Muscle Growth (Hypertrophy)

See “Summary & Conclusion” at the bottom for a concise takeaway.

Muscular hypertrophy can be a very confusing topic, and the billions of dollars spent annually in pursuit of looking bigger, more toned, or “shredded”, have only made the topic murkier.

Starting with the basics, muscle hypertrophy is generally considered an increase in size or number of muscles fibers in skeletal muscles. We differentiate skeletal muscle from smooth and cardiac muscles, or other types of muscle in the human body because skeletal muscle is the only type we have conscious control over.

Muscle Physiology

Skeletal muscles come in a variety of shapes and sizes, largely based on their connection points (tendons attached to bone). For example, bicep muscles are considered “fusiform” because they connect to two distinct tendons (one by the elbow, the other by the shoulder), while the pectoralis muscles (chest), are considered “convergent” because they have a single tendon connection point, also near the shoulder, while the rest is fused to your chest.

You don’t need to know all the different forms of muscle architecture to get bigger or fitter, but it’s important to understand that muscles move and pull in different ways. Knowing how a muscle moves helps us understand how we should exercise in order to influence that muscle.

Because if you don’t fire it, why would it grow?

Now, how do muscles work, and what does “firing” mean? Firing is the catch all term we use to refer to muscle contraction without getting overly scientific. Skeletal muscle is made up of bundles of muscle fibers, which all work together in unison to contract and pull on the connection points like a system of ropes and levers. Muscle fibers contract when two alternating protein filaments, myosin and actin, ratchet together and past each other, thereby shortening the fiber. Zooming out, this process occurs in every fiber within a given muscle, and so we see a “shortening” of the muscle during a contraction.

If you hang an arm by your side and lift your hand up towards your shoulder, you will see your bicep contract and shorten, and as you move your hand back down again you will see it lengthen.

In addition to muscle architecture and function, we also have various muscle fiber types, specially types I, IIa, and IIx (you do not have type IIb, that’s in rats, I have been yelled at for that). Type I muscle fibers, sometimes called “slow-twitch” are fibers that contract relatively slowly, but are very fatigue resistant. Muscles with a lot of type I fibers are generally postural muscles (the soleus muscle in your calf, your core musculature, your neck muscles, etc), because they have to stay active for a very long time. Type II muscle fibers, both a and x, are called “fast-twitch”, and make up most of the highly visible muscles (quadriceps, pectoralis, bicep, gluteus, etc).

Finally, it's important to note that muscles have different compositions of slow and fast twitch fibers, which is based on both genetics and training. No one is 100% fast twitch or 100% slow twitch, but some have more than others, which tends to present in peoples preferred sports. For example, marathon runners have a lot of slow twitch fibers while sprinters have a lot of fast twitch fibers.

Practical Muscle Hypertrophy 

Now you have a lot of information about muscles you didn’t ask for, what does it all mean?

At minimum, to stimulate muscle growth you to pull your muscles in the right direction, you need to contract them quite hard, and you should focus on muscles with more fast twitch fibers.

Now this shouldn’t be a huge surprise, but how do we put this into practice? To continue past the minimum of muscle growth, we also need to “damage” the muscle, then focus on heavily on recovery. When we perform exercises that cause high levels of muscle protein degradation (damage), there will be a corresponding activation of cells and molecules that will overcompensate  during recovery in anticipation of future damage.

So the big question, how do we cause this muscle protein degradation?

Typically, lots of sets of 8-12 reps at relatively high intensity.

There are a lot of different ways people try to grow muscle, there are cluster sets, drop sets, pyramids sets, and tons of other bodybuilding strategies. Ultimately, they all follow the same principle of trying to cause muscle protein degradation by lifting relatively heavy weights a lot.

This is also why people trying to build muscle tend to target specific parts of the body on different days, because they want the damaged muscle to recover before working it again. This practice underlines how important the intensity of the work should be.

Here’s a quick example workout highlighting all the above principles:

In this workout we have a lot of sets with reps of a relatively high intensity, and we’re targeting the specific direction that the pectoralis muscle pulls. Is it the most optimal workout for everyone? Probably not, there is no such thing as a universally optimal exercise, but I do know that the target muscle will be getting a workout.

As I’ve discussed above, what we’re really looking for when it comes to growth is muscle protein degradation (muscle damage), and that comes from a balance of volume and intensity. When you train at heavier loads, you might not see all the growth you’re looking for. Powerlifters, who seek pure strength, will typically have smaller muscles than bodybuilders but be able to lift larger loads. While all types of resistance training will increase skeletal muscle strength, we know that lifting very heavy loads with less frequency (eg. 3 x 3 sets of deadlifts) will increase raw strength without necessarily causing major muscle growth. This is due to a host of factors and theories around neuromuscular coordination and different forms of fiber hypertrophy, but the takeaway here is if you lift very heavy loads for a few reps, and aren’t getting the growth you want, you may want to investigate higher volumes of lighter weights.

Why Should You Increase Your Muscle Mass?

For most people, muscle growth is an excellent tool for increasing your total quantity of metabolically active tissue, which leads to sustainable fat loss and improved body composition. It will support greater strength gains in runners, while placing less acute strain on tendons and ligaments, and can even increase endurance when correctly programmed. While hypertrophy workouts aren’t the main path to maximal strength, simply having more muscle mass is going to contribute to your strength, and your ability to build strength.

In short, muscle growth is not just for bodybuilders, who represent the highest possible level of muscle growth. Just like most people don’t run expecting to become an Olympic marathoner, you can also grow muscle on your terms without becoming huge.

I’ve heard from a lot of people concerned about getting “bulky” while lifting weights, but it’s important to remember that this isn’t easy. Some people train for years to achieve 30lbs of muscle growth, given a natural average while training hard is 2-5lbs a month. You don’t need to become Arnold Schwarzenegger to see the benefits of muscle growth, but knowing the science behind how muscles grow can be a powerful tool.

Summary & Conclusion

Remember, muscles come in a variety of shapes and forms, knowing how they move, and how they contract, can help inform your training.

When it comes to muscle growth we want to follow a formula of high sets of relatively high reps, with a relatively high intensity. Eg:

-5 sets of 8 reps of a weight you can lift with pretty good form for 8-10 times max.

-4 sets of 6 reps of a weight you can lift 7-8 times max.

-4 sets of 10 reps of a weight you can lift 12 times max AFTER the previous sets.

Essentially, really make the muscle you want bigger do the WORK, then rest it for at least 48 hours.

This doesn’t just apply to bodybuilders, everyone can benefit from muscle growth, even if it’s only a couple of pounds. Runners, climbers, cyclists, your grandma, it works for everyone. The benefits include better body composition, more strength, muscular endurance, and even power.

If you need more advice on muscle growth, workouts, or how to effectively incorporate it into your current training, give us a shout!