The consumption of food and drink is a multisensory experience, with colour often a characteristic that is manipulated to enhance subsequent taste perception and psychophysiological response. The perception of sweetness, for example, is known to be enhanced if a food or drink product is presented with a pink appearance.
If the colour pink is associated with perceived sweetness and expectations of sugar/carbohydrate intake, the authors of the current study hypothesised it may be plausible that the provision of a pink-coloured mouth rinse during exercise may elicit a similar performance benefit to that of carbohydrate mouth rinse through a placebo effect.
The aim of the current study therefore was to investigate whether mouth rinsing with a pink non-caloric, artificially sweetened solution can improve self-selected running speed, distance covered and feelings of pleasure.
The study's results, involving ten healthy men, suggest that mouth rinsing with a pink non-caloric, artificially sweetened solution improved self-selected running speed and total distance covered during a 30 min run. The improvement in self-selected running speed and total distance covered was also paired with an increase in feelings of pleasure reported by participants during exercise.
This is the first study to report a performance benefit of mouth rinse colour during submaximal exercise of ≤ 1 h duration.
The report concludes: "It may be plausible to suggest that the “feel good” effect and corresponding ergogenic benefit reported in the pink mouth rinse condition may have been underpinned by a placebo effect, with the colour pink often associated with sweetness and thus expectations of sugar/carbohydrate intake (11)."
The study
All participants visited the laboratory on three occasions separated by one week (one preliminary trial and two experimental trials) at a similar time of day.
During the two experimental trials, participants rinsed with one of two randomly assigned solutions. Each solution was prepared identically by adding 0.12 g of pure sucralose (Bulk Powders, UK) to 500 mL of plain water. One solution, however, had no colourant added (clear), whereas the other had two drops of non-caloric pink colourant added to achieve the desired pink appearance.
Despite being identical apart from colour, a pilot study conducted prior to the current investigation reported that participants (n = 18) preferred the pink solution, perceiving it as both sweeter and tastier.
Participants were provided with 25 mL of solution (pink or clear) and instructed to rinse it around the oral cavity for five seconds.
The results suggest mouth rinsing with a pink non-caloric, artificially sweetened solution improved self-selected running speed and subsequent distance covered during a 30 min self-paced running protocol when compared to an isocaloric and taste-matched clear solution. This equates to a mean 0.5 km·h−1, 213 m or 4.4% improvement in performance.
Discussing the possible mechanism of action at play, the report states: "The detection of carbohydrates (i.e., glucose or maltodextrin) in the buccal cavity are reported to activate the central reward systems of the brain, such as the anterior cingulate cortex and ventral striatum, that are believed to mediate positive emotional, cognitive and behavioural responses to this stimuli.
"In the current study, as a non-caloric artificial sweetener (sucralose) was added to both mouth rinse solutions, a carbohydrate stimulus was not present. As such, it may be plausible to suggest that the “feel good” effect and corresponding ergogenic benefit reported in the pink mouth rinse condition may have been underpinned by a placebo effect, with the colour pink often associated with sweetness and thus expectations of sugar/carbohydrate intake."
Source: Frontiers in Nutrition
Brown .D. R., et al
Mouth Rinsing With a Pink Non-caloric, Artificially-Sweetened Solution Improves Self-Paced Running Performance and Feelings of Pleasure in Habitually Active Individuals