The Relationship Between the Heart Rate Performance Curve Deflection and the Heart Rate Recovery

Abstract

2287 PURPOSE: Previous research established two facts. An abnormal heart rate recovery after exercise is linked to cardiovascular risk and the deflection of the heart rate performance curve (kHR) that reflects the myocardial function. In this investigation we studied the relationship between the heart rate recovery (HRR) and kHR in a sample of healthy subjects and patients. METHODS: 63 healthy and 36 diseased subjects (hypertension and/or coronary artery disease) underwent a sitting symptom limited cycle ergometer exercise test. We measured maximal heart rate, maximal power output per weight (W-max/kg) and calculated lactate turn points (LTP1, LTP2), kHRs. The HRR is calculated as the time the heart rate decreases from the maximum level to the level of LTP2. RESULTS: We observed significant correlation between kHR and time (t) t-LTP2 in healthy subjects (p<0.0001), however the sample data of patients did not provide significant evidence for correlation between kHR and t-LTP2. After adjusting for age and W-max/kg, we found statistically significant correlation for the healthy subjects. The healthy subjects recovered from exercise considerably faster (t-LTP2=59.6 ± 44.1sec) than the patients (t-LTP2=83.8 ± 71.6 sec). The kHRs of the patients tend to be negative and that of the healthy subjects positive. There was a statistically significant difference between the average kHRs of the two groups. CONCLUSION: We found a significant correlation between the HRR and kHR for the healthy subjects only. The lack of correlation for the patient's group may be due to the relatively small sample size. In recent years, there has been ample data available on heart rate recovery and also on the significance of kHR value. In this regard, we consider further research on the relationship between these two parameters of high relevance. Our current research results warrant new and additional inquiry.