Abstrac analysis of heart rate variability in a group of high level
Background: Heart rate variability (HRV) can be used to analyse the autonomic changes associated with period of training in hypoxia. Objectives: The aim of our study is to determine the impact of a period of 3 weeks training in hypoxia condition on HRV. Design: An experimental descriptive prospective design. Participants: High level swimmers that are training at High Altitude Sport Training Center in Sierra Nevada (n=21). Main outcome measures: Temporal domain heart rate variability (SDNN, RMSSD, HRV Index) and Frequency domain heart rate variability (VLF, LF, HF frequency components and balance LF/HF). All outcomes measures were assessed at five conditions during a period of 21 days. All the measurements were recorded at rest in supine position, between 8-10 am in a short-term period (5 min.): first, fifth, tenth, fifteenth and twentieth day of the stage in CAR, Sierra Nevada. Equipment: Holter ECG Model DL800 (Braemar, Brunville) with 3 ECK and Norav Holter XbraV, 2.70 software. Results: Studying / Taking the variables along 21 days showed that this was significant to LF component (P=0.04) and LF/HF ratio (P=0.04). LF decrease between moments 1-4 (P= 0.04) and 1-5 (P=0.04) of study and LF/HF balance significative (P=0.04) decrease between 1-4 moments and 1-5 moment (P=0.04). The modification of others parameters are not significant at all. Conclusions: The decrease of LF component and LF/HF ratio during a stage in altitude, suggests that exposure to hypoxic training change the response of the autonomic nervous system mainly over the stage. In future studies we are focusing on the relationship between increased sympathetic activity and subjetive sensation performance during stay.