The Dynamic Strain of Acute Physiological Stress: Tracking Micro-Fluctuations in Epigenetic Clocks and Leukocyte Telomere Length During High-Intensity Interval Training (HIIT)
- Jun 6
- 2 min read
https://doi.org/10.66715/jsccr/2026.v3.i2.5058 Original Research | 2026 | Volume 3 | Issue 2 | Page 50-58
Dr. Shahan Layek, Independent Researcher, West Bengal, India
Dr. Manoj Kumar, Tutor, Department Physiology, JHMC, WB
Abstract
Background: Acute physiological stress induced by high-intensity interval training (HIIT) triggers rapid metabolic, inflammatory, and hormonal responses that may influence molecular markers associated with biological aging. Epigenetic clocks and leukocyte telomere length (LTL) have emerged as important biomarkers for assessing cellular aging and physiological adaptation. However, the short-term dynamics of these biomarkers during acute bouts of intense exercise remain insufficiently understood. Objective: This study aimed to investigate micro-fluctuations in epigenetic age estimates and leukocyte telomere length in response to acute physiological stress induced by HIIT and to explore their associations with exercise-induced biochemical and inflammatory changes. Methods: A prospective observational study was conducted involving healthy adult participants who completed a standardized HIIT protocol. Peripheral blood samples were collected at baseline, immediately post-exercise, and during recovery intervals. DNA methylation profiles were analyzed using established epigenetic clock algorithms, including Horvath, Hannum, and PhenoAge clocks. Leukocyte telomere length was assessed using quantitative polymerase chain reaction (qPCR). Concurrent measurements of cortisol, lactate, C-reactive protein (CRP), and pro-inflammatory cytokines were performed to evaluate physiological stress responses. Results: Acute HIIT elicited significant elevations in cortisol, lactate, and inflammatory biomarkers, confirming a robust physiological stress response. Transient increases in epigenetic age acceleration were observed immediately following exercise, with partial normalization during recovery. Leukocyte telomere length demonstrated short-term fluctuations, characterized by an apparent post-exercise reduction followed by recovery toward baseline values. Correlation analyses revealed significant associations between changes in epigenetic age metrics and circulating stress biomarkers, particularly cortisol and interleukin-6 levels. Participants exhibiting greater physiological resilience showed more rapid restoration of molecular aging markers during the recovery phase.Conclusion: Acute physiological stress induced by HIIT is associated with measurable but reversible alterations in epigenetic clock estimates and leukocyte telomere length. These findings suggest that biological aging biomarkers are highly dynamic and responsive to short-term physiological challenges. Understanding the temporal behavior of these molecular indicators may provide valuable insights into exercise adaptation, stress resilience, and the mechanisms linking physical activity to healthy aging.Keywords: High-Intensity Interval Training, HIIT, Epigenetic Clock, DNA Methylation, Leukocyte Telomere Length, Biological Aging, Physiological Stress, Exercise Adaptation, Aging Biomarkers,