Bernardi L, Salvucci F, Suardi R, Soldá P L, Calciati A, Perlini S, Falcone C, Ricciardi L
Department of Internal Medicine, University of Pavia, Italy.
Cardiovasc Res. 1990 Dec;24(12):969-81. doi: 10.1093/cvr/24.12.969.
The aim was to assess the changes in sympatho-vagal balance which occur with exercise.
The power spectrum of RR interval fluctuations (low frequency [LF] and high frequency components [HF]) was determined before, during, and after graded work load exercise on a cycle ergometer. The power spectrum of the respiratory signal, oxygen consumption, and respiratory volumes were also evaluated. In all subjects HF was considered to be an index of respiratory sinus arrhythmia. In normal subjects HF and LF were considered to be indices of relative vagal and sympathetic activity, respectively, whereas in heart transplant subjects HF was considered as a respiratory modulation of the intrinsic heart rate, and not dependent on autonomic tone. Heart rate variability was evaluated as RR interval variance.
15 normal subjects (six trained cyclists and nine healthy sedentary subjects) and six orthotopic heart transplant recipients took part in the study.
During the first part of exercise, heart rate increased, RR interval variance decreased, HF decreased, and the relative amount of LF increased both in sedentary and athletic subjects, suggesting a relative increase in sympathetic tone. However, when approaching peak exercise, while heart rate further increased and the variance slightly decreased, the relative proportion of LF decreased and HF proportionally increased. At peak exercise HF accounted for 99.9% of heart rate variability in athletic subjects and for 88.9% in sedentary subjects (p less than 0.001 v baseline and v LF in both groups). In heart transplant subjects both the variance and the HF increased from the beginning of exercise (p less than 0.05), and showed a direct correlation with ventilatory variables and an inverse correlation with heart rate (r = 0.794, p less than 0.001, multiple regression analysis). No measurable LF components could be obtained in these subjects. During recovery, while the heart rate decreased and the RR interval variance increased, there was a relative increase in LF and a relative decrease in HF in normal subjects (either sedentary or athletic). Similarly, in heart transplant subjects, there was a decrease in HF during recovery. Thus the increase in HF at peak exercise in normal subjects contrasts with all the other data which suggest a prevalence in sympathetic tone during the entire exercise and the early recovery period, but appears similar to the increase in HF observed in heart transplant subjects due to the effect of increased ventilation during exercise.
These findings suggest that at peak exercise a non-autonomic mechanism, possibly intrinsic to the heart muscle, may determine heart rate fluctuations in synchrony with ventilation in the intact as well as in the denervated human heart.
旨在评估运动时交感 - 迷走神经平衡的变化。
在自行车测力计上进行分级运动负荷试验，分别于运动前、运动中和运动后测定RR间期波动的功率谱（低频[LF]和高频成分[HF]）。同时评估呼吸信号的功率谱、耗氧量和呼吸量。在所有受试者中，HF被视为呼吸性窦性心律不齐的指标。在正常受试者中，HF和LF分别被视为相对迷走神经和交感神经活动的指标，而在心脏移植受试者中，HF被视为固有心率的呼吸调节，不依赖于自主神经张力。心率变异性以RR间期方差来评估。
15名正常受试者（6名训练有素的自行车运动员和9名健康的久坐者）和6名原位心脏移植受者参与了该研究。
在运动的第一阶段，久坐者和运动员的心率均增加，RR间期方差减小，HF降低，LF相对量增加，提示交感神经张力相对增加。然而，接近运动峰值时，虽然心率进一步增加且方差略有减小，但LF的相对比例降低，HF成比例增加。在运动峰值时，HF在运动员中占心率变异性的99.9%，在久坐者中占88.9%（两组与基线及LF相比，p均小于0.001）。在心脏移植受试者中，从运动开始方差和HF均增加（p小于0.05），且与通气变量呈正相关，与心率呈负相关（r = 0.794，p小于0.001，多元回归分析）。在这些受试者中无法获得可测量的LF成分。恢复期间，正常受试者（无论是久坐者还是运动员）心率下降，RR间期方差增加，LF相对增加，HF相对减少。同样，心脏移植受试者在恢复期间HF也降低。因此，正常受试者运动峰值时HF的增加与所有其他提示在整个运动及早期恢复期间交感神经张力占优势的数据形成对比，但由于运动期间通气增加的影响，其与心脏移植受试者中观察到的HF增加相似。
这些发现表明，在运动峰值时，一种可能源于心肌本身的非自主机制，可能决定完整和去神经支配的人体心脏中与通气同步的心率波动。
