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04.09.2014


Bitter taste - faster sprint

Endurance athletes perform better if they rinse their mouth out with a high-sugar sports drink and then spit it out. We wrote about this a couple of years ago. Research on this curious phenomenon continues: sports scientist Sharon Gam of the University of Western Australia published in Medicine & Science in Sports & Exercise the results of a human study which showed that tasting and spitting out bitter drinks also improve sports performances.

Calorie receptor
Bitter taste  faster sprint
There are receptors in your mouth that respond to carbohydrates and their caloric value. Stimulating these receptors makes the body expend more energy. This is the theory that sports scientists use to explain why endurance athletes return better times if they taste a high-sugar sports drink and then spit it out. Sounds convincing, but this theory can't explain the results of Gam's experiment.

Experimental setup
Bitter taste  faster sprint
Gam got 14 male cyclists to perform 30-second sprints a couple of times. Just before sprinting the cyclists rinsed their mouth out. On one occasion they did so with fluid that contained quinine [structural formula shown above]. Quinine is the substance that gives tonic water its bitter taste. On another occasion the fluid contained aspartame, and on yet another it contained nothing. Gam also got the cyclists to sprint once without having had anything in their mouth.

Faster
The cyclists produced 2-4 percent more power after they'd had the bitter quinine-containing liquid in their mouth. More power means more speed.


Bitter taste  faster sprint


Gam found no effects on the cyclists' blood sugar levels, acidification or heart rate.


Bitter taste  faster sprint


Speculation
There are about fifty receptors for bitter substances in the human mouth. They are extremely sensitive because many bitter substances are poisonous. The receptors warn us about foods that could kill us.

Gam suspects that this warning stimulus is responsible for the performance-enhancing effect of quinine and that it works via the autonomous nervous system.



Just in case you're thinking of experimenting with quinine: Gam's measurements indicate that the performance-enhancing effect of tasting something bitter lasts only 80-120 seconds.

Conclusion
"This study shows for the first time that mouth rinsing and ingestion of a quinine solution immediately before a maximal 30-s sprint can improve mean and peak power output", writes Gam. "These findings are likely to be meaningful for sprinters or power athletes involved in short duration events."

"The mechanisms underlying the effect of quinine remain to be elucidated, as well as the effect of quinine (or other bitter tastants) mouth rinsing and ingestion on different modes of exercise, including endurance and resistance exercise."

Source:
Med Sci Sports Exerc. 2014 Aug;46(8):1648-57.

More:
Endurance athletes are faster if they just taste carbs and spit them out 03.01.2011