Despite attenuating cardiovascular and thermal strain, ingesting a cold carbohydrate beverage during exercise in the heat did not enhance exogenous carbohydrate oxidation, substrate utilization, or performance compared with a warm beverage.
Key Findings
Results
Exogenous carbohydrate oxidation did not differ between cold and warm carbohydrate beverages during prolonged cycling in the heat.
Average (40-100 min) exogenous carbohydrate oxidation was 0.50 ± 0.10 g/min in COLD vs. 0.51 ± 0.10 g/min in WARM (P = 0.80).
Peak exogenous carbohydrate oxidation also did not differ between trials (all P ≥ 0.34).
Eleven trained, non-heat-acclimated cyclists completed two trials of 100 min cycling at 50% Wpeak at 36.2 ± 0.3°C and 55 ± 3% relative humidity.
Participants ingested a 15% dextrose solution enriched with [U-13C] glucose at 60 g/h (bolus every 20 min), either at 4.0 ± 1.6°C or 35.8 ± 0.5°C.
Results
Total carbohydrate oxidation, fat oxidation, and blood glucose, lactate, and insulin concentrations were not affected by beverage temperature.
The abstract reports no differences between trials for total carbohydrate and fat oxidation, or for blood glucose, lactate, and insulin (all P ≥ 0.34).
This indicates that overall substrate utilization was similar in COLD and WARM.
Results
Cold beverage ingestion reduced heart rate and rectal temperature during exercise in the heat, but skin temperature was unchanged.
Heart rate and rectal temperature were lower in COLD than in WARM during the 100-min exercise (P ≤ 0.006).
Skin temperature did not differ between conditions.
This shows the cold beverage attenuated cardiovascular and thermal strain.
Results
Sweat losses and body mass changes were unaffected by beverage temperature.
Sweat losses and body mass changes did not differ between conditions (P ≥ 0.40).
Results
Time-trial performance following the 100-min submaximal cycling did not differ between cold and warm beverage conditions.
Time-trial performance was not different between COLD and WARM (P = 0.38).
The time trial followed 100 min of cycling at 50% Wpeak in the heat.
Conclusions
The authors conclude beverage temperature is not a relevant factor for optimizing carbohydrate availability during exercise under heat stress.
Despite physiological cooling benefits, no metabolic or performance advantage was observed with the 4°C vs. 36°C beverage.
The authors suggest athletes can choose beverage temperature based on palatability and preference rather than metabolic benefit.
What This Means
This study tested whether drinking a cold sports drink instead of a warm one helps the body use the carbohydrates in the drink as fuel during long exercise in hot conditions. Eleven trained cyclists rode for 100 minutes at a moderate intensity in a hot room (about 36°C), followed by a time trial. On two occasions they drank the same carbohydrate drink, once very cold (about 4°C) and once warm (about 36°C). The drink contained a labeled form of glucose so researchers could track how much of it was burned for energy.
The cold drink did lower heart rate and core body (rectal) temperature compared with the warm drink, but skin temperature, sweat loss, and body mass change did not differ. The amount of drink-derived carbohydrate burned was essentially identical (about 0.50 vs. 0.51 g/min), as were total carbohydrate and fat use, blood glucose, lactate, and insulin. Time-trial performance was also not different.
This research suggests that drink temperature does not change how well the body uses ingested carbohydrate during hot-weather endurance exercise, even though cold drinks reduce some measures of physical strain. Athletes may therefore choose drink temperature based on what they prefer or find palatable. The study was small and involved young, trained cyclists, so the findings may not apply to all groups or conditions.
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Mougin L, Will B, Bongers C, James L, Mears S. (2026). Cold fluid ingestion does not enhance exogenous carbohydrate oxidation during prolonged endurance exercise in the heat.. Journal of applied physiology (Bethesda, Md. : 1985). https://doi.org/10.1152/japplphysiol.00617.2026