SCIENCE FRIDAY: CAFFEINE RESEARCH NEWS...

…AND CAUTIONS. CAFFEINE IS A KNOWN exercise performance enhancer, especially in trained athletes.  It works on a number of different body tissues, although not all changes may be responsible for improved performance, which include:  

• Metabolism: Increases the breakdown and burning of fat for fuel and spares muscle glycogen 
• Hormones:  enhances adrenaline release that plays a role in ‘fight or flight’ responses
• Muscle: doesn’t harm muscle recovery, which was suggested by earlier research 
• Brain and nervous system: activates areas that help improve focus and alertness, lessen feelings of fatigue, and increase feelings of wellness, being energized, and heightened mood
• Body temperature: increases thermogenesis (heat production)

 
An article in BusinessInsider.com by Kevin Loria and Erin Brodwin explains how caffeine, a drug, works as a stimulant to produce multiple positive effects.  However, for each good effect related to caffeine intake the authors described the downside effect, especially in sensitive individuals.  The properties of caffeine that provide a boost may also result in anxiety, irritation, and jitteriness they advise. 
 
It’s benefit to exercise is described in the article; “It’s one of the best athletic performance enhancers out there,” declares the section title.  Embedded in this section is a link to a 2014 item in the TheAtlantic.com, which lays out the ways in which the small improvements associated with caffeine supplementation can be important in competition.
 
Thus, elite athletes and average endurance sport enthusiasts are interested in enjoying the positive effects of caffeine on exercise performance. Especially those who also enjoy the wake-me-up and pick-me-up benefits of consuming caffeinated substances in the morning or other times of the day, while not involved in exercise activities. 
 
However, the popular scientific thinking that ‘habituation’ reduces or wipes out the performance boost has troubled some regular caffeine-imbibing athletes, who have been advised to stop taking caffeine-containing substances for several days to weeks before using it to enhance performance. 
 
Fortunately, a study published in the Journal of Applied Physiology, titled “Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation”, has provided evidence which dismisses this theory. 
 
The study was conducted by scientists at the University of Brazil at Sao Paulo who had actually hypothesized that the opposite would happen! That the athletes’ “habitual caffeine intake would influence the ergogenic effects of caffeine supplementation, with greater aerobic exercise performance gains in individual with lower regular consumption.” A lower pre-performance intake habit would translate to bigger gains with supplementation just before exercise.
 
Forty, male, endurance-trained cyclists were grouped according to daily caffeine intake: low (~58mg/day, about 1 small cup/day), moderate (143mg/day; 2-3 cups/day) and high (~351mg/day; 5 cups/day). Each performed 3 simulated time trials, ~30 minutes duration. They were instructed to cycle as fast as possible to achieve a set amount of work, after receiving a gelatin capsule dose of caffeine (CAF: 6mg/kg body mass), a placebo (PLA; dextrose, 0mg caffeine), and no supplement (CON; 0mg caffeine).*
 
The results revealed that low, moderate, and high “caffeine consumers showed similar absolute and relative improvements in cycling time-trial performance following acute supplementation” compared with placebo and control subjects.  
 
In other words, those who regularly took in significantly more caffeine received the same performance benefit from a dose just before performance as those who usually took in small or moderate amounts. 
 
The scientists indicated that the dosing strategy was based on previous “meta-analytic data” which showed that consumption of 6mg/kg body mass, taken 60 minutes prior to exercise, “improves performance” by +1.9%, both during high intensity exercise and endurance protocols. In their study, “caffeine supplementation improved exercise performance by 3.3% compared with” controls, and “2.4% compared with” placebo, roughly in line with the reported +1.9% overall improvement.  But the effects were individualized. Fifty percent of participants improved above the variation of the test; the others did not.
 
Perceived negative side effects (increased heart rate, gastrointestinal upset, anxiety, tremors, insomnia) were similarly reported among the different groups; the level of previous habitual caffeine consumption did not make a difference. This also seems to a dispel myth about caffeine, that high consumers may be less susceptible to these effects than non-consumers.
 
The authors acknowledged that the level of acute caffeine supplementation required to enhance performance, 3 mg/kg BM, is lower than the amount administered in their protocol, 6mg/kg BM.
 
The work of these and other investigators was reviewed and discussed by exercise physiologist and sports nutritionist Asker Jeukendrup in a piece for mysportscience.com.  He concludes that to experience a boost in performance from caffeine, a withdrawal period is NOT needed.  His recommendation to athletes is to “maintain your normal caffeine consumption during preparation for competition.  You will still be able to benefit from the effects of caffeine in competition and avoid any possible withdrawal symptoms in the days before”.
 
For average endurance athletes, this is likely good news. Caffeine supplementation may be something many will be encouraged to try an hour before a competition or exercise session. Be aware that caffeine has been added to many endurance sport fuels (gels, drinks, gummies, shots). It’s easy to overlook when purchasing these items.  Best to check the product information to be sure you’re getting the intended amount, not too much.  
 
And remember that the 6mg/kg this study used was considered twice the amount needed to generate a performance boost. Consider what has already been taken in as coffee, tea, soda when calculating what to add to the lower amount.
 
Powdered pure caffeine is a dangerous substance and should NEVER be used!
 
Use a caffeine calculator to see how much daily intake is safe for your body weight. A 125-pound woman (57kg) wishing to take 3mg/kg caffeine only requires 171mg as a supplement. An 8oz. cup of brewed store-brand (like Folgers) coffee contains about 95mg. Thus, a bit less than 2 (8oz) cups will do the trick for her. A 170-pound man (77kg) would try for a dose of 231mg, so about 2.5 cups.  That’s not much for a regular coffee drinker who has easy access to this beverage every morning. Extra supplementation isn’t necessary. Soda drinkers and energy-beverage drinkers will have a different calculation.
 
The use of caffeine as a performance enhancer was made less complicated by this research.  No need to abstain before an endurance workout or race. For me it would be simply drinking my usual amount of pre-breakfast wake-up coffee.  
 
RUN & MOVE HAPPY!
 
*More method details. The study participants were either professional or amateur competitive cyclists who, each week, cycled at least 150 km and trained 4+ times. Experimental exercise sessions were randomly assigned.  Each was performed following 6 hours of fasting, on different days, at least 7 days apart, and 60 minutes after the ingestion of a caffeine or placebo capsule or no supplement. Participants had been instructed to abstain from training, alcohol, and caffeine-containing substances in the 24-hour period prior to each exercise session, and completed a 24-hour food recall survey.

http://www.businessinsider.com/physical-mental-effects-of-caffeine-2017-7

https://www.ncbi.nlm.nih.gov/pubmed/28495846

https://www.theatlantic.com/health/archive/2014/03/how-athletes-strategically-use-caffeine/283758/
 
http://www.mysportscience.com/single-post/2017/06/18/Do-you-need-to-refrain-from-coffee-to-get-the-maximal-effect-of-caffeine

https://www.caffeineinformer.com/caffeine-safe-limits
 
https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/caffeine/art-20049372
 
http://abcnews.go.com/Health/pure-caffeine-teaspoon-powder-fatal/story?id=38688979