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The Pros and Cons of Pre-Workout Supplements (Science-Based)

Connor Sellers
Published by Connor Sellers | Senior Coach
Last updated: July 4, 2023
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As a fitness coach, I always use pre-workouts for my exercise routines. But I’ve recently found that most of my clients don't trust this supplement.

So, in addition to my long-standing experience with pre-workouts, I decided to do in-depth research and review relevant literature on the pros and cons of pre-workout supplements.

I even scheduled an interview with a renowned nutritionist and expert in the field.

Here’s what I found.

Quick Summary

  • Pre-workouts are beneficial when used correctly as they boost athletic performance, energy levels, and focus.
  • Some cons of pre-workouts include overstimulation, jitteriness, headache, and digestive upset.
  • Nitric oxide, caffeine, creatine, beta-alanine, and BCAAs are some of the ingredients found in pre-workout supplements.

Should You Use Pre-workout Supplements?

A buff male drinking pre-workout

Yes, you should use pre-workout supplements if you want to reap maximum benefits from your workouts, granted you’re not allergic to the ingredients or have certain medical conditions.

However, to enjoy the full benefits of a pre-workout, I always advise my clients to consider addressing other factors such as diet, sleep quality, and hydration before turning to these supplements.

To fully understand why these are necessary, let's begin by analyzing the pre-workout ingredients.

5 Ingredients in Pre-Workout Supplements

A person mixing pre-workout

Research on pre-workout supplements is still limited. But a few studies have established that certain ingredients are necessary to improve energy levels and athletic performance [1].

With that in mind, here are some of the ingredients you should expect in these supplements:

1. Caffeine

Caffeine is one of the most common ingredients in pre-workout formulas.

Even without exercise, caffeine boosts metabolic rates, increases endurance, and reduces fatigue.

However, a far more essential role caffeine plays in the function of a pre-workout supplement is stimulating the central nervous system to keep you mentally alert and focused, which leads to a boost in exercise performance [2].

2. Nitric Oxide

The human body produces natural nitric oxide compounds that improve blood flow by relaxing blood vessels.

Pre-workout supplements often contain common compounds that your body uses to make nitric oxide. These elements include L-citrulline, L-arginine, some dietary nitrates, and beetroot juice [3].

3. Creatine

Close up shot of a person holding pre-workout

Just like nitric oxide, creatine is also produced naturally in the body and plays a massive role in muscular strength and energy production.

A healthy pre-workout formula has creatine monohydrate as part of its ingredients, although it's often sold as a standalone product to bodybuilders, weightlifters, and power athletes.

According to the International Society of Sports Nutrition, supplementing the body with creatine boosts its natural supply, thereby improving strength, workout intensity, athletic performance, muscle mass, and recovery time [4].

4. Beta-Alanine

Pre-workout formulas also contain beta-alanine, an amino acid that prevents the build-up of lactic acid in the muscle tissue.

The purpose of beta-alanine is to increase muscle endurance (muscle’s ability to work harder and for longer) and to delay muscle fatigue [5].

Related: Why Does Pre-Workout Make You Tingle?

5. Branched-Chain Amino Acids (BCAAs)

Pre-workout formulas contain BCAAs, usually included to increase muscle growth and decrease muscle soreness [6].

Other ingredients you’re likely to find in a pre-workout supplement include L-Taurine and L-Leucine.

Now that we know what to expect in a pre-workout, let's get into the crux of the matter. Below are the pros and cons of pre-workout supplements.

Pros of Pre-Workout

A buff tattooed male lifting weights

There are tons of benefits associated with taking the supplements, so let’s start with pre-workout pros:

1. Alertness and Focus

As mentioned earlier in this piece, the caffeine in pre-workout supplements boosts alertness and keeps you focused. This reduces your risk of injury when working out [7].

2. Improved Blood Flow

Pre-workout drinks can also aid in blood circulation within the body, especially within the muscles.

The nitric oxide in pre-workout supplements might assist in improving cardiovascular functions, in particular, the dilation of blood vessels when delivering nutrients and oxygen [8].

The improved circulation should result in less acid build-up and a boost in strength and muscular endurance.

“Whether you're looking to set a new PR, get a few more reps, or just get the most out of your cardio, a good pre-workout can be your ally.”

- Hobart Swan, Writer & Editor at 

3. Enhanced Fat Loss

A buff male lifting weights in the gym

Some pre-workouts have L-carnitine, an essential compound that aids the muscle in fat-burning [9].

Other components in a pre-workout supplement prevent the formation of fat and suppress eating by stimulating the production of the GLP-1 hormone, which regulates appetite [10].

4. Muscle Strength

Creatine is an essential ingredient found in most pre-workout supplements. Its work is to enhance strength by increasing biochemical mechanisms that give you that energy boost you need during a workout.

The result is a boost in strength, endurance, and, eventually, muscle mass [11].

Additionally, the nitrates in most pre-workout supplements allow the body to carry amino acids to your muscles, resulting in increased strength [12].

5. Muscle Growth and Lean Body Mass

As mentioned earlier, pre-workouts contain BCAAs, one of the essential amino acids necessary for protein synthesis.

Pre-workouts also contain citrulline, another amino acid that boosts blood flow to the muscles [13].

When you undergo stress training, oxygen levels are elevated, and nutrients are carried to the muscles to promote muscle gain.

What Are the Downsides / Cons of Pre-Workout?

A gym person having a headache

There is a dimmer side to pre-workout supplements, although they primarily affect those with underlying health conditions.

Let’s take a look at the cons of pre-workout supplements.

1. Overstimulation

One of the first things I check when I meet a new client is their health background. If the client has a history of heart problems, high blood pressure, and insomnia, then certain exercises are a no-go-zone.

It's more serious when it comes to recommending supplements.

A sharp increase in heart rate can develop complications for the patient and put their lives at risk, especially if they have a preexisting health condition.

That's because pre-workouts contain caffeine, a notorious ingredient that rapidly increases heart rates and energy levels.

Now, 400 mg of caffeine is safe for healthy adults. That's about four cups of brewed coffee.

However, because most pre-workouts contain 200 mg on average, I advise my clients to minimize their coffee intake, especially when taking the supplements, or instead opt for caffeine-free pre-workout supplements.

2. Headache

Earlier, we saw how citrulline is essential in boosting muscle blood flow. What’s the downside to this?

When blood pressure changes due to increased blood flow to the muscles, it might lead to migraines and headaches [14]. To reduce this effect, the best practice is to decrease the dosage or look for an alternative supplement with no citrulline as an ingredient.

3. Jitteriness

A buff male shivering in the gym

Caffeine has multiple downsides, especially when taken in excess. Side effects of pre-workout include an increased heart rate, nausea, anxiety, headaches, and jitteriness [15].

Most pre-workout supplements contain caffeine in excess (reportedly more than the amount in a cup of coffee), making these side effects more common among pre-workout users.

To curb this effect, I always advise clients to start with a small dose before graduating to levels they can tolerate. If need be, I recommend pre-workout supplements with no caffeine.

4. Digestive Upset

Bloating and diarrhea symptoms are surprisingly common when taking pre-workout supplements.

That's because the supplement contains compounds such as caffeine, creatine, sodium bicarbonate, and magnesium that can cause problems, especially when consumed in excess [16].

In addition, not mixing the supplement with enough water might also lead to diarrhea due to the high concentration of the same [17].

Now that we’ve covered the pros and cons of pre-workout supplements, below are some tips and precautions to guide you through when taking them.

Related: Does Pre-Workout Cause Bloating?

Tips When Taking the Supplements

A person mixing pre-workout

First, It's wise to consult a doctor even before purchasing a pre-workout supplement. I cannot emphasize enough how important this step is, especially if you have a preexisting health condition.

That said, here are a few pre-workout tips to follow: 

  • The best time to take pre-workout is more effective when taken daily. Research on their efficacy revealed that taking them daily had more positive results in three weeks than caffeine alone [18].
  • Consume them 30 minutes before training. This is to give the pre-workout enough time to kick in.
  • Due to the caffeine content in the supplement and the fact that you need enough sleep for the workout to be effective, avoid taking them after 9 pm.
  • It's wise to check the ingredients first before purchasing to avoid ones that contain obscure ingredients.
  • It's tempting to take lots of it. But it won't lead to better results. In any case, it turns up the side effects we mentioned.


Who Should Take Pre-Workout and Who Should Not?

Children should not take pre-workout supplements. Also, if you’re caffeine sensitive, you should avoid pre-workouts with caffeine.

Pre-workouts are only good for folks who want to step up their training a notch higher. All in all, consult a doctor before using a pre-workout.

Is It Good to Take Pre-Workouts Every Day?

Yes, it's good to take a pre-workout every day. In fact, it's recommended to do so for the pre-workout to be effective.

But if you have a medical condition, you should first seek the advice of a doctor before taking the supplement.

Is Pre-Workout Addictive?

Some pre-workouts are addictive, while others are not. You see, the caffeine ingredient in most pre-workouts is the only addictive component.

Are Pre-Workouts Harmful?

Taking pre-workouts is perfectly fine. But it’s always wise to avoid pre-workouts with questionable ingredients and fillers.

Government agencies do not explicitly regulate them, so some may contain artificial and dangerous ingredients that can harm your health.

That’s why we tested out many pre-workout supplements with a strong reputation in the market for maintaining strict health standards and compiled the results in these lists:

Check them out to find the one that suits you the best.


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