Sample entropy analysis of cardiac and respiratory responses during four limbs exercise

Abstract

This study was aimed to elucidate the effects of exercise on sample entropy of beat-to-beat (RR) intervals (SampEn-RR) and breath-to-breath (BB) intervals (SampEn- BB). A four limbs-based exercise equipment was used for the experiment and a wireless wearable respiration and heart rate monitoring system was used for recording the RR and BB intervals during lower limbs (LL), upper limbs (UL), and all four limbs (AL) exercises. A significant increment in both SampEn-RR and SampEn-BB was observed during exercises when compared with pre and post-exercise states. Further comparisons of statistical parameters during AL and UL exercises showed the highest and the lowest mean of SampEn values. Moreover, the comparison between exercise duration and the linear trend line gradients obtained from both SampEn- RR and SampEn-BB during exercise revealed an inversely proportional relationship between them. Thereby, this work supports analysis of trend line gradients of SampEn would be helpful to determine the fatigue level during exercise.