The Relationship Between Plasma Volume Changes Following Heat Acclimation And Thermotolerance During Uncompensable Heat Stress In Sedentary Males
Bibliographic record
Abstract
Sedentary individuals can not tolerate the same increase in rectal temperature (Tre) during uncompensable heat stress (UHS) compared with endurance trained subjects, partially due to intestinal ischemia and endotoxin leakage that occurs with the redistribution of splanchnic blood flow. Heat acclimation (HA) may be an adaptive strategy for these individuals to increase plasma volume and delay endotoxin leakage, thus increasing thermotolerance during UHS. PURPOSE: The purpose was to examine the relationship between plasma volume (PV) changes and thermotolerance during UHS following 9 days of HA in sedentary males. METHODS: Seven sedentary males (mean±SD: 28±7 y, 75.3±8.0 kg, VO2peak= 42±6 mL·kg-1·min-1) walked to exhaustion on a treadmill (4.5 km·h-1, 2% grade) in 40°C and 30% R.H. wearing combat clothing and a protective hooded overgarment on 9 days (over 2 consecutive weeks). PV was determined prior to beginning HA using Indocyanine Green™ and resting hematocrit and hemoglobin values measured on subsequent days were used to calculate the change in PV. RESULTS: PV increased significantly over the 9 days from 49.6±9.0 to 53.3±10.3 mL·kg-1. The change in Tre from beginning to end of the UHS also increased significantly over the 9 days from 1.94±0.38 to 2.37±0.3°C owing to both a significant reduction in resting Tre from 36.83±0.32 to 36.59±0.26°C and a non-significant increase (p<0.08) in Tre at exhaustion (38.76±0.4 to 38.95±0.31°C). Total heat storage increased significantly from 6.7±1.3 to 8.0±1.2 kJ·kg-1. However, PV changes were not related to changes in heat storage or the changes in initial or final core temperatures during UHS. CONCLUSION: Although 9 days of HA induced an expansion of PV in these sedentary males, these changes were not directly related to the increase in heat storage that occurred. Funded by a Defence R&D Canada Technology Investment Fund and the US Navy Office of Naval Research.
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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 | 0.000 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".