James Carl A, Willmott Ashley G B, Richardson Alan J, Watt Peter W, Maxwell Neil S
Environmental Extremes Laboratory, Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Welkin Laboratories, Denton Road, Eastbourne, BN20 7SN, UK.
Eur J Appl Physiol. 2016 Sep;116(9):1735-45. doi: 10.1007/s00421-016-3430-y. Epub 2016 Jul 12.
Ischaemic preconditioning (IP) has been shown to be ergogenic for endurance performance in normothermic conditions and alleviate physiological strain under hypoxia, potentially through haemodynamic and/or metabolic mechanisms. Exertional hyperthermia is characterised by competition for blood flow between the muscles and skin, an enhanced metabolic strain and impaired endurance performance. This study investigated the effect of IP on the determinants of endurance performance, through an incremental exercise test in the heat.
Eleven males completed two graded exercise tests in the heat (32 °C, 62 % RH) until volitional exhaustion, preceded by IP (4 × 5 min 220 mmHg bilateral upper leg occlusion) or a control (CON) condition (4 × 5-min 50 mmHg bilateral).
IP did not improve running speeds at fixed blood lactate concentrations of 2 and 4 mMol L(-1) (p = 0.828), or affect blood glucose concentration throughout the trial [mean (±SD); CON 5.03 (0.94) mMol L(-1), IP 5.47 (1.38) mMol L(-1), p = 0.260). There was no difference in [Formula: see text]O2max [CON 55.5 (3.7) mL kg(-1) min(-1), IP 56.0 (2.6) mL kg(-1) min(-1), p = 0.436], average running economy [CON 222.3 (18.0) mL kg(-1) km(-1), IP 218.9 (16.5) mL kg(-1) km(-1), p = 0.125], or total running time during graded exercise [CON 347 (42) s, IP 379 (68) s, p = 0.166]. The IP procedure did not change muscle temperature [CON ∆ = 0.55 (0.57) °C, IP ∆ = 0.78 (0.85) °C, p = 0.568], but did reduce T CORE during exercise (~-0.1 °C, p = 0.001).
The novel application of IP prior to exercise in the heat does not enhance the determinants of endurance performance. For events where IP appears ergogenic, muscle warming strategies are unnecessary as IP does not influence deep muscle temperature.
缺血预处理（IP）已被证明在常温条件下对耐力表现具有促力作用，并可能通过血流动力学和/或代谢机制缓解低氧状态下的生理应激。运动性体温过高的特征是肌肉和皮肤之间对血流的竞争、代谢应激增强以及耐力表现受损。本研究通过在热环境中进行递增运动试验，探讨了IP对耐力表现决定因素的影响。
11名男性在热环境（32°C，62%相对湿度）下完成两次分级运动试验，直至自愿力竭，试验前进行IP（双侧大腿4×5分钟220mmHg闭塞）或对照（CON）条件（双侧4×5分钟50mmHg）。
在固定血乳酸浓度为2和4mmol·L⁻¹时，IP并未提高跑步速度（p = 0.828），且在整个试验过程中未影响血糖浓度[平均值（±标准差）；CON为5.03（0.94）mmol·L⁻¹，IP为5.47（1.38）mmol·L⁻¹，p = 0.260]。最大摄氧量[CON为55.5（3.7）mL·kg⁻¹·min⁻¹，IP为56.0（2.6）mL·kg⁻¹·min⁻¹，p = 0.436]、平均跑步经济性[CON为222.3（18.0）mL·kg⁻¹·km⁻¹，IP为218.9（16.5）mL·kg⁻¹·km⁻¹，p = 0.125]或分级运动期间的总跑步时间[CON为347（42）秒，IP为379（68）秒，p = 0.166]均无差异。IP程序未改变肌肉温度[CON变化量=0.55（0.57）°C，IP变化量=0.78（0.85）°C，p = 0.568]，但确实降低了运动期间的核心体温（约-0.1°C，p = 0.001）。
在热环境中运动前进行IP的新应用并未增强耐力表现的决定因素。对于IP似乎具有促力作用的项目，由于IP不影响深部肌肉温度，因此无需采用肌肉升温策略。
