Muscle Twitch, the Building Block of Strength Training

Maryam asked "What are the phases of a muscle twitch?"

Hey Maryam!

Picture our muscles as a squad of dancers, each led by an alpha motor neuron. These neurons branch out, connecting to a bunch of muscle fibers, forming a motor unit. When these guys get the signal, they contract, creating a muscle twitch.

A muscle twitch has three main phases:

1. Latent period - the calm before the storm, a short delay where things gear up for action.
2. Contraction phase - when the muscle is flexing its power, generating tension.
3. Relaxation phase - where the muscle chills out and goes back to its normal state.

Title: File:1012 Muscle Twitch Myogram.jpg; Author: OpenStax College; Site:https://commons.wikimedia.org/wiki/File:1012_Muscle_Twitch_Myogram.jpg; License: This file is licensed under the Creative Commons Attribution 3.0 Unported license.

Now, imagine if all our motor units fired at once. We'd be moving like robots, all jerky and awkward. Instead, they fire asynchronously, taking turns in a smooth sequence, like a well-coordinated team. Even when we're at rest, there's this random firing of motor units, giving us that muscle tone. It's never completely relaxed, always ready for action.

Muscle contractions come in different flavors:

1. Isometric contractions: Tension increases without a change in length – perfect for holding a posture.
2. Isotonic contraction: The muscle length changes while tension stays constant. This one's split into concentric (muscle shortens) and eccentric (muscle lengthens) contractions. Eccentric contractions are like the secret weapon, causing more muscle soreness but also building strength.

Resistance training or strength training, with its mix of concentric and eccentric contractions, triggers muscle growth. It's like a cascade of events, starting with tiny tears in the muscle fibers that lead to hypertrophy – muscle enlargement. But hey, endurance training, like long-distance running, won't make you Hulk-sized. It's more about improving ATP production for sustained activity.

Motor units are key to muscle contraction force. The more we have, the merrier. We've got motor unit summation, where recruiting more units increases force. Then there's wave summation, a fancy term for firing motor units at a super-fast frequency, leading to tetanus – prolonged contraction.

Sarcomere length matters too. Too short or too stretched, and we lose force. It's all about finding that sweet spot for optimal muscle contraction. Oh, and energy for all this action? ATP is the MVP. Cytosolic ATP, creatine phosphate, glycolysis, and aerobic respiration – these are the power sources, each with its own role in fueling muscle function.

Title: 1011_Muscle_Length_and_Tension.jpg; Author: OpenStax; Site: Ch. 1 Introduction - Anatomy and Physiology | OpenStax; License: This work is licensed by Rice University under a Creative Commons Attribution License License ( 3.0).

Fatigue is the nemesis we all face. There's central fatigue – the psychological wear and tear that hits first. Then, there's peripheral fatigue, which can be low frequency (think marathon running) or high frequency (like intense circuit training). Factors like inorganic phosphates, hydrogen ions, and glycogen depletion contribute to this fatigue struggle.

Muscle fiber types play a big role too. We've got slow-twitch oxidative, fast-twitch oxidative-glycolytic, and fast-twitch glycolytic fibers. They determine our muscle's speed of contraction and resistance to fatigue. And yes, it's partly genetic, but training can tweak the ratios a bit.

Imagine our muscles as a team of skilled craftsmen, each with their own unique talents. Just as the Israelites built the Tabernacle in the wilderness, each craftsman contributing their expertise to create a magnificent structure, our muscles work together in a coordinated effort to produce movement.

The alpha motor neurons act as the master architects, sending signals to the muscle fibers, which are like the skilled artisans shaping and molding the building blocks. The motor units, like specialized teams within the construction crew, work together to execute the architect's plans, contracting and relaxing in sequence to achieve precise movements.

Just as the Tabernacle was a symbol of God's presence among His people, our muscles are a testament to the Creator's intricate design. Each muscle fiber, each motor unit, each alpha motor neuron plays a vital role in allowing us to move, run, jump, and perform all the countless actions that make up our daily lives.

"I praise you because I am fearfully and wonderfully made; your works are amazing, I know that full well." (Psalm 139:14)

So, the next time you admire a stunning piece of architecture or marvel at the intricate details of a handcrafted masterpiece, remember that our muscles are also a testament to the Creator's craftsmanship, a symphony of coordinated efforts that allows us to experience the world around us in all its fullness.

Hope this helps. If it does, please UPVOTE, COMMENT, & SHARE.

May you be blessed with the power of David and the wisdom of Solomon.

Faithfully yours,

Strength Training with Gary