An Introduction to Slow Twitch vs. Fast Twitch Muscle - What should you be training?

I decided to start my first ever post on my blog with an article about the two basic types of muscle fibers due to a conversation with a few friends of mine that have been recently lifting. One is a very successful roller hockey player and the other your more common gym enthusiast trying to get a little more built and back in shape after a long departure from organized sports. Here is the answer to a question most people want to know, but do not know where to acquire the right answer.

A lot of the time, even your local gym trainer does not know the answer. Why? Most of the ones I have at least come into contact with tend to be "bodybuilders" - do it for looks, not sport or practical muscle gain. For a lot of people that is enough, but for many others and myself this is not why we go to the gym. The gym for me is a supplementation workout to my sport, which is racquetball.

Before we go into types of muscle I think it is best to summarize the muscle training goals (articles to come will cover these in greater detail, with detailed routines, and meal plans based upon your weight/gender). 

1.) Hypertrophy - This is done to increase the size of muscle cells. Within this group there are two subcategories. One is for bodybuilders and the other is for one repetition Olympic weightlifters. Michael Colgan, a famous Sport Guru (of nutrition, weight lifting,...) would be a little ticked off that Olympic lifting is in this category, but I'll save that for another time. Think about why category 3 and 4 would be more beneficial and why those people training in those categories win gold.

2.) Endurance - This is mostly your runners, people that go to the gym to run like hamsters (I kid, but really?), and cyclists. People that want to do a motion continuous for periods of time usually greater then 45 minutes.

3.) Strength - Producing your maximum force.

4.) Power - How quick the force can be executed.

A lot of programs encompass one or many combinations of the listed categories above. Other muscle categories exist as well.

What is slow-twitch muscle?

Also known as red fibers due to the large number of capillaries. The more capillaries you have the more blood supply that muscle receives. They also have more mitochondria, so they can produce more energy, but as the name would imply they are slow to react. Most of the energy is in the form of muscle glycogen  (carbohydrates that were stored directly in the muscle) and fat. These energy sources burn slow. Slow reactions do not produce a lot of power, but they can output large amounts of energy over long periods of time. When thinking slow-twitch, think of the endurance component of your muscle.

If you have been to the gym before you have probably seen the biggest people at the gym grunting while short tossing (lack of full motion) weights. They are not controlling the motion of the weights. What does this "pump" do? It temporarily increases the muscle size and hardness from increased blood and water flow. Over time this leads to growing more capillaries and teaches the muscle to hold more water. This will not help with athletic related motions. DO NOT DO THIS IS YOU WANT TO PLAY SPORTS! This methodology will turn a workout intended to increase fast-twitch muscle into a waste of time and a step in the wrong direction.

Bodybuilding techniques produce large inefficient muscles with lots of slow-twitch fibers. Over time these slow-twitch muscle bulk interferes with the efficiency of the fast twitch, rendering them worthless. Being able to fire your fast-twitch muscle quickly is important. You want lean muscle that is not weighed down by excess bulk. If you want to compete in sports leave the “pump and burn” workout for the beach boys.

If you’re purely an endurance athlete don’t waste your time in the gym when you could be improving your time of your run and efficiency of your movements by simply running (this does not apply to sprinters or fast-twitch muscle runners).

What is fast-twitch muscle?

The complete opposite of slow-twitch. It is white, does not require a large supply of oxygen, contains more contractile proteins, and has more neurotransmitters (finer muscle control).  The major difference is the ability to produce force quickly from larger supplies of creatine phosphate, which regenerates adenosine triphosphate (ATP), your primary energy molecule. This allows for swift maximum force, but for very short periods of time. Think about fast-twitch fibers as the power component of your muscle.

If you are curious to learn more physiological knowledge about fast twitch muscles I recommend reading about the types of fast twitch. Authors usually break them into 2 or 3 classes and each has specific advantages/disadvantages over each other.

Lets better understand why quick motion is more important in sports than slow motion to output power. Lets refresh your basic physics knowledge.

Kinetic Energy (KE) = 1/2 mv ² (for you nerds, like myself, I understood so much more once this was pointed out to me).

Lets see how this works.  A college football player weights 86 kg (190lbs) and he is going to attempt to tackle another player. 

When he runs at 4.4704 m/s (10mph) he produces 861 J (Joules of energy).

When he runs at 8.9408 m/s (20mph) he produces 3445 J.

That's a massive difference!

That's the difference between you tackling the player or him running over you. 

I will leave you today with 3 major tips for training fast-twitch fibers.

1.) By the 5th rep most of your fast twitch muscles have stopped firing (Lieber RL. Skeletal Muscle: Structure and Function. Baltimore: Williams and Wilkins, 1992.). Keep your reps low. Keep your sets limited to 1 warm-up motion and 2 additional sets. Anymore then that is a waste of time and the beginning of slow-twitch growth.

2.) Use heavy weights that barely let you finish your short sets. Light weights grow slow-twitch fibers because they do not rip your muscles. The burn you are feeling using light weights is purely a build-up of lactic acid.

3.) Avoid slow up/slow down movements of your weights. Trigger your fast-twitch fibers with quick; full range up motion and then control the weight going down.

Lets recap (its a lot of material to take in quickly):

Slow-twitch muscle should be gained by people training/competing in long time period events. It is better to train these muscles doing your own sport than in the gym, unless you’re a bodybuilder. There are slight exceptions, like everything in life, but for the most part I would say this is a golden rule. 

Fast-twitch muscle is designed for sports requiring agility and speed. Remember KE = 1/2 mv ². Keep you reps and sets low in quantity, use heavy weights, and fire your fast-twitch fibers during lifts. 

Thanks for reading. Hope this is a good start to your understanding of different muscles and how to train them. Look for more details in future posts.

You’re one step closer to happiness,

Vital Lifestyle