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From Fellrnr.com, Running tips
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* Moderate levels of caffeine can improve athletic performance by about 2%, which is about 5 minutes on a 4 hour marathon. This improvement appears to happen regardless of how regularly caffeine is used.
* For running, the best recommendation is a dose of 3 to 5 mg/kg before exercise, followed by 1 to 2 mg/kg periodically after that. For runners, a [[Comparison of Energy Gels| caffeinated energy gel]] is probably the best source.
* While it's commonly believed that caffeine causes hydrationdehydration, this is only true when high doses are given to those not used to it. Drinking a caffeinated beverage will produce about the same amount of urine, which is probably the source of the myth. People will drink caffeinated beverages when they're not thirsty, so they assume it's the caffeine that's causing them to need to urinate, not the fluid they've drunk.
* Obviously caffeine can interfere with sleep, but this effect can last much longer than you might expect. Even caffeine taken early in the morning can impact your nights' sleep.
* Caffeine in coffee does not seem as effective at improving performance, so other sources should be used.
* Caffeine increases blood pressure, and should be avoided during exercise by those with high blood pressure.
* There may be genetic differences in the effect of caffeine; see the section on "Caffeine and Genetics" below for details.
=Introduction=
Man has been searching for ways of improving athletic performance since at least 400 BC, when the hearts of lion were believed to impart benefits<ref name="CaffLionHeart"/>. Today, caffeine can improve performance in endurance running, and three of every four elite athletes take caffeine when competing<ref name="CaffUse"/>. Caffeine is one of the most widely used drugs in the world<ref name="CaffWorld"/>, with average daily intakes worldwide of 70mg/day, but higher in the US (~200mg/day) and the UK (~400mg/day)<ref name="CaffDependence"/>. Caffeine has many effects on many different tissue types, directly and through its metabolites, as well as stimulating adrenaline release<ref name="CaffMetaAndPerf"/>.
=How much?=
Most studies use 3-13mg/Kg, average 6mg, but within that dose range there was no obvious dose response<ref name="CaffMeta"/>. A smaller intake of 3 to 5 mg/kg dose before exercise and then 1 to 2 mg/kg intakes during prolonged exercise has been recommended<ref name="CaffMetaAndPerf"/>. Too much caffeine (9 mg/kg), especially for those that do not regularly take caffeine, can cause impairment, such as becoming talkative, giddy, and unable to perform simple tasks such as telling the time<ref name="CaffMetaAndPerf"/>. Low levels of exercise (30% [[VO2max|V̇O<sub>2</sub>max]]) seem to increase the metabolism of caffeine<ref name="CafModEx"/>, but higher intensities have no impact<ref name="CafExThermal"/>. Below is a listing of caffeine in common beverages.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
! '''Source'''
! '''Caffeine (mg) '''
| 80 per 8.3oz Can
|}
=Caffeine and Genetics=
There is some research indicating that there are genetic differences that change how caffeine effects people, but the research is a little unclear. However, it seems that having your genome tested could provide valuable information into how to use caffeine. The enzyme CYP1A2 metabolizes many drugs, and it's been shown to be responsible for over 95% of the metabolism of caffeine<ref name="BegasKouvaras2007"/>. The CYP1A2 enzyme is produced by the CYP1A2 gene, and a genetic change at rs762551 impacts how the enzyme is produced, with AA having greater activity than the AC or CC genotypes<ref name="snpe_rs76"/>. Sometimes the subjects with the AA variant are called "fast metabolizers". (I had my genome tested using 23andme.com which showed I have the AA variant of CYP1A2/rs762551.)
* A study of 101 recreationally competitive male athletes on a 10K cycling time trial with 2 or 4 mg/Kg caffeine, there was an improvement only in those with the AA variant of CYP1A2, with no effect on the AC and diminished performance for the CC<ref name="Guest-2018"/>.
* A study of 21 active subjects given 3 mg/Kg of caffeine and tested using a 30 second Wingate test showed performance improvements did not vary between AA and AC/CC variants, though AC/CC reported increased nervousness while the AA variants did not<ref name="Salinero-2017"/>.
* A study of caffeine and basketball related performance (jump, change of direction) in 19 elite basketball players found that caffeine benefited the AA variants slightly more than the AC/CC variants<ref name="Puente-2018"/>. Strangely, the AA variants suffered tended to suffer from insomnia in the 24 hours after the test (I'd have expected AA variants to clear the caffeine faster and thus not suffer from insomnia as much as other variants.)
* A study of 35 male recreationally competitive cyclists performing a simulated 40K time trial following 6 mg/Kg of caffeine showed the AA variants improved more (4.9%) with caffeine than the AC/CC variants (1.8%)<ref name="WomackSaunders2012"/>. Beyond those averages, 15 of 16 AA variants improved their time by at least 60 seconds, while that only happened for 10 of the 19 C variants.
* A study of 20 healthy but untrained subjects did not show any statistically significant improvement in performance with 225mg caffeine in either AA or C variants<ref name="AlgrainThomas2016"/>. Looking at the data, it appears that a larger group of subjects might be needed to provide the statistical power required.
* A study of 20 collage level tennis players showed that 6 mg/Kg caffeine improved intermittent treadmill performance with no differences between AA and C variants<ref name="KleinClawson2012"/>.
* Other factors beyond genetics impact CYP1A2 enzyme activity, with exercise, caffeine intake, broccoli all increasing it<ref name="Vistisen-1992"/>.
It seems rather counterintuitive to me that the faster you metabolize caffeine, the greater the benefit. It suggests that maybe it's a metabolite of caffeine that improves performance rather than the caffeine itself, but that's pure supposition on my part.
=Caffeine, Blood Pressure and Heart Rate=
Caffeine increases blood pressure at rest and under stress, including exercise stress. The effect of caffeine on heart rate is unclear, with both increases and decreases observed in studies. Generally caffeine decreases heart rate at rest and moderate intensity exercise, but increases it at maximal workloads.
Caffeine raises blood pressure during exercise, increasing the possibility of excessively high blood pressure. Caffeine can increase or decrease heart rate during exercise, possibly lowering it during lower intensity exercise and increasing it at highest intensities.
* The effect of Caffeine on heart rate during exercise is ambiguous, with some studies showing an increase in heart rate<ref name="Bell-1998"/><ref name="Mcnaughton1987"/><ref name="Sasaki-1987"/><ref name="Sung-1995"/><ref name="Bell-2002"/>, while others show a decrease<ref name="Sullivan-1992"/><ref name="TurleyGerst2006"/><ref name="Gaesser-1985"/><ref name="McClaranWetter2007"/><ref name="SungLovallo1990"/>. Examining the studies in more detail however, and it appears that the increase in heart rate may be mostly at the highest intensities, with caffeine reducing heart rate at the lower intensities. The effect does not appear different for those that are caffeine habituated or those that are caffeine naïve.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
! Study
! Subjects
Caffeine has a shorter duration of effect at high altitude, possibly due to increased blood flow to the liver, and withdrawal from caffeine would likely make altitude problems more severe<ref name="CafAltitude"/>.
=Caffeine clearance=
Caffeine is rapidly absorbed, and its clearance varies with multiple variables, including exercise. It seems that exercise might increase clearance, which in turn might increase the needed dosage for ultra-endurance events. * About 99% of consumed caffeine is absorbed within 45 minutes, with peak concentrations after about 30 minutes<ref name="NehligAlexander2018"/>.* Caffeine half-life is generally 2.5-5 hours with some dose dependency and individual variability<ref name="CamandolaPlick2018"/>.* A study found that lean subjects cleared caffeine faster than the obese, with the half life of 2.6 hours rather than 4.4 hours<ref name="Kamimori-1987"/>.* An hour's light exercise (30% [[VO2max|V̇O<sub>2</sub>max]]) reduced the half life from 4 hours to 2.3 hours in healthy subjects<ref name="Collomp-1991"/>.* A study of 14 active ([[VO2max|V̇O2max]] of 50) subjects (8 women) found no change in caffeine clearance with exercise<ref name="McLeanGraham2002"/>. Subjects exercised for 1.5 hours at 60-65% of [[VO2max|V̇O<sub>2</sub>max]], starting 1 hour after ingesting 6 mg/Kg of caffeine. Half life was ~6 hours. * The half-life of caffeine seems dose dependent<ref name="ChengMurphy1990"/>. In healthy subjects, the half-life at 70mg was 4.5 hours, at 200mg was 60 hours, and at 300mg was 6.4 hours. (Impaired liver function can dramatically increase the half-life to 25-30 hours.)* Caffeine is metabolized by the liver enzyme CYP1A2<ref name="KalowTang1993"/>, and the activity of this enzyme can be effected affected by drugs and diet, with tobacco and chargrilled meat increasing levels<ref name="Flockhart-2007"/>. Things may not be so simple, as about 85% of caffeine is metabolized to Paraxanthine <ref name="GuerreiroToulorge2008"/> and Paraxanthine in mice is a stronger stimulant than caffeine<ref name="Okuro-2010"/>, while similar in humans<ref name="BenowitzJacob1995"/>. Paraxanthine has a half-life of 3.1-4.1 hours<ref name="CamandolaPlick2018"/>, and levels become higher than caffeine after 8-10 hours<ref name="NehligAlexander2018"/> (There is a common genetic mutation in dogs that prevents the formation of CYP1A2, making these dogs unable to metabolize caffeine and some other substances<ref name="AretzGeyer2011"/>.)
=Glucose Absorption, Insulin Resistance and Glycemic index =
Caffeine changes the way glucose is absorbed, but this effect is different for those at rest compared with those exercising.
==Soda==
The caffeine levels in soda vary widely, with some common values shown below.
{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
! Soda
! Caffeine per 12oz<ref name="ChouBell2007"/>
* A milk intake of 500 to 900 ml/day<ref name="CaffBabyMilk"/>
* The nursing mother's caffeine intake of 200mg/day (one double shot espresso),
We get a resulting caffeine concentration in the milk of 4ug/ml to 8ug/ml<ref name="Stavchansky-"/>, which is a total caffeine intake of between 2mg to 13mg, or 0.6 to 4 mg/Kg body weight. The upper end of that level is quite high. However, the baby's half-life for caffeine is 31-132 hours (average 82 hours)<ref name="Parsons-1981"/>, compared with an adult's 2-10 hour half-life, so the caffeine will build up over time. A 24 hour half live (which is easier to calculate) would result in about a 3mg to 26mg, which is 1 to 8 mg/Kg. I'm guessing that would result in the baby not sleeping well! Conversely, a baby whose mother takes caffeine during pregnancy and is then given formula milk may undergo caffeine withdrawal after birth<ref name="McGowan-1988"/>. Even if the mother breast feeds, the varying levels of caffeine may cause withdrawal symptoms<ref name="Martín-2007"/>. Also, caffeine has been shown to increase fetal [[Heart Rate]]<ref name="Buscicchio-2012"/>. There is research indicating that Caffeine may not reduce to subtherapeutic levels until around 11-12 days<ref name="Doyle-2016"/>.
=References=
<references>
<ref name="Doyle-2016">J. Doyle, D. Davidson, S. Katz, M. Varela, D. Demeglio, J. DeCristofaro, Apnea of prematurity and caffeine pharmacokinetics: potential impact on hospital discharge., J Perinatol, volume 36, issue 2, pages 141-4, Feb 2016, doi [http://dx.doi.org/10.1038/jp.2015.167 10.1038/jp.2015.167], PMID [http://www.ncbi.nlm.nih.gov/pubmed/26562367 26562367]</ref>
<ref name="Martín-2007">I. Martín, MA. López-Vílchez, A. Mur, O. García-Algar, S. Rossi, E. Marchei, S. Pichini, Neonatal withdrawal syndrome after chronic maternal drinking of mate., Ther Drug Monit, volume 29, issue 1, pages 127-9, Feb 2007, doi [http://dx.doi.org/10.1097/FTD.0b013e31803257ed 10.1097/FTD.0b013e31803257ed], PMID [http://www.ncbi.nlm.nih.gov/pubmed/17304161 17304161]</ref>
<ref name="McGowan-1988">JD. McGowan, RE. Altman, WP. Kanto, Neonatal withdrawal symptoms after chronic maternal ingestion of caffeine., South Med J, volume 81, issue 9, pages 1092-4, Sep 1988, PMID [http://www.ncbi.nlm.nih.gov/pubmed/3420441 3420441]</ref>
<ref name="Pasman-1995">WJ. Pasman, MA. van Baak, AE. Jeukendrup, A. de Haan, The effect of different dosages of caffeine on endurance performance time., Int J Sports Med, volume 16, issue 4, pages 225-30, May 1995, doi [http://dx.doi.org/10.1055/s-2007-972996 10.1055/s-2007-972996], PMID [http://www.ncbi.nlm.nih.gov/pubmed/7657415 7657415]</ref>
<ref name="CaffRedBull">Nutrition Facts and Analysis for Energy drink, RED BULL, with added caffeine, niacin, pantothenic acid, vitamins B6 and B12 http://nutritiondata.self.com/facts/beverages/7399/2 </ref>
<ref name="Macfarlane">author Alan Macfarlane, Iris Macfarlane !!coauthors!!, The Empire of Tea, publisher The Overlook Press, isbn 1-58567-493-1, page 32 !!page!!, 2004</ref>
<ref name="Lin-2003">YS. Lin, YJ. Tsai, JS. Tsay, JK. Lin, Factors affecting the levels of tea polyphenols and caffeine in tea leaves., J Agric Food Chem, volume 51, issue 7, pages 1864-73, Mar 2003, doi [http://dx.doi.org/10.1021/jf021066b 10.1021/jf021066b], PMID [http://www.ncbi.nlm.nih.gov/pubmed/12643643 12643643]</ref>
<ref name="ShishikuraKhokhar2005">Yoko Shishikura, Santosh Khokhar, Factors affecting the levels of catechins and caffeine in tea beverage: estimated daily intakes and antioxidant activity, Journal of the Science of Food and Agriculture, volume 85, issue 12, 2005, pages 2125–2133, ISSN [http://www.worldcat.org/issn/0022-5142 0022-5142], doi [http://dx.doi.org/10.1002/jsfa.2206 10.1002/jsfa.2206]</ref>
<ref name="Flockhart-2007">Flockhart DA. Drug Interactions: Cytochrome P450 Drug Interaction Table. Indiana University School of Medicine (2007). "/clinpharm/ddis/clinical-table/" Accessed June 2015.</ref>
<ref name="AretzGeyer2011">J. S. Aretz, J. Geyer, Detection of the CYP1A2 1117C > T polymorphism in 14 dog breeds, Journal of Veterinary Pharmacology and Therapeutics, volume 34, issue 1, 2011, pages 98–100, ISSN [http://www.worldcat.org/issn/01407783 01407783], doi [http://dx.doi.org/10.1111/j.1365-2885.2010.01222.x 10.1111/j.1365-2885.2010.01222.x]</ref>
<ref name="KleinClawson2012">Courtney S. Klein, Adam Clawson, Michael Martin, Michael J. Saunders, Judith A. Flohr, Marta K. Bechtel, Wade Dunham, Melyssa Hancock, Christopher J. Womack, The Effect of Caffeine on Performance in Collegiate Tennis Players, Journal of Caffeine Research, volume 2, issue 3, 2012, pages 111–116, ISSN [http://www.worldcat.org/issn/2156-5783 2156-5783], doi [http://dx.doi.org/10.1089/jcr.2012.0019 10.1089/jcr.2012.0019]</ref>
<ref name="AlgrainThomas2016">Haya A. Algrain, Rebecca M. Thomas, Andres E. Carrillo, Emily J. Ryan, Chul-Ho Kim, Robert B. Lettan, Edward J. Ryan, The Effects of a Polymorphism in the Cytochrome P450 CYP1A2 Gene on Performance Enhancement with Caffeine in Recreational Cyclists, Journal of Caffeine Research, volume 6, issue 1, 2016, pages 34–39, ISSN [http://www.worldcat.org/issn/2156-5783 2156-5783], doi [http://dx.doi.org/10.1089/jcr.2015.0029 10.1089/jcr.2015.0029]</ref>
<ref name="Vistisen-1992">K. Vistisen, HE. Poulsen, S. Loft, Foreign compound metabolism capacity in man measured from metabolites of dietary caffeine., Carcinogenesis, volume 13, issue 9, pages 1561-8, Sep 1992, PMID [http://www.ncbi.nlm.nih.gov/pubmed/1394840 1394840]</ref>
<ref name="WomackSaunders2012">Christopher J Womack, Michael J Saunders, Marta K Bechtel, David J Bolton, Michael Martin, Nicholas D Luden, Wade Dunham, Melyssa Hancock, The influence of a CYP1A2 polymorphism on the ergogenic effects of caffeine, Journal of the International Society of Sports Nutrition, volume 9, issue 1, 2012, ISSN [http://www.worldcat.org/issn/1550-2783 1550-2783], doi [http://dx.doi.org/10.1186/1550-2783-9-7 10.1186/1550-2783-9-7]</ref>
<ref name="Puente-2018">C. Puente, J. Abián-Vicén, J. Del Coso, B. Lara, JJ. Salinero, The CYP1A2 -163C>A polymorphism does not alter the effects of caffeine on basketball performance., PLoS One, volume 13, issue 4, pages e0195943, 2018, doi [http://dx.doi.org/10.1371/journal.pone.0195943 10.1371/journal.pone.0195943], PMID [http://www.ncbi.nlm.nih.gov/pubmed/29668752 29668752]</ref>
<ref name="Salinero-2017">JJ. Salinero, B. Lara, D. Ruiz-Vicente, F. Areces, C. Puente-Torres, C. Gallo-Salazar, T. Pascual, J. Del Coso, CYP1A2 Genotype Variations Do Not Modify the Benefits and Drawbacks of Caffeine during Exercise: A Pilot Study., Nutrients, volume 9, issue 3, Mar 2017, doi [http://dx.doi.org/10.3390/nu9030269 10.3390/nu9030269], PMID [http://www.ncbi.nlm.nih.gov/pubmed/28287486 28287486]</ref>
<ref name="BegasKouvaras2007">E. Begas, E. Kouvaras, A. Tsakalof, S. Papakosta, E. K. Asprodini, In vivo evaluation of CYP1A2, CYP2A6, NAT-2 and xanthine oxidase activities in a Greek population sample by the RP-HPLC monitoring of caffeine metabolic ratios, Biomedical Chromatography, volume 21, issue 2, 2007, pages 190–200, ISSN [http://www.worldcat.org/issn/02693879 02693879], doi [http://dx.doi.org/10.1002/bmc.736 10.1002/bmc.736]</ref>
<ref name="Guest-2018">N. Guest, P. Corey, J. Vescovi, A. El-Sohemy, Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes., Med Sci Sports Exerc, volume 50, issue 8, pages 1570-1578, 08 2018, doi [http://dx.doi.org/10.1249/MSS.0000000000001596 10.1249/MSS.0000000000001596], PMID [http://www.ncbi.nlm.nih.gov/pubmed/29509641 29509641]</ref>
<ref name="snpe_rs76">rs762551 – SNPedia, snpedia.com !!work!!, 18 March 2019 !!access-date!!, [https://www.snpedia.com/index.php/Rs762551 https://www.snpedia.com/index.php/Rs762551]</ref>
<ref name="CamandolaPlick2018">Simonetta Camandola, Natalie Plick, Mark P. Mattson, Impact of Coffee and Cacao Purine Metabolites on Neuroplasticity and Neurodegenerative Disease, Neurochemical Research, volume 44, issue 1, 2018, pages 214–227, ISSN [http://www.worldcat.org/issn/0364-3190 0364-3190], doi [http://dx.doi.org/10.1007/s11064-018-2492-0 10.1007/s11064-018-2492-0]</ref>
<ref name="BenowitzJacob1995">Neal L. Benowitz, Peyton Jacob, Haim Mayan, Charles Denaro, Sympathomimetic effects of paraxanthine and caffeine in humans*, Clinical Pharmacology & Therapeutics, volume 58, issue 6, 1995, pages 684–691, ISSN [http://www.worldcat.org/issn/0009-9236 0009-9236], doi [http://dx.doi.org/10.1016/0009-9236(95)90025-X 10.1016/0009-9236(95)90025-X]</ref>
<ref name="Okuro-2010">M. Okuro, N. Fujiki, N. Kotorii, Y. Ishimaru, P. Sokoloff, S. Nishino, Effects of paraxanthine and caffeine on sleep, locomotor activity, and body temperature in orexin/ataxin-3 transgenic narcoleptic mice., Sleep, volume 33, issue 7, pages 930-42, Jul 2010, PMID [http://www.ncbi.nlm.nih.gov/pubmed/20614853 20614853]</ref>
<ref name="GuerreiroToulorge2008">S. Guerreiro, D. Toulorge, E. Hirsch, M. Marien, P. Sokoloff, P. P. Michel, Paraxanthine, the Primary Metabolite of Caffeine, Provides Protection against Dopaminergic Cell Death via Stimulation of Ryanodine Receptor Channels, Molecular Pharmacology, volume 74, issue 4, 2008, pages 980–989, ISSN [http://www.worldcat.org/issn/0026-895X 0026-895X], doi [http://dx.doi.org/10.1124/mol.108.048207 10.1124/mol.108.048207]</ref>
<ref name="NehligAlexander2018">Astrid Nehlig, Stephen P. H. Alexander, Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption, Pharmacological Reviews, volume 70, issue 2, 2018, pages 384–411, ISSN [http://www.worldcat.org/issn/0031-6997 0031-6997], doi [http://dx.doi.org/10.1124/pr.117.014407 10.1124/pr.117.014407]</ref>
<ref name="McLeanGraham2002">C. McLean, T. E. Graham, Effects of exercise and thermal stress on caffeine pharmacokinetics in men and eumenorrheic women, Journal of Applied Physiology, volume 93, issue 4, 2002, pages 1471–1478, ISSN [http://www.worldcat.org/issn/8750-7587 8750-7587], doi [http://dx.doi.org/10.1152/japplphysiol.00762.2000 10.1152/japplphysiol.00762.2000]</ref>
<ref name="Collomp-1991">K. Collomp, F. Anselme, M. Audran, JP. Gay, JL. Chanal, C. Prefaut, Effects of moderate exercise on the pharmacokinetics of caffeine., Eur J Clin Pharmacol, volume 40, issue 3, pages 279-82, 1991, PMID [http://www.ncbi.nlm.nih.gov/pubmed/2060565 2060565]</ref>
<ref name="Kamimori-1987">GH. Kamimori, SM. Somani, RG. Knowlton, RM. Perkins, The effects of obesity and exercise on the pharmacokinetics of caffeine in lean and obese volunteers., Eur J Clin Pharmacol, volume 31, issue 5, pages 595-600, 1987, PMID [http://www.ncbi.nlm.nih.gov/pubmed/3830245 3830245]</ref>
<ref name="ChengMurphy1990">Wendy S C Cheng, Therese L Murphy, Maree T Smith, W Graham E Cooksley, June W Halliday, Lawrie W Powell, Dose-dependent pharmacokinetics of caffeine in humans: Relevance as a test of quantitative liver function, Clinical Pharmacology and Therapeutics, volume 47, issue 4, 1990, pages 516–524, ISSN [http://www.worldcat.org/issn/0009-9236 0009-9236], doi [http://dx.doi.org/10.1038/clpt.1990.66 10.1038/clpt.1990.66]</ref>
</references>
