.5摄氏度），随后以约6.5摄氏度×小时−1的恒定速率冷却，直到血管收缩和寒战阈值明确确立。然后将水温升至37.5摄氏度。受试者保持浸泡约20分钟，之后离开水，用毛巾擦干，坐在室内空气中（22摄氏度），直到食管温度和平均皮肤温度（Tsk）恢复到接近基线值。受试者随后要么进行15分钟的蹬车运动（以最大耗氧量的65%），接着进行30分钟的恢复（运动组），要么静坐45分钟不运动（对照组）。然后再次对受试者进行冷却。运动后，血管收缩和寒战的核心温度阈值均显著升高0.2摄氏度（P<0.05）。由于运动前和运动后冷却时血管收缩和寒战开始时的Tsk不同，我们使用已确定的皮肤对血管收缩和寒战控制的线性皮肤贡献（20%）对皮肤温度变化进行数学补偿。运动后，血管收缩的计算核心温度阈值（在指定皮肤温度32.0摄氏度时）从37.1（0.3）摄氏度显著升至37.5（0.3）摄氏度（P<0.05）。同样，运动后寒战阈值从36.2（0.3）摄氏度升至36.5（0.3）摄氏度（P<0.05）。与运动后冷热反应阈值升高相反，连续测量表明，对照组前后血管收缩和寒战阈值存在时间依赖性相似性。这些数据表明，运动对两种冷体温调节反应的运动后阈值有长期影响。
