Transparent Labs Bulk Black Pre-Workout Review

Transparent Labs makes some of Pre-Workout World’s favorite products, including their original Bulk. So what about their newly re-formulated BULK BLACK? Does it stand up to the Transparent Labs reputation? 


Our reviews are based on testing with our unique, multi-point methodology. We may earn a commission on your purchase of some products.

FunctionBulk Black Pre-Workout Primary Ingredient(s)Score
EnergyOrganic Caffeine (Purcaf), Theobromine90
FocusCaffeine, L-Tyrosine80
PumpCitrulline Malate, Taurine90
EnduranceBeta-alanine, Taurine100
MoodL-Tyrosine, Theobromine, L-Theanine90
Strength & Body CompBetaine Anhydrous80
Flavors5 flavors as of this review75
Ingredient QualityGood ingredient selection, good dosage, all natural 80
Feel/VibeStrong beta-alanine tingles, low stim 80
Overall Score85

Based on my personal testing and research, I’m happy to say Bulk Black does not disappoint. Transparent Labs has put together such a well-thought-out formula that this product is as great for the most demanding muscle head as for the beginner athlete. I got such a satisfying feeling from the energy and pump that I’d be glad to use it every day. 

Pre-Workout World Review are based on these key factors:

  • Ingredients: Backed by scientific research? Optimally dosed?
  • Flavors: Plenty of choices? Good flavor?
  • Overall Effect: How does this product enhance our workout? 

With Pre-Workout World’s team of amateur athletes, fitness professionals, and researchers, you can find the pre-workout product that works best for your unique body and fitness goals.

Medical Disclaimer: This article is not intended as a substitute for medical advice. Its sole purpose is to educate and inform. Consult a licensed healthcare provider before beginning any fitness or nutritional program. 


With its all-black-everything look, Transparent Labs is really leaning into the Bulk Black vibe. Black letters on a black background are, honestly, a little hard to read unless you get it in the light just right. 

I like the design on top that says “Clinically Dosed, 100% Natural. No Artificial Colors or Sweeteners.” It underlines Transparent Labs whole deal – transparency.

I hate to nitpick because I like the security of a good seal, but Transparent Labs went a little overboard. Maybe a lot overboard. I ripped a whole layer off before I could finally break through the seal. Transparent Labs must have some ex-welders working in the factory. 

Get out the blowtorch!

Open it up, there’s the desiccant and the scoop right on top for easy access. Not a strong scent, I get a whiff of fruit. The powder isn’t super-fine like a lot of pre-workouts, which makes me think I might have a settling issue. 


I mixed up the recommended 1 scoop in 8oz of water to get the full effect. You might do more or less water depending on your preference. Some of us don’t like a lot of liquid sloshing around during a workout. 

I picked the watermelon peach flavor for this review. Sounded decent. Took a sip and man, it’s bitter. I get a hint of watermelon, no peach at all, and everything is overwhelmed by bitterness. 

A lot of pre-workouts use artificial sweeteners like sucralose and ace K that taste bitter to some people. But I’ve never tasted an artificially-flavored pre that was as bitter as Bulk Black. 

I was right on the settling, too – those big particles head straight for the bottom of the shaker within seconds. I needed a good shake between every sip. It’s a very nice reddish-pink color, though, from natural beet root powder. 

Look, whether you want to deal with the flavor is your choice. I go to a pre-workout for the energy and focus, so I’m not worried about flavor. I’ll hold my nose and suck it down if it works. But if you can’t do that, consider this your warning. 


In Pre-Workout World reviews, the Big 3 ingredients are key:

  • Caffeine
  • Citrulline
  • Beta Alanine 

I look for ingredients for focus, pump, strength support, and the whole nine yards, but the Big 3 are basic to a good pre-workout. If they’re not right, I’m not interested.

Transparent Labs Bulk Black325mg8g4g


One of the smartest changes Bulk Black has made from their older formula is upping the caffeine – 325mg of caffeine. The other thing they’re doing right is skipping the caffeine anhydrous that most other pre-workouts use for pure caffeine. 

Transparent Labs is using trademarked organic caffeine from green coffee by the name Purcaf. The effect is real. It’s more like drinking coffee than the more artificial jittery feeling I sometimes get from too much caffeine anhydrous. 

Bulk Black also includes 50mg of theobromine. In tests, scientists see evidence that theobromine (a cacao derivative) has similar energy effects as caffeine with less negative effects. There’s not a clear consensus on the optimal dosage, though, so it’s hard to say if 50mg does much.

The combination gave me a smooth, feel-good energy, no jitters or head-exploding, just ready to go workout. In my opinion, other pre-workout companies should consider pure caffeine. 


Beta-alanine is one of Pre-Workout World’s Big 3, and Bulk Black is dialed in with 4g. 4g of beta-alanine isn’t the highest dose I’ve seen, but it’s well above average and enough to give you some real tingles. 

It’s also the dosage typically used in research, so there’s solid scientific backing to show that beta has some real results at that level. 

I felt the beta tingles hit first, and that energy carried me right through my workout. But to add to the endurance, Bulk Black throws in 1.3g of taurine – right in line with optimal dosing and above what you typically get with pre-workout formulas. So far, everything’s lining up with Bulk Black. 


I can’t say enough about how well Transparent Labs has planned its pump ingredients in Bulk Black. With 8g of citrulline malate, Bulk Black is right in there with our optimal dosing. Plus, they’ve made a good choice going with citrulline malate, where most competitors use L-citrulline. 

Adding malic acid to the citrulline can add an energy boost by increasing ATP production, on top of the vasodilation effect. Where the positive impact of l-citrulline has been shown consistently, there’s still some research to be done to find the optimal dose of CM.  

What I can say is that with the combo of CM and taurine, I got a good dry, vascular pump that I could feel throughout my body. Citrulline really opens up those blood vessels and get the juices flowing. 


If you’re working out – especially if you’re bodybuilding or powerlifting – you want a pre-workout with some strength support. Typically, that’s coming from creatine or betaine. Transparent Labs is giving you 2.5g of betaine anhydrous under the trademarked name BetaPure. That puts Bulk Black right in line with our optimal dose

If you’re looking for creatine, you’re going to have to supply your own. Not a big deal, but I like if a pre-workout gets a dose in so I don’t have to add on other products. Just don’t want a lot of stuff in my stomach slowing me down. 


We love our nootropics at Pre-Workout World, and Bulk Black is giving you a nice suite of focus and mood-enhancing ingredients: 

  • L-tyrosine 1g
  • Theobromine 50mg
  • L-Theanine 200mg 

L-tyrosine is a good choice, but 2g is what I would consider an optimal dose based on research. However, research is clear in showing that the combo of caffeine, tyrosine, and theanine has an enhancing effect. 

The nice thing about L-theanine (an amino acid found in green tea) is that it levels out the caffeine, since it has a relaxing effect, but it doesn’t counteract the stim – just calms the jitters. 

I mentioned theobromine earlier, but I’ll mention it here again for its effect on focus. It’s not a substitute for caffeine, but it brings that energy without the same kind of stim effect. 

When it comes to focus and mood, Bulk Black was a nice surprise – it gave me a strong sense of well-being and mood enhancement, much more than I would expect from just looking at the label. Bulk Black doesn’t look like a serious nootropic product on paper, but it has just the right combination of ingredients to make me feel good through a session. 


Lately I’ve been seeing a lot of pre-workouts that are skipping the electrolytes, and that doesn’t sit well with me. Like with creatine, it means I have to supplement my supplement. 

Bulk Black includes 150mg of sodium chloride and 100mg of potassium chloride, which is perfect for electrolyte support. It’s just 7% and 2% (respectively) of the daily value, so you’re not overdoing the electrolytes. 

Transparent Labs has also included huge doses of:

  • Vitamin D 
  • Vitamin B6
  • Vitamin B12
  • Zinc

It’s not necessary, and I’m used to not seeing vitamins in a pre-workout, but it’s nice to know those are taken care of for the day. 


At the time of this review, Transparent Labs makes Bulk Black in 5 flavors: 

  • Cherry Kiwi
  • Blue Raspberry
  • Peach Mango
  • Sour Gummy
  • Black Cherry 

Unfortunately, as I mentioned earlier, flavors don’t seem to be Transparent Labs’ strong suit, at least not the Watermelon Peach I reviewed. (Note: Watermelon Peach was out of stock at time of publication.) Maybe their commitment to natural flavors means they’re not going to knock it out of the park. 


Transparent Labs takes pride in making products with no artificial colors, flavors, or sweeteners. So unlike most pres, Bulk Black uses stevia for sweetness. 

Now, a lot of people complain about artificial sweeteners having a bitter aftertaste. But the stevia extract in Bulk Black, I have to say, might be the most bitter I have experienced. Maybe a lot of pre-workouts with artificial flavors and sweeteners have thrown off my sense of taste. It’s like lemon juice after a diet of Kool-Aid. 

Whatever the case, if you don’t like stevia, either try a different product, or be ready to chug and tough it out. 


Just about all of the best pre-workout supplements are going to have some side effects for users who are sensitive to caffeine or beta-alanine. They’re the ingredients that fuel a good pre-workout. 

So with 325mg of caffeine, some users are going to feel over stimulated and jittery. For my part, I think the addition of L-theanine helps mellow that out some. I just felt a sense of urgency, but not nerves. 

The same goes for beta-alanine. Technically, the old beta tingles might be considered a side effect. But if you’re used to pre-workout supplements, that’s the sign that it’s working. Like caffeine, your beta-alanine tolerance is something you’re going to have to figure out on your own, by trial and error. 


Transparent Labs Bulk Black is a really, really great product. The dosages go along with recommended levels, they’re incredibly well-balanced, and they felt very effective for me. I think I could use it every day. 

I want to love everything about it, but the taste is pretty gnarly. No getting around that, gotta go through it. 

Bulk Black should work as well for a serious bodybuilder as it would for a beginner. There’s nothing so extreme that a beginner has anything to be afraid of, but it’s a solid daily driver for a stim junkie’s intense workouts. 


  • Great mix of ingredients
  • Optimal dosages 
  • Excellent pump
  • Sustained energy
  • Overall feeling of well-being


  • Flavor
  • Flavor, again
  • Did I mention flavor?
  • Also, a little more strength support with creatine


  • Stim-heads
  • Beginners
  • Daily users
  • Long sets 


  • Users who want extreme sweetness and flavor
  • Caffeine intolerant users

Scientific Studies

1. Eva Martínez-Pinilla, Ainhoa Oñatibia-Astibia, and Rafael Franco. The relevance of theobromine for the beneficial effects of cocoa consumption

2. Eric T. Trexler, Abbie E. Smith-Ryan, Jeffrey R. Stout, Jay R. Hoffman, Colin D. Wilborn, Craig Sale, Richard B. Kreider, Ralf Jäger, Conrad P. Earnest, Laurent Bannock, Bill Campbell, Douglas Kalman, Tim N. Ziegenfuss, and Jose Antonio. International society of sports nutrition position stand: Beta-Alanine

3. Jennifer A. Kurtz, Trisha A. VanDusseldorp, J. Andrew Doyle & Jeffrey S. Otis. Taurine in sports and exercise

4. Lewis A. Gough, S. Andy Sparks, Lars R. McNaughton, Matthew F. Higgins, Josh W. Newbury, Eric Trexler, Mark A. Faghy, and Craig A. Bridge. A critical review of citrulline malate supplementation and exercise performance

5. Van Every, Derrick W.; Plotkin, Daniel L.; Delcastillo, Kenneth; Cholewa, Jason; Schoenfeld, Brad J. Betaine Supplementation: A Critical Review of Its Efficacy for Improving Muscle Strength, Power, and Body Composition

6. Javier Zaragoza, Grant Tinsley, Stacie Urbina, Katelyn Villa, Emily Santos, Angelie Juaneza, Matthias Tinnin, Cory Davidson, Susan Mitmesser, Zhiying Zhang, and Lem Taylor. Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes