REF-967 · Riera et al., 2014 · PLoS ONE, Vol. · Paper · PubMed

Physical and Perceptual Cooling with Beverages to Increase Cycle Performance in a Tropical Climate

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

Neutral-temperature, cold and ice-slush drinks, each with or without 0.5% menthol, were compared for their effect on cycling performance, core temperature and stress responses in a tropical climate. Twelve trained male cyclists/triathletes rode six 20-km time trials in heat of 30.7°C±0.8°C with 78%±0.03% relative humidity.

They drank 190 mL before and after the warm-up, just before the start and every 5 km during the ride — either flavoured with 0.5 mL menthol (5 gr/L) or unflavoured, at 23°C±0.1°C (neutral), 3°C±0.1°C (cold) or -1°C±0.7°C (ice-slush). Aroma (P<0.02) and drink temperature (P<0.02) each improved performance significantly.

Ice-slush with menthol and cold with menthol gave the best performances. Heart rate and core temperature did not differ between trials.

Participants

n=12 trained male cyclists/triathletes. Age and fitness values are not given in the abstract.

Protocol

Six 20-km time trials, ridden in heat of 30.7°C±0.8°C with 78%±0.03% relative humidity.
Beverage: 190 mL drunk before and after warm-up, before exercise and every 5 km during exercise.
Two factors: aroma (aromatized with 0.5 mL of menthol (5 gr/L) vs non-aromatized) × temperature (neutral 23°C±0.1°C, cold 3°C±0.1°C, ice-slush -1°C±0.7°C).
Heart rate monitored continuously; core temperature, thermal comfort, thermal sensation and rate of perceived exertion measured before and after warm-up, every 5 km, at the end of exercise and after recovery.

Key Results

Beverage aroma (P<0.02) and beverage temperature (P<0.02) both had significant and positive effects on performance.
Ice-slush beat a neutral-temperature drink by a considerable margin, regardless of aroma (P<0.002), and menthol beat no menthol (P<0.02).
Ice-slush/menthol and cold/menthol produced the best performances, in contrast to neutral/menthol.
No differences in heart rate and core temperature between trials.
The abstract gives no times, speeds or percentage differences.

Practical Application

In twelve trained male cyclists/triathletes doing 20-km time trials at 30.7°C and 78% relative humidity (crossover, six drinks), performance was better with a menthol-aromatized drink than without (P<0.02) and better with ice-slush than with a neutral-temperature drink (P<0.002); the best trials were with ice-slush/menthol and cold/menthol, and heart rate and core temperature did not differ between drinks. To "what should I drink in a hot, humid time trial?": a cold or ice-slush drink, and adding menthol to it helped further in this trial.
Temperature and menthol are separate levers here, and the drink was swallowed, not rinsed and spat. Do not carry this result over to a mouth rinse.
Do not quote a percentage or a time gain from this entry; the abstract reports none.
Inference, not tested here: performance improved with no difference in core temperature, which fits a perceptual effect rather than a lower heat load.
Not from this paper: the same group's test of how long to precool with an ice-slush menthol drink is REF-968; pooled route comparisons are in REF-964; physical precooling evidence is in REF-111 and REF-112; the base's protocol is in SYNTH-25.

Limitations

n=12, men only; randomisation and blinding not stated in the abstract (drink temperature and a menthol aroma cannot be hidden from the rider).
No effect sizes, times or power values in the abstract.
A 20-km laboratory trial in one hot, humid condition; the authors call for field studies.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

crossover, n=12; randomisation and blinding are not stated in the abstract