Recently there has been increasing interest in the study of ultra-short-term heart rate variability (HRV) in sports performance and exercise physiology. In order to improve standardization of this specific analysis, we evaluated the ultra-short-term HRV analysis through SD1Poincaré Index to identify exercise induced responses. We investigated 35 physically active men aged between 18 and 35 years old. Volunteers performed physical exercise on treadmill with intensity of 6.0 km/hour + 1% slope in the first five minutes for physical "warming up." This was followed by 25 minutes with intensity equivalent to 60% of maximal oxygen consumption, with the same slope according to the Conconi threshold. HRV was analyzed in the following periods: the five-minute period before the exercise and the five-minute period immediately after the exercise, the five minutes were divided into five segments of 60 RR intervals. Ultra-short-term RMSSD and SD1 analysis were performed. Ultra-short-term RMSSD and SD1 were significantly (P<0.0001) reduced during the initial five minutes divided into five segments of 60 RR intervals compared to (at rest) control. Heart rate was significantly (P<0.0001) increased 1 min and 3 min immediately after exercise compared to (at rest) control. At rest ultra-short-term SD1 presented significant correlation with short-term (256 RR intervals) RMSSD (r=0.78; P<0.0001), HF (r=0.574; P=0.0007) and SD1 (r=0.78; P<0.0001). Additionally, visual analysis with the Poincaré plot detected changes in HRV after exercise. Ultra-short-term HRV analysis through Poincaré plot identified heart rate autonomic responses induced by aerobic exercise.
Read full abstract