A science-based leg workout for max muscle growth

Posted by Dayne Hudson in Muscle Building

Estimated reading time: 7mins

A science-based leg workout for max muscle growth

The best leg exercises for muscle growth

Let's start from scratch -- the word quad obviously means four because there are four muscles within your quadriceps:

Leg Muscles Quadriceps

So, there are all the four muscles in your "quads."

And with that, this 2022 study investigated a few different crown-favourite leg exercises:

  • Squats
  • Split squats
  • Step-ups

And it wanted to see which exercise worked which of these quadricep muscles the most, and how much.

It also looked at muscles within the hamstrings, glutes, and calves. And all exercises were found to work the:

  • gluteus maximus
  • m. gluteus medius
  • vastus lateralis
  • m. vastus medius
  • m. vastus intermedius
  • m. semitendinosus
  • m. semimembranosus
  • m. biceps femoris long head
  • m. soleus
  • m. gastrocnemius lateralis
  • m. gastrocnemius medialis

In other words, they worked the quads, hamstrings, calves, and glutes.

But here's where it gets interesting:

"In addition, load-dependent increases in m. gluteus maximus, vastus lateralis, m. vastus medius, m. vastus intermedius, and m. biceps femoris long head forces were often more pronounced during the split squat and step up than the squat across the range of loads used in this study."


In English, this means that split squats work our glutes, quads (THREE of the four heads!), and long head of the hamstrings BETTER than squats.

One more time: split squats work our glutes, quads (THREE of the heads!), and long head of the hamstrings BETTER than squats.

But does that mean squats are out?

Absolutely not.

Because they are still a vital exercise that allows you to really load up your quads and test them.

And the squats are still a multi-joint exercise that works our quads well.

But there's still one big muscle it doesn't hit that well: the rectus femoris.

And it's a big muscle. Here's a reminder:

Rectus Femoris

EMG studies show us that while the aforementioned vastus muscles contract well during the squat, the rectus femoris only contracts about half as much. For example, this study found that the squats didn't grow the rectus femoris adequately.

But there's no reason to be concerned because we can grow our rectus femoris with leg extensions.

This study found leg extensions resulted in more growth of the rectus femoris (26%) than the vastus medialis (12%), the vastus intermedius (6%), and the vastus lateralis (11%) after 12 weeks of training.

So, you can see what's happening here. Right before our eyes, the program is coming together based on the findings of science: the squats will work 3 of 4 muscles, Bulgarian split squats will be even better, and leg extensions will make up for the inadequate growth of the rectus femoris.

Other research has compared:

And has found the rectus femoris to be activated more during Spanish squats than the wall squat and the general squat. It also activated the vastus lateralis more, too!

So, adding in some Spanish squats can help bring out the rectus femoris along with leg extensions.

So, with that being said, here's a great place to start:

Leg training workout for maximal muscle growth

5 x barbell back squats

4 x Bulgarian split squats (do these with dumbells or kettlebells)

5 x leg extensions

3 x Spanish squats

Rep ranges can be anywhere from 4-6 right up 25.

If you're training until muscle failure, you'll grow muscle either way.

So now you've got your exercises, but that's only half the story.

You need to ensure you're practising the principle of Progressive Overload in your leg training.

Progressive overload with leg training

So, what is it exactly? It's increasing the workload for muscles beyond present capacity.

And this is what induces further muscle growth.

Adding more weight to the bar is critical for muscle growth.
Adding more weight to the bar is critical for muscle growth.

Research shows we can practice progressive overload in the following four ways:

  1. Increasing the amount of weight we lift
  2. Increasing the training volume by increasing the number of reps, sets, or exercises performed
  3. Altering rest periods
  4. Increasing rep speed during lighter loads

Research tells us the most popular method is number 1.

And this falls in line with the first principle of muscle growth, mechanical tension; the tension a muscle is under in response to the load being lifted.

In other words, lifting heavy induces more mechanical tension, one of the three principles of muscle growth:

  1. Mechanical Tension
  2. Metabolic Stress
  3. Muscle Damage

Implementing progressive overload for maximal quadricep growth

Progressive overload should be slowly implemented into your leg training program.

But how slowly?

Well, research suggests that changes in total training volume (reps, sets, load) be made in increments of 2.5% to 5.0% per week to avoid the chance of overtraining.

Now whilst this all seems like common sense, no one at the gym is really doing it!

It's not uncommon to see certain gym-goers do the same volume and weight, week in and week out.

This is why most people's physiques never change.

The importance of progressive overload for muscle growth

In order for muscle to keep growing, it must be tested beyond what it is used to.

The same principle applies to most things in life; we don't get better by doing what we've always done!

Specifically, as muscles become more capable of producing greater force, power or endurance, it's time to increase the workload.

Because without these forced measures, muscle adaptations (like growth) can't occur.

And if we chose to not adapt, then we will hit a plateau.

But it's a balancing act; we must continue to lift weights with enough frequency, weight, and time, to allow for progressive overload to occur without producing fatigue.

Of course, adding more weight to the bar leads to an increase in strength, which is partially due to an increase in muscle size.

But this isn't the only way to grow muscle, of course. Lighter loads help as we went through, too.

The bottom line on a science-based leg workout

Different quadricep exercises will work the different muscles of the quadricep. The squats will work the vastus lateralis, vastus medialis, and vastus intermedius, but not the large rectus femoris as effectively.

But we can make up for that with leg extensions, and Spanish squats, which work the rectus femoris better than the general squat, and the vastus lateralis, too!

Bulgarian split squats work the vastus lateralis, vastus medialis, and vastus intermedius better than the normal squat in one study.

By performing all exercises, with the principle of progressive overload, we're giving ourselves a great chance at maximal quadricep growth!


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