Nitric oxide (NO) boosters, also called “pump supplements,” are held in high regard by fitness fiends for giving that sought-after muscle pump, improving blood flow, and even supporting recovery. But despite the many people who regularly use these supplements, there remains some confusion about when to take them. Before your workout? After? Both? The answer, which may not surprise you, is that it all depends on your goals and routine.
Here, I’ll break it down, starting with how NO-boosters work. I’ll get into why people use them pre-workout, as well as why they might be just as good (or even better) post-workout. Ready? Let’s go.
What Are NO-Boosters?
Think of nitric oxide as adding another lane to your body’s highways: It helps blood flow smoothly by relaxing and widening blood vessels. This process is called vasodilation.
Increases in nitric oxide production that occur during exercise are the reason you experience epic muscle pumps at the gym. When your body produces more nitric oxide during exercise, it also delivers oxygen and nutrients faster to your working muscles. But here’s the thing: Your body doesn’t just produce nitric oxide out of thin air. It needs raw materials to create it—and that’s where supplements come in. NO-boosters often include ingredients like:
- L-arginine: a building block for NO production.
- L-citrulline: a more efficient precursor to l-arginine.
- Nitrates: Found in foods like beets, your body converts these to NO during exercise.
So, how do these ingredients operate? Here’s a quick science-to-English translation: L-arginine is broken down to produce NO, but it’s not very efficient because most of the l-arginine we consume gets destroyed during digestion. On the other hand, l-citrulline skips that digestion trap and travels to your kidneys, where it gets converted into l-arginine. This makes it a superstar ingredient in pump supplements. As for nitrates? They’re like a slow-burning fuel that gets converted into NO during exercise, especially when oxygen levels are low.
The Benefits of Taking NO-Boosters Pre-Workout
Let’s start with the obvious: Pre-workout supplements are all about maximizing your performance in the gym. Taking a NO-booster before your workout can:
Supercharge Your Performance: Improved blood flow means your muscles get more oxygen and nutrients when they need them most, helping you lift heavier and train harder.
Delay Fatigue: By enhancing oxygen delivery and removing waste products like lactate, NO-boosters can help you push through those last reps.
Enhance “The Pump”: You know that full, tight feeling in your muscles after a killer set? NO-boosters contribute to that by increasing blood volume in the muscles.
Read More: 6 Times A Pump Supplement Comes In Clutch
To maximize these benefits, take your NO-booster about 60 to 90 minutes before hitting the gym. That’s how long it takes for ingredients like l-citrulline (six to eight grams is ideal) or nitrates (go for around 400 milligrams) to be absorbed and kick into high gear. My personal go-to here is a citrulline-based pre-workout (that specifically includes citrulline malate), which is excellent for boosting performance and endurance. Many pump supplements formulated for pre-workout use also contain caffeine for an all-around amp-up.
The Benefits of Taking NO-Boosters Post-Workout
That said, NO-boosters don’t just belong in your pre-workout arsenal. They can be just as beneficial after your workout—especially for recovery. Here’s why:
They Speed Up Recovery: After you’ve crushed your workout, your muscles need nutrients to repair and grow. NO-boosters help by increasing blood flow and nutrient delivery to your muscles.
They Reduce Muscle Soreness: Research shows that l-citrulline-enriched drinks can significantly reduce soreness 24 to 48 hours post-workout. This way, you can get back in the gym faster and stronger.
They Support Long-Term Gains: While most NO studies focus on performance, emerging research suggests they may also promote muscle protein synthesis, the process through which your body builds new muscle.
If recovery is your focus, take your NO-booster immediately after your workout alongside your post-workout meal or shake. This ensures you’re replenishing nutrients and optimizing recovery. I recommend going for a nitrate-based, non-stimulant formula (look for between 400 and 800 milligrams of dietary nitrates) to enhance recovery and reduce muscle soreness.
Timing Your NO-Booster: Pre, Post, or Both?
Now, this is where things get fun. Should you take your NO-booster before your workout, after, or both?
When deciding whether to take a pump supp before or after your workout, it’s important to consider your goals and training phase. For instance, if you’re aiming for a personal record (PR) or tackling an intense workout, prioritizing a pre-workout NO-booster makes sense as it enhances blood flow, strength, and endurance to help you perform at your best (while giving you an epic pump, of course). Think of it as a turbo-charge for your session.
Read More: After Muscle Gains? Make Sure Your Workouts Check These Boxes
Conversely, if you’re in a training phase that involves less recovery time or you’re extra focused on repairing muscle damage, a post-workout NO-booster can be particularly beneficial to speed up recovery and reduce soreness (particularly after grueling sessions).
That said, you can have the best of both worlds here by taking pump supplements before and after your workouts. Just remember to use the right formula for each application. Go for a citrulline-based NO-booster (perhaps with some added stimulant perks) before training and a stim-free option rich in dietary nitrates afterward. By tailoring the type of NO-booster to your timing and goals, you can maximize both performance and recovery without overloading your system. No one needs extra caffeine after hitting the gym, after all.
The Bottom Line
NO-boosters are some of the simplest and most versatile tools in your fitness toolkit. Whether you’re an elite athlete chasing PRs or a weekend warrior trying to recover faster, they’re a great addition to any sports nutrition stack. And they’re not just about the pump! NO-boosters are about unlocking your body’s full potential, both during and after your workouts. Whether you’re looking to hit new performance highs, recover faster, or just feel like a gym legend, timing your NO-booster right can make all the difference.
So, go ahead, down some citrulline before your workout, crush some weights, walk out with your veins popping and muscles bulging, and then sip on a post-workout beet shot while your body rebuilds.
Known as ‘The Muscle Ph.D.,’ Dr. Jacob Wilson has a knack for transforming challenging, complex concepts into understandable lessons that can support your body composition and health goals. A skeletal muscle physiologist and sports nutrition expert, Wilson is a leader in muscle sports nutrition. As the CEO of The Applied Science & Performance Institute, he researches supplementation, nutrition, and their impact on muscle size, strength, and power.