Atkinson Greg, Holder Anna, Robertson Caroline, Gant Nicholas, Drust Barry, Reilly Thomas, Waterhouse Jim
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
J Pineal Res. 2005 Nov;39(4):353-9. doi: 10.1111/j.1600-079X.2005.00256.x.
We examined the effects of a single 2.5-mg dose of melatonin on the thermoregulatory and circulatory responses to intermittent exercise at a room temperature of 27.2+/-0.4 degrees C (mean+/-S.D.), a relative humidity of 55+/-3% (mean+/-S.D.), and a light intensity of 200-300 lux. In a double-blind cross-over study, six male participants ingested either melatonin or placebo at 11:45 hr. Participants then rested in a semi-supine position for 75 min and completed an intermittent running protocol for 66 min at alternating intensities of 40, 60 and 80% of maximal oxygen uptake. Rectal and mean skin temperature, heart rate, blood pressure, skin blood flow, subjective alertness and sleepiness, ratings of perceived exertion (RPE) and thermal strain were recorded. No effects of melatonin were found on these variables measured during the resting period (P>0.10). During exercise, melatonin was found to moderate the increase in rectal temperature by approximately 0.25 degrees C (P=0.050) and magnify the increase in skin blood flow (P=0.047). Postexercise systolic blood pressure was 7.8+/-2.5 mmHg (mean+/-S.D.) lower than before the exercise in the melatonin trial; a change which differed significantly to that in the placebo trial (P=0.018). Melatonin did not influence subjective alertness and sleepiness before or after exercise and did not change the responses of mean skin temperature, RPE and thermal strain during the exercise (P>0.10). In summary it is apparent that a 2.5-mg dose of melatonin has hypothermic, but not soporific, effects during 66 min of intermittent exercise performed under moderate heat stress. Whether such effects improve endurance athletic performance in hot conditions remains to be confirmed. Our data also suggest that postexercise systolic hypotension is more marked after ingestion of melatonin.
我们研究了在室温27.2±0.4摄氏度（均值±标准差）、相对湿度55±3%（均值±标准差）、光照强度200 - 300勒克斯的条件下，单次服用2.5毫克褪黑素对间歇性运动的体温调节和循环反应的影响。在一项双盲交叉研究中，六名男性参与者于11:45时服用褪黑素或安慰剂。参与者随后以半仰卧姿势休息75分钟，然后以最大摄氧量的40%、60%和80%的交替强度完成66分钟的间歇性跑步方案。记录直肠温度、平均皮肤温度、心率、血压、皮肤血流量、主观警觉性和嗜睡程度、自觉用力程度（RPE）以及热应激情况。未发现褪黑素对休息期间测量的这些变量有影响（P>0.10）。在运动期间，发现褪黑素可使直肠温度升高幅度降低约0.25摄氏度（P = 0.050），并放大皮肤血流量的增加（P = 0.047）。在褪黑素试验中，运动后收缩压比运动前低7.8±2.5毫米汞柱（均值±标准差）；这一变化与安慰剂试验中的变化有显著差异（P = 0.018）。褪黑素在运动前或运动后均未影响主观警觉性和嗜睡程度，且在运动期间未改变平均皮肤温度、RPE和热应激的反应（P>0.10）。总之，显然在中等热应激下进行66分钟间歇性运动期间，2.5毫克剂量的褪黑素具有降温作用，但无催眠作用。这种作用是否能改善炎热条件下的耐力运动表现仍有待证实。我们的数据还表明，服用褪黑素后运动后收缩期低血压更为明显。
