Does Oral Ingestion Of Diphenhydramine Alter Thermoregulatory Responses During Exercise In A Warm Environment?
Bibliographic record
Abstract
Diphenhydramine (DPH) is a first generation antihistamine with anticholinergic effects due to its high affinity for muscarinic receptors which may impair sweating. Reductions in sweating could result in a higher core temperature during heat stress, and possibly increase the risk of heat-related complications. However, to our knowledge, no systematic evidence exists to confirm or refute whether DPH alters the sweating response and core temperature during heat stress. PURPOSE: To assess whether the oral ingestion of DPH independently alters the sweating response and core temperature during 60 minutes of exercise in a warm environment. METHODS: To date, six healthy young adults (27 ± 5 y, 1.8 ± 0.1 m, 72.0 ± 16.4 kg, 2 females) have participated in a double-blind, crossover randomized controlled trial. On separate occasions, participants consumed either i) 50 mg of DPH or ii) placebo pill (PLA), rested for 2 hours, then began a 60-minute treadmill march at a fixed rate of heat production (500 W) in a climate-controlled room (29.1 ± 0.6 °C & 26.6 ± 2.6%RH). Rectal temperature (Trec), mean skin temperature (Tsk), local sweat rates of the forearm (LSRarm) and chest (LSRchest), and total and steady-state (i.e. 46 - 60 minutes of exercise) whole-body sweat losses (WBSL) were measured. RESULTS: Resting Trec was not different between conditions (PLA: 37.2 ± 0.4 °C, DPH: 37.2 ± 0.3 °C, p = 0.99). At end-exercise, absolute Trec was not different between PLA (37.9 ± 0.5 °C) and DPH (37.9 ± 0.3 °C, p = 0.88). Baseline Tsk was not different between PLA (33.5 ± 0.7 °C) and DPH (33.3 ± 0.9 °C, p = 0.48), and end-exercise Tsk was not different between PLA (33.1 ± 0.7 °C) and DPH (33.1 ± 0.8 °C, p = 0.99). No end-exercises differences between PLA and DPH were observed for LSRarm (PLA: 0.7 ± 0.2 mg/cm2/min, DPH: 0.8 ± 0.3 mg/cm2/min, p = 0.99) and LSRchest (PLA: 0.2 ± 0.1 mg/cm2/min, DPH: 0.2 ± 0.1 mg/cm2/min, p = 0.99). Lastly, no differences in total WBSL were observed between PLA (380 ± 89 g) and DPH (364 ± 80 g, p = 0.53), and steady-state WBSL was not different between PLA (109 ± 11 g) and DPH (111 ± 17 g, p = 0.57). CONCLUSION: Preliminary results suggest that oral consumption of DPH does not modify the sweating response and core temperature of healthy young adults during 60 minutes of exercise in a warm environment. Funded by the Centre for Research in Occupational Safety and Health (CROSH)
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".