Work

Effects of carbohydrate-electrolyte solutions with and without L-menthol on hydration and performance recovery following simulated firefighting exercise

Year: 2026

Type: article

Abstract: Background Firefighting tasks performed in full protective equipment (PPE) impose extreme thermal and physical strain, providing a model of high-intensity exercise with substantial fluid and electrolyte loss. This study compared the effects of plain water (W), a carbohydrate-electrolyte solution (CES), and a menthol-supplemented carbohydrate-electrolyte solution (MCES) on hydration and performance recovery during the first hour of post-exercise recovery.Methods Twenty-four male firefighters completed a standardized simulated firefighting protocol in protective clothing. Participants were randomly assigned to W, CES, or MCES (n = 8 each) and consumed 1.0 L of fluid during 60 minutes of recovery. Hydration status was evaluated using body-mass restoration, salivary osmolality, urine specific gravity, urine color, and urinary electrolytes. Renal markers, lactate clearance, cardiovascular and thermal responses, thirst ratings, and lower-limb explosive power were also assessed.Results Body mass restoration showed significant group effects, with MCES greater than W and CES at 60 min (p < 0.05). Rehydration rate was higher for both CES and MCES than W (p < 0.05). Salivary osmolality and urinary sodium favored electrolyte solutions over water (p < 0.05), while urine specific gravity was lower in MCES compared with W and CES (p < 0.05). Blood urea nitrogen and BUN/creatinine ratios were higher in W than both electrolyte conditions at 30 and 60 min (p < 0.05). Lactate clearance was reduced in W compared with CES and MCES (p < 0.05). Jump height declined from pre- to post-recovery in the W and CES groups but was maintained within the MCES group.Conclusions Carbohydrate-electrolyte solutions improved hydration compared with water. L-menthol did not enhance rehydration but maintained explosive performance, supporting its role as a perceptual adjunct to electrolyte strategies for recovery after exercise in protective clothing.

Source: Journal of the International Society of Sports Nutrition

DOI: 10.1080/15502783.2026.2676193

Authors: Yi-Ju Hsu, Chin-Shan Ho, Chun-Hao Chang, Tsan-Wei Chuang, Shao-Hua Shang

Institutions: National Taiwan University of Sport, National Taiwan Sport University, Taipei City Government

Language: English

Topic: Thermoregulation and physiological responses

Subfield: Physiology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,490