目的:研究的目的是研究下坡跑步和热应激对肌肉损伤的联合作用,以及在随后的高温运行期间的热应变和肾脏压力。
方法:在一项随机交叉研究中,十个非热适应,身体活跃的男性在温带(Temp中的EIMD)和高温(Hot中的EIMD)条件下完成下坡跑步,然后在休息3小时后进行运动热应激(HS)测试。在EIMD和HS之前和之后立即收集血液和尿液样本,以及EIMD后24小时(24小时后)。测量核心温度和热感觉以评估热应变。血清肌酸激酶(CK),测量股四头肌的最大自愿性等距收缩(MVC)和感觉到的肌肉酸痛,以评估肌肉损伤。测量尿中性粒细胞明胶酶相关脂质运载蛋白(NGAL)和肾损伤分子-1(KIM-1)水平以指示急性肾应激。
结果:CK,MVC和感知的酸痛在任何时间点的条件之间没有差异。在EIMD处于高温状态时,尿NGAL从HS前显著升高到HS后(HS前:6.56{1.53-12.24}ng/min,HS后:13.72{7.67-21.46}ng/min,p=0.034)。在Temp条件下的EIMD中未发现NGAL或KIM-1的这种升高。
结论:与在温带环境下下坡行驶相比,在炎热的环境中下坡跑步似乎不会加重肌肉损伤。然而,高温环境下EIMD后NGAL水平升高,提示此类运动可能会增加高温耐力运动后轻度急性肾损伤的风险.
OBJECTIVE: The purpose of the study was to investigate the combined effect of downhill running and heat stress on muscle damage, as well as on heat strain and kidney stress during subsequent running in the heat.
METHODS: In a randomized cross-over study, ten non-heat-acclimated, physically active males completed downhill running in temperate (EIMD in Temp) and hot (EIMD in Hot) conditions followed by an exercise-heat stress (HS) test after 3-h seated rest. Blood and urine samples were collected immediately pre- and post-EIMD and HS, and 24 h post-EIMD (post-24 h). Core temperature and thermal sensation were measured to evaluate heat strain. Serum creatine kinase (CK), maximal voluntary isometric contraction of the quadriceps (MVC) and perceived muscle soreness were measured to evaluate muscle damage. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels were measured to indicate acute kidney stress.
RESULTS: CK, MVC and perceived soreness were not different between conditions at any timepoints. In the EIMD in Hot condition, urinary NGAL was significantly elevated from pre- to post-HS (pre-HS: 6.56 {1.53-12.24} ng/min, post-HS: 13.72 {7.67-21.46} ng/min, p = 0.034). Such elevation of NGAL or KIM-1 was not found in the EIMD in Temp condition.
CONCLUSIONS: As compared with downhill running in a temperate environment, downhill running in a hot environment does not appear to aggravate muscle damage. However, elevated NGAL levels following EIMD in a hot environment suggest such exercise may increase risk of mild acute kidney injury during subsequent endurance exercise in the heat.