Our product in use
4.8/5 · 253 verified reviews
HIGH-STIM PRE-WORKOUT

Built for Athletes Who Train Hard.

OP Sentinel delivers clinical doses of L-Citrulline, Betaine, and L-Tyrosine — the ingredients serious lifters actually need. No fillers. No proprietary blends. Just what works.

Order Sentinel — from €42.95
Free shipping over €50 · Delivered tomorrow · 14-day returns
Our product in use
THE FORMULA

No fillers. Only what works.

Every ingredient in OP Sentinel is clinically dosed and listed on the label. No proprietary blends, no hidden amounts — exactly what your body needs to perform.

10g L-Citrulline for maximum pump & endurance

5g Betaine Anhydrous for strength output

5g L-Tyrosine for focus under heavy load

Layered caffeine — no spike, no crash

Real Athletes. Real Results.

"I've tried a lot of pre-workouts. Sentinel is the first one where I can actually feel the citrulline working. Pump is insane, focus is locked in from warm-up to last set. No jitters, no crash."

Tijmen P. — Professional Dutch rugby player
After
Before
Before Sentinel
With Sentinel
Feel the Difference

OP Sentinel is not a stimulant rush. It's controlled, sustained output — from your first set to your last rep. Clinical doses mean you feel exactly what's working and why.

Order Now — from €42.95
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent
High-Output Performance
Clinically Dosed
Enhanced Focus
For Experienced Athletes
Train with Intent

Why Serious Athletes Choose Sentinel

Our product in use

Not for Everyone. Built for You.

OP Sentinel is a high-stimulant product. It's not designed for beginners or low-intensity training. If you train hard and need your pre-workout to keep up — this is it.

Heavy strength training

High-intensity bodybuilding

Late-day or demanding sessions

Athletes who know their stimulant tolerance

Trusted by athletes who train with intent

OP Sentinel: Clinically Dosed. Nothing Hidden.

Every ingredient on the label. Every dose clinically effective. No proprietary blends hiding underdosed ingredients behind a flashy name.

  • Full ingredient transparency — exact doses listed

  • 40 full servings per container

  • Ships next business day
Order Now — Bundle saves 15%

Join Serious Athletes

4.8 253 reviews
4.8 out of 5

"The citrulline pump is real — you can feel the difference in blood flow within 20 minutes. Focus holds all the way through. No jitters, no crash after. Best pre-workout I've used in 4 years of lifting."

Marcus V.

"I was skeptical about a new brand but the formula is transparent and properly dosed. L-Citrulline at 10g is rare at this price point. Energy is clean and I'm still going strong on my last working sets."

Jessica L.

"The layered caffeine system actually works. I've tried stims that hit hard and then drop you — Sentinel stays consistent from warm-up to the end. Clinical dosing, no fluff."

David R.

"Finally a pre-workout that doesn't underdose everything and hide it in a proprietary blend. You know exactly what you're taking and why. Highly recommend for anyone serious about training."

Sarah M.

"Ordered the Flavour Bundle. Sour Raspberry is my go-to now. The focus is different from other pre-workouts — it's not a scattered buzz, it's actual locked-in concentration. Worth every euro."

Chris B.

OP Sentinel vs. Generic Pre-Workouts

Most pre-workouts underdose key ingredients and hide behind proprietary blends. Here's how Sentinel compares.

Order Sentinel
Clinical doses. Full transparency. No shortcuts.
OP Sentinel Generic brands
Full ingredient transparency (no blends)
Clinical dose L-Citrulline (10g)
Clinical dose Betaine (5g)
Layered caffeine (no crash)
No artificial dyes or unnecessary fillers

Straight Answers. No Fluff.

Common questions about OP Sentinel Pre-Workout.

1
What makes OP Sentinel different from other pre-workouts?

Full ingredient transparency. Every dose is listed on the label — no proprietary blends hiding underdosed ingredients. L-Citrulline at 10g, Betaine at 5g, L-Tyrosine at 5g. These are clinical doses, not marketing doses.

2
How do I use OP Sentinel?

Mix 1 scoop (10g) with 300ml water, 20 minutes before training. If you're new to high-stim products, start with half a scoop to assess tolerance. Do not exceed one scoop per 24 hours.

3
Is this suitable for beginners?

No — and we're being honest about that. OP Sentinel is a high-stimulant product designed for experienced athletes. If you're new to pre-workouts, start with something milder. If you train seriously and know your stimulant tolerance, this is built for you.

4
Will I crash after using it?

No. The layered caffeine system is designed specifically to prevent this. You get fast activation and sustained energy without the sharp drop-off that single-source caffeine causes.

5
Does it contain any banned substances?

No. OP Sentinel contains only legal, high-quality ingredients. No banned substances. Full ingredient list is on the label and on the product page.

6
What is the return policy?

Unopened products can be returned within 14 days of delivery. Opened supplements cannot be returned for hygiene reasons.

To request a return, email info@obsidianperformance.nl