The Side Effects of Caffeine and Influence on Performance

Caffeine Supplementation

When it comes to performance, whether it be for athletic performance for a sport or performance within a recreation setting, most individuals are exercising to become a better version of themselves. With improvements comes the want for an edge or to acquire their goals at the fastest rate possible. Not everyone understanding the concept of time and progression, but even then, we try to get the most out of every session. Whether we have lack of sleep, long day of work, or simply lack of “motivation: to train, there is typically one drug we turn to in order to light a fire under us and get the job done.


Caffeine-based products (typically in the form of Caffeine Anhydrous) might be the most common form of pre-performance or pre-workout supplementation in the American culture, being as that caffeine follows water in being the most common beverage consumed world wide (Cappelletti, Piacentino, Sani, & Aromatario, 2015). Most of us know the effects of caffeine, as we have either ingested it in some form or fashion over our lifetime. You might remember the surge of energy, hype, and focus. This means we have a basic understanding of the signs of the effects that go on in our body. But maybe, just maybe that’s a very small portion of what is happening. Let’s explore how caffeine works and the pros and cons to consumption.

First off, we notice the effects of caffeine rather fast due to the small 30 to 60 minute window that it takes to reach maximum plasma concentration, although there are some differences in timing due to individual circumstances. The small window is primarily due to the short time it takes for caffeine to be transferred into the circulatory system after being quickly absorbed from the gastrointestinal tract. After absorption occurs, caffeine is then transferred to “all the body tissues and crosses the blood-brain, blood-placenta, and blood-testis barriers (Cappelletti, et al., 2015).”

With the never-ending debate on whether caffeine is “good” or “bad”, we can take a moment to briefly explore a couple of the pros and cons to caffeine consumption.


  • Caffeine, in the dosage of 8 mg/kg body weight, coingested with carbohydrates, is responsible for higher rates of post-exercise muscle glycogen stacking in comparison to the ingestion of carbohydrates alone in well-trained athletes after the depletion of glycogen that follows exercise (Cappelletti, et al., 2015).” This means that caffeine, at the right amount, would assist carbohydrates in the absorption and utilization process.
  • By stimulating HSL activity and inhibiting glycogen phosphorylase activity, caffeine increases lipolysis through transitioning the substrate preference to lipids, rather than glycogen (Cappelletti, et al., 2015).
  • Caffeine agonist stimulation of endogenous nitric oxide production through augments endothelium-dependent vasodilation by in young, healthy individuals (Cappelletti, et al., 2015).
  • Caffeine improvements cognitive performance and increases wakefullness and alertness (Cappelletti, et al., 2015). Vasodiation meaning the widening or increase in diameter of blood vessels. An increase in blood vessel diameter could result in increasing blood flow and nutrients to the body.
  • Caffeine may aid in the treatment and prevention of the effects of neurodegenerative diseases such as Parkinson’s and Alzheimer’s (Cappelletti, et al., 2015).


  • High doses of caffeine has shown to induce phosphodiesterases inhibition and adenosine antagonism. Adenosine is a negative inotropic and chronotropic agent in the heart, acting through specific receptors. “The blockade of cardiac adenosine receptors inhibits adenosine’s effects and can cause tachycardia and arrhythmias through intense β1-receptor activity (Cappelletti, et al., 2015).”
  • If you knew that ingestion of a drug would increase your chances of obtaining heart arrhythmias, would you continue to consume that product daily? It is shown that due to caffeine in higher concentrations, intracellular cAMP and cyclic guanosine monophosphate (cGMP) are increased by a nonspecific phosphodiesterases inhibition, which will then affect cardiac contractility secondary to calcium release. The latter mechanism may increase the susceptibility for arrhythmias is increased via the latter mechanism described (Cappelletti, et al., 2015).
  • Caffeine can influence antagonism of A1 and A2 receptors, possibly resulting in seizures and cerebral vasoconstriction (Cappelletti, et al., 2015).

Possible Short Term Effects

  • With proper dosing, caffeine’s effect of higher rates of post-exercise muscle glycogen stacking could aid in training recovery. This could lead to both short term and long term performance and improvement.
  • Vasodiation of bloodvessels resulting from consumption of caffeine could aid in the performance and recovery of training. Increased performance in training results in better progression, while increased performance in competition possibly creates a favored outcome of sport.

Possible Long Term Effects

  • Just like any drug, we could investigate the possibility of addiction as well as withdrawal. After long term ingestion of caffeine by an individual comes to a sudden stop, individuals experience a withdrawal syndrome dominated by fatigue and headache (Cappelletti, et al., 2015). The withdrawal might indicate the body’s desire to continue use of the drug or concept that consumption limits or inhibits receptors within the body that result in heachaches or fatigue with the elimination of caffeine ingestion.
  • With the chances of heart arrythmias increased with high doses of caffeine consumption, we must consider the fact that long term use might further increase the odds of this happening. The same could be said for cerebral vasoconstriction and seizures.
  • Due to caffeine’s ability to increase lipolysis, long term use could aid in a fatloss supplement protocol, with consideration of the cons to utilizing the drug. Any and all drugs/supplements should be reviewed with your doctor or physician. Now, at the end of the day, I doubt many people actually do that. But if you ever have any questions or concerns, please discuss your possible intake with a qualified individual. And yes, not just your prep or fitness coach.

Although caffeine supplementation possesses cognitive, metabolic, and performance effects, the consumption of the product is of the athlete’s decision. The best thing you could do is inform and refer out when in doubt.

Citation of Resources

Cappelletti, S., Piacentino, D., Sani, G., & Aromatario, M. (2015). Caffeine: cognitive and physical performance enhancer or psychoactive drug?. Current neuropharmacology, 13(1), 71–88. Retrieved from

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