Department of Biological Psychology, VU University, EMGO+ institute, VU medical center, Amsterdam, The Netherlands.
Int J Psychophysiol. 2011 Sep;81(3):169-76. doi: 10.1016/j.ijpsycho.2011.06.007. Epub 2011 Jun 30.
To examine whether ceiling effects at long inter beat intervals (IBIs)cause an underestimation of cardiac vagal control in regular exercisers by time and frequency-domain measures of respiratory sinus arrhythmia (RSA).
24-hour ECG and respiration recordings were performed in 26 regularly exercising subjects, actively engaged in aerobic training for the past year, and enrolled in supervised training in the six weeks pre-study, and in 26 age- and sex-matched non-exercisers. Sleep and waking levels of cardiac vagal control were estimated by RSA obtained through the peak-valley method, by the standard deviation of the IBIs, the root mean square of successive IBIs, and the high frequency IBI spectral power.
In 11 of the exercisers the IBI-RSA relationship was characterized by a quadratic relationship. This reflected a ceiling effect at very long IBI values attained by regular exercisers, particularly during the nighttime recording. Irrespective of this ceiling effect, RSA as well as other heart rate variability (HRV) measures was still significantly larger in the exercisers with a quadratic IBI-RSA relationship than in non-exercisers or exercisers with a linear IBI-RSA relationship.
We conclude that a subgroup of regular exercisers is characterized by a low heart rate paired to high levels of cardiac vagal control. In these exercisers, vagal control is underestimated from HRV measures in ambulatory recordings. Inspection of the IBI-RSA relationship should be routinely added when HRV measures are used to index cardiac vagal control.
通过呼吸窦性心律失常（RSA）的时频域测量，研究长心动间期（IBI）时的上限效应是否导致定期锻炼者的心脏迷走神经控制被低估。
对 26 名定期锻炼者进行 24 小时心电图和呼吸记录，他们在过去一年中积极参与有氧运动训练，并在研究前六周参加监督训练，同时还招募了 26 名年龄和性别匹配的非锻炼者。通过峰值-谷值法获得 RSA，通过 IBI 的标准差、连续 IBI 的均方根和高频 IBI 频谱功率来估计睡眠和清醒时的心脏迷走神经控制水平。
在 11 名锻炼者中，IBI-RSA 关系呈二次关系。这反映了定期锻炼者在非常长的 IBI 值时出现上限效应，尤其是在夜间记录时。尽管存在这种上限效应，但具有二次 IBI-RSA 关系的锻炼者的 RSA 以及其他心率变异性（HRV）测量值仍然明显大于非锻炼者或具有线性 IBI-RSA 关系的锻炼者。
我们得出结论，一小部分定期锻炼者的特征是心率低但心脏迷走神经控制水平高。在这些锻炼者中，从动态记录中的 HRV 测量值低估了迷走神经控制。当使用 HRV 测量值来指示心脏迷走神经控制时，应常规添加 IBI-RSA 关系的检查。
