The Influence of Ingestion Time on the Validity of Gastrointestinal Pill Temperature as an Index of Body Core Temperature During Work in the Heat
Bibliographic record
Abstract
Ingestible, telemetric pills are increasingly used to estimate body core temperature from the gastrointestinal tract when gold‐standard measurements (e.g., rectal temperature) are unfeasible. While gastrointestinal temperature has been shown to provide acceptable validity, it has been suggested that the time between pill ingestion and the measurement period can influence the precision of those estimates, with sensors spending a greater time in the gastrointestinal tract providing better agreement with rectal temperature. However, a within‐subjects comparison of the effects of various sensor ingestion times on the validity of gastrointestinal temperature as an index of body core temperature during steady‐state and variable‐intensity exercise (more reflective of occupational tasks) is currently unavailable. We therefore sought to quantify the agreement between rectal temperature and gastrointestinal temperatures measured from telemetric pill sensors ingested at various periods prior to exercise in the heat. On two separate occasions, six young (mean±SD; 27±4 years) males consumed a telemetric pill sensor (Vital Sense capsule thermometer; Mini Mitter, Bend, OR) 12, 6, 3 and 1 hour(s) prior to arriving at the laboratory. Thereafter, participants performed 15‐min seated rest followed by 90‐min of either constant or variable intensity cycling eliciting an average rate of metabolic heat production of ~200 W/m 2 and a 45‐min recovery, in hot, dry conditions (40°C, ~20% relative humidity). Metabolic heat production as well as rectal and gastrointestinal temperatures were measured continuously (1 min intervals). Agreement between pairs of measurements from each pill sensor and the criterion (rectal temperature) were assessed by the residual mean square error and the percentage of data points exceeding a meaningful threshold of acceptance (±0.25°C). Individual rectal temperature ranged between 36.62–38.43°C, while gastrointestinal temperature ranged between 36.51–38.32°C, 36.46–38.46°C, 36.29–38.34°C and 36.19–38.32°C for the sensors ingested 12, 6, 3 and 1 hour(s) prior to work in the heat (respectively) across both trials. During the constant work trial, the residual mean square error for each sensor averaged 0.12±0.10°C (12 hours), 0.14±0.11°C (6 hours), 0.12±0.09°C (3 hours) and 0.13±0.11°C (1 hour), with 13±16 %, 17±21 %, 11±14 % and 8±9 % of measurements exceeding the predefined acceptance threshold (±0.25°C). Residual square errors averaged 0.18±0.12°C (12 hours), 0.14±0.12°C (6 hours), 0.19±0.16°C (3 hours) and 0.14±0.10°C (1 hour) during the variable work trial, while 27±28 %, 14±15 %, 28±24 % and 14±7 % of measurements exceeding the predefined acceptance threshold. These preliminary outcomes indicate that ingestion times ranging between 12‐1 hour(s) prior to use do not demonstrably modify the precision of estimates of body core temperature from the gastrointestinal tract during either constant or variable work of moderate intensity under hot, dry conditions, with 72–92% of measurements falling within an acceptable error range. Support or Funding Information Funded by the Government of Ontario and Natural Sciences and Engineering Research Council of Canada. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.009 | 0.030 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".