Single versus Split Dose of Iron Optimizes Hemoglobin Mass Gains at 2106 m Altitude
Bibliographic record
Abstract
PURPOSE: To determine if a single versus a split equivalent daily dose of elemental iron was superior for hemoglobin mass (Hbmass) gains at altitude while minimizing gastrointestinal (GI) discomfort. METHODS: Twenty-four elite runners attended a 3.1 ± 0.3 wk training camp (Flagstaff, AZ; 2106 m). A two-group design, randomized and stratified to baseline Hbmass, sex, and ferritin (>30 μ·L), was implemented daily as: 1) single dose of 1 × 200 mg (PM only, SINGLE) versus 2) split dose of 2 × 100 mg (AM and PM; SPLIT) elemental iron (ferrous fumarate). The Hbmass and venipuncture assessments were completed upon arrival and departure (±2 d) from camp for ferritin, hepcidin, and erythroferrone (ERFE) concentrations. Validated food frequency, GI distress, menstrual blood loss (MBL) and training questionnaires were implemented throughout. Univariate analysis was used to compare Hbmass, with baseline ferritin, dietary iron intake, MBL, and training volume used as covariates. RESULTS: Both conditions increased Hbmass from baseline (P < 0.05), with SINGLE (867.3 ± 47.9 g) significantly higher than SPLIT (828.9 ± 48.9 g) (P = 0.048). The GI scores were worse in SINGLE for weeks 1 and 2 combined (SINGLE, 18.0 ± 6.7 points; SPLIT, 11.3 ± 6.9 points; P = 0.025); however, GI scores improved by week 3, resulting in no between-group differences (P = 0.335). Hepcidin significantly decreased over time (P = 0.043) in SINGLE, with a nonsignificant decrease evident in SPLIT (~22%). ERFE significantly decreased in both groups (~28.5%; P < 0.05). No between-group differences existed for ERFE, hepcidin, food frequency, MBL, or daily training outcomes (P > 0.05). CONCLUSIONS: A single nightly 200-mg dose of elemental iron was superior to a split dose for optimizing Hbmass changes at altitude in runners over an approximately 3-wk training camp.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| 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".