Department of Nutrition, Dietetics and Food, Monash University, Notting Hill, Victoria, AUSTRALIA.
Med Sci Sports Exerc. 2021 May 1;53(5):1056-1067. doi: 10.1249/MSS.0000000000002546.
The study aimed to determine the effect of diurnal versus nocturnal exercise on gastrointestinal integrity and functional responses, plasma lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14) concentrations (as indirect indicators of endotoxin responses), systemic inflammatory cytokine profile, gastrointestinal symptoms, and feeding tolerance.
Endurance runners (n = 16) completed 3 h of 60% V˙O2max (22.7°C, 45% relative humidity) running, on one occasion performed at 0900 h (400 lx; DAY) and on another occasion at 2100 h (2 lx; NIGHT). Blood samples were collected pre- and postexercise and during recovery to determine plasma concentrations of cortisol, catecholamines, claudin-3, I-FABP, LBP, and sCD14 and inflammatory cytokine profiles by ELISA. Orocecal transit time (OCTT) was determined by lactulose challenge test given at 150 min, with concomitant breath hydrogen (H2) and gastrointestinal symptom determination.
Cortisol increased substantially pre- to postexercise on NIGHT (+182%) versus DAY (+4%) (trial-time, P = 0.046), with no epinephrine (+41%) and norepinephrine (+102%) trial differences. I-FABP, but not claudin-3, increased pre- to postexercise on both trials (mean = 2269 pg·mL-1, 95% confidence interval = 1351-3187, +143%) (main effect of time [MEOT], P < 0.001). sCD14 increased pre- to postexercise (trial-time, P = 0.045, +5.6%) and was greater on DAY, but LBP decreased (MEOT, P = 0.019, -11.2%) on both trials. No trial difference was observed for systemic cytokine profile (MEOT, P = 0.004). Breath H2 responses (P = 0.019) showed that OCTT was significantly delayed on NIGHT (>84 min, with n = 3 showing no breath H2 turning point by 180 min postexercise) compared with DAY (mean = 54 min, 95% confidence interval = 29-79). NIGHT resulted in greater total gastrointestinal symptoms (P = 0.009) compared with DAY. No difference in feeding tolerance markers was observed between trials.
Nocturnal exercise instigates greater gastrointestinal functional perturbations and symptoms compared with diurnal exercise. However, there are no circadian differences to gastrointestinal integrity and systemic perturbations in response to the same exertional stress and controlled procedures.
本研究旨在确定日间与夜间运动对胃肠道完整性和功能反应、血浆脂多糖结合蛋白（LBP）和可溶性 CD14（sCD14）浓度（作为内毒素反应的间接指标）、全身炎症细胞因子谱、胃肠道症状和喂养耐受性的影响。
耐力跑运动员（n=16）在一次实验中，分别于 0900 h（400 lx；日间）和 2100 h（2 lx；夜间）进行 3 h 的 60%最大摄氧量（22.7°C，45%相对湿度）跑步。运动前后和恢复期间采集血液样本，通过 ELISA 测定皮质醇、儿茶酚胺、闭合蛋白-3、I-FABP、LBP 和 sCD14 的血浆浓度以及炎症细胞因子谱。在 150 分钟时给予乳果糖挑战试验，同时测定口-盲肠传输时间（OCTT）和胃肠道症状。
与日间（+4%）相比，夜间（+182%）运动前到运动后的皮质醇显著增加（试验时间，P=0.046），但肾上腺素（+41%）和去甲肾上腺素（+102%）试验差异无统计学意义。两次试验中 I-FABP（但不是闭合蛋白-3）在运动前到运动后的水平均升高（平均值=2269 pg·mL-1，95%置信区间=1351-3187，+143%）（时间的主要效应[MEOT]，P<0.001）。sCD14 在运动前到运动后增加（试验时间，P=0.045，+5.6%），且日间更高，但 LBP 在两次试验中均降低（MEOT，P=0.019，-11.2%）。两次试验的全身细胞因子谱均无试验差异（MEOT，P=0.004）。呼吸氢（H2）反应（P=0.019）表明，夜间（>84 分钟，n=3 名运动员在运动后 180 分钟时无呼吸 H2 转折点）的 OCTT 显著延迟，而日间（平均值=54 分钟，95%置信区间=29-79）。夜间的总胃肠道症状（P=0.009）明显高于日间。两次试验间的喂养耐受性标志物无差异。
与日间运动相比，夜间运动引起更大的胃肠道功能紊乱和症状。然而，对于相同的运动应激和受控程序，胃肠道完整性和全身应激反应没有昼夜差异。
