School of Health Sciences, Central Michigan University, Mt Pleasant, Michigan.
School of Rehabilitation and Medical Sciences, Central Michigan University, Mt Pleasant, Michigan.
J Strength Cond Res. 2019 Oct;33(10):2616-2621. doi: 10.1519/JSC.0000000000003330.
Bradley, LJ, Miller, KC, Wiese, BW, and Novak, JR. Precooling's effect on American football skills. J Strength Cond Res 33(10): 2616-2621, 2019-Precooling (i.e., cooling before exercise) may reduce the risk of exertional heatstroke (EHS) in American football athletes. However, implementation of precooling by coaches or medical staff would likely be poor if it impaired performance. We investigated whether precooling impacted American football skill performance in this randomized, crossover, counterbalanced study. Twelve men (24 ± 2 years, mass = 85.5 ± 6.3 kg, height = 181.8 ± 8.1 cm) completed a familiarization day to practice each skill and then 2 testing days. On testing days (wet-bulb globe temperature = 19.3 ± 4.1° C), subjects were either precooled for 15 minutes using cold-water immersion (10.1 ± 0.3° C) or not (control). Then, they donned an American football uniform and completed several bouts of 8 different football skills. Rectal temperature (Trec) was measured before, during, and after skill testing. Precooling did not affect vertical jump, broad jump, agility, dynamic or stationary catching, or maximum throwing distance (p ≥ 0.13). Precooling impaired 40-yard dash time (precooling = 5.72 ± 0.53 seconds, control = 5.31 ± 0.34 seconds; p = 0.03, effect size = 1.2) and throwing accuracy (precooling = 4 ± 1 points, control = 7 ± 2 points; p = 0.001, effect size = 1.4). On average, Trec was 0.58 ± 0.35° C lower during skills testing after precooling and statistically differed from control from minute 10 to the end of testing (∼35 minutes; p < 0.05, effect size ≥ 1.2). Precooling may be a useful EHS prevention strategy in American football players because it lowered Trec without impacting most skills. By lowering Trec, precooling would prolong the time it would take for an athlete's Trec to become dangerous (i.e., >40.5° C). If precooling is implemented, coaches should alter practice so that throwing accuracy and speed drills occur after an athlete's Trec returns to normal (i.e., >35 minutes).
布拉德利，LJ，米勒，KC，怀斯，BW，和诺瓦克，JR。预冷对美式足球技能的影响。J 力量与调节研究 33（10）：2616-2621，2019-预冷（即运动前冷却）可能会降低美式足球运动员中暑的风险。然而，如果预冷会影响表现，那么教练或医务人员实施预冷的可能性就会很差。在这项随机交叉对照研究中，我们研究了预冷是否会影响美式足球技能表现。12 名男性（24 ± 2 岁，体重 = 85.5 ± 6.3 千克，身高 = 181.8 ± 8.1 厘米）完成了一次熟悉日的练习，然后进行了 2 次测试日。在测试日（湿球温度 = 19.3 ± 4.1°C），受试者要么用冷水浸泡 15 分钟进行预冷（10.1 ± 0.3°C），要么不进行预冷（对照）。然后，他们穿上美式足球服，完成了 8 项不同足球技能的几次比赛。直肠温度（Trec）在技能测试前、中、后进行测量。预冷并没有影响垂直跳跃、跳远、敏捷性、动态或静态接球或最大投掷距离（p≥0.13）。预冷会影响 40 码冲刺时间（预冷=5.72±0.53 秒，对照=5.31±0.34 秒；p=0.03，效应量=1.2）和投掷准确性（预冷=4±1 分，对照=7±2 分；p=0.001，效应量=1.4）。平均而言，预冷后在技能测试期间 Trec 降低了 0.58 ± 0.35°C，从第 10 分钟到测试结束时与对照相比统计学上有差异（约 35 分钟；p<0.05，效应量≥1.2）。预冷可能是美式足球运动员中暑预防的有用策略，因为它降低了 Trec，而不影响大多数技能。通过降低 Trec，预冷会延长运动员 Trec 达到危险水平（即>40.5°C）所需的时间。如果实施预冷，教练应该改变练习，使投掷准确性和速度训练在运动员的 Trec 恢复正常（即>35 分钟）后进行。
