Caffeine is the most widely consumed psychoactive substance on the planet, and it also forms the foundation of the best preworkouts and fat burners on the market, including our very own  Convict Stim and  Arsyn.

Despite the ubiquity with which caffeine is utilized by the masses, there remains a great deal of misunderstanding among the gym-going crowd, and a lot of that misunderstanding is caused by blatant misinformation from “influencers” and “gurus.”

You’ll hear all sorts of things like, caffeine restricts blood flow, caffeine hurts performance, caffeine ruins pumps, and similar fear-mongering drivel.

Sadly, each of these things is a gross-oversimplification of the facts surrounding the safety and efficacy of caffeine.

That brings us to the topic at hand today -- is caffeine safe? If so, does it actually enhance performance or is it really the blood flow restricting, pump-killing stimulant many make it out to be.

Let’s discuss.


Caffeine is a bitter-tasting compound found in dozens of plants, the two most popular sources are tea leaves and coffee beans.

As many of you know (through endless usage of the compound), caffeine increases feelings of mental energy, alertness, motivation and mood.

It does this by antagonizing adenosine -- a neurotransmitter that causes feelings of lethargy and fatigue -- since it’s structurally similar to adenosine. By preventing adenosine from binding to its receptor, caffeine helps you feel more awake, alert, and motivated to get sh*t done!

But, that’s not all!

Caffeine also stimulates the release of dopamine in the brain. Dopamine is one of the “feel-good” neurotransmitters that not only heightens mood, but also aids concentration, motivation, motor control, and decision-making.

In other words, caffeine is pretty awesome -- it makes us feel awake and happy, which are two of the main reasons people  love them some caffeine.

Beyond that, caffeine  also enhances mental and physical performance.

Without going too far down the research-rabbit hole, caffeine has been found to increase[1]:

  • Muscular strength
  • muscular endurance
  • Sprinting
  • Jumping
  • Reaction time
  • Attention
  • Vigilance
  • Movement velocity
  • Throwing performance
  • And several other aerobic and anaerobic sport-specific actions

By now, you’re probably wondering “if caffeine is so great, why does it get so much hate from certain segments of the population?”

Great question.

Well, as with everything, there is the individual’s response to caffeine, meaning one individual may respond favorably to it while another person may react unfavorably.

For instance, caffeine-habituated individuals, as well as those that metabolize caffeine well, will get all of the “good” benefits of caffeine -- increased energy, mood, focus, etc -- with very little if any of the drawbacks. On the flip side, individuals who don’t have a high caffeine tolerance and/or those who do not metabolize it well, tend to feel jittery, on edge, anxious, have trouble sleeping, etc.

Ok, great, but why do so many people think that caffeine restricts blood flow and kills muscle pumps?

Well, it’s true that incertain areas of the body, caffeine does act as a vasoconstrictor --in the brain.[2] This is why you commonly see caffeine included as one of the primary ingredients in migraine relief formulas.

However,  in the body, caffeine has actually been shown to increase nitric oxide production and increase blood flow.[2]

Moreover, caffeine also increases calcium ion (Ca2+) mobilization, which facilitates force production by each motor unit potentially benefiting muscle contraction.[1] Caffeine also delays the onset of fatigue, helping you to bang out more reps and make more gains. To top it off, caffeine may increase sodium/potassium (Na+/K+) pump activity to potentially boost excitation-contraction coupling, which is required for muscle contraction.

Besides, who doesn’t love the “jolt” that caffeine gives a pre workout to help get things moving and grooving when you’re in the gym?


Oftentimes you’ll hear individuals say you shouldn’t go above 200 or 300mg of caffeine, and any more will lead to difficulty breathing or reduced blood flow.

Again, this isn’t the case for all individuals. Some individuals may experience elevated heart rate with even low doses (~80mg) of caffeine, but it’s not the same for everyone across the board.

In fact, caffeine has a very high safety profile, and in research settings, caffeine has been administered to individuals between the range of 3mg-9mg/kg of bodyweight.[1,4,5]

To put that in perspective, this equates to  300-900mg for a 220-lb (100kg) bodybuilder.

Convict Stim contains 300mg of caffeine per full serving, which is well within the research-supported range of efficacy and safety.

And, if you’re worried about caffeine and cortisol or testosterone, don’t be.

Research in professional rugby players found that caffeine administered at varying doses (200, 400, and 800mg) increased the testosterone response to training.[6]


Caffeine has remained a staple ingredient in sports nutrition products for a reason -- it’s well-tolerated, effective, and safe when used appropriately.

The optimal dose for one individual will in all likelihood vary from another individual, but that’s half the fun of supplements and pre workouts in general -- finding the right one for  your needs.

As far as caffeine “ruining” pumps or hurting performance, those two misconceptions can be effectively tossed in the trash.

Caffeine not only enhances performance (both mentally and physically), but it can also support increased nitric oxide production, blood flow to working muscles, and fatigue resistance -- which culminates in more reps performed and bigger, badder pumps!


  1. Guest, N.S., VanDusseldorp, T.A., Nelson, M.T. et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr 18, 1 (2021).
  2. Gererd D.  Coffee and Health. John Libbey Eurotext; Esher, UK: 1994
  3. Umemura T, Ueda K, Nishioka K, Hidaka T, Takemoto H, Nakamura S, Jitsuiki D, Soga J, Goto C, Chayama K, Yoshizumi M, Higashi Y. Effects of acute administration of caffeine on vascular function. Am J Cardiol. 2006 Dec 1;98(11):1538-41. doi: 10.1016/j.amjcard.2006.06.058. Epub 2006 Oct 16. PMID: 17126666.
  4. Jodra, P., Lago-Rodríguez, A., Sánchez-Oliver, A.J. et al. Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes. J Int Soc Sports Nutr 17, 2 (2020).
  5. Domaszewski P, Pakosz P, Konieczny M, Bączkowicz D, Sadowska-Krępa E. Caffeine-Induced Effects on Human Skeletal Muscle Contraction Time and Maximal Displacement Measured by Tensiomyography. Nutrients. 2021 Mar 2;13(3):815. doi: 10.3390/nu13030815. PMID: 33801251; PMCID: PMC8001539.
  6. Wilk M., Filip A., Krzysztofik M., Maszczyk A., Zajac A. The Acute Effect of Various Doses of Caffeine on Power Output and Velocity during the Bench Press Exercise among Athletes Habitually Using Caffeine. Nutrients. 2019;11:1465. doi: 10.3390/nu11071465. 
  7. Beaven CM, Hopkins WG, Hansen KT, Wood MR, Cronin JB, Lowe TE. Dose effect of caffeine on testosterone and cortisol responses to resistance exercise. Int J Sport Nutr Exerc Metab. 2008 Apr;18(2):131-41. doi: 10.1123/ijsnem.18.2.131. PMID: 18458357.