Author(s): FOLIO, S., DABIC, S., KERAUTRET, L., ARSAC, L., DESCHODT-ARSAC, V., Institution: UNIVERSITY OF BORDEAUX, Country: FRANCE, Abstract-ID: 1987

INTRODUCTION:
Most studies investigating stress-related autonomic responses have focused on intense acute stressors. However, in everyday life and sport-specific contexts, individuals are more frequently exposed to moderate stressors, whose physiological impact remains less documented. Within the neurovisceral integration model, heart rate variability (HRV) reflects the capacity of the autonomic nervous system to dynamically regulate physiological responses to cognitive and environmental demands. Importantly, autonomic flexibility may differ between men and women due to sex-related differences in central stress-processing mechanisms. Therefore, this study aimed to investigate autonomic responses to a moderate stress induced during a cognitive task in healthy young subjects, using HRV indices, and to examine potential sex-related differences.
METHODS:
Twenty-nine healthy sports students (18 males, 11 females; 20 ± 2 years) completed a 14-min driving-like vigilance task including reaction tasks. A moderate auditory stressor was applied for 15 s, 6 min after task onset. Continuous ECG was recorded, and HRV indices were computed in the time (RMSSD), frequency (LF, HF, Total Power), and non-linear domains (Refined Composite Multiscale Entropy, RCMSE) before (PRE) and after (POST) stress.
RESULTS:
Significant main effects of sex were observed for cardiac entropy (F(1,26) = 6.987, p = 0.014) and total autonomic power (F(1,26) = 5.712, p = 0.024). Females exhibited higher cardiac entropy at PRE (p = 0.036), while males displayed higher total autonomic power across time (PRE and POST).
To better characterize individual profiles of autonomic modulation in response to moderate stress, a factor analysis of mixed data incorporating HRV indices and sex suggested three autonomic response profiles. Sex significantly differentiated these clusters (p < 0.001), with one cluster composed predominantly of women (91%) characterized by higher entropy and lower autonomic power. In females, a linear regression analysis indicated that higher cardiac entropy before stress tended to be associated with lower low frequency (LF) power after moderate stress induction (β = −5.73 × 10⁻⁵), suggesting a trend toward attenuated sympathetic modulation in women exhibiting greater baseline autonomic flexibility.
CONCLUSION:
In female athletes, higher cardiac entropy during cognitive task performance without stress may reflect a flexible autonomic state supporting a more controlled sympathetic modulation when exposed to moderate stress.