Contextualizing Parasympathetic Hyperactivity in Functionally Overreached Athletes With Perceptions of Training...

Area of Science:

• Sports Science
• Exercise Physiology
• Autonomic Neuroscience

Background:

• Heart-rate variability (HRV) is a key indicator of autonomic nervous system function.
• Interpreting HRV responses to training is complex due to varied effects on performance.
• Contextualizing HRV with subjective athlete feedback is crucial for accurate assessment.

Purpose of the Study:

• To investigate the relationship between vagally mediated HRV and subjective training tolerance.
• To determine if HRV changes can be better understood when analyzed alongside measures of athlete well-being and performance.

Main Methods:

• Daily measurements of vagally mediated HRV (RMSSD) and training tolerance (questionnaires, energy, fatigue, soreness) were collected.
• Data were gathered during periods of light training, heavy training, and tapering in male runners and triathletes.
• Performance was assessed via a 5-km treadmill time trial.

Main Results:

• Performance improved after tapering, with decreased time on the 5-km treadmill time trial.
• Training tolerance significantly worsened after heavy training and improved during tapering.
• Standing RMSSD (root-mean-square difference of successive normal RR intervals) increased after heavy training and remained elevated during tapering.

Conclusions:

• Vagally mediated HRV, particularly in a standing position, increased with functional overreaching and performance improvements.
• Changes in HRV alone are insufficient for interpretation; incorporating training tolerance is essential.
• Subjective measures provide necessary context for understanding autonomic adaptations during training cycles.