Exertional Heat Strain After an Energy Drink and Caffeine-Equivalent Beverage in Wildland Firefighting Garments
Bibliographic record
Abstract
ABSTRACT: Bartman, NE, Temple, JL, Hess, HW, Colburn, D, and Hostler, D. Exertional heat strain after an energy drink and caffeine-equivalent beverage in wildland firefighting garments. J Strength Cond Res 39(8): e1026-e1035, 2025-Caffeine is widely consumed for its stimulant properties and potential ergogenic benefits. Wildland firefighters consume caffeine, but caffeinated energy drinks (ED) are discouraged. The purpose of this investigation was to assess physiologic and perceptual strain walking in wildland firefighting garments after consuming an ED or another equally caffeinated beverage (CAF). Twelve subjects {age (mean [95% confidence interval]): 27 (23-32) years, height: 173 (169-177) cm, mass: 76 (70-83) kg, V̇ o2 max: 43 (36-50) ml·kg -1 ·min -1 } walked on a treadmill 90 min at 40-50% V̇ o2 max in 30° C, 80% RH conditions after consuming ED or CAF (200 mg caffeine). Significance was set at p ≤ 0.05. Peak core temperature (CAF: 39.1° C [38.9-39.3° C]; ED: 39.1° C [38.8-39.4° C], p = 0.94), physiologic strain index (CAF: 8.5 [7.9-9.2] score; ED: 8.5 [7.7-9.4] score, p = 0.87), and perceptual strain index (CAF: 7.9 [6.7-9.0] score; ED: 8.0 [6.8-9.1] score, p = 0.75) were not different between conditions. There were no differences in sweat rate (CAF: 18 [10-26] mL·min -1 ; ED: 19 [14-24] mL·min -1 , p = 0.66), peak heart rate (CAF: 175 [167-184] b·min -1 ; ED: 177 [168-186] b·min -1 , p = 0.86), perceived exertion (CAF: 8 [6-9] rating; ED: 8 [7-8] rating, p = 0.68), and fatigue (CAF: 7 [6-9] rating; ED: 7 [5-8] rating, p = 0.07). Consuming ED did not worsen physiologic or perceptual strain compared with consuming caffeine alone. For regular caffeine users, an ED may be an acceptable alternative caffeine source for wildland firefighters hiking in hot conditions.
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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 | 0.000 |
| 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) | 0.000 | 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".