Dynamic thermal stress modeling for outdoor running: Integrating psychological adaptation and body energy variations

Outdoor running in summer is influenced by fluctuating metabolic activity and thermal environments, both of which affect individuals’ thermal sensation and physiological responses. However, most existing thermal index models rely on steady-state assumptions and cannot accurately capture real-time variations in thermal and physiological states during exercise. To enrich the empirical foundation of dynamic thermal response research, this study conducted field measurements at the athletic track of Guangzhou University, collecting subjective sensations, physiological indicators, and thermal environmental parameters under different shading conditions. The results indicate that: 1) Auditory canal temperature (ACT) responds with a time lag and stabilizes slowly. 2) Incorporating dynamic metabolic rate, heat storage, and thermal pleasure improved model accuracy (e.g., R 2 increased from 0.58 to 0.74). 3) Individuals under direct sunlight exhibited lower recovery in both skin conductance level (SCL) and heart rate (HR), with all other indicators recovering over 80% after 15 minutes of rest, except SCL. 4) Physiological equivalent temperature (PET) effectively predicted the recovery rates of blood oxygen saturation (SpO 2 ), SCL and HR (R 2 > 0.75), but performed poorly in predicting ACT recovery under shade (R 2 < 0.6). This study proposes a dynamic model for thermal stress, providing guidance for outdoor activity planning and personalized heat risk management.