University of Tehran Press Sport Biosciences 2008-9325 Articles in Press 2026 04 12 Investigating Stress Markers in Adolescents: Emphasis on the Role of Physical Activity in Modulating Cortisol and Salivary Aalpha- Investigating Stress Markers in Adolescents: Emphasis on the Role of Physical Activity in Modulating Cortisol and Salivary Aalpha- 106485 10.22059/jsb.2026.406548.1690 FA Mitra Khademosharie Department of Sport Sciences, Faculty of Humanities, Kosar University of Bojnord, Bojnord, Iran 0000-0003-4422-8093 Marzieh Azarniveh Department of Sports Sciences, Faculty of Literature and Humanities, Zabol University, Zabol, Iran. Tavakoli Khormizi Tavakoli Khormizi PhD student in Exercise Physiology, Department of Exercise Physiology, Faculty of Sport Sciences, Hakim Sabzevari University, Sabzevar, Khorasan Razavi, Iran / Physical Education Teacher, Modares Yazdi High School, District 1, Education, Yazd, Yazd, Journal Article 2025 11 19 Introduction: Changes in adolescents’ lifestyle have posed serious challenges to their physical and mental health. Therefore, the aim of this study was to investigate the effect of different levels of physical activity on salivary stress biomarkers (cortisol and salivary alpha-amylase (sAA)) in adolescents. Methods: In this descriptive cross-sectional study, 60 adolescent boys aged 14–16 years from District 1 of Yazd were voluntarily selected through simple random sampling and divided into three groups of inactive, active, and athletic (n=20 each) based on Baecke Physical Activity Questionnaire scores. Morning saliva samples (8–9 a.m.) were collected to control for circadian fluctuations and cortisol and sAA concentrations were measured using ELISA kits (DiaMetra, Italy for cortisol; Eastbiopharm, China for sAA). Data were analyzed using one-way ANOVA followed by Bonferroni and James-Howell post-hoc tests in SPSS version 16 (significance level p ≤ 0.05). Results: The results revealed that cortisol (p = 0.004) and sAA (p < 0.001) levels were significantly lower in the athletic and active groups compared to the inactive group, with the greatest reduction observed in the athletic group. Conclusion: Regular physical activity, especially at high levels, can significantly reduce salivary stress biomarkers (cortisol and sAA) through modulation of the HPA axis and autonomic nervous system, and serves as an effective non-pharmacological intervention to reduce stress and promote mental health in adolescents. Introduction: Changes in adolescents’ lifestyle have posed serious challenges to their physical and mental health. Therefore, the aim of this study was to investigate the effect of different levels of physical activity on salivary stress biomarkers (cortisol and salivary alpha-amylase (sAA)) in adolescents. Methods: In this descriptive cross-sectional study, 60 adolescent boys aged 14–16 years from District 1 of Yazd were voluntarily selected through simple random sampling and divided into three groups of inactive, active, and athletic (n=20 each) based on Baecke Physical Activity Questionnaire scores. Morning saliva samples (8–9 a.m.) were collected to control for circadian fluctuations and cortisol and sAA concentrations were measured using ELISA kits (DiaMetra, Italy for cortisol; Eastbiopharm, China for sAA). Data were analyzed using one-way ANOVA followed by Bonferroni and James-Howell post-hoc tests in SPSS version 16 (significance level p ≤ 0.05). Results: The results revealed that cortisol (p = 0.004) and sAA (p < 0.001) levels were significantly lower in the athletic and active groups compared to the inactive group, with the greatest reduction observed in the athletic group. Conclusion: Regular physical activity, especially at high levels, can significantly reduce salivary stress biomarkers (cortisol and sAA) through modulation of the HPA axis and autonomic nervous system, and serves as an effective non-pharmacological intervention to reduce stress and promote mental health in adolescents.