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.[1] Caffeine consumption has also been shown to enhance performance on attention tasks, regardless of the participants’ caffeine consumption habits.[2] 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.[3]
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,[4][5] 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.[6][7]
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.[8][9]
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.[10] 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,[11][12] and shorter withdrawal periods (24–48 hours) don’t appear to be useful either.[10] 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.