Background. Exercise intensity can influence functional recovery after stroke, but the mechanisms remain poorly understood. Objective. In chronic stroke, an intensity-dependent increase in circulating brain-derived neurotrophic factor (BDNF) was previously found during vigorous exercise. Using the same serum samples, this study tested acute effects of exercise intensity on other circulating molecules related to neuroplasticity, including vascular-endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF1), and cortisol, with some updated analyses involving BDNF. Methods. Using a repeated-measures design, 16 participants with chronic stroke performed 3 exercise protocols in random order: treadmill high-intensity interval training (HIT-treadmill), seated-stepper HIT (HIT-stepper), and treadmill moderate-intensity continuous exercise (MCT-treadmill). Serum molecular changes were compared between protocols. Mediation and effect modification analyses were also performed. Results. VEGF significantly increased during HIT-treadmill, IGF1 increased during both HIT protocols and cortisol nonsignificantly decreased during each protocol. VEGF response was significantly greater for HIT-treadmill versus MCT-treadmill when controlling for baseline. Blood lactate positively mediated the effect of HIT on BDNF and cortisol. Peak treadmill speed positively mediated effects on BDNF and VEGF. Participants with comfortable gait speed ≥0.4 m/s had significantly lower VEGF and higher IGF1 responses, with a lower cortisol response during MCT-treadmill. Conclusions. BDNF and VEGF are promising serum molecules to include in future studies testing intensity-dependent mechanisms of exercise on neurologic recovery. Fast training speed and anaerobic intensity appear to be critical ingredients for eliciting these molecular responses. Serum molecular response differences between gait speed subgroups provide a possible biologic basis for previously observed differences in training responsiveness.

中文翻译：

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运动强度对卒中后急性循环分子反应的影响

背景。运动强度可以影响卒中后的功能恢复，但其机制仍知之甚少。客观的。在慢性中风中，先前在剧烈运动期间发现循环脑源性神经营养因子 (BDNF) 的强度依赖性增加。本研究使用相同的血清样本，测试了运动强度对与神经可塑性相关的其他循环分子的急性影响，包括血管内皮生长因子 (VEGF)、胰岛素样生长因子-1 (IGF1) 和皮质醇，并进行了一些更新的分析涉及BDNF。方法。使用重复测量设计，16 名慢性中风参与者以随机顺序执行 3 种运动方案：跑步机高强度间歇训练 (HIT-treadmill)、坐式踏步机 HIT (HIT-stepper)、和跑步机中等强度持续运动（MCT-treadmill）。比较方案之间的血清分子变化。还进行了中介和效果修正分析。结果。在 HIT 跑步机期间 VEGF 显着增加，在 HIT 方案期间 IGF1 增加，并且在每个方案期间皮质醇均非显着降低。当控制基线时，HIT 跑步机与 MCT 跑步机的 VEGF 反应显着更高。血乳酸正介导 HIT 对 BDNF 和皮质醇的影响。跑步机峰值速度对 BDNF 和 VEGF 有正向调节作用。舒适步态速度 ≥ 0.4 m/s 的参与者具有显着较低的 VEGF 和较高的 IGF1 反应，在 MCT 跑步机期间皮质醇反应较低。结论。BDNF 和 VEGF 是有前途的血清分子，可用于未来研究中测试运动对神经功能恢复的强度依赖性机制。快速的训练速度和无氧强度似乎是引发这些分子反应的关键因素。步态速度亚组之间的血清分子反应差异为先前观察到的训练反应性差异提供了可能的生物学基础。