Arrhythmia is an abnormality of the heart's rhythm, caused by problems in the conductive system and resulting in irregular heartbeats. There is increasing evidence that undertaking frequent endurance sports training elevates one's risk of arrhythmia. Arrhythmia is diagnosed using an electrocardiogram (ECG) but this is not typically available to athletes while exercising. Previous research by Crickles investigates the usefulness of commonly available heart rate data in detecting signs of arrhythmia. It is hypothesised that a feature termed 'gappiness', defined by jumps in the heart rate while the athlete is under exertion, may be a characteristic of arrhythmia. A correlation was found between the proportion of 'gappy' activities and survey responses about heart rhythm problems. We develop on this measure by exploring various methods to detect spikes in heart rate data, allowing us to describe the extent of irregularity in an activity via the rate of spikes. We first compare the performance of these methods on simulated data, where we find that smoothing using a moving average and setting a constant threshold on the residuals is most effective. This method was then implemented on real data provided by Crickles from 168 athletes, where no significant correlation was found between the spike rates and survey responses. However, when considering only those spikes that occur above a heart rate of 160 beats per minute (bpm) a significant correlation was found. This supports the hypothesis that jumps at only high heart rates are informative of arrhythmia and indicates the need for further research into better measures to characterise features of heart rate data.

翻译：心律失常是心脏节律的异常，由传导系统问题引起并导致心跳不规则。越来越多的证据表明，频繁进行耐力运动训练会增加心律失常的风险。心律失常通常通过心电图（ECG）诊断，但运动员在运动过程中通常无法使用该设备。Crickles团队先前的研究探讨了利用常见心率数据检测心律失常迹象的有效性。研究假设一种称为“间隙性”的特征——定义为运动员在负荷状态下心率的跳跃式变化——可能是心律失常的一个特征。研究发现，“间隙性”活动比例与关于心律问题的调查反馈之间存在相关性。我们在该度量方法的基础上进行拓展，探索多种检测心率数据尖峰的方法，从而通过尖峰发生率来描述活动中的不规则程度。我们首先在模拟数据上比较这些方法的性能，发现使用移动平均进行平滑处理并对残差设置恒定阈值的方法最为有效。随后将此方法应用于Crickles提供的168名运动员的真实数据，结果发现尖峰发生率与调查反馈之间无显著相关性。然而，当仅考虑心率高于160次/分钟（bpm）时出现的尖峰时，则发现了显著相关性。这支持了“仅在高心率下出现的跳跃对心律失常具有指示意义”的假设，并表明需要进一步研究更好的度量方法来表征心率数据的特征。