Optimizing pre-workout formulations: the role of caffeine

By Jillian Jastrzembski

Pre-workout formulations are an up-and-coming industry with a huge market of athletes and casual gym-goers alike. These formulations, often in the form of drinks, contain a cocktail of ingredients advertised to improve physical performance and cognitive function, including amino acids, creatine, and most importantly, caffeine.

As with most exciting new industries, it’s not uncommon for the marketing to get ahead of the science, so if you’re extra savvy, you might be thinking ahead. Which of these ingredients have scientifically proven ergogenic effects? Have they been tested alone or in combination, and what do we know about chronic use? Who are they being marketed to, and who are they right for?

Caffeine is the major ingredient responsible for performance enhancement. In fact, caffeine was even briefly banned in competition by the World Anti-doping Agency from 2000 to 2004, and is still monitored.

What it does

Also known as 1,3,7-trimethylxanthine, caffeine is shown to have ergogenic (performance-enhancing) effects at dosages as low as 1 or 2 mg/kg of bodyweight. For a 150 pound person, that’s just about one cup of coffee.

Ergogenic effects of caffeine are most pronounced for aerobic endurance type exercise (think long distance running), but are also proven for other forms of exercise, including strength training, plyometrics, sprinting, and even more strategy-based sports, thanks in part to the additional cognitive boost of caffeine.

How it does it

To understand how caffeine acts on your body, let’s take a look at the biochemistry. As a molecule, caffeine falls somewhere in between hydrophilic and hydrophobic. In other words, it is water soluble, yet also sufficiently lipid soluble so that it can readily pass through most biological membranes, including the blood-brain barrier. The bioavailability of caffeine is close to 100%!

Caffeine’s performance enhancing powers are thought to be enacted primarily though the central nervous system, which consists of the brain and the spinal cord only. Part of the reasoning behind this is that even low dosages (2 mg/kg body weight) of caffeine, which do not affect things like glucose or blood lactate, can still have performance enhancing benefits.

If you know a little bit about the biochemistry of caffeine, you’ve probably learned that the molecule is similar in shape to another molecule, called adenosine. Due to this property, caffeine, when available, “parks in the parking spot” (in scientific speak, binds to the receptor) normally taken up by adenosine. Under normal circumstances, adenosine decreases the amounts of neurotransmitters like serotonin, dopamine, and acetylcholine. So when caffeine gets in its way, those neurotransmitters increase. That explains the mood lift and the dopamine hit you get from your visit to your favorite coffee shop. Acetylcholine is the neurotransmitter responsible for stimulating muscle activation, so having this available is important for physical activity.

Who’s it for?

Here’s what we know so far. Caffeine isn’t just for elite athletes, or devout gym goers. The ergogenic effects of caffeine have been shown across the board, from trained to untrained individuals alike. But… that doesn’t mean it’s for everyone.

Caffeine metabolism varies greatly between individuals, mainly due to genetic differences. The average half-life – aka the amount of time required to metabolize half the quantity of caffeine – is reported to be between 4-6 hours, but could be as short as 1.5 hours or as long as 10 hours, depending on the person. Some people are just naturally less able to metabolize caffeine. Long-term use may increase ability to metabolize caffeine, whereas pregnancy and use of hormonal contraceptives could decrease the rate of metabolism.

It’s important to take into consideration the half-life of caffeine when timing your consumption. Objective sleep measurements demonstrate reduced quality of sleep when caffeine is still in the body’s system. So even though pre-workout aids are intended for consumption within 60 minutes before a workout, they should not be consumed too late in the day. No matter how much caffeine you have, good sleep is still the most important consideration for optimizing performance.

Another important consideration is your particular form of physical activity. Caffeine is most helpful for aerobic endurance activities. If your sport or activity is more skill-based, then you need to be careful that the side-effects of caffeine (jitteriness and anxiety) aren’t over-riding the positive effects.

What’s the optimal formulation?

Is a pre-workout better than a cup of coffee? Not necessarily.

Some studies have already established that the source of caffeine will have at most only slight differences in the rate of metabolism. So whether you prefer a cup of coffee or a pre-workout novelty, have your pick.

Multi-ingredient pre-workout supplements often contain other ingredients such as creatine and amino acids. In these formulations, caffeine is thought to be the primary ingredient responsible for performance enhancing effects. The effects of the other ingredients are poorly understood, since it is difficult to pull apart which ingredients are doing what.

Furthermore, current research only goes up to about 8-12 weeks – so while the positive ergogenic effects may be true within this time period, little is known about chronic intake.

In particular, caution is advised when consuming caffeine and creatine in combination, until further research is available. Other safety concerns exist with respect to potential drug-supplement reactions, including both prescription and over-the-counter drugs when taking a multi-ingredient pre-workout supplement.

The take-away

Whether you’re looking to buy a pre-workout supplement, concoct your own, or market to others, it’s essential to understand the science behind the gimmick. Caffeine is the primary ingredient responsible for the physical and cognitive boost. Other ingredients in pre-workout supplements have not been studied extensively. And most importantly: there is no one size fits all – what works for some may not work for others.

References

Guest, Nanci S et al. “International society of sports nutrition position stand: caffeine and exercise performance.” Journal of the International Society of Sports Nutrition vol. 18,1 1. 2 Jan. 2021, doi:10.1186/s12970-020-00383-4

Harty, Patrick S et al. “Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review.” Journal of the International Society of Sports Nutrition vol. 15,1 41. 8 Aug. 2018, doi:10.1186/s12970-018-0247-6

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