Coffee is most often used for
Coffee, black gold, 'poison of choice'. Whatever you call it, it is the world's second most popular non-water beverage (second only to all forms of tea combined) and consumed world-wide.
Coffee can be seen as a nutritional product as it is a mixture of many nutriceutical compounds that all have individual purposes. Coffee can also exert effects like any supplement or drug and rival some of them in potency. It is not just an inert food product, coffee is a supplement.
There are benefits associated with chronic caffeine consumption, and there are benefits associated with acute caffeine consumption that fade with tolerance; if you like the latter, cycling is mandatory. If you like the former, cycling is not needed.
Chronic non-cycled caffeine consumption (in the form of coffee and tea, both of which contain many bioactive components in addition to caffeine) is associated with a reduced risk of several diseases, including Parkinson’s disease, type 2 diabetes, and chronic liver disease.[reference|url=https://pubmed.ncbi.nlm.nih.gov/32706535|title=Coffee, Caffeine, and Health.|published=2020-07-23|authors=van Dam RM, Hu FB, Willett WC|journal=N Engl J Med|] Caffeine consumption has also been shown to enhance performance on attention tasks, regardless of the participants’ caffeine consumption habits.[reference|url=https://pubmed.ncbi.nlm.nih.gov/23241646|title=Caffeine as an attention enhancer: reviewing existing assumptions.|published=2013-Jan|authors=Einöther SJ, Giesbrecht T|journal=Psychopharmacology (Berl)|] Clearly, cycling isn’t needed to obtain these benefits. So why cycle? The question usually comes up in the context of exercise performance enhancement.
Supplementation with 3–6 mg of caffeine per kg of body weight before exercise has been consistently shown to enhance performance over a wide range of exercise intensities and durations, with beneficial effects on aerobic exercise performance, muscular endurance and strength, sprinting, jumping, and throwing performance.[reference|url=https://pubmed.ncbi.nlm.nih.gov/33388079|title=International society of sports nutrition position stand: caffeine and exercise performance|published=2021 Jan 2|authors=Nanci S Guest, Trisha A VanDusseldorp, Michael T Nelson, Jozo Grgic, Brad J Schoenfeld, Nathaniel D M Jenkins, Shawn M Arent, Jose Antonio, Jeffrey R Stout, Eric T Trexler, Abbie E Smith-Ryan, Erica R Goldstein, Douglas S Kalman, Bill I Campbell|journal=J Int Soc Sports Nutr|]
Caffeine elicits an ergogenic effect (i.e., enhances exercise performance) primarily by affecting the central nervous system. Caffeine blocks adenosine receptors in the brain, resulting in increased release of neurotransmitters such as dopamine and norepinephrine, and thus increased alertness and focus. It can also reduce pain and perceived exertion during exercise.
It seems to many habitual caffeine users that habitual use reduces, or even eliminates, the ergogenic effect of acute caffeine ingestion. The rationale is that habitual caffeine use increases the number of adenosine receptors in the brain, and as such, reduces the adenosine-blocking effect of caffeine. This has been shown in rodents,[reference|url=https://pubmed.ncbi.nlm.nih.gov/6291335|title=Adenosine actions and adenosine receptors after 1 week treatment with caffeine.|published=1982-Jun|authors=Fredholm BB|journal=Acta Physiol Scand|][reference|url=https://pubmed.ncbi.nlm.nih.gov/2110844|title=Effects of long-term theophylline treatment on adenosine A1-receptors in rat brain: autoradiographic evidence for increased receptor number and altered coupling to G-proteins.|published=1990-Jan-22|authors=Fastbom J, Fredholm BB|journal=Brain Res|] but has yet to be studied in humans. Evidence from human studies does suggest that habitual caffeine use can blunt some aspects of the physiological response to caffeine, such as an increase in plasma epinephrine levels.[reference|url=https://pubmed.ncbi.nlm.nih.gov/8226485|title=Caffeine metabolism and epinephrine responses during exercise in users and nonusers.|published=1993-Aug|authors=Van Soeren MH, Sathasivam P, Spriet LL, Graham TE|journal=J Appl Physiol (1985)|][reference|url=https://pubmed.ncbi.nlm.nih.gov/7009653|title=Tolerance to the humoral and hemodynamic effects of caffeine in man.|published=1981-Apr|authors=Robertson D, Wade D, Workman R, Woosley RL, Oates JA|journal=J Clin Invest|]
In further support of the idea that athletes should cycle caffeine in order to maximize its ergogenic effect, some studies indicate that when individuals with low habitual caffeine intake (< 75 mg/day) consume 3 mg of caffeine per kg of body weight daily for 20–28 days, the ergogenic effect of caffeine is reduced.[reference|url=https://pubmed.ncbi.nlm.nih.gov/27762662|title=Chronic ingestion of a low dose of caffeine induces tolerance to the performance benefits of caffeine|published=2017 Oct|authors=Ross Beaumont, Philip Cordery, Mark Funnell, Stephen Mears, Lewis James, Phillip Watson|journal=J Sports Sci|][reference|url=https://pubmed.ncbi.nlm.nih.gov/30673725|title=Time course of tolerance to the performance benefits of caffeine|published=2019 Jan 23|authors=Lara B, Ruiz-Moreno C, Salinero JJ, Del Coso J|journal=PLoS One|]
However, in a 2022 meta-analysis of 59 studies that investigated the effect of acute supplementation with caffeine on exercise performance in habitual caffeine consumers, it was found that acute supplementation with caffeine improved performance during endurance, power, and strength exercises.[reference|url=https://pubmed.ncbi.nlm.nih.gov/35536449|title=Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine|published=2022 May 10|authors=Arthur Carvalho, Felipe Miguel Marticorena, Beatriz Helena Grecco, Gabriel Barreto, Bryan Saunders|journal=Sports Med|] Moreover, the performance-enhancing effects of an acute dose of caffeine were independent of whether or not that dose was greater or smaller than participants' habitual consumption, as well as being independent of sex or training status.
The results of this meta-analysis indicate that caffeine does not lose its ergogenicity with chronic use; that is, even with daily caffeine consumption, ingesting some caffeine about an hour before exercise will still have a positive impact on performance in people who benefit from caffeine (which is not everyone). But is it possible that skipping a cup of coffee today will enhance the effects of a cup of coffee on exercise performance tomorrow? Probably not.
Two separate studies reported that abstaining from caffeine for four days prior to an exercise test did not enhance the effect of acute supplementation with caffeine,[reference|url=https://pubmed.ncbi.nlm.nih.gov/21279864|title=Caffeine withdrawal and high-intensity endurance cycling performance|published=2011 Mar|authors=Irwin C, Desbrow B, Ellis A, O'Keeffe B, Grant G, Leveritt M|journal=J Sports Sci|][reference|url=https://pubmed.ncbi.nlm.nih.gov/9760346|title=Effect of caffeine on metabolism, exercise endurance, and catecholamine responses after withdrawal.|published=1998-Oct|authors=Van Soeren MH, Graham TE|journal=J Appl Physiol (1985)|] and shorter withdrawal periods (24–48 hours) don’t appear to be useful either.[reference|url=https://pubmed.ncbi.nlm.nih.gov/35536449|title=Can I Have My Coffee and Drink It? A Systematic Review and Meta-analysis to Determine Whether Habitual Caffeine Consumption Affects the Ergogenic Effect of Caffeine|published=2022 May 10|authors=Arthur Carvalho, Felipe Miguel Marticorena, Beatriz Helena Grecco, Gabriel Barreto, Bryan Saunders|journal=Sports Med|] Therefore, the available evidence does not support the common practice of utilizing a caffeine withdrawal period before an important training session or competition to maximize caffeine’s ergogenic effect. In fact, doing so may even be detrimental, as a four-day withdrawal period was found to result in a number of side effects, including headaches, fatigue, impaired focus, and a lack of motivation.
It remains to be determined whether a longer withdrawal period can boost caffeine’s ergogenic effect, but considering the fact that acute supplementation with caffeine enhances exercise performance in habitual users, and abstaining from caffeine tends to result in unfavorable symptoms, the juice is unlikely to be worth the squeeze if the purpose of a caffeine withdrawal period is solely to maximize caffeine’s ergogenic effect on a specific day.