Altitude, heart rate variability and aerobic capacities

Area of Science:

• Sports Science
• Altitude Training Physiology
• Cardiovascular Regulation

Background:

• Living high-training low (Hi-Lo) is a common altitude training strategy.
• Understanding physiological adaptations to Hi-Lo is crucial for athlete performance.
• Heart rate variability (HRV) is a sensitive indicator of autonomic nervous system function and training status.

Purpose of the Study:

• To investigate the relationship between aerobic capacity changes and HRV alterations in elite Nordic skiers during a Hi-Lo protocol.
• To determine if HRV can serve as a monitoring tool for altitude training adaptations.

Main Methods:

• Eleven Nordic skiers underwent an 18-day Hi-Lo protocol, with two groups: continuous low-level hypoxia (LL) and intermittent high-level hypoxia (HL).
• Aerobic capacity (VO2max, peak power output, VO2 and power at respiratory compensation point) and HRV were measured before, during, and after the intervention.
• Statistical analyses correlated changes in HRV parameters (TP, HF, LF) with changes in aerobic capacity metrics.

Main Results:

• No significant improvements in VO2max or peak power output were observed in either group.
• Significant increases in VO2 and power at the respiratory compensation point (VO2RCP, PRCP) were found only in the HL group.
• The LL group showed significant increases in resting heart rate (HR) and decreases in total spectral power (TP) and high-frequency activity (HF) in the standing position.
• Pooled analysis revealed significant correlations between supine HRV parameters (HF, LF, TP) and changes in VO2RCP and PRCP.

Conclusions:

• The study confirms a relationship between HRV changes and aerobic capacity adaptations in athletes undergoing altitude training.
• HRV parameters, particularly when measured in the supine position, show potential as a non-invasive tool for monitoring the effectiveness of Hi-Lo altitude training protocols.
• These findings underscore the utility of HRV for optimizing training load and adaptation assessment in endurance athletes.