Short-term overtraining: effects on performance, circulatory responses, and heart rate variability

Area of Science:

• Sports Science
• Exercise Physiology
• Human Performance

Background:

• Elite athletes undergo intense training to optimize performance.
• Monitoring physiological markers is crucial for managing training load and preventing overtraining.

Purpose of the Study:

• To investigate the effects of a 6-day high-load training camp on elite canoeists' performance, heart rate variability (HRV), and blood-chemical parameters.
• To assess physiological adaptations and potential fatigue indicators in response to increased training volume.

Main Methods:

• Nine elite canoeists participated in a 6-day training camp involving cross-country skiing and strength training, increasing training load by 50%.
• Performance metrics (time to exhaustion, VO2max, maximal lactate), heart rate (HR) at various workloads, plasma volume, and resting hormone levels (cortisol, adrenaline, noradrenaline) were measured.
• Heart rate variability (HRV) was assessed at rest and after a tilt test.

Main Results:

• Time to exhaustion, VO2max, and maximal lactate levels significantly decreased.
• Submaximal and maximal heart rates were significantly reduced.
• Plasma volume increased, and resting cortisol levels decreased, while adrenaline and noradrenaline remained unchanged.
• No significant changes were observed in high or low-frequency HRV.

Conclusions:

• The observed reduction in maximal performance suggests a state of fatigue or overreaching in the canoeists.
• Peripheral factors likely limited performance, despite reductions in maximal heart rate and lactate.
• Increased plasma volume may explain the reduced submaximal heart rates.
• Short-term overtraining did not significantly affect HRV in this elite athlete group.