Caffeine is the world’s most commonly consumed psychoactive substance, found in coffee, tea, soda, chocolate, and energy drinks (1,4). It is widely used to fight fatigue, increase alertness, and enhance focus. But how much do we really know about caffeine? What are its effects on humans and more importantly, what is its effects on athletes? In this article we are going to explain what caffeine is, who should use it, when to use it, and the physiological effects it has on humans as well as cheerleaders.
What is Caffeine and how it works
Caffeine is a naturally occurring substance that can be found in over 60 different plants such as coffee beans, tea leaves, and cocoa beans. In more technical terms it’s a xanthine alkaloid which increases cellular cyclic-AMP levels by breaking it down and metabolizing. Don't let the biochemical jargon confuse you, the concepts here are simple. Caffeine blocks the action of adenosine, a chemical in the brain that promotes feelings of fatigue by blocking the adenosine receptors, specifically, the adenosine A2A receptor or ADORA2 (4). This leads to increased alertness and improved mental performance. However, overstimulation of the central nervous system can lead to feelings of anxiety, jitters, and difficulty sleeping. It’s important that anyone who ingests caffeine understands that caffeine doesn't replace the fuel of the human body—food; It simply inhibits the action of adenosine as well as some of its physiological effects.
The positive effects of caffeine (1,3,5):
- Neuroprotective effects
- Inversely related to depression
- Positive effect on mood and sense of well-being
- Ergogenic aid (performance enhancing)
- Increase in alertness
- Enhanced reaction time
- Increase in focus and memory
When caffeine is consumed, it is broken down into a number of different metabolites in the liver: theophylline, paraxanthine, and theobromine. These metabolites perform various functions in the body. Theophylline has anti-inflammatory effects and increase responsiveness to glucocorticoids (2). Paraxanthine has been shown to reduced force sensation (allowed the athlete to perform the exercise longer) via neural effects that need further elucidation (7,8). Theobromine has been shown to have ergogenic effects during longer bouts of exercise relative to the other metabolites by enhancing to blow flow to muscles (5). Collectively, caffeine and its metabolites stimulate the release of dopamine which is another neurotransmitter that is associated with the feeling of pleasure and happiness. Caffeine has also been known to increase mental acuity and reaction time. This makes it easier to think clearly and respond quickly in various situations when used properly. Caffeine has neurological and physiological effects that can aid in numerous ways when it comes to athletic performance.
The potential negative effects of caffeine (3,6):
- Elevated heart rate
- Digestive issues
Caffeine increases the heart rate which can be a problem for individuals with heart conditions or high blood pressure. This increased heart rate can lead to feelings of restlessness and anxiety. With all this comes difficulty sleeping. Caffeine has a disruptive effect on sleep, leading to difficulty falling and staying asleep (6). With this comes fatigue, reduced cognitive function and other health issues. Caffeine is a diuretic, which means it increases the fluid loss when consumed. This can easily lead to dehydration, so it’s very important athletes who are undergoing strenuous exercise are drinking adequate amounts of water before, during, and after consumption of caffeine. This means that for athletes who don't regularly consume enough water they should build that habit prior to incorporating caffeine into their supplement regimen (more on that to come in a future blog post).
So what is a healthy amount of caffeine?
Normal amount of caffeine per day is 6mg/kg of body weight (9). So for the average healthy adult that is around 400mg. That’s 4 cups of coffee, 10 cans of coke, or 2 energy drinks. Now, we have to be aware of what else is inside the drink that we're consuming. When we reference beverages and the amount of caffeine, we are not recommending that you drink 10 cans of coke, that's equivalent to 350g of sugar... We're using this as a frame of reference. Anything over the 6mg/kg body weight is when the negative effects of caffeine start to set in. So, for example, a 180 lb male should not ingest more than 490 mg of caffeine a day (81.6 kg * 6mg of caffeine = 489.7mg caffeine). Understanding that this is all average for a normal and healthy adult is key. Literature suggests that any child under the age of 12 shouldn’t ingest any caffeine and for those 12-18 a dose of 2.5mg/kg/day is ideal (11).
Delaying caffeine intake
When most people wake up in the morning, they ingest caffeine to increase alertness. While this is industry standard and commonplace, it has been shown to result in an energy crash around mid-day. The reason behind this is via the same mechanism by which caffeine fights off the feeling of fatigue. When caffeine binds adenosine receptors and blocks adenosine, the adenosine doesn't just disappear, it begins to build up. Once the caffeine begins to dissociate from the receptors around ~6 hours after consumption, then adenosine is able to bind again and we get a rush of feelings of fatigue.
In addition, when you wake up, adenosine needs about 90 minutes to 2 hours to clear from our system. If you drink caffeine before its gone then you will end up leaving it in your system and while immediately it doesn’t affect you, once that caffeine is gone you crash. It’s recommended that you wait at least 90 minutes after waking to drink caffeine (4).
Our take on cheerleading, caffeine consumption, and how it can affect athletes
Cheerleading is a physically and mentally demanding sport that requires athletes to perform at their best for 2 minutes and 30 seconds. However, the pressure to excel can lead to the adoption of unhealthy habits, including the overuse of caffeine. Cheerleaders often turn to caffeine to provide them with a quick boost of energy before practice or competition, especially in the absence of food. However, this can lead to a false perception that they need caffeine to perform, leading to an increased dependence on the substance. This dependence can be dangerous, as it can cause anxiety, self-doubt, and fear in high pressure situations. While caffeine can be beneficial for sports that last longer than 30 minutes, research has shown that it has little to no effect on physical activities under 3 minutes other than at extremely high doses far beyond the recommended dose. This means that caffeine is not an effective solution for athletes on competition days. Additionally, relying on caffeine for energy can lead to decreased food intake and other unhealthy habits, further, endangering the athlete’s health and performance. To perform at their best, cheerleaders should focus on maintaining healthy habits, such as eating properly, drinking plenty of water, and getting enough sleep. By doing so, they can reduce their dependence on caffeine and avoid the negative effects it can have on their performance and well-being.
As a reminder, feel free to comment down below on the topics that you're interested in seeing us cover!
- Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., Grgic, J., Schoenfeld, B. J., Jenkins, N. D. M., … Campbell, B. I. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1). doi:10.1186/s12970-020-00383-4
- Hansel TT, Tennant RC, Tan AJ, Higgins LA, Neighbour H, Erin EM, Barnes PJ. Theophylline: mechanism of action and use in asthma and chronic obstructive pulmonary disease. Drugs Today (Barc). 2004 Jan;40(1):55-69. doi: 10.1358/dot.2004.40.1.799438. PMID: 14988770.
- Iranpour, S., & Sabour, S. (2018). Inverse association between caffeine intake and depressive symptoms in US adults: data from National Health and Nutrition Examination Survey (NHANES) 2005–2006. Psychiatry Research. doi:10.1016/j.psychres.2018.11
- Kolahdouzan, M., & Hamadeh, M. J. (2017). The neuroprotective effects of caffeine in neurodegenerative diseases. CNS Neuroscience & Therapeutics, 23(4), 272–290. doi:10.1111/cns.12684
- Kennedy, M. (2020). Effects of theophylline and theobromine on exercise performance and implications for competition sport: A systematic review. Drug Testing and Analysis, 13(1), 36–43. doi:10.1002/dta.2970
- Nehlig, A. (2018). Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption. Pharmacological Reviews, 70(2), 384–411. doi:10.1124/pr.117.014407
- Orrú, M., Guitart, X., Karcz-Kubicha, M., Solinas, M., Justinova, Z., Barodia, S. K., … Ferré, S. (2013). Psychostimulant pharmacological profile of paraxanthine, the main metabolite of caffeine in humans. Neuropharmacology, 67, 476–484. doi:10.1016/j.neuropharm.2012.
- Plaskett CJ, Cafarelli E. Caffeine increases endurance and attenuates force sensation during submaximal isometric contractions. J Appl Physiol (1985). 2001 Oct;91(4):1535-44. doi: 10.1152/jappl.2001.91.4.1535. PMID: 11568134.
- Reyes, C., & Cornelis, M. (2018). Caffeine in the Diet: Country-Level Consumption and Guidelines. Nutrients, 10(11), 1772. doi:10.3390/nu10111772
- Ullrich S, de Vries Y, Kühn S, Repantis D, Dresler M, Ohla K. Feeling smart: effects of caffeine and glucose on cognition, mood and selfjudgment. Physiol Behav. 2015;151:629‐637.
- Xu F, Liu P, Pekar JJ, Lu H. Does acute caffeine ingestion alter brain metabolism in young adults? NeuroImage. 2015;110C:39‐47.