BACKGROUND: Exercise training improves heart rate variability, and evidence suggests it can mitigate the detrimental effects of stress. This study aims to evaluate the relationship between surgeons' physical activity habits and their stress, assessed as heart rate variability, at the start of surgery. MATERIALS AND METHODS: This multispecialty prospective cohort study included surgeons from fourteen cardiac, endocrine, digestive, gynecologic, orthopedic, thoracic, and urologic surgical departments of four university hospitals. Surgeons wore accelerometers 24/7 from 1 November 2020 to 31 December 2021 to quantify the mean daily step counts and daily sedentary time for 7 days prior to each operation. RMSSD, the root mean square of successive differences between normal heart beats, is a heart rate variability (HRV) metric that reflects cardiac vagal tone. We evaluated RMSSD during the first 5 minutes of surgeries performed over five 15-day periods. Data were analyzed using a multivariable linear mixed model with a random effect for surgeons. RESULTS: We analyzed 722 surgeries performed by 37 surgeons (median age = 47 (IQR 42-55)
29 (78.4%) male). On average (SD), surgeons walked 9762 (2447) steps and were sedentary 391 (102) minutes daily. The model showed a positive relationship between steps and cardiac vagal tone, with an increase in lnRMSSD (0.028, 95% CI 0.003 to 0.053, P = 0.026) for every 1000 more steps per day, but not for sedentary behavior. Surgeon professors presented lower lnRMSSD (-0.437, -0.749 to -0.126, P = 0.006), as did surgeons who spent less total time operating over the study period (-0.337, -0.646 to -0.027, P = 0.033), compared to their counterparts. CONCLUSIONS: Higher daily step counts the week before surgery were associated with increased cardiac vagal tone, indicating lower stress levels at the beginning of surgery. This relationship highlights the influence of physical activity on surgeons' stress in the operating room.