Sookan Takshita, McKune Andrew J
Department of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
Cardiovasc J Afr. 2012 Mar;23(2):67-72. doi: 10.5830/CVJA-2011.108.
To evaluate the reliability of short-term recordings (five minutes) of heart rate variability (HRV) and the association between HRV and gender.
HRV time- and frequency-domain parameters were calculated in 44 physically active students (21 males and 23 females) over four consecutive days. A Suunto t6 heart rate monitor was used to obtain inter-beat intervals (IBIs) that were then transferred to Kubios HRV analysis software. The relative reliability [intra-class correlation (ICC)] and absolute reliability, [typical error of measurement (TEM) and typical error of measurement as a percentage (TEM%)] of the HRV parameters were then calculated for day 2 versus day 3 and day 3 versus day 4, with day 1 being a familiarisation day. The following HRV parameters were calculated: (1) time domain: resting heart rate (RHR), R-R intervals (IBI), standard deviation of normal-to-normal intervals (SDNN), root mean square differences of the standard deviation (RMSSD), percentage of beats that changed more than 50 ms from the previous beat (pNN50); and (2) frequency domain: low-frequency normalised units (LFnu), high-frequency normalised units (HFnu), low-frequency to high-frequency ratio in normalised units (LF/HFnu). An analysis of variance (ANOVA) with Tukey post-hoc testing was performed to compare HRV parameters in males and females. Significance was set at p ≤ 0.05.
The ICCs for both relationship 1 and 2 indicated primarily good to excellent (> 0.8) relative reliability. The lowest value was found in the LF/HFnu ratio (ICC = 0.36) for males. Absolute reliability was low with TEM% greater than 10% for all HRV parameters, except IBIs. Females demonstrated better relative (higher ICCs) and absolute reliability (lower TEM and TEM% ) compared to males for the frequency domain. The relative and absolute reliability for the time domains were similar except for SDNN where the absolute reliability was higher in males. ANOVA illustrated significant gender differences for the LF/HFnu ratio (41% higher in males, p = 0.003), HFnu (12% higher in females, p = 0.02) and IBI (21% higher in females, p < 0.0001).
Short-term recordings of HRV over three consecutive days demonstrated a high relative reliability. However, a low absolute reliability indicated large day-to-day random variation in HRV, which would make the detection of intervention effects using HRV difficult in individual participants. Females were shown to have a higher parasympathetic modulation of HRV, which may indicate an underlying cardioprotective mechanism in females compared to males.
评估心率变异性（HRV）短期记录（五分钟）的可靠性以及HRV与性别的关联。
对44名身体活跃的学生（21名男性和23名女性）连续四天计算HRV的时域和频域参数。使用Suunto t6心率监测仪获取心跳间期（IBIs），然后将其传输到Kubios HRV分析软件中。以第1天为适应日，计算第2天与第3天以及第3天与第4天HRV参数的相对可靠性[组内相关系数（ICC）]和绝对可靠性[测量的典型误差（TEM）和测量的典型误差百分比（TEM%）]。计算以下HRV参数：（1）时域：静息心率（RHR）、R-R间期（IBI）、正常到正常间期的标准差（SDNN）、标准差的均方根差（RMSSD）、与前一次心跳相比变化超过50毫秒的心跳百分比（pNN50）；（2）频域：低频标准化单位（LFnu）、高频标准化单位（HFnu）、标准化单位中的低频与高频之比（LF/HFnu）。进行方差分析（ANOVA）并采用Tukey事后检验来比较男性和女性的HRV参数。显著性设定为p≤0.05。
关系1和关系2的ICC均表明相对可靠性主要为良好到优秀（>0.8）。男性的LF/HFnu比值的ICC最低（ICC = 0.36）。除IBIs外，所有HRV参数的绝对可靠性较低，TEM%大于10%。在频域方面，女性的相对可靠性（ICC较高）和绝对可靠性（TEM和TEM%较低）优于男性。时域的相对和绝对可靠性相似，但SDNN除外，男性的绝对可靠性更高。方差分析表明，LF/HFnu比值（男性高41%，p = 0.003）、HFnu（女性高12%，p = 0.02）和IBI（女性高21%，p < 0.0001）存在显著的性别差异。
连续三天的HRV短期记录显示出较高的相对可靠性。然而，绝对可靠性较低表明HRV存在较大的每日随机变化，这将使在个体参与者中使用HRV检测干预效果变得困难。结果表明女性对HRV具有较高的副交感神经调节作用，这可能表明与男性相比女性存在潜在的心脏保护机制。
