The Effects Of Quinine On Performance And Brain Activity During 5 Time Sit To Stand

Abstract

Bitter-tasting oral stimulants can produce an ergogenic effect during power activities in younger, athletic populations. It has been proposed that this response may be mediated by enhanced excitability of the motor cortex by stimulation of taste receptors in the mouth. PURPOSE: To determine the effects of a bitter-tasting quinine solution on performance and brain activity during the 5 time sit to stand test (5TSTS). METHODS: 10 healthy young adults (10 female) (Age 22-31 years) were provided 4 bitter quinine solutions immediately prior (20 s) to 5TSTS. Brain activity was monitored during each trial using a 128-channel EGI Geodesic EEG system 400. 5TSTS time and trunk lean angle were measured using wearable sensors. The four solutions provided were placebo (PLAC), 80 ppm quinine (Qlow). 320 ppm quinine (Qmid), and 640 ppm quinine (Qhigh). Researchers and participants were blinded to the solutions and trials were applied in randomized, counterbalanced fashion. RESULTS: Perceived bitterness was different across the treatments (PLAC = 0.3 ± 0.1, Qlow = 2.8 ± 0.5, Qmid = 4.8 ± 0.7, Qhigh = 6.1 ± 0.7) (p = 0.001). 5TSTS time was faster in Qhigh(7.55 ± 0.39 s) compared to PLAC (8.06 ± 0.37 s) (p = 0.02), but was similar to Qlow (7.95 ± 0.32 s) and Qmid (7.87 ± 0.38 s). No differences across treatments existed with lean angle. Electrical activity in the motor cortex was also not changed by quinine consumption. Beta frequency power was greater during Qhigh(7.58 ± 1.21 μV2, p = 0.03) and Qmid (9.25 ± 2.05 μV2, p = 0.01) compared to PLAC (5.08 ± 0.91 μV2) in the premotor cortex. CONCLUSION: Bitter solutions may be effective in improving functional performance during 5TSTS in young healthy adults by altering brain activity in the premotor cortex.