Using Fast Twitch and Slow Twitch Fibers to Improve Playing

By Caileen W.

If you’ve ever watched a recording of a professional musician, you’ve probably had the same thought as I have — how do their fingers move like that? 

The answer you’ve most likely heard is a lifetime of practice, a good bit of talent, and plenty of performance experience. But in this post, we’ll be briefly exploring how the brain facilitates movement. 

INTRODUCTION

The type of muscle we’ll be focusing on in this post is skeletal muscle. As its name suggests, these muscles connect to bones in the skeleton and make these bones move [1]. 

Each muscle is made up of cells known as muscle fibers [1]. Muscle fibers are attached to the brain via nerve fibers from motor neurons. These motor neurons can be divided into two major categories:

1. Upper motor neurons, which travel from the cerebral cortex (outside layer of the brain) to the brain stem or spinal cord [2]

2. Lower motor neurons, which travel from the spinal cord to other parts of the body, including muscles. 

Oftentimes, lower motor neurons connect to multiple muscle fibers. These form a motor unit: all the fibers connected to a single motor neuron.  

NEURAL SIGNALS

The brain controls movement by sending neural signals through motor neurons to activate muscles throughout the body. Action potentials from upper motor neurons trigger the release of the neurotransmitter glutamate. Lower motor neurons then transmit these signals and release the neurotransmitter acetylcholine. 

The muscle fibers connected to the lower motor neurons undergo a series of chemical changes (see The Sliding Filament Model for more) that cause them to contract, resulting in the movement of muscles. 

MUSCLE FIBER TYPES

Muscle fibers can be divided into two main categories: slow twitch (type 1) and fast twitch (type 2) muscle fibers [3].

These muscle fibers have various differences, including:

1. Slow twitch muscle fibers are used for endurance-based activities, while fast twitch muscle fibers are used for high-intensity activities [3]. 

2. Fast twitch muscle fasters get tired and degrade faster [3]. 

These muscles work together to help move your body, which is key to playing an instrument. Like any activity, playing an instrument requires endurance and rest. 

Practice all your shifts and movements — especially fast runs or virtuosic passages — at a slow tempo with slow twitch movements, meaning they’re controlled and tension-free. And most importantly, as you slowly speed up, make sure you maintain control and relaxation with all your movements. 

In the next post, we’ll discuss the role of the cerebellum in fine motor control, which is especially relevant to playing an instrument! 

CITATIONS

1. Clinic, C. (2023, July 26). Muscle Stiffness: Causes & Treatment. Cleveland Clinic. https://my.clevelandclinic.org/health/symptoms/25147-muscle-stiffness

2. Structure of Skeletal Muscle | SEER Training. (2026). Cancer.gov. https://training.seer.cancer.gov/anatomy/muscular/structure.html

3. The difference between fast and slow twitch muscle fibers. (2025, February 24). Nebraskamed.com; Nebraska Medicine. https://www.nebraskamed.com/health/healthy-lifestyle/orthopaedics/the-difference-between-fast-and-slow-twitch-muscle-fibers

4. Zayia, L. C., & Prasanna Tadi. (2023, July 24). Neuroanatomy, Motor Neuron. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK554616/