Impact of construction workers' physical fatigue on unsafe behavior: An ecg-based field experiment study

Physical fatigue is a major factor contributing to construction safety incidents, as it significantly increases the probability of workers' unsafe behavior. To better understand the impact of physical fatigue on unsafe behavior, this research conducted a field experiment employing real-time electrocardiogram (ECG) data to evaluate workers' physical fatigue levels. Three workers were recruited to perform material handling tasks in a controlled basement environment. Over a three-day experiment, workers' ECG signals and unsafe behaviors were continuously monitored. Finally, 42 valid samples were collected and analyzed. The results show a rising trend in unsafe behavior after 30 minutes of physically demanding tasks, with a notable increase as physical fatigue accumulates. Moreover, significant variations were observed in both time-domain and frequency-domain ECG indexes, including R-R interval (RR), standard deviation of NN intervals (SDNN), root mean square of successive differences (rMSSD), total power (TP), high-frequency power (HF), and ratio of low-frequency power to high-frequency power (LF/HF). Specifically, unsafe behavior is negatively correlated with RR, SDNN, and HF, but positively correlated with rMSSD and TP. TP shows the strongest association with unsafe behavior among the ECG indexes. These findings contribute to construction workers' occupational health and safety and offer valuable insights for further research on workers' fatigue based on physiological metrics.