Heart Rate Variability Analysis During Exercise in Hypoxia Chamber

Heart Rate Variability (HRV) is an important measure to understand the overall physical fitness of an individual especially in cardiovascular training. Clinical applications of HRV are well established for assessing cardiovascular and metabolic illness. Recent observations have suggested its applicability in physical exercise training as well. There is still more understanding needed in the use of HRV for interpreting the internal effects of physical exercise and planning the training routines accordingly. Athletes show more interest in hypoxia training or high-altitude training to improve their exercise performance at sea level and to acclimatize to compete at high-altitude regions. It is important to understand the changes in HRV parameters of the subjects while training in a hypoxia chamber. In this study, we have analysed both the time-domain and frequency-domain HRV parameters and the Heart Rate (HR) values to understand the effects of training inside a hypoxia chamber. The changes in HRV parameters during cardio training sessions over 3 weeks for a study group of 4 subjects are reported in this study. Over the weeks, there was an increase in the total HRV and hence a decreasing LF/HF trend. pNN25 also decreased over the 3 weeks whilst rMSSD showed an increasing trend. Also, the recovery rate for the second minute of exercise cessation has been reported where a decrease of 55 +/- 6 bpm from the maximum HR was observed for the study group for week 3 when compared to 30 +/- 5 bpm for week 1, thus proving the effectiveness of hypoxia training. In addition, the changes observed in the maximum HR values during strength training sessions also decreased by 21 +/- 4 bpm over 3 weeks for the study group, which again proves the significance of hypoxia training.