Individual Interdependence between nocturnal ANS activity and performance in swimmers

Area of Science:

• Sports Science
• Physiology
• Biomedical Engineering

Background:

• Autonomic nervous system (ANS) activity and athletic performance variations are linked at the group level in swimmers.
• Individual-level correlations between ANS activity and performance require further investigation.

Purpose of the Study:

• To determine the strength of the relationship between autonomic nervous system (ANS) activity and performance at the individual level in swimmers.
• To explore how changes in ANS activity during training and tapering periods influence swimming performance.

Main Methods:

• Seven regional swimmers underwent a 3-week intensive training period followed by a 2-week tapering period.
• Maximal aerobic performance was assessed via a 400-m freestyle race before and after training/tapering.
• Autonomic nervous system (ANS) activity was measured using heart rate variability (HRV) indices.

Main Results:

• Heart rate variability (HRV) indices showed individual variations, with some swimmers exhibiting increased parasympathetic activity during tapering, while others showed a continuous decrease.
• Peak swimming performances correlated with the highest global and parasympathetic HRV indices.
• A strong relationship was found between performance changes and HRV index changes (R² = 0.5), indicating that greater ANS recovery during tapering led to improved performance.

Conclusions:

• Nocturnal autonomic nervous system (ANS) activity is a significant predictor of individual swimming performance.
• Decreased ANS activity during intensive training correlates with performance loss, and its rebound during tapering correlates with performance gains.
• Monitoring ANS activity can aid in tailoring training regimens and optimizing tapering strategies for individual swimmers.