热环境中间歇性冲刺运动预冷的体积依赖性反应。
Volume-dependent response of precooling for intermittent-sprint exercise in the heat.
机构信息
School of Human Movement Studies, Charles Sturt University, Bathurst, New South Wales, Australia.
出版信息
Med Sci Sports Exerc. 2011 Sep;43(9):1760-9. doi: 10.1249/MSS.0b013e318211be3e.
PURPOSE
This study aimed to assess the effects of precooling volume on neuromuscular function and performance in free-paced intermittent-sprint exercise in the heat.
METHODS
Ten male, team-sport athletes completed four randomized trials involving an 85-min free-paced intermittent-sprint exercise protocol in 33°C ± 33% relative humidity. Precooling sessions included whole body (WB), head + hand (HH), head (H), and no cooling (CONT) applied for 20 min before exercise and 5 min during exercise. Maximal voluntary contractions were assessed before and after intervention and during and after exercise. Exercise performance was assessed with sprint times, percent decline and distances covered during free-paced bouts. Measures of core (Tc) and skin (Tsk) temperatures, HR, perceptual exertion, and thermal stress were monitored throughout. Venous and capillary blood samples were analyzed for metabolite, muscle damage, and inflammatory markers.
RESULTS
WB precooling facilitated the maintenance of sprint times during the exercise protocol with reduced percent decline (P = 0.04). Mean and total hard running distances increased with precooling 12% compared with CONT (P < 0.05); specifically, WB was 6%-7% greater than HH (P = 0.02) and H (P = 0.001), respectively. No change was evident in mean voluntary or evoked force before to after exercise with WB and HH cooling (P > 0.05). WB and HH cooling reduced Tc by 0.1°C-0.3°C compared with other conditions (P < 0.05). WB Tsk was suppressed for the entire session (P = 0.001). HR responses after WB cooling were reduced (P = 0.05; d = 1.07) compared with CONT conditions during exercise.
CONCLUSIONS
A relationship between precooling volume and exercise performance seems apparent, as larger surface area coverage augmented subsequent free-paced exercise capacity, in conjunction with greater suppression of physiological load. Maintenance of maximal voluntary contraction with precooling despite increased work output suggests the role of centrally mediated mechanisms in exercise pacing regulation and subsequent performance.
目的
本研究旨在评估预冷量对热环境下自由节奏间歇性冲刺运动中神经肌肉功能和表现的影响。
方法
10 名男性团队运动运动员完成了四项随机试验，涉及 33°C±33%相对湿度下 85 分钟的自由节奏间歇性冲刺运动方案。预冷阶段包括全身（WB）、头+手（HH）、头（H）和无冷却（CONT），分别在运动前进行 20 分钟和运动期间进行 5 分钟。在干预前后以及运动中和运动后评估最大自主收缩。通过冲刺时间、下降百分比和自由节奏回合中覆盖的距离来评估运动表现。监测核心（Tc）和皮肤（Tsk）温度、心率、感知用力和热应激的指标。分析静脉和毛细血管血样以评估代谢物、肌肉损伤和炎症标志物。
结果
WB 预冷有助于维持运动方案中的冲刺时间，下降百分比降低（P=0.04）。与 CONT 相比，平均和总硬跑距离增加了 12%（P<0.05）；具体而言，WB 比 HH（P=0.02）和 H（P=0.001）分别高 6%-7%。WB 和 HH 冷却后，最大自主和诱发力在运动前后没有变化（P>0.05）。与其他条件相比，WB 和 HH 冷却使 Tc 降低了 0.1°C-0.3°C（P<0.05）。WB 和 HH 冷却使整个会话的 Tsk 受到抑制（P=0.001）。与 CONT 条件相比，WB 冷却后的 HR 反应减少（P=0.05；d=1.07）。
结论
预冷量与运动表现之间似乎存在关系，因为更大的表面积覆盖增强了随后的自由节奏运动能力，同时更大程度地抑制了生理负荷。尽管输出功增加，预冷仍能维持最大自主收缩，这表明中枢介导机制在运动节奏调节和随后的表现中发挥作用。
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