The muscle pump: Why your muscles look bigger during workouts

How to temporarily get Schwarzenegger-worthy muscles.

Amanda Capritto
4 min read

Learn what "chasing the pump" means.

Luis Alvarez/Getty Images

Ever wanted to see your muscles literally grow before your eyes? You totally can with a muscle pump. Most fitness enthusiasts spend at least some time "chasing the pump" regardless of what their overall goal is. That instant muscle growth just makes you feel strong, accomplished and, to be quite honest, super sexy

But what exactly is going on when you get a muscle pump? How is it possible that your muscles grow so much in just an hour, and the next morning they're back to normal? I answer those questions and more in this no-nonsense guide to muscle pumps -- including whether or not the muscle pump actually helps you build muscle

Read more: How to lose fat and build muscle at the same time 

What is a muscle pump? 

illustration of a bicep muscle flexed

A muscle pump happens when your muscles seemingly grow before your eyes.

Malte Mueller/Getty Images.

"Muscle pump" is really just fitness slang for a phenomenon called transient hypertrophy. Hypertrophy refers to the growth of a muscle, and transient means it's only temporary. Transient hypertrophy, or the sought-after muscle pump, is a rather complex physiological process, so I'll spare you the jargon. 

In short, a muscle pump occurs when fluids, including water and blood, accumulate in your muscles during movement. This happens in response to two primary triggers: 

  • Lactic acid begins to build up in your working muscles and draws water into them. 
  • Your heart pumps more blood to your working muscles because they need more oxygen and nutrients to power them. 

This surge of fluids causes your muscle cells to swell up, making your muscles look larger than usual. When you get a muscle pump, it might feel like your muscles are "full," in a sense. 

Read more: Cardio before or after weight lifting? Which is better for muscle growth?

How do you get a muscle pump?

A young man performing bicep curls at the gym.

Lifting weights is the best way to get a muscle pump.

Inti St Clair/Getty Images

Most people get a muscle pump from lifting weights -- in fact, bodybuilders take advantage of this transient hypertrophy phenomenon before they go on stage at a bodybuilding competition to make their muscles appear larger than they really are. 

You could theoretically get a muscle pump doing anything that increases circulation to your muscles, but research (and anecdotes from any die-hard lifter) suggests that high-volume weight training is the best way to get a muscle pump. 

High-volume resistance training means a lot of reps and a lot of sets, typically with shorter rest periods. You can achieve high-volume training by manipulating a few variables:

  • You can do more reps
  • You can do more sets (five sets of 10 instead of your usual three sets of 10) 
  • You can shorten your rest interval (60-second rest versus your usual two-minute rest)

In general, the more contractions your muscles make, the more fluid engorges your muscles. Serious bodybuilders and weightlifters may even follow "pump training" protocols, wherein the primary goal is achieving a muscle pump. Pump training focuses solely on muscle contraction and increasing blood flow to working muscles.

If you're really serious about maximizing your muscle pump, make sure to hydrate before your workout to encourage more water uptake by your muscles. There's limited evidence that eating carbohydrates and supplementing with creatine before your workouts can also increase the muscle pump. 

Citrulline malate is another supplement that might help. This supplement  enhances nitric oxide production, and nitric oxide dilates your blood vessels, thus encouraging blood flow.

Read more: Does lifting weights make women bulky?

Does a muscle pump help you build muscle? 

A young woman preparing to perform a deadlift in a gym.

Don't chase the pump as your primary method of building muscle.

Getty Images

Yes and no. In the fitness industry, the muscle pump is one of those controversial things that some pros swear by and other pros scoff at. 

There's not much research specifically surrounding the muscle pump and its contribution to muscle growth, but there's a key correlation we can make: Muscle pumps happen in response to high-volume training, and research shows that high-volume training is key for building muscle, especially in people who have experience with strength training. 

However, you can't discount the proof that low-volume weight training with heavier loads also contributes to muscle growth, nor the fact that volume loses its efficacy as you get more advanced. 

The best approach for optimal strength and muscle growth, in my professional opinion, is to follow a balanced training program that includes both low-volume and high-volume days, or to change up your training volume by week. 

For instance, if I was trying to build strength and muscle mass in my legs, I might embark on the following squat plan: 

  • Week one: two squat days per week, five sets of five reps
  • Week two: two squat days per week, four sets of eight reps
  • Week three: three squat days per week, three sets of 10 reps
  • Week four: three squat days per week, two sets of 15 reps 

Read more: How lifting weights revs your metabolism and helps you lose weight

Don't get down if you don't get a pump 

While getting a muscle pump is certainly fun, it shouldn't be your only fitness goal. 

Don't feel bad if your latest weightlifting session didn't leave you with bulging muscles -- the muscle pump is only temporary, anyway, and long-term muscle growth comes from consistent effort, not just one intense workout. 

My best advice: Forget chasing aesthetics. Chase strength and health, and muscle definition will follow. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.