# Exploring training-sleep characteristics and bidirectional lagged relationships in Chinese recreational runners: insights from a year-long wearable monitoring study

## TL;DR

This study tracks training and sleep patterns of Chinese recreational runners over a year to understand how they affect each other and offer personalized training advice.

## Contribution

The study reveals bidirectional relationships between training load and sleep quality in recreational runners, influenced by sex, performance level, and seasonal factors.

## Key findings

- Male runners ran faster and farther than females, and elite runners outperformed others in all training metrics.
- High training loads reduced deep and REM sleep, increased light sleep and wake time, and lowered heart rate variability, indicating poor recovery.
- Insufficient sleep led to slower running pace and reduced training efficiency the next day, though runners compensated by running longer.

## Abstract

This study aims to explore training and sleep characteristics among recreational runners, along with their interrelationships, to provide more scientific and personalised training guidance.

Recreational runners wearing Garmin smartwatches were recruited, and continuous data on training and sleep were collected via the device Application Programming Interface from June 2024 to June 2025. Training data included pace, distance, duration, and heart rate, while sleep data included stage durations and nocturnal heart rate variability Linear mixed models were applied to examine differences in training and sleep characteristics across sex, performance classification, season, and day of the week, and to explore the effects of training load on subsequent sleep and the influence of sleep duration on training performance on the following day.

The average distance per training session was 12.10 ± 3.36 km, with an average pace of 6.02 ± 1.00 min/km. Male runners exhibited significantly faster paces and longer distances than females, and elite runners outperformed other groups across all training parameters. Significant seasonal and weekly variations were observed. Specifically, pace was slowest and distance shortest in summer, while training volume, intensity, and heart rate were higher on rest days than on workdays. The average nightly sleep duration was 6.61 ± 0.69 h, indicating general insufficiency. Female runners had significantly longer deep sleep than males, and elite runners showed a more pronounced early sleep-wake rhythm. A bidirectional relationship was identified, with the finding that high training loads led to reductions in deep and REM sleep, increases in light sleep and wake duration, and lower HRV, collectively indicating impaired sleep quality and autonomic recovery despite longer total sleep duration. Conversely, insufficient sleep resulted in slower pace and decreased training efficiency on the following day, though runners tended to compensate by extending running duration.

The training and sleep characteristics of recreational runners were significantly influenced by sex, performance classification, season, and weekday-weekend rhythm. A bidirectional association between training and sleep was observed, with high training loads and insufficient sleep posing potential risks to performance and recovery. It is recommended that recreational runners monitor both training and sleep, take individual differences and temporal rhythms into account when scheduling training, and avoid excessive training loads to achieve a balance between training and recovery.