Inflammatory Response to Ultramarathon Running: A Review of IL-6, CRP, and TNF-α
Bibliographic record
Abstract
Ultramarathon running elicits a profound inflammatory response, characterized by significant increases in interleukin-6 (IL-6) and C-reactive protein (CRP), with comparatively modest changes in tumor necrosis factor-alpha (TNF-α). We reviewed approximately 80 field studies of ultramarathon events (distances >42.2 km) that measured IL-6, CRP, and TNF-α before and after races. IL-6 typically spiked immediately post-race-often rising dozens or even thousands of times above baseline-then rapidly declined, usually returning to near baseline within 24-48 h. CRP, an acute-phase protein, exhibited a slower, sustained elevation, peaking 24-72 h after race completion and remaining above baseline for 2-3 days before gradually returning to normal. TNF-α responses were variable: some studies reported small but significant post-race increases (roughly 1.2-1.7-fold above baseline), while others found no significant change in circulating TNF-α despite the extreme effort. Longer race durations and distances generally correlated with higher peak IL-6 and CRP levels. Experienced ultramarathon runners tended to exhibit attenuated inflammatory responses compared with less-trained individuals, and anti-inflammatory cytokines (e.g., IL-10) increased in tandem with IL-6 in well-trained athletes, helping to mitigate TNF-α elevations. In total, 28 studies were included in the final synthesis, and their quality was assessed using the Newcastle-Ottawa Scale. Visual synthesis tools, including a PRISMA flowchart and time course plots, are provided to enhance the narrative's interpretability. In summary, ultramarathon running elicits a robust systemic inflammatory response with distinct temporal patterns for IL-6, CRP, and TNF-α. These findings have important implications for athlete recovery, monitoring, and understanding the physiological limits of the inflammatory response to extreme endurance stress.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".