Monitoring Sleep and Nightly Recovery with Wrist-Worn Wearables: Links to Training Load and Performance Adaptations

Area of Science:

• Sports Science
• Exercise Physiology
• Sleep Science

Background:

• Previous research on intensified training and sleep quality yields contradictory results.
• Recreational athletes track sleep metrics, but their link to training adaptations remains unclear.

Purpose of the Study:

• To investigate the impact of intensified training on sleep and nightly recovery.
• To explore the association between sleep/recovery metrics and training adaptations in athletes.

Main Methods:

• 24 participants underwent a 3-week baseline, 2-week overload, and 1-week recovery period.
• Endurance performance was assessed via a 3000 m running test.
• Nightly recovery was monitored using a wrist-worn wearable (sleep, heart rate, heart rate variability, autonomic nervous system charge), alongside daily perceived strain and muscle soreness.

Main Results:

• 3000 m running performance improved significantly after the overload period.
• Perceived strain and muscle soreness increased, while subjective sleep quality and nightly recovery metrics remained unchanged.
• Autonomic nervous system charge and changes in heart rate/heart rate variability during sleep were associated with changes in running performance.

Conclusions:

• Intensified training negatively affected subjective recovery but not objective sleep or nightly recovery metrics.
• Significant interindividual differences in nightly recovery were observed.
• Monitoring individual nightly recovery can aid in optimizing training prescriptions and recognizing athlete responses.