Neuromuscular Research Laboratory/Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA.
Neuromuscular Research Laboratory/Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA.
Physiol Behav. 2021 Jul 1;236:113413. doi: 10.1016/j.physbeh.2021.113413. Epub 2021 Mar 31.
To study the impact of 48 h of simulated military operational stress (SMOS) on executive function, in addition to the role of trait resilience (RES) and aerobic fitness (FIT) on executive function performance. Associations between executive function and neuropeptide-Y (NPY), brain-derived neurotropic factor (BDNF), insulin-like growth factor-I (IGF-I), oxytocin, and α-klotho (klotho) were assessed to elucidate potential biomarkers that may contribute to cognitive performance during a multi-factorial stress scenario.
Fifty-four service members (SM) (26.4 ± 5.4 years, 178.0 ± 6.5 cm, 85.2 ± 14.0 kg) completed the 5-day protocol, including daily physical exertion and 48 h of restricted sleep and caloric intake. Each morning subjects completed a fasted blood draw followed by Cognition, a 10-part cognitive test battery assessing executive function. SMs were grouped into tertiles [low (L-), moderate (M-), high (H-)] based on Connor Davidson Resilience Score (RES) and V˙O (FIT). Repeated measures ANOVA were run to analyze the effect of day on cognitive performance and biomarker concentration. Separate two-way mixed ANOVAs were run to determine the interaction of group by day on cognitive function. Friedman test with Bonferroni-corrected pairwise comparisons were used if assumptions for ANOVA were not met. Associations between changes in biomarkers and cognitive performance were analyzed using parametric and non-parametric correlation coefficients.
SMOS reduced SM vigilance -11.3% (p < 0.001) and working memory -5.6% (p = 0.015), and increased risk propensity +9.5% (p = 0.005). H-RES and H-FIT SMs demonstrated stable vigilance across SMOS (p > 0.05). Vigilance was compromised during SMOS in L- and M-RES (p = 0.007 and p = 0.001, respectively) as well as L- and M-FIT (p = 0.001 and p = 0.031, respectively). SMOS reduced circulating concentrations of α-klotho -7.2% (p = 0.004), NPY -6.4% (p = 0.001), and IGF-I -8.1% (p < 0.001) from baseline through the end of the protocol. BDNF declined -19.2% after the onset of sleep and caloric restriction (p = 0.005) with subsequent recovery within 48 h. Oxytocin remained stable (p > 0.05). Several modest associations between neuroendocrine biomarkers and cognitive performance were identified.
This study demonstrates H-FIT and H-RES may buffer the impact of SMOS on vigilance. SMOS negatively impacted circulating neuroendocrine biomarkers. While BDNF returned to baseline concentrations by the end of the 5 d protocol, NPY, IGF-I, and α-klotho may require a longer recovery period. These data suggest that the military may benefit by training and/or selection processes targeting at augmenting trait resilience and aerobic fitness for increased readiness.
研究模拟军事作业应激（SMOS）对执行功能的影响，以及特质韧性（RES）和有氧健身（FIT）对执行功能表现的作用。评估执行功能与神经肽 Y（NPY）、脑源性神经营养因子（BDNF）、胰岛素样生长因子-I（IGF-I）、催产素和α-klotho（klotho）之间的关联，以阐明在多因素应激情况下可能有助于认知表现的潜在生物标志物。
54 名现役军人（SM）（26.4±5.4 岁，178.0±6.5cm，85.2±14.0kg）完成了为期 5 天的方案，包括每天的体力活动和 48 小时的限制睡眠和热量摄入。每天早上，受试者在进行认知测试前先进行空腹采血，认知测试由 10 个部分组成，评估执行功能。根据康纳戴维森韧性评分（RES）和 V˙O（FIT），SM 被分为三分位数[低（L-）、中（M-）、高（H-）]。重复测量方差分析用于分析认知表现和生物标志物浓度随时间的变化。使用双向混合方差分析来确定组间和时间的交互作用对认知功能的影响。如果方差分析的假设不成立，则使用 Friedman 检验和 Bonferroni 校正的两两比较。使用参数和非参数相关系数分析生物标志物变化与认知表现之间的关系。
SMOS 使 SM 的警觉性降低了 11.3%（p<0.001），工作记忆降低了 5.6%（p=0.015），风险倾向增加了 9.5%（p=0.005）。H-RES 和 H-FIT 的 SM 在 SMOS 期间保持警觉（p>0.05）。在 L-和 M-RES（p=0.007 和 p=0.001）以及 L-和 M-FIT（p=0.001 和 p=0.031）中，警觉性在 L-和 M-RES 中受到了损害。SMOS 使循环中的α-klotho 减少了 7.2%（p=0.004），NPY 减少了 6.4%（p=0.001），IGF-I 减少了 8.1%（p<0.001），与基线相比。BDNF 在睡眠和热量限制开始后下降了 19.2%（p=0.005），并在 48 小时内恢复。催产素保持稳定（p>0.05）。几项神经内分泌生物标志物与认知表现之间存在中等程度的关联。
这项研究表明，高 FIT 和 H-RES 可能缓冲 SMOS 对警觉性的影响。SMOS 对循环神经内分泌生物标志物产生负面影响。虽然 BDNF 在 5 天方案结束时恢复到基线浓度，但 NPY、IGF-I 和α-klotho 可能需要更长的恢复时间。这些数据表明，军队可能受益于培训和/或选拔过程，以提高适应性和有氧健身，以提高战备状态。
