The present study assessed the influence of physical training on cardiac autonomic activity in individuals with spinal cord injury (SCI) during different sleep stages. Twenty-six volunteers were allocated into three groups: 9 sedentary individuals without SCI (control, CON); 8 sedentary tetraplegic individuals with chronic SCI (SED-SCI); 9 physically trained tetraplegic individuals with chronic SCI (TR-SCI). All participants underwent nocturnal polysomnography to monitor sleep stages: wakefulness, non-rapid eye movement (NREM) sleep (N1, N2, and N3 stages), and REM sleep. The electrocardiography data obtained during this exam were extracted to analyze the heart rate variability (HRV). Sleep stages influenced HRV in the time [RR interval and root mean square of successive RR interval differences (RMSSD)] and frequency [low-frequency (LF) and high-frequency (HF) powers and LF-to-HF ratio] domains ( < 0.05). SED-SCI individuals showed unchanged HRV compared to CON ( > 0.05). When comparing the TR-SCI and SED-SCI groups, no significant differences in HRV were reported in the time domain ( > 0.05). However, in the frequency domain, more accentuated HF power was observed in TR-SCI than in SED-SCI individuals during the N2 and N3 stages and REM sleep ( < 0.05). Moreover, TR-SCI had higher HF power than CON during the N3 stage ( < 0.05). TR-SCI individuals have greater HF power, indicative of parasympathetic modulation, than sedentary (injured or not injured) individuals during different sleep stages. Therefore, enhanced parasympathetic activity induced by physical training may improve cardiac autonomic modulation during sleep in individuals with chronic SCI.

中文翻译：

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脊髓损伤患者不同睡眠阶段心脏自主神经活动：体能训练的影响

本研究评估了不同睡眠阶段体能训练对脊髓损伤（SCI）个体心脏自主活动的影响。 26 名志愿者被分为三组：9 名久坐且无 SCI 的个体（对照组，CON）； 8 名久坐四肢瘫痪的慢性 SCI 患者 (SED-SCI)； 9 名经过体能训练的慢性 SCI（TR-SCI）四肢瘫痪患者。所有参与者均接受夜间多导睡眠图监测睡眠阶段：清醒、非快速眼动 (NREM) 睡眠（N1、N2 和 N3 阶段）和 REM 睡眠。提取本次检查期间获得的心电图数据来分析心率变异性（HRV）。睡眠阶段在时间 [RR 间隔和连续 RR 间隔差值的均方根 (RMSSD)] 和频率 [低频 (LF) 和高频 (HF) 功率以及低频与高频比率] 域中影响 HRV（ < 0.05）。与 CON 相比，SED-SCI 个体的 HRV 没有变化 (> 0.05)。比较 TR-SCI 和 SED-SCI 组时，时域 HRV 没有显着差异 (> 0.05)。然而，在频域中，在 N2 和 N3 阶段以及 REM 睡眠期间，TR-SCI 个体比 SED-SCI 个体观察到更突出的高频功率 (< 0.05)。此外，在 N3 阶段，TR-SCI 的高频功率高于 CON（< 0.05）。 TR-SCI 个体在不同睡眠阶段比久坐（受伤或未受伤）的个体具有更大的高频功率，表明副交感神经调节。因此，体育训练引起的副交感神经活动增强可能会改善慢性 SCI 患者睡眠期间的心脏自主调节。