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Over the past six months, I’ve tested each Transparent Labs pre-workout for at least 30 days—through everything from intense strength training to hypertrophy sessions, steady-state cardio, and HIIT workouts.
I used them in the morning, at night, during bulking, cutting, and even deload weeks to see how they stack up.
Transparent Labs has five pre-workout products:
- Bulk
- Bulk Black
- Pump
- Stim-Free
- Lean
Now, after 100+ workouts, I know which ones deliver the best results.
Whether you’re new to pre-workouts or just curious about Transparent Labs, this article will help you figure out which one is worth your money… and which one you might want to skip.
Medical Disclaimer: The material presented in this article aims to offer informational insights. It should not be perceived as medical guidance. The views and writings are not designed for diagnosing, preventing, or treating health issues. Always consult with your physician prior to starting any new dietary or supplement routine.
1. Best Overall: Transparent Labs Bulk
Overall Rating
4.9/5
Key Features
- Price: $ ($1.66 per serving)
- Calories: 10
- Caffeine Content: 200mg
- Other Stimulants: 50mg Theobromine
- Clinically Dosed Ingredients: Yes
- Artificial Additives: None (No artificial flavors, sweeteners, or preservatives)
Transparent Labs Bulk stands out as a comprehensive pre-workout designed for those focused on increasing strength and muscle mass.
Its formula meets clinical dosing standards across all nine key ingredients, including 8g of citrulline malate and 4g of beta-alanine, which are essential for improving blood flow, strength, and endurance.
For those that don’t know, “clinical dosing standards” mean that the ingredients have the exact same dosages that are proven effective in research trials.
Despite its relatively moderate caffeine content (200mg), Bulk delivers a substantial energy boost without the jitteriness that often comes with higher caffeine pre-workouts.
Over my testing period, I found Bulk consistently improved strength and stamina.
My morning workouts, which are usually constrained by time, left me feeling like I could push harder, lift heavier, and complete additional sets.
For example, if I had four sets of 10 weighted chin-ups, I could sustain the same weight across all four sets, which isn’t typical for me. I normally have to drop the weight by the time I reach my 4th set. In addition, I could usually add an extra set to my prescribed plan, going from 4 sets to 5 sets quite easily.
The Pina Colada flavor mixed well with the recommended 12oz of water, though I personally found that volume to be a bit much pre-workout, often leaving me feeling full and needing bathroom breaks during cardio-heavy sessions.
Mixing with less water resulted in a more bitter taste, which could be off-putting for some, but this is largely due to the absence of artificial sweeteners, which, in my view, is a plus.
The full clinical dose of 8g of citrulline gave me impressive muscle pumps, especially during my hypertrophy sessions. Whether I was focusing on arms, chest, or legs, I consistently noticed increased vascularity and a strong pump, which helped keep me motivated throughout longer workouts.
The primary drawback is the amount of water required for proper mixing. I prefer a more concentrated mix to avoid the pre-workout bloat. Additionally, the slight residue left at the bottom of my shaker was manageable but worth mentioning for those sensitive to texture.
Overall, if you’re looking to gain strength while avoiding excessive caffeine, Transparent Labs Bulk is a top choice. It strikes a perfect balance between clinically dosed ingredients and a moderate stimulant profile, making it suitable for both beginners and seasoned lifters.
Out of all the pre-workouts I’ve tested on our YouTube channel, Transparent Labs Bulk consistently comes out on top as one of my favorite pre-workouts, and it’s something I plan to always have in my supplement cupboard for my everyday workouts.
2. Best for High Stimulants: Transparent Labs Bulk Black
Overall Rating
4.7/5
Key Features
- Price: $$ ($1.83 per serving, $1.65 with subscribe and save)
- Calories: 10
- Caffeine Content: 350mg
- Other Stimulants: 100mg Theobromine
- Clinically Dosed Ingredients: Yes
- Artificial Additives: None (No artificial flavors, sweeteners, or preservatives)
Transparent Labs Bulk Black delivers an intense energy boost for those who thrive on high-stim pre-workouts.
When comparing Bulk Black to the original Bulk, the formulas are nearly identical, aside from the higher caffeine content in Bulk Black at 350mg. I created a separate video discussing the differences between Bulk and Bulk Black if you’re interested in a deep dive.
Both pre-workouts excel at increasing strength, muscle pumps, and recovery, but Bulk Black offers an extra edge in sustained energy thanks to its dual-caffeine approach.
The inclusion of 75mg of dicaffeine malate (Infinergy™), a slow-release form of caffeine, extends your energy levels well beyond a typical workout without the crash or jitters.
Over my testing period, despite inconsistent training leading up to this cycle, I was impressed by how strong and energized I felt, especially during longer lifting sessions. I regularly found myself adding extra sets and exercises after completing my prescribed workout simply because I had so much energy left in the tank.
It would not be unusual, for example, to finish my arm workout and add another four sets of bicep exercises simply because I didn’t want to leave the gym with how much energy I still had.
The 8g of citrulline malate and 4g of beta-alanine contributed to great pumps and delayed fatigue, which allowed me to lift heavier and recover quicker between sets.
If you’re someone who takes short rest periods between sets, or does supersets of two or more exercises, Bulk Black definitely makes you able to continue working hard across short amounts of rest.
Even though Bulk Black contains almost twice the caffeine of the original Bulk formula, I didn’t notice a massive jump in energy levels between the two. However, that might be due to my high caffeine tolerance (I usually consume around 400mg daily between pre-workout and coffee).
If you aren’t as caffeine-adapted, you’ll likely feel the difference much more.
As such, I recommend starting with Bulk pre-workout first, and only move to Bulk Black once you know how you respond to the original formula. If you’re brand new to pre-workout, Bulk Black will probably feel too intense.
Despite the high caffeine content, I appreciated that there was no post-workout crash like other high-stim formulas.
I tried the Cherry Kiwi flavor, which was quite sour, something I’ve noticed across most of Transparent Labs’ pre-workouts. You can dilute it with extra water to tone down the sourness, but personally, I prefer to limit water intake during my workouts. Mixability was excellent, with minimal residue left at the bottom of my shaker.
The downsides? Bulk Black is harder to integrate into your daily routine, especially if you also enjoy coffee or energy drinks. According to the FDA, the safe upper daily caffeine limit is 400mg, so the 350mg in Bulk Black doesn’t leave a lot of room.
If you prefer evening workouts, you might want to steer clear of this one, too.
Overall, I like to keep Bulk Black in my cupboard for “peak weeks” of training at the end of a training cycle, or when I’m shooting for a PR, but it’s not the pre-workout I grab for my everyday workouts.
3. Best for Cardio and Fat Loss: Transparent Labs Lean
Overall Rating
4.0/5
Key Features
- Price: $ ($1.66 per serving)
- Calories: 10
- Caffeine Content: 180mg
- Other Stimulants: 50mg Theobromine
- Total Stimulants: 230mg
- Clinically Dosed Ingredients: Partially (7 out of 10)
- Artificial Additives: None (No artificial flavors, sweeteners, or preservatives)
Transparent Labs Lean is designed for those prioritizing fat loss and cardio performance. Its moderate stimulant profile, with 180mg of caffeine and 50mg of theobromine, delivers long-lasting energy without the jitters or post-workout crash.
Where Lean really excels is its ability to keep energy levels steady during longer cardio workouts. For example, when training for a 10km race, I would take Lean for my long runs and feel a consistent energy boost.
A unique aspect of Transparent Labs Lean is that it’s formulated with ingredients like Acetyl L-Carnitine and Choline Bitartrate, which help convert fat into energy and support fat metabolism.
These ingredients, combined with the thermogenic effect of caffeine and theobromine, make it a solid choice for those looking to increase fat oxidation during workouts.
I definitely noticed sweating a lot more during my HIIT-style workouts, so it’s an excellent option for those who do circuit training or intervals.
I also appreciated the added focus and mental clarity, though it didn’t quite match the laser-like focus I experienced with Transparent Labs Bulk or Stim-Free (which I’ll talk about next).
I tried the Fruit Punch flavor, which was enjoyable when mixed with 10-12oz of water. It did leave a slightly bitter aftertaste, which is typical of pre-workouts without artificial sweeteners.
To avoid feeling too full before my workout, I diluted it with around 6-8oz of water, resulting in a more concentrated and sour flavor. Lean’s mixability was impressive, with no clumps or residue if consumed quickly.
For those looking to boost strength and muscle pump, Lean is definitely not the best option.
The 6g of citrulline malate provides decent vascularity, but I didn’t experience the same fullness or muscle pump that I’ve felt with other Transparent Labs pre-workouts. Strength-wise, Lean also fell short, which is unsurprising given that it’s geared more toward fat loss and cardio than pure strength training.
Overall, if you’re looking for a high-intensity strength pre-workout, Lean may feel a bit too subtle. However, for cardio-based training, or if you’re new to pre-workouts, it provides solid energy without overwhelming side effects.
I still keep a bottle of Lean in my supplement cupboard, especially if I’m just planning a cardio day, but if the focus for my workout is strength training, which is usually the case, I’m picking Bulk (even if I’m in a cutting phase).
4. Best for Caffeine-Free Workouts: Transparent Labs Stim-Free
Overall Rating
4.5/5
Key Features
- Price: $ ($1.66 per serving)
- Calories: 10
- Caffeine Content: 0mg (Stimulant-Free)
- Other Stimulants: None
- Clinically Dosed Ingredients: Yes
- Artificial Additives: None (No artificial flavors, sweeteners, or preservatives)
Transparent Labs Stim-Free is an ideal option for anyone who wants to avoid stimulants but still needs solid workout performance. Out of all the caffeine-free products I’ve tested, Transparent Labs Stim-Free has been my go-to.
Whether you’re sensitive to caffeine, prefer evening workouts, or need a stimulant break during deload weeks, this pre-workout can fit seamlessly into your routine.
While I normally work out in the morning before work, I really like having an option in my supplement cupboard that I can turn to if I’m forced to work out in the evening and don’t want to sacrifice my sleep.
During testing, I found Stim-Free worked exceptionally well for strength and hypertrophy workouts. What sets it apart is the clinical dosing of key ingredients like 8g of citrulline malate and 4g of beta-alanine, which deliver great pumps and muscle endurance.
Despite the lack of stimulants, I definitely noticed I could push an extra rep or two, or three, beyond what I’m normally able to do. The formula’s ingredients like elevATP® gave me the strength and stamina I typically expect from a stimulant-based pre-workout.
For example, I specifically remember programming AMRAP sets at the end of some of my exercises while testing Stim-Free.
I would do four sets of leg press, and the last set would be an AMRAP set to fatigue. I consistently set new PRs on these AMRAP sets while taking Stim-Free. I’m not saying my PRs were 100% because of taking Stim-Free, but it definitely contributed.
While Stim-Free doesn’t offer the quick mental sharpness of caffeinated pre-workouts, it provides a steady boost in physical energy.
I particularly appreciated how well it supported my deload weeks, giving me the stamina to keep lifting without overwhelming my system. You definitely feel energized while taking this pre-workout, even though it’s not the buzzy type of energy that you normally get from caffeine.
Peach Mango was a pleasant surprise—smooth and not overly sweet. I did notice a slight bitter aftertaste, but it was minor compared to other pre-workouts. It also mixed easily with minimal residue, even when using less water than the recommended amount, which is a bonus if you prefer a more concentrated drink.
The absence of mental energy boosts might be a drawback for those used to caffeinated pre-workouts. However, the strength and endurance benefits more than makeup for it.
For me, I love caffeinated pre-workouts, so I prefer using something like Bulk for the majority of my workouts. But I still have a bottle of Stim-Free in my supplement cupboard if I’m ever working out after 7 PM, which happens a couple of times a month.
5. Best for Muscle Pumps: Transparent Labs Pump
Overall Rating
4.0/5
Key Features
- Price: $ ($1.66 per serving)
- Calories: 0
- Caffeine Content: 0mg (Stimulant-Free)
- Other Stimulants: None
- Clinically Dosed Ingredients: Yes
- Artificial Additives: None (No artificial flavors, sweeteners, or preservatives)
Transparent Labs Pump is a stim-free pre-workout. However, unlike Transparent Labs Stim Free, it focuses solely on delivering muscle pumps and increasing blood flow during workouts.
Because it doesn’t contain caffeine, it’s a solid choice for evening lifters or anyone cycling off caffeine.
This simple formula includes clinically dosed ingredients like 8g of citrulline malate and 2500mg of arginine nitrate to enhance nitric oxide production.
For me, it was especially good for isolation exercises where you really want to see that muscle pump—my delts, glutes, and arms looked fuller and more vascular, particularly when I was well-hydrated and fueled up.
Therefore, if you have sessions throughout your training week where you do a lot of high rep, isolation movements, or tempo exercises where you’re really focusing on slowing the movement down, you’re going to love the pump you get from this pre-workout.
What surprised me during my testing, though, was how much it improved my stamina (on top of the pumps).
While I didn’t notice a direct increase in strength, like lifting more weight per se, I did find that I could get to the end of my prescribed number of sets and reps and feel less overall muscle fatigue creeping in. Because of this, I sometimes added an extra set, which led to increased volume for that workout.
The Blue Raspberry flavor was okay, but there’s a noticeable sourness typical of pump-focused pre-workouts. That said, it mixes well, though it did get foamy initially, which caught me off guard. The foam quickly settled, so it didn’t hinder the experience.
The downsides of Transparent Labs Pump? If you’re looking for something to boost mental focus or raw energy, Pump won’t be the best option.
If you’re looking for a stimulant-free pre-workout and trying to decide between Transparent Labs Pump and Stim-Free, the choice largely depends on your workout goals.
Stim-Free is your go-to option if you’re looking for a well-rounded formula that covers everything—strength, endurance, energy, and muscle pumps.
On the other hand, Pump is designed specifically for maximizing nitric oxide production and delivering intense muscle pumps. It’s perfect for those prioritizing pump and blood flow in their training, especially if you want to stack it with another pre-workout or avoid stimulants altogether.
Because I’m not looking for a pre-workout specifically for muscle pumps, I won’t be re-buying Transparent Labs Pump. The pumps I get from Bulk or Stim-Free are excellent anyway, and my preference is to keep more well-rounded pre-workouts in my supplement cupboard.
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About The Author
Avi Silverberg is an author, coach, and the Founder of FeastGood.com. Avi has a Master of Science in Exercise Science and has published over 400 articles on the topics of health, exercise, and nutrition.