Pre-workout supplements have a reputation as a “hardcore” product category — something used by bodybuilders, serious athletes, and other advanced trainees. This reputation is just as much a result of supplements’ usual users as it is their apparent complexity (a typical pre-workout blend may have over a dozen ingredients, and if you’re a newbie, that can be pretty overwhelming).    

This reputation of being inaccessible or overly niche is largely unwarranted when it comes to supplements, though. Pre-workout supplements are, when you get right down to it, stimulants that give you a burst of energy, not unlike an energy drink. To help you get a better understanding of this fitness fixture and how it can have a place in your own fitness routine — whether you’re a beginner or consider yourself a pro — we’re doing a deep dive into the world of pre-workout supplementation. We’ll go over some of the common ingredients in pre-workout blends ( some of which are far more important than others), as well as examine the mechanisms of action and the possible side effects of these supplements. Once you’ve got those things down, you can make an informed decision about which pre-workout supplements to use, and when to use them.  

Common Ingredients in Pre-Workout Supplements

Before we can talk too much about the function of supplements, it’s important to actually break down those supplements and understand the different components that go into them. Here are a few of the key ingredients that often appear on a pre-workout supplement’s label, along with what each might bring to the table in any given formula:

Caffeine– Despite the presence of many “exotic” ingredients in pre-workout blends, caffeine is actually the main ingredient in almost every pre-workout supplement.  Usually dosed somewhere between 100–300mg per serving, caffeine works primarily to promote wakefulness and decrease subjective sensations of fatigue, and is a lot more effective and beneficial for endurance or speed-endurance activities (those lasting over a minute) as opposed to strength and power activities, such as weightlifting.   

L-Tyrosine– Tyrosine is an amino acid, and the main precursor to noradrenaline and dopamine. Anecdotally, it slightly reduces stress, increases energy levels, and potentiates the effects of caffeine and other stimulants. It’s usually dosed in the 500mg–3g range in most pre-workout supplements.

L-Carnitine– Another amino acid, carnitine is usually sold in the form of acetyl-L-carnitine. Dosed at half a gram to several grams, carnitine can slightly increase muscular work capacity and decrease fatigue and muscle damage.  

Citrulline malate– Citrulline is an amino acid, and citrulline malate is citrulline mixed with malate, usually at a 2:1 ratio. Several grams taken about an hour before exercise can reduce fatigue.  

β-alanine A modified version of the amino acid alanine, several grams a day of beta-alanine can slightly increase muscular endurance and decrease fatigue. Dosage in a pre-workout supplement isn’t particularly significant since this ingredient’s efficacy is largely dependent on daily supplementation.  

Creatine monohydrate– Another modified amino acid, 5-10 grams of creatine a day increases strength, power and muscle mass. Like β-alanine, there’s really no need to dose it specifically before a workout, since this particular ingredient tends to work its best when taken consistently each day.  

B vitamins– This includes niacin, b6, b12 — they’re different vitamins, but all serve similar roles in supporting energy metabolism and alertness. In general, B vitamins have little direct physical effect but can slightly boost subjective motivation and energy levels.

Taurine– An amino acid you might recognize as an ingredient in Red Bull, taurine is not a stimulant at all.  Mainly it serves to reduce cramping caused by high-dose stimulants, but if that’s an issue, you’d be better off just using fewer stimulants.  

How Do Pre-Workout Supplements Work?

Once you’ve got a handle on the ingredients, you start getting a sense of all the physiological ways that different ingredients work. Many ingredients in pre-workout supplements are frequently under-dosed, however. Plus, certain ingredients, like beta-alanine and creatine, should both be dosed at least once a day, every day as opposed to purely before a workout. When it comes to the efficacy of pre-workout supplements, the mechanism of action is often purely psychological. These supplements increase your motivation to exercise and decrease subjective sensations of fatigue.

Some ingredients in pre-workout blends also exert physical effects on muscle tissue, such as decreasing muscle damage and lactic acid buildup, increasing intracellular nutrient storage, or increasing glycogen resynthesis.  Citrulline, carnitine, creatine and beta-alanine all work this way.

In practice, most pre-workout blends derive most of their effects from caffeine. And while it has some physical effects on endurance, caffeine’s main effects are to motivate you to exercise, especially when you’re tired.    

Side Effects of Pre-Workout Supplements

While pre-workout supplements can be useful to help improve your workout, that doesn’t mean they don’t come without their downsides. Pre-workout supplements can sometimes cause tachycardia —a racing heart — if you take too much. High doses can also cause anxiety. Both of these side effects are mainly due to the caffeine.

Some people experience indigestion from pre-workout supplements. This tends to be caused by the combination of caffeine, citrulline malate, and creatine, but can usually be prevented by not taking pre-workout on an empty stomach. 

The biggest side effect of using pre-workout supplements, though, is sleep impairment due to the caffeine. The equivalent of a single double espresso in the morning can measurably impair sleep that night, even if you don’t consciously notice it.

So Are Pre-Workout Supplements Worth Using?

Long story short: yes. The energy boost that you get from incorporating a pre-workout supplement into your routine can payoff a good deal when it comes to your focus and the overall quality of your workout. However, you can get most of the same results from simply drinking a caffeinated beverage.  

If you’re going to try to reap the benefits of a pre-workout supplement, it’s worth considering what kind of pre-workout supplement you turn to. For example, it’s worth noting that powders have the advantage of allowing precise dosing compared to pills or canned beverages. 

As a general rule, you should also take less of whatever your chosen pre-workout supplement is the later in the day it is. As a general guideline, limit yourself to at most one serving of pre-workout or 200 mg of caffeine early in the morning, half a serving of pre-workout or 100 mg of caffeine around noon, or a quarter serving of pre-workout or 50 kg of caffeine in the afternoon. Caffeine should never be consumed in the evening.  

Pre-workout supplements are clearly helpful, particularly for people who are tired or less motivated to exercise. Due to the potential for anxiety or sleep impairment, it is advisable to take the minimum dose that provides some noticeable effect.