In general, people have two main types of muscle fibers in their bodies - Type 1 (slow twitch) and Type 2 (fast twitch).  

I'm going to describe the main differences between fast twitch and slow twitch muscle fibers, how you can spot a person with a certain muscle fiber type, what happens to muscle fibers as we age, and how you can enhance your post-workout muscle recovery. 

Let's start with slow twitch muscle fibers - also known as Type 1, they have the following main traits:

• They have a smaller fiber size
• Low force production
• Highly fatigue resistant
• Slow contractile force
• Lots of mitochondria, which are the powerhouses of the cells
• Lot of capillaries in and around them to deliver blood for energy
• Lots of myoglobin, which is an oxygen storage protein in the muscles
• They can maintain longer term contractions - think posture

A person with lots of slow twitch muscle fibers will generally look lean - think of a marathon runner.  Lots of lean muscles, made to go on and on without fatiguing. 

Fast twitch muscle fibers (type 1) have these traits: 

• Larger muscle fibers
• High force production
• Short, powerful contractions
• They fatigue rapidly - contractions last for under 10 seconds, typically
• Less blood supply in comparison to they type 2 slow twitch fibers

Whereas a person with a majority of fast twitch muscle fibers will have larger muscles - think of how a sprinter looks - they have larger muscles for the very powerful, yet short-lived bursts of strength. 

Appearance:

How do fast twitch and slow twitch muscle fibers look? 

Well, the best example I can give you is your Thanksgiving turkey! 

Slow twitch fibers are the 'dark meat' - due to the rich blood supply and presence of myoglobin, a protein that stores oxygen in the muscle fibers. The 'white meat' is the fast twitch fibers - they're white because of the relatively poor blood supply and less myoglobin!

Aging:

As we age, we lose fast twitch fibers and gain more slow twitch fibers. Younger sprinters (fast twitch) often set world records at a relatively young age - mid 20's and under. It's rare to see an older sprinter set world records, whereas endurance athletes (slow twitch) peak and set records later in life - mid 30's in many instances!

Recovery:

Regardless of muscle fiber type, they both need adequate nutrients for recovery.  Aside from obtaining enough protein in your diet, here are our top 3 nutritional supplements that we use in clinic to optimize natural muscle recovery. 

1. Omega-3 fatty acids - work to 'turn on' a specific anabolic (muscle building) pathway in the body - this effect is amplified when omega-3's are consumed with protein

2. Branched Chain Amino Acids - long studied for their role in specific muscle protein synthesis, study after study shows this specific group of proteins can boost muscle protein recovery. Tip - combine with omega-3's for an additive effect!

3. Creatine - good old creatine! Perhaps the most studied nutritional supplement out there, creatine helps re-assemble ATP, the energy currency of our cells. Faster ATP recovery means quicker muscle recovery, repair and protein synthesis.

There you have it - the main differences between fast twitch muscle fibers and slow twitch muscle fibers, and our best muscle recovery nutritionals.