Oxylipin Responses during the Yukon Arctic Ultra: The Longest and Coldest Ultramarathon in the World
Bibliographic record
Abstract
INTRODUCTION: Aerobic exercise and cold exposure modulate lipid mediator production, which may optimize physiological resilience. The Yukon Arctic Ultra (YAU), a 692-km self-provisioned multiday endurance event, offers a unique opportunity to examine lipidomic adaptations to nutrients and environmental and physical stress. This study aimed to identify lipid mediators responsive in YAU athletes compared to control participants. METHODS: Nine athletes and six controls were recruited from the 2017 and 2019 YAU events. Targeted liquid chromatography-tandem mass spectrometry/mass spectrometry-based signaling lipidomic analysis was conducted on serum samples collected from participants at pre-event, during the event, and post-event time points. RESULTS: Athletes and controls did not differ significantly in age, body mass index (BMI), fat mass index (FMI), or fat-free mass index. During the event, athletes exhibited significant reductions in BMI, fat mass, and FMI, whereas no changes were observed in controls. Athletes showed higher baseline levels of anti-inflammatory oxylipins, including resolvin D2 and lipoxin A4 (LXA4), and lower levels of the pro-inflammatory leukotriene E4 compared to controls. Linoleic acid- and α-linolenic acid-derived oxylipins were also elevated in athletes. Notably, these anti-inflammatory lipids remained elevated throughout the event. Certain hydroxy-eicosapentaenoic acids demonstrated a declining trend during the event in athletes. DISCUSSION: YAU athletes exhibit a distinct lipidomic signature marked by persistently elevated anti-inflammatory oxylipins, likely reflecting a complex interplay between adipose tissue and skeletal muscle. Overall, the oxylipin shifts point to anti-inflammatory and thermogenic adaptations that support physiological resilience during physical, nutrient, and environmental stress in austere circumstances.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".