Caffeine in Various Forms – Does It Matter? (#124)

Caffeine is one of the most well-documented performance enhancers in endurance sports. But does it matter how you consume it? In January 2018, a new study was released that explored just that. Does it matter if I consume caffeine via caffeine pills, as energy drink/PWO like U Intend, gum, as coffee, or for that matter as mouth spray or nasal spray? The key is not only how much caffeine you consume but also how quickly it is absorbed by the body and when the effect kicks in. It turned out that most forms work, but the absorption time can vary significantly. Some forms give a quick kick, while others are better suited when you want a more steady effect over longer performances.

Caffeine is a well-proven performance enhancer in doses of 3 mg/kg body weight and higher. Negative effects start to appear at 10 mg/kg body weight, but within the range of 3-10 mg/kg, most of us seem to reach maximum performance-enhancing effects.

Caffeine can be consumed in many different ways. The effect we aim for is that caffeine molecules enter the bloodstream, get transported to adenosine receptors, and compete with adenosine. The result is that adenosine can't attach where it usually makes us feel tired – a pretty ingenious solution to avoid feeling sluggish. If you want to read more about how caffeine works, we recommend our previous article on Caffeine. There is also a new meta-analysis that wasn't included in our previous article, for those who want to delve deeper into the research.

The way we consume caffeine influences how rapidly it's absorbed and, subsequently, how soon we experience its effects. At times, we might crave a quick boost for a short adrenaline surge, such as during 4-minute intervals or 20-minute Functional Threshold Power (FTP)/threshold sessions. Other times, we seek a more sustained effect for longer distances, like a 5,000 m threshold run or the concluding marathon in an Ironman.

This is a popular method for consuming caffeine. Pills and capsules come in various strengths, are swallowed whole, travel through the stomach, and are absorbed through the intestinal membrane before entering the bloodstream. In terms of logistics, this is one of the easiest ways to consume caffeine during activity: a pill in your mouth, swallow – done. The effect has been shown in countless studies, but this review concentrates more on alternative administration methods and therefore does not specifically cover pills.

Compared to caffeine in the form of pills, drinks, gels, and bars—which must pass through the stomach and often take 20–30 minutes before the caffeine starts to appear in the blood and up to 60 minutes to reach peak levels—absorption via the oral cavity is significantly faster.

This attracted military interest because they often need to quickly restore physical and cognitive abilities in exhausting situations. The oral cavity is a large mucous membrane, and if the caffeine is kept in contact with the mucous membrane, absorption can be effective. An excellent way to achieve this is through chewing gum—tadaaa.

In a first study where participants received doses of 50, 100, or 200 mg of caffeine in a swallowed capsule or as chewing gum, the chewing gum allowed participants to reach maximum caffeine levels in the blood twice as fast as the capsule (range 44-80 min for chewing gum vs. 84-120 min for capsule). The time span in this study is higher than in many other studies, and we don't know exactly why, but the difference was significant.

In a subsequent study with a similar setup, participants reached peak levels after just 15–20 minutes with chewing gum (see the small image above). However, the peak wasn't as high as for capsules, where the peak occurred after 60–90 minutes but was higher.

Caffeine gum can be a great idea if the goal is to quickly jumpstart the body and mind when the planning hasn't been optimal. Example: group intervals begin in 20 minutes and you haven't had time to mix or drink your coffee/Intend yet — gum can save the day.

Rinsing your mouth with caffeine can work similarly to a sports drink mouth rinse. A sports drink mouth rinse tricks the brain into thinking energy is coming in, without actually swallowing carbs, which can be beneficial when the gut is acting up.

Rinsing your mouth with caffeine for 5–20 seconds can enhance performance without increasing blood caffeine levels. The mechanism is partly similar to a carb mouth rinse (which we covered in a previous article). Caffeine is a bitter substance that activates specific receptors in the oral cavity, leading to a rewarding feeling and increased well-being.

The performance-enhancing effect of a pure caffeine mouth rinse is debatable: to our knowledge, there is only one study that investigated this and found no performance-enhancing effect in cyclists with eight repeated 10-second rinses with 35 mg of caffeine per rinse.

If you still want to rinse your mouth during a race, you can, for example, crush a caffeine pill or mix a bit of caffeine-containing powder in the liquid. It likely won't hurt, but the effect is probably minimal if you only rinse for 10 seconds. A practical tip could be to grab a cup of cold coffee at the stations and at least rinse your mouth if you don’t want to drink the whole cup.

This is all the more exciting. Caffeine delivered airborne via spray format (aerosols) is more popular in the USA than in Sweden. There are nasal sprays, mouth sprays, and small inhalers available.

The nose and mucous membranes have a close connection to the brain. Administering caffeine through these mucous membranes is certainly intriguing—though it's advisable not to insert a caffeine pill into your nose.

This is a relatively new research area, and the review repeatedly highlights that much remains unexplored. In January 2017, a first study demonstrated that caffeine nasal spray activated many of the same brain regions as glucose-containing nasal spray. In that study, several cognitive functions improved: memory, perception, decision-making, and more.

In October 2017, a follow-up study also included sports tests like a 30-minute time trial and Wingate sprint tests. Here, participants received caffeine nasal spray twice in each nostril for 20 seconds. The result showed no performance-enhancing effect. The researchers discuss whether the dosage was too low (15 mg/ml). It is possible that participants did not receive more than about 15 mg of caffeine (1 ml nasal spray), which seems quite limited.

Caffeine as a mouth spray: unfortunately, there is no published research available yet, but the effects should, in theory, resemble a mouth rinse. A potential advantage, and risk, is that the caffeine amount in these aerosols can quickly become high. Some products in the USA provide 30-100 mg per dose if sprayed in the mouth. For instance, the manufacturer's (Instavit) instruction is to spray four times in the mouth (0.5 ml), providing 30 mg of caffeine. There are stronger sprays available if you browse Amazon. However, logistically, this administration route still seems somewhat unrefined.