Replication Data for PONE-D-21-19666 article

Changes in heart rate and heart rate variabilty (HRV) were investigated in young (starting their first racing season) and adult (with 1-3 years of race experience) racehorses before and after a 12-week conventional training. HRV was measured at rest over 1 h between 9:00 and 10:00 AM on the usual rest day of the horses. The smallest worthwhile change (SWC) rate was calculated for all HRV parameters. Young horses had significantly higher heart rate compared to adults (P<0.001) which may be the result of training experience between groups. There were no gender- or training-related differences inheart rate. The root-mean-square of successive differences (rMSSD) in the consecutive inter-beat-intervals obtained after the 12-week training period was lower compared to pre-season rMSSD (P<0.001) indicating decreased vagal tone for the post-season recordings. The rMSSD was not influenced by breed, age or gender. In adult horses, there was a significant decrease in the high frequency (HF) component of HRV (P=0.030) as the result of the 12-week training. These results may reflect saturation of high-frequency oscillations of inter-beat intervals rather than the reduction in parasympathetic influence on the heart. The HF did not differ significantly between the two measurements in young horses; however, 16.6% of the animals showed a decrease in HF below SWC (P=0.012). This supports the likelihood of parasympathetic saturation. Although no significant decrease in heart rate was found for the post-season, 30.0% of adult and 58.3% of young horses still showed a decrease in heart rate below the SWC. Also by individual examination, it was also visible that despite significant post-season decrease in rMSSD, 1 (4.6%) adult and 2 (6.7%) young horses reached SWC increase in rMMSD. In the case of these horses, the possibility of maladaptation should be considered.The present results suggest that heart rate and vagal tone-related HRV might be useful to assess physiological adaptation to training in racehorses. Detailed analysis of HRV parameters based on SWC highlights the importance of fitness evaluation at individuallevel. However, a more frequent recording would be necessary to provide relevant results in the field of equine sport science.本研究考察了刚进入首个赛事赛季的青年赛马与拥有1至3年赛事经验的成年赛马，在12周常规训练前后的心率及心率变异性（Heart Rate Variability, HRV）变化。HRV的测量于马匹常规休息日的上午9:00至10:00间进行，在静息状态下连续采集1小时数据。研究为所有HRV参数计算了最小可感知变化（Smallest Worthwhile Change, SWC）率。结果显示，青年赛马的静息心率显著高于成年赛马（P<0.001），该差异或源于两组马匹的训练经验差异；未观察到与性别或训练相关的心率差异。12周训练后，连续心搏间期逐差均方根（root-mean-square of successive differences, rMSSD）较赛季前水平显著降低（P<0.001），提示赛季后测量时马匹的迷走神经张力有所下降，且rMSSD不受品种、年龄或性别的影响。成年赛马的HRV高频（High Frequency, HF）成分在12周训练后出现显著降低（P=0.030），该结果或反映心搏间期的高频振荡趋于饱和，而非心脏受到的副交感神经调控减弱。青年赛马的两次测量间HF成分无显著差异，但其中16.6%的个体HF下降幅度超过SWC阈值（P=0.012），这支持副交感神经饱和的可能性。尽管赛季后整体心率未出现显著下降，但仍有30.0%的成年赛马与58.3%的青年赛马的心率下降幅度超过SWC阈值。个体分析亦显示，尽管整体上赛季后rMSSD显著降低，但仍有1匹（4.6%）成年赛马与2匹（6.7%）青年赛马的rMSSD升高幅度达到SWC阈值；对于此类个体，应考虑其存在训练适应不良的可能性。本研究结果提示，心率与迷走神经张力相关的HRV指标或可用于评估赛马对训练的生理适应情况。基于SWC的HRV参数精细化分析凸显了个体层面体能评估的重要性。然而，若要在赛马运动科学领域获得可靠的研究结果，仍需提高数据记录频率。