Effect of acupuncture on heart rate variability at rest and on stride length and frequency at gallop in thoroughbred racehorses

Methodology

Ethical approval (REC185-19) was obtained from the Animal
Ethics Committee of the University of Pretoria. This study was a quantitative
randomised control trial during field conditions. The racing trainer selected 30 horses that
qualified for the study. The mean (±SD) age of Group A was 4 ± 0.8 years. In
Group A there were five fillies, three colts and eight geldings. In this group
one horse was eliminated due to injury. The control group had a mean (±SD) age
of 3 ± 0 years and consisted of seven geldings and eight colts with no fillies.
All participants were kept in uniform
conditions within one stable yard, received identical nutrition and training. The
researcher randomly allocated these horses into an acupuncture treatment group
(A) and a control or non-treatment group (B), with 15 horses in each group. All
individuals involved in the study, except the researcher, were blinded to which
group was the control or treatment group.

The researcher performed a clinical health examination on
each horse participating in the project and the horses were habituated to the
equipment. The HRV and SP were measured pre-treatment and post-treatment, i.e.,
after the treatment group received three dry needle acupuncture treatments
spaced evenly over a three-week period.

The dry needle
acupuncture technique was performed by inserting acupuncture needles into
pre-selected acupuncture points (GB21, ST36, LI10, Bai Hui, Shen Shu, Shen
Peng, Shen Jiao, Yan Chi, BL40, GB27, LU1, BL54 and SI9). Needles were inserted
for 20 minutes and stimulated in a clockwise direction every five minutes. The
non-treatment group was haltered and kept in the stable for the same
period.

Heart Rate Variability

The Televet100
echocardiogram (ECG) device was used to record, digitally on a laptop 15
minutes of echocardiogram data. It was attached with gel on the skin surface by
four ECG electrodes (Trachsel et al., 2010), and secured with a surcingle. The data were recorded
pre- and post-treatment at the stables midmorning on a Sunday when the horses
were rested, one hour after feeding.

The data was downloaded from the recording monitor using
the Televet100 software, then transferred to the HRV Analysis Software 2.1 for
Windows or Kubios. The RR-intervals were
quantified (determining the various HRV parameters) using the Kubios software.
The frequency band widths in Kubios were set at 0.01- 0.06 Hz for low frequency
and 0.07-0.6 Hz for high frequency. A five-minute segment (within the 15
minutes recording) with the least number of artefacts (visually) was chosen.
This five-minute segment was then analysed using no correction, very low, low
correction, medium- and high-correction factors (CF) for each of the horses pre-
and post-treatment. The lowest CF that corrected the data without affecting the
variability was then chosen on an individual basis as recommended by the Kubios
website. Where the tachogram quality
was extremely poor the results were excluded from the analysis.

Using Kubios software,
the variability of the beat-to-beat (RR) intervals was quantified with the aid
of time domain, frequency domain and Poincaré plot analyses. The
following HRV indicators (SDNN, RMSSD, LF, HF, LF/HF, LF nu, HF, SD2) and heart
rate measures (mean RR, mean HR) were determined and statistically analysed.

Stride parameters

A GPS girth-mounted device EquinITy™ was used to measure
stride parameters and running performance in a gallop over 600m. The following
was recorded by the EquinITy™ software: maximum stride length (SL Max), average
stride length (SL Avg), maximum stride frequency (SF Max), average stride count
(SC Avg), maximum stride count (SC Max), maximum speed (Max Speed), stride count
at maximum speed (SC Max Speed), stride length at maximum speed (SL Max Speed)
and average speed (Avg Speed). Once the EquinITy™ data was downloaded from the
device at the end of the training session it was processed by the EquinITy™
Technology website per horse and work session.

研究方法

本研究已获得比勒陀利亚大学动物伦理委员会的伦理批准（REC185-19）。本研究为野外条件下开展的定量随机对照试验。赛事驯马师遴选了30匹符合研究纳入标准的马匹。A组马匹的平均（±标准差）年龄为4±0.8岁，包含5匹牝马、3匹公马驹与8匹骟马，该组中有1匹马匹因受伤被剔除出研究。对照组的平均（±标准差）年龄为3±0岁，包含7匹骟马与8匹公马驹，无牝马。所有受试马匹均饲养于同一马厩，接受统一的饲养管理与训练方案。研究者将所有马匹随机分为针灸治疗组（A组）与对照组（B组，即非治疗组），每组各15匹马匹。本研究所有参与者（除研究者本人外）均对分组情况设盲，无法得知哪一组为对照组、哪一组为治疗组。

研究者对所有参与研究的马匹开展临床健康检查，并让马匹适应实验设备。分别于治疗前与治疗后测量受试马匹的心率变异性（HRV, Heart Rate Variability）与相关指标，其中治疗组在为期三周的周期内均匀接受三次干式针灸治疗。

干式针灸操作流程为：将针灸针刺入预先选定的穴位（GB21、ST36、LI10、百会（Bai Hui）、肾俞（Shen Shu）、神蓬、神交、阳池（Yan Chi）、BL40、GB27、LU1、BL54与SI9），留针时长20分钟，每5分钟沿顺时针方向行针一次。非治疗组马匹将被佩戴笼头，于马厩内停留相同时长。

心率变异性（HRV）

使用Televet100型超声心动图（ECG）设备，于笔记本电脑上数字化记录15分钟的超声心动图数据。该设备通过导电胶与4个心电图电极（Trachsel等，2010）固定于马匹皮肤表面，并以腹带加固。数据采集于治疗前与治疗后，均在周日上午中段马匹休息且喂食1小时后于马厩内开展。

使用Televet100软件从记录显示器中导出数据，随后将数据传输至Windows平台的HRV分析软件2.1或Kubios软件。使用Kubios软件对RR间期进行量化分析（即计算各类HRV参数）。Kubios软件中的频带设置为：低频段0.01~0.06 Hz，高频段0.07~0.6 Hz。从15分钟的记录数据中选取视觉上伪迹最少的5分钟片段。针对每匹马匹的治疗前、后数据，分别采用无校正、极低校正、低校正、中等校正与高等校正因子（CF）进行分析。随后按照Kubios官网的建议，为每匹马匹选取既能校正数据又不影响变异性的最低校正因子。若心动周期图（tachogram）质量极差，则将其结果排除在分析之外。

借助Kubios软件，通过时域分析、频域分析与庞加莱图（Poincaré plot）分析对逐搏RR间期的变异性进行量化。最终计算并统计分析以下HRV指标：SDNN、RMSSD、LF、HF、LF/HF、LF nu、HF、SD2，以及心率相关指标：平均RR间期、平均心率（mean HR）。

步幅参数

使用安装于腹带的GPS设备EquinITy™，测量600米疾驰过程中的步幅参数与奔跑表现。EquinITy™软件将记录以下指标：最大步长（SL Max）、平均步长（SL Avg）、最大步频（SF Max）、平均步幅次数（SC Avg）、最大步幅次数（SC Max）、最高速度（Max Speed）、最高速度下的步幅次数（SC Max Speed）、最高速度下的步长（SL Max Speed）与平均速度（Avg Speed）。训练结束后从设备中导出EquinITy™数据，随后由EquinITy™ Technology网站针对每匹马匹与每一次训练任务进行数据处理。