Big Leg Pump Workout for Mass with Regan Grimes

Do you constantly wear pants to the gym, hoping nobody sees that you’ve been phoning in your leg workouts for the last year?

Well, we’ve got just the thing you need, courtesy of Primeval Labs athlete and IFBB Pro Bodybuilder Regan Grimes.

Regan takes you step-by-step through his complete leg pump exercise, showing you had to add some mass to quads, glutes, and hamstrings with his Big Pump Leg Workout.

Here’s the complete leg day pump workout:

Regan Grimes: Big Leg Pump Workout for Mass




Hack Squat (with bands)



Lying Hamstring Curl



Vertical Leg Press



Seated Leg Curl



Leg Press



Leg Extension



Regan Grimes Mass Building Tips for Legs

Hack Squat (with bands)

The hack squat is a machine-based alternative to the barbell back squat that’s great for building bigger, stronger quads. Since less stabilization is involved with machine-based exercises, you can heavy up the weight and focus on building a strong mind-muscle connection.

And for those who may not feel comfortable squatting with the bar on their back or those with a history of low back injuries, the hack squat represents an effective way to train the upper legs as it helps avoid compression of your back. 

For this workout, Regan is performing reverse band hack squats.

The reverse band hack squat may be more suitable for those who typically experience knee pain when squatting as the reverse setup of the bands makes the load lightest at the bottom of the movement (thereby taking pressure off of the knees), which is typically the spot where it is the heaviest.

Essentially, this variation of the hack squat allows you to get the benefits of heavier weights during the exercise while also sparing wear and tear on the knees at the bottom of the movement.

Another take on banded hack squats is to use the regular setup where the bands are wrapped around the pegs at the bottom of the machine rather than the top. In this setup, the bands are resisting on the way up, making the lockout portion of the lift the most challenging.

Experiment with both the banded and reverse banded hack squat to find the one that’s best for your training goals and biomechanics.

As you noticed in the video, Regan isn’t completely locking out at the top of each rep. By only going up three-quarters of the way, he maintains tension on the quads throughout the entire exercise, placing maximal stress on the muscles.

Leg Curls (Seated and Lying)

You’ll notice that Regan uses two different variations of leg curls in this workout -- seated leg curls and lying leg curls.

Why use both?

Well, due to the different angle of force and body position, you’ll be able to generate a slightly different stimulus in the hamstrings with each variation.

If your gym doesn’t have one or both types of leg curl machine, feel free to swap in stability ball leg curls and kettlebell swings. Stability ball leg curls are a phenomenal leg curl alternative as it trains both functions of the hamstrings at the same time -- knee flexion and hip extension.

Typical hamstring exercises (RDLs, seated leg curls, etc.) tend to only address one function of the hamstrings.

As with all leg curl exercises, make sure to get a firm squeeze on the hamstrings at the top of the movement, and use a controlled eccentric on the way down to thoroughly tax the muscle fibers on the backside of your legs.

Additionally, pointing your toes also helps eliminate assistance from the calves when performing the exercise.

Vertical Leg Press

The vertical leg press is arguably one of the most intriguing leg exercise machines ever developed. Typical leg presses either have you pressing horizontally (as with a seated leg press) or at a 45-degree angle, which is the most common one you’ll find at commercial gyms.

However, the vertical leg press has you lying flat on your back with the weight-bearing straight down on you with gravity.

Since the weights are moving perfectly in line with gravity, you’ll be able to get “more” from a lighter weight compared to what you would normally use on a 45-degree or seated leg press machine due to the weights being in the same direction as gravity. 

As with other leg press exercises, make sure your hips do not come off the pad at the bottom of the movement and do not let your lower back round. That is a one-way ticket to getting injured.

If your gym does not have a vertical leg press machine, consider substituting in another quad-focused leg exercise, such as Bulgarian split squats, split squats, lunges, or goblet squats.

45-Degree Leg Press

Moving on to the 45-degree leg press allows us to play with some different foot placements on the sled to help bring up any aspects of the quads that may be lacking.

For instance, if you want to work more on your outer quad sweep, you would want to use a narrow stance with your feet close together. If you want to emphasize more of the inner thigh, you would want to use a slightly wider stander where your feet are outside of your hips.

Additionally, if you want to work your hamstrings more on the leg press (because your quads are still reeling from the vertical leg press), you can place your feet higher on the sled. Conversely, if you want more quad-emphasis and less hamstring, place your feet lower on the sled.

Regan Grimes Workout Stack

Mega Pre

Before every gym session, Regan takes two scoops of Primeval Labs Mega Pre white.

Mega Pre is a stimulant-free pre-workout supplement designed to enhance blood flow, performance, and muscle pumps.

Contained in every serving of Mega Pre are quality doses of research-backed ingredients, including L-Citrulline, Betaine, elevATP, and VasoDrive-AP.

Since Mega Pre contains no stimulants, it can be used any time of day (morning, noon, and night) for a great training session without having to worry about feeling jittery or having difficulty sleeping.


After a tough workout, your muscles are screaming for some much-needed nutrition.

Regan’s post-workout meal of choice is Primeval Labs’ great-tasting protein powder -- ISOLIT.

ISOLIT contains 100% cold-processed whey protein isolate, supplying 25 grams of high-quality protein per serving.

ISOLIT mixes easily, tastes delicious, comes in SEVEN flavors, and provides your muscles with a fast-digesting, highly bioavailable source of protein.