Button Chris, Croft James L, Cotter James D, Graham Matthew J, Lucas Samuel J E
School of Physical Education, Sport and Exercise Sciences, University of Otago, New Zealand.
Centre for Exercise and Sports Science Research, Edith Cowan University, Perth, Australia.
Physiol Behav. 2015 Jan;138:254-9. doi: 10.1016/j.physbeh.2014.10.024. Epub 2014 Oct 30.
We examined the initial physiological responses and subsequent capacity to swim following cold-water immersion. An ecologically-valid model was used whereby immersion was sudden (<2s) and participants had to actively remain afloat. Participants (15 skilled swimmers, 17 less-skilled swimmers) undertook four experimental test sessions: a physiological test and a swimming test in both cold (10°C) water and temperate (27°C) water in a swimming flume (temperature order counter-balanced). For physiological testing, measures of brain perfusion [flow velocity (MCAv, Doppler) and oxygenation (NIRS)] and cardiorespiratory function [ventilation parameters and end-tidal PCO2 (PETCO2)] were recorded whilst treading water for 150s. The swimming test involved treading water (150s) before swimming at 60% (up to 120s) and 90% (to intolerance) of pre-determined maximum velocity. Multifactorial analysis revealed that swimming duration was influenced most heavily by water temperature, followed by respiratory variables and MCAv in the first 30s of immersion. The time course and severity of cold shock were similar in both groups (p=0.99), in terms of initial physiological changes (MCAv down ~20 ± 11%, respiratory frequency increased to 58 ± 18 breaths·min(-1), PETCO2 dropped to 12 ± 9 mmHg). Treading water following cold-water immersion increased MCAv by 30% above resting values despite maintained cold-shock-induced hyperventilation. In comparison to temperate water, swimming capacity was also reduced similarly between groups in the cold (i.e., distance decreased by 34 ± 26% skilled; 41 ± 33% less-skilled, p=0.99). These integrative findings verify that sudden cold-water immersion followed by physical activity leads to similar physiological responses in humans when contrasting between skilled and less-skilled swimmers.
我们研究了冷水浸泡后的初始生理反应以及随后的游泳能力。采用了一种生态有效模型，即浸泡是突然发生的（<2秒），参与者必须积极保持漂浮状态。参与者（15名熟练游泳者，17名不太熟练的游泳者）进行了四个实验测试环节：在游泳水槽中分别在冷水（10°C）和温水（27°C）中进行生理测试和游泳测试（温度顺序进行了平衡）。对于生理测试，在踩水150秒期间记录脑灌注指标[血流速度（MCAv，多普勒）和氧合（近红外光谱法）]以及心肺功能指标[通气参数和呼气末二氧化碳分压（PETCO2）]。游泳测试包括在以预定最大速度的60%（最长120秒）和90%（至耐受极限）游泳之前踩水（150秒）。多因素分析表明，游泳持续时间受水温影响最大，其次是呼吸变量和浸泡最初30秒内的MCAv。两组的冷休克时间进程和严重程度相似（p=0.99），就初始生理变化而言（MCAv下降约20±11%，呼吸频率增加到58±18次·分钟-1，PETCO2降至12±9毫米汞柱）。尽管冷休克引起的过度通气持续存在，但冷水浸泡后踩水使MCAv比静息值增加了30%。与温水相比，两组在冷水中的游泳能力也同样下降（即熟练游泳者距离减少34±26%；不太熟练的游泳者减少41±33%，p=0.99）。这些综合研究结果证实，在熟练和不太熟练的游泳者之间进行对比时，突然的冷水浸泡后进行体力活动会在人类身上引发相似的生理反应。
