The exploration of immune system function changes in marathon athletes after high-intensity training by Agent-Based...

Area of Science:

• Immunology
• Exercise Physiology
• Computational Biology

Background:

• Marathon running causes significant metabolic stress.
• Chronic effects of high-intensity training (HIT) on elite athlete immunity are complex and debated.
• The role of post-exercise lymphopenia (reduced lymphocytes) is unclear, with ongoing discussion about immunosuppression versus immune cell redistribution.

Purpose of the Study:

• To investigate the chronic impact of a four-week HIT block on immune markers in professional marathon runners.
• To assess the effectiveness of an Agent-Based Model (ABM) in visualizing immune system dynamics during intensified training.

Main Methods:

• Twenty-two professional marathon athletes completed a four-week HIT protocol.
• Blood samples were analyzed pre- and post-training for leukocytes, immunoglobulins (Ig), cytokines (IL-6, IL-8, IL-10, TNF-α), and lymphocyte subsets.
• A NetLogo-based Agent-Based Model (ABM) was developed to simulate immune system responses.

Main Results:

• Significant decreases in total leukocyte counts and serum IgG levels were observed post-training.
• A CD4+/CD8+ T-cell ratio inversion occurred, decreasing to 0.98 due to reduced CD4+ cells.
• Cytokine analysis showed increased pro-inflammatory markers (IL-6, IL-8, TNF-α) and a significant decrease in anti-inflammatory IL-10, indicating a 'resolution failure'.

Conclusions:

• A four-week HIT block induces immunometabolic perturbation in elite marathoners, marked by reduced leukocytes, CD4+/CD8+ imbalance, and impaired cytokine regulation.
• While plasma volume expansion might influence cell concentrations, suppressed IL-10 and CD4+ cells suggest a potentially maladaptive response to training load.
• The ABM effectively visualized complex immune dynamics and potential immunological tipping points during intensified training.