The main difference between stim and non stim pre-workout is the caffeine content. Stim pre workouts contain caffeine which induces an ergogenic effect, thereby giving it the edge for exercise performance. Stim free pre-workouts contain all of the other “good stuff” like citrulline malate and Beta-alanine without caffeine.
What is High-Stim Pre-Workout?
If you have ever taken a high-stim pre-workout, you may have noticed a burst of energy, approximately 30-45 minutes after consumption. This is known as the stimulant effect, which is caused by an ingredient called caffeine. A high stimulant pre-workout could contain over 300 mg of caffeine per serving. But why exactly does a high caffeine pre-workout have this effect?
Caffeine is a natural ingredient that can have ergogenic effects when it is taken in “high doses”. The research suggests that 3-6 mg of caffeine (high dose) per each kilogram of weight is effective in inhibiting the adenosine receptors within the brain. These receptors are responsible for keeping us relaxed.
Once these brain receptors are blocked off by caffeine, the central nervous system is stimulated, giving a sense of energy and wakefulness. In turn, this can modify training variables like power output, strength, and endurance. Without a doubt, making all the difference when it comes to overall sport and exercise performance, along with conditioning of the muscles in the long term.
To reap this ergogenic effect, most individuals would need to be in the ballpark of at least 150-350 mg (3 mg/kg) of caffeine before a workout. This includes a variety of male and females from a variety of athletic backgrounds, with varying body weights ranging from 50-117kg (110-258 lbs). The effect also depends on individual sensitivity, the ability to metabolize caffeine, and developed tolerance (how often a person consumes caffeinated beverages). For some people, 200 mg is just a mild stimulant, while for others such a dose would make their heart jump out of their chest.
Is it possible to get even more stimulation from an additional dose increase? Once adenosine receptors are "closed" by caffeine, which requires 300-500 mg, further increasing the dose does not increase the stimulating effect, but increases the risk of side effects such as nervousness, tremors, or high blood pressure.
A major disadvantage for a high-stim pre-workout is that it may cause some sleep disturbances if it is taken too close to bedtime. We all hate being wide awake or in light sleep, frustrated and rolling around in bed. Taking caffeine too close to bed could reduce deep and overall sleep. Most of you must be aware of the importance of sleep towards your health and fitness goals.
Caffeine has a half life of 6 hrs and is not fully eliminated from the body for 12 hrs. For some people, it may be necessary to maintain a gap of at least 8-12 hours between consuming stim pre-workouts and going to bed in order to avoid any potential disruptions to their sleep. As a result, consuming such supplements in the morning may be a more appropriate option for them.
Another downside of the stim pre-workout is that it may cause stomach upsets in some individuals. In my experience, this is short term and usually only occurs shortly after taking the pre-workout.
Caffeine can also lead to heightened heart rate and anxiety. One of the common side effects of caffeine is jitters or tremors, which can cause discomfort and distraction during a workout. Usually, these effects are not dangerous, but they can be unpleasant.
Also people with hypersensitivity to caffeine and those who have heart disease or high blood pressure should be careful with high doses. Such persons should get a doctor's recommendation on dosages or carefully monitor their reactions, starting with a lower dose.
Along with caffeine, high-stim pre-workouts often contain ingredients like L-Citrulline and Beta-Alanine. Without delving into too much detail, these ingredients help increase blood flow and buffer lactate, supporting both resistance training and endurance performance.
What is Non-Stim Pre-Workout?
Now that you have learned all about high-stim pre-workouts, you might be wondering “what is stim free pre-workout?” Well without exaggerating, it is simply a pre-workout without stimulant. So it should come as no surprise that you will not get the same burst of energy like a caffeine based pre-workout.
So the next question is how does stim free pre-workout work? Regardless of not having the same stimulant effect, stim free pre-workouts contain all of the other “good stuff” like Citrulline malate and Beta-alanine, which as mentioned can modify exercise performance.
Not to mention, some stim-free pre-workouts contain other additional ingredients branched chain amino acids, which may give you the edge when it comes to muscle recovery and growth in certain circumstances.
Non-stim pre-workouts can be advantageous in that they should not cause any sleep disturbances and it may suit those who can not tolerate caffeine.
Stim vs Non Stim Pre-Workout
We have compared stim and non stim pre-workout in 5 different areas, which include:
- Nutrition label transparency
- Value for money
- Overall performance modification
Do stim free pre-workouts work? Absolutely! But do they contain a stimulant? No! For this reason, there should be no doubt as to which pre-workout induces the better stimulation effect (stim based pre-workout).
Taste and flavor is entirely subjective and will depend on the manufacturers. In my personal experience, I have always found stim based pre-workouts to be more flavourful.
Nutrition label transparency
Generally the nutrition labels of stim and non stim pre-workouts are very similar. They usually both contain a "pump agent" like Citrulline and a lactate buffer known as beta-alanine. Non stim pre-workouts may include some additional sodium and amino acids, where stim pre-workouts contain caffeine.
Value for money
This varies from supplement to supplement, when we look on the market. When we compare our product recommendation (listed below), the stim based pre-workout was slightly cheaper and can provide 10 more servings if you opt for the 1 scoop (30 servings vs 40 servings)
Overall Performance Modification
When it comes to performance, we can not deny that the stim based pre-workout would be more effective for most. Why so? The stim pre-workout contains all of the main performance enhancing ingredients that the non stim variant contains, plus caffeine.
Furthermore, caffeine has a thermic effect, meaning your body burns calories to metabolize it. The typical thermogenic effect of 200mg of caffeine is around 30 calories. This calorie burning effect may not seem like much, but overtime can accumulate to help keep you leaner.
Caffeine can also make you more aroused in the short term, so you may be able to burn more calories from non exercise related activities. Similarly, you may be able to workout at a higher intensity, thereby burning more calories.
Stim vs Non Stim Pre-Workout: Summary
To summarize, we have highlighted the positives and negatives surrounding the use of stim and non stim pre-workouts.
Induces stimulant effects
Induces the other effects you expect from a pre-workout
Overall more optimal performance modifications
Burns a little more calories thanks to the thermogenic effect
Increases calorie burning from exercise and non exercise activities
Caffeine may reduce symptoms of depression
May be better value for money (comparing our product recommendations)
Could be better:
May cause sleep disturbances
May cause stomach upsets
The ingredients may amplify symptoms of anxiety (caffeine and beta-alanine)
Not suitable for people with low caffeine tolerance
People with heart disease, high blood pressure should be careful
Non Stim Pre-workout
Better option for those who can not tolerate caffeine
Does not cause sleep disturbances
Induces other effects you expect from a pre-workout like “pump effect” or endurance enhancement
Could be better:
Does not have a stimulant effect
Rare but may cause stomach upset
The ingredients may amplify symptoms of anxiety despite the absence of caffeine (itching/tingly effect of beta-alanine)
Products We Recommend
Stim Pre-Workout: WRECKED PRE-WORKOUT
- Item Form: Powder
- Best For: High-Intensity Exercise Performance, Muscular Endurance, Reducing Fatigue, Training Volume, Enhanced “Pumping” Effect
- Flavors: Raspberry Mojito, Bomb popsicle, Rainbow burst, Peach rings, Sour gummy
- Caffeine Anhydrous: 125-250 mg
- Di Caffeine Malate: 50-100 mg
- Special ingredients: L-Citrulline, Beta-alanine, Glycerol
- Servings Size: ≈15.5g-30.1g
- Serving per container: 20-40
- Company Founded: 2019
- Recommend By Athletes: Joe Linder, Joe Shulk, Brett Mossing
photo by @hugesupplements
Wrecked pre-workout ticks all the boxes when it comes to the ingredients list and dosing. The main Ingredients are: Caffeine, L-Citrulline, and Beta-alanine. It can help sports participants, high level gym goers, bodybuilders, and powerlifters.
Good stimulation effect
Enhanced "pumping" effect
Improved strength and endurance performance
Could be better:
Contains many additional ingredients that have little scientific support
Not third-party tested
Non Stim Pre-Workout: STIM-FREE NON CAFFEINATED PERFORMANCE FORMULA
- Item Form: Powder
- Best For: Overall Athletic Performance, Training Volume, Enhanced “Pumping” Effect
- Flavor: Sour Grape, Blue Raspberry, Green Apple
- Caffeine: Zero
- Special ingredients: elevATP, Bioperine, Betapure, Huperzine A
- Serving Size: 23g
- Servings: 30
- Company Founded: 2015
- Recommended By Athletes: Hafthor Jullius Bjornsson, Kelsey Henson, Paul Sclar
photo by @transparentlabs
This product can rightfully be considered as a great option for those who can not tolerate stimulants. The blend of Ingredients can maximize the blood "pump" and lactate buffering effect. In turn, this could modify both aerobic and anaerobic exercise performance. Moreover, this pre-workout contains additional Ingredients that may increase nutrient absorption and muscle recovery. There are no artificial sweeteners or coloring, and it is third party tested.
Strong "pump" effect
Lactate buffering effect
May support muscle recovery
Suitable for those who can not tolerate caffeine
No jitters, caffeine crashes, or heart palpitations
Third party tested
No artificial colors or flavors
Could be better:
No stimulating effect
High price per serving
Do Stim Free Pre-workouts Work?
They work with an effective pump,lactate buffering effect, increasing rates of creatine synthesis, which improve muscular endurance and overall exercise performance. But you should not expect stimulation from them.
Are Stim Free Pre-workouts Safe?
For most, stim free pre-workouts are safe, some of the ingredients may cause some minor effects like stomach upsets or tingling sensation.
Do All Pre-workouts Have Caffeine?
As we have stressed all throughout the article, stim free pre-workouts do not contain any caffeine
What Does Stimulant Free Mean?
It simply means that there is not stimulant/caffeine in the pre-workout
We have learned that the main difference between a stim and non stim pre-workouts is the caffeine content. Caffeine gives an extra edge towards performance as it acts as an ergogenic aid. It also boosts the metabolism and overall activity levels.
To get this performance boost, a caffeine content of at least 3 mg per kilogram of body weight looks promising based on the current research. For most, a dose of about 150-200 mg of caffeine is enough to get a high level of stimulation without significant side effects. Higher doses require caution.
However, the most significant downside of a stim based pre-workout is that there is a higher chance of sleep disturbances if it is taken too close to bedtime. Caffeine also can lead to heightened heart rate, anxiety and jitters
Another negative point is that caffeine is a natural laxative, therefore increasing the risk of gastrointestinal distress, or better understood as an upset stomach.
Nevertheless, I am willing to make the claim that both types of pre-workouts are effective in boosting exercise performance due to the range of ingredients like citrulline and beta-alanine. These ingredients may help increase blood flow to the muscles and buffer lactate.
If we compare our recommended products, it seems as if the wrecked stim based pre-workout has more appealing flavors and gives you more value for your money.
Last but not least, we really hope you enjoyed the article! Please feel free to leave a comment or send in any questions or queries and we will get back to you as soon as possible.
- International Society of Sports Nutrition Position Stand // TandfOnline: https://www.tandfonline.com/doi/full/10.1186/s12970-020-00383-4
- The Effect of Caffeine on Subsequent Sleep // Science Direct: https://www.sciencedirect.com/science/article/pii/S1087079223000205
- Acute Caffeine Supplementation Enhances Several Aspects of Shot Put Performance in Trained Athletes // TandfOnline: https://www.tandfonline.com/doi/full/10.1080/15502783.2022.2096415
- Comparison of Pre-workout Nitric Oxide Stimulating Dietary Supplements on Skeletal Muscle Oxygen Saturation // TandfOnline: https://www.tandfonline.com/doi/full/10.1186/1550-2783-7-16
- Thermogenic Synergism Between Ephedrine and Caffeine in Healthy Volunteers // Science Direct: https://www.sciencedirect.com/science/article/abs/pii/002604959190117F
Oleksandr is a professional fitness nutritionist, certified by FPA (Fitness Professional Association). Oleksandr adheres to the principles of evidence-based dietetics and instills in his clients a healthy relationship with food - without strict prohibitions on favorite foods and regular disruptions. His main task – not only get a result for you, but also maintain it for many years, enjoying tasty and delicious food.