The Bitter Taste that Gets You Going: Quinine Mouthrinse Provides Instant 4% Power Boost During 30s All-Out Sprint

The Bitter Taste that Gets You Going: Quinine Mouthrinse Provides Instant 4% Power Boost During 30s All-Out Sprint

ergogenic mean power mouthrinse peak power performance power powerlifting quinine sprinting sprints

Getting ready for an all-out sprint? A bitter mouth rinse W/ quinine will provide instant power boost of 4% in ‘ur 30s cycle sprint more than a sweet mouth rinse could do .

If you're a powerlifter, the idea that rinsing your mouth with a bitter substance can improve your performance is probably no news for you... even though, powerlifters smell, not taste ammonia, smelling and tasting are, after all, more or less two sides of the same coin (Rozin. 1982).

Against that background and in view of the similar brain activation patterns scientists have observed in response to bitter and sweet taste perception, it appears only logical for Sharon Gam et al. to speculate in a 2014 paper, which is still worth its own SuppVersity article (!), that rinsing w/ quinine, a distinctly bitter substance, could produce the same or at least similar power increments as sweet substances.

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Of the latter, previous research has shown that they will elevate both peak power (+22.1 ± 19.5 W; ES, 0.81; p = 0.0667) and mean power (+39.1 ± 26.9 W; ES, 1.08; p = 0.0205 | Beaven, et al. 2013), during all out sprints. The goal of the researchers from the University of Western Australia was thus to elucidate, "whether combining mouth rinsing with the ingestion of a bitter-tasting solution composed of quinine acutely improves mean and peak power during a 30-s maximal cycling sprint effort" (Gam. 2016) would yield similar benefits.

To be able to tell how similar sweet and bitter taste effects on sprinting performance actually are, they scientists compared the effects of 0.36 mL/kg body mass of a 2-mM quinine HCl solution (QUI; Sigma-Aldrich), not just to plain water and a no rinse control (CON), but also to a 0.05% w/v aspartame solution (ASP; Sigma-Aldrich), all of which were used immediately before the 30s all-out sprint on an Exertech EX-10 front access cycle ergometer.

Figure 1: My graphical "illustration" of the study design (based on facts from Gam. 2014).

As the authors explain, the "volume of 0.36 mL/kg was chosen to account for differences in body size, with each participant receiving approximately 25–35 mL of solution per session" (Gam. 2014) and the "[p]articipants were instructed to rinse their mouth for 10 s and then ingest the solution", a practice that was prescribed to ensure "that bitter receptors at the back of the tongue were activated because there is evidence that the strongest sensation of bitterness occurs in that area of the oral cavity" (Gam. 2014).

Bitter perception (Mennella. 2013).

Have you ever asked yourself how "bitter works"? Here is the answer from a 2013 paper by Mennella, et al. → "The generation of bitter taste starts when a bitter compound enters the oral cavity, where the ligand binds to a T2R G-protein coupled receptor expressed in the apical membrane of receptor cells found in taste buds, triggering a cascade of signaling events, leading to the release of neurotransmitter that activates an afferent nerve fiber that transmits the signal via the cranial nerve to the brain. Taste buds are distributed in distinct fields in the oral, pharyngeal, and laryngeal epithelia, with each field innervated by a different cranial nerve branch. Only the taste buds on the tongue are depicted in the figure."

As you can see in the selected performance markers I've plotted for you in Figure 2, the fourteen competitive male cyclists, who performed a 30-s maximal cycling sprint immediately after rinsing their mouth for 10 s and then ingesting the aforementioned solutions (QUI, water, ASP, CON), experienced significant increases in both mean power output by 2.4%–3.9% [P < 0.021, effect size (ES) = 0.81–0.85] and peak power output in the quinine condition.

Figure 2: Relative changes in mean & peak power (%) + effects sizes for quinine vs. CON, WAT or ASP (Gam. 2014).

For the latter, it is yet important to point out that a significant performance enhancement in terms of the peak power output was recorded only in comparison to the water (3.7%, P = 0.013, ES = 0.71) and the control (3.5% P = 0.021, ES = 0.84) conditions, yet not compared to the aspartame condition (1.9%, P = 0.114, ES = 0.47), in which the scientists observed a non-significant increase in performance compared to the water and control trial. Differences in heart rate, perceived exertion, or blood variables between any of the conditions were not observed.

Bitter taste increases ghrelin, ghrelin rapidly increases noradrenaline and adrenaline - if that's what explains the effects of quinine will yet have to be elucided in future studies.

So what's the mechanism, here? Unfortunately, the researchers don't speculate about the mechanism behind this, for sprinters and power athletes highly relevant effect of quinine (or other bitter tastants). My brief research of the existing research on bitter taste receptors, however, suggests various possible mechanisms with the release of ghrelin in response to bitter taste sensing (Janssen. 2011) and its effects on gluconeogenesis, noradrenaline and adrenaline (Enomoto. 2003 | see Figure on the right) being a candidate that would usually have us expect to see more pronounced increases in heart rate than they were observed in the study at hand, where quinine raised the heart rate only in the absence of exercise (by ~3-4 bpm).

It is thus questionable, whether the ghrelin => (nor-)adrenaline hypothesis provides the correct explanation - not just, but also because previous research suggests that the benefits of rinsing your mouth with bitter substances before sprinting may have the same origin as those that occur in response to carbohydrate mouth-rinsing, the triggers of which are likewise believed to "reside in the central nervous system" (Jeukendrup. 2010) and thus to be of non-metabolic origin.

Since the quinine solution was also swallowed, effects that were triggered by bitter taste receptors (ghrelin remains the most likely candidate) in endocrine cells along the gut (figure from Depoortere. 2014) could also explain the performance increases.

Speaking of carbohydrate / sweet mouth rinses, it should be mentioned that the lack of significant performance differences (1.9%, P = 0.114, ES = 0.47) between the aspartame and the quinine trial in the study at hand appears to suggest that sweet and bitter mouth rinses work by the same, still to be elucidated mechanism (it should be said, though that structural analogues of aspartame have been found to active the bitter taste receptor, as well | Benedetti. 1995).

In view of the fact that this hypothesis is, as Gam et al. point out, in line with the results of "studies based on functional magnetic resonance imaging [, which] have shown that the brain areas activated in response to the bitter tastant, quinine, overlap to a great extent" with those brain areas that are stimulated when you rinse with CHOs / sweet solutions (Zald. 2002; Small. 2003), finding mechanistic explanations for one of these performance enhancer (e.g. the sweet mouthrinse) may also yield explanations for the performance enhancing effects of the other one. Whether that's the actual reason for the preformance increases does yet appear questionable. After all, a 2015 follow up study by the same researchers showed that that mouth rinsing with the same bitter quinine solution without ingesting it won't improve young athletes' sprint cycling performance (Gam. 2015) - in view of the presence of ghrelin producing cells in the digestive tract (see Figure in this bottom line), this does not falsify the "ghrelin" => (nor-)adrenaline hypothesis, which would also be in line with the increases in corticomotor excitability Gam et al. observed in yet another follow up study in male competitive cyclists (Gam. 2015b), in which the quinine was ingested, too | Comment!

References:

• Beaven, C. Martyn, et al. "Effects of caffeine and carbohydrate mouth rinses on repeated sprint performance." Applied Physiology, Nutrition, and Metabolism 38.6 (2013): 633-637.
• Benedetti, Ettore, et al. "Sweet and bitter taste: Structure and conformations of two aspartame dipeptide analogues." Journal of Peptide Science 1.6 (1995): 349-359.
• Depoortere, Inge. "Taste receptors of the gut: emerging roles in health and disease." Gut 63.1 (2014): 179-190.
• Enomoto, Mitsunobu, et al. "Cardiovascular and hormonal effects of subcutaneous administration of ghrelin, a novel growth hormone-releasing peptide, in healthy humans." Clinical Science 105.4 (2003): 431-435.
• Gam, Sharon, Kym J. Guelfi, and Paul A. Fournier. "Mouth rinsing and ingesting a bitter solution improves sprint cycling performance." Medicine and science in sports and exercise 46.8 (2014): 1648-1657.
• Gam, Sharon, et al. "Mouth rinsing with a bitter solution without ingestion does not improve sprint cycling performance." European journal of applied physiology 115.1 (2015a): 129-138.
• Gam, Sharon, et al. "Mouth rinsing and ingestion of a bitter-tasting solution increases corticomotor excitability in male competitive cyclists." European journal of applied physiology 115.10 (2015b): 2199-2204.
• Janssen, Sara, et al. "Bitter taste receptors and α-gustducin regulate the secretion of ghrelin with functional effects on food intake and gastric emptying." Proceedings of the National Academy of Sciences 108.5 (2011): 2094-2099.
• Jeukendrup, Asker E., and Edward S. Chambers. "Oral carbohydrate sensing and exercise performance." Current Opinion in Clinical Nutrition & Metabolic Care 13.4 (2010): 447-451.
• Rozin, Paul. "“Taste-smell confusions” and the duality of the olfactory sense." Attention, Perception, & Psychophysics 31.4 (1982): 397-401.
• Small, Dana M., et al. "Dissociation of neural representation of intensity and affective valuation in human gustation." Neuron 39.4 (2003): 701-711.
• Zald, David H., Mathew C. Hagen, and José V. Pardo. "Neural correlates of tasting concentrated quinine and sugar solutions." Journal of Neurophysiology 87.2 (2002): 1068-1075.

Fit and Lean in 4 Min / Week: 1kg Fat Loss, +9% VO2Max, +13% Fat Oxidation - Men Lose Trunk, Women Leg Fat

Fit and Lean in 4 Min / Week: 1kg Fat Loss, +9% VO2Max, +13% Fat Oxidation - Men Lose Trunk, Women Leg Fat

fitness health HIIT lose fat sprints vo2max workouts

No excuse: You don't need an ex-pensive spinning bike for the workout.

This is not an article for the hardcore trainees among you... unless, obviously you are a trainer or have friends and family who fall into the same "I just wannabe fit and healthy" category as the subjects of a recent study by scientists from the Manchester Metropolitan University and the Cambridge University School of Clinical Medicine (Bagley. 2016),  24 men and 17 women with a mean age of 39 (±2) years, a normal weight (BMI 24.6 +/- 0.6) and average fitness levels.

In this group of "normal people", Bagley et al. aimed to examine the hypothesis that very short duration, very high-intensity sprinting exercise (on cycle ergometers) could not just improve their subjects fitness (as measured by VO2max), but also their ability to burn fat and to actually lose it.

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After baseline measurements on the DEXA scan (body fat and lean mass) and cycle ergometers (VO2max), the participants were told to do only one thing: A sprint-interval training (SIT) program on a standard cycle ergometer.

"The training consisted of a 2 min warm-up at a self-selected moderate intensity. This was followed by four bouts of 20 s ‘maximal effort’ sprints at a workload that was set at 175% of the workload attained in the VO2max test. Each of these intervals was separated by 2 min of very low intensity cycling (a workload of approximately 20% of that attained at VO2max). Thus, each training session lasted less than 10 min and only 80 s was completed at an inten sity that would be expected to improve physical fitness" (Bagley. 2016). 

The first training session for each participant, who were told to maintain their their usual dietary and exercise habits throughout the intervention, was fully supervised in the research laboratory. To ensure that the subjects would indeed do their three weekly workouts 80s-workouts, the participants were then provided with clear instructions on the use of the cycle ergometers and the training regimen.

But you said "fit in 4 minutes", now the subjects train for almost 10 minutes? Yes and no. They train for 20 minutes, but the actual "exercise", which is something I define as being significantly exerted is 80s per workout. With three workouts per week, that's 3x80s = 240s = 4 minutes! So, I don't want to hear complaints ;-)

The training work load was increased by 5% every 2 weeks. Gym staff were fully informed of the research and training protocols, they logged the training session and were available to offer advice to research participants if needed during training sessions. Participants maintained a training-log to record workloads during training sessions.

Figure 1: Maximal oxygen uptake and rates of fat oxidation measured during exercise in men and women before and after 12 weeks of SIT; all changes were stat. sign. p < 0.05 (Bagley. 2016).

As you can see in Figure 1, the effects these short, highly time-efficient, and absolutely manageable (everyone can workout at max intensity for 4x20s) had on the subjects' fitness were not just statistically significant, they were also practically relevant and, at least for VO2max, differed significantly for men and women.

But how did they lose weight without dieting? The secret is the proven lack of compensation for SIT sessions, which have been show to be as low as <50kcal/week - compared with endurance exercise where compensation is 10x higher, i.e. 500 kcal/week (Burgomaster. 2008). Still, the direct energy expenditure during the short SIT sessions cannot fully explain the fat loss. Therefore, Bageley et al. speculate that "[o]ther contributing factors might include an increase in post exercise energy expenditure [that's unlikely, learn why] or overall shift towards greater fatty acid oxidation during habitual activities throughout the day" (Bagley. 2016).

Overall, the increase in VO2max averages out at 9% - the reasons for the sex-differences is not clear. After all, the scientists point out that men have been shown to have higher gains in VO2max following conventional endurance exercise. The mixed results of previous studies into the effects of sprint interval training, however, are mixed and thus not necessarily contrary to the evidence from the study at hand. While Scalzo et al. (2014), for example, found that young women had similar gains in VO2max as young men, the results Allemeier et al. (1994) et al. presented in the Journal of Applied Physiology suggest that men don't see any increase in VO2max. What could be the reason? Well, this is what the scientists say:

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"A higher relative amount of lean mass in men compared to women, coupled with a higher relative body fat mass in women compared to men, may go some way in explaining the differences between men and women in maximal oxygen consumption. However, the supply of oxygen to the working skeletal muscles is thought to be a limiting factor in VO2max, so the higher VO2max response in women might point to higher adaptations of oxygen supply than those in men following SIT, but more focused studies examining cardiac output, blood volume, haematocrit and blood flow distribution are needed to clarify this finding.

Conversely, after regular endurance training, men had higher gains in VO2max compared with women. It is possible that the training volume (higher in endurance) and training intensity (higher in SIT) lead to disparate adaptations between men and women in the oxygen carrying capacity of blood (eg, total blood volume, haemoglobin or cardiac output) or local vasculature, but physiological mechanisms driving such responses are unclear" (Bagley. 2016).

No sex differences were observed for the measured health markers, namely glucose, insulin, HOMA, triglycerides, total cholesterol or LDL - only for HDL there was a significantly more pronounced increase in the female vs. male subjects. Eventually, the improvement of the total cholesterol to HDL ratio was yet similarly pronounced in both sexes (-16% in the men, -11% in the women).

Figure 2: Body composition before and after 12 weeks of SIT; * after the categories denotes p < 0.05 (Bagley. 2016).

The previously discussed changes were accompanied by a significant loss of total, leg and trunk fat, as well as significant increases in lean mass in both groups - with inter-sex-differences in total body mass, body fat %, leg fat, and lean mass. That's quite a result, if you take into account the total and actual exercise time the subjects had to invest.

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Bottom line: I am not sure how feasible this protocol would be for an obese person, but in the healthy normal-weight subjects in the study at hand, the 12x4 minutes of working out intensely made quite a change. Ok, you have to work out thrice a week, but 10 minutes on an exercise bike? That's something you could easily do every morning before showering or when you come home from work.

Ah, and before I forget to highlight that - even though the fat loss in the female subjects may have been smaller than in the male subjects, the women lost fat where many of them hate it the most: on their legs - not bad!? Comment!

References:

• Allemeier, CRAIG A., et al. "Effects of sprint cycle training on human skeletal muscle." Journal of Applied Physiology 77.5 (1994): 2385-2390.
• Bagley, Liam, et al. "Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise." BMJ Open Sport & Exercise Medicine 2.1 (2016): e000056.
• Burgomaster, Kirsten A., et al. "Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans." The Journal of physiology 586.1 (2008): 151-160.
• Scalzo, Rebecca L., et al. "Greater muscle protein synthesis and mitochondrial biogenesis in males compared with females during sprint interval training." The FASEB Journal 28.6 (2014): 2705-2714.