Week 10 - Muscle Contraction: Engage/Explore

 Based on what you have been learning about muscles so far, what specific events are taking place at the cellular and molecular level of actin and myosin that allow you to contract muscles during these workouts?   

Please try to write at least 3 sentences to share what mechanisms are taking place to allow muscle movement and muscle building.  If you are uncertain, that's completely OK!  No research is necessary now.  This is just a chance to explore your existing ideas.

submission

1. During strength training, such as CrossFit workouts, muscle fibers experience microscopic damage due to the intense contractions.
2.  The body activates satellite cells, which fuse with existing muscle fibers.
3. These fused cells contribute additional nuclei to the muscle fiber, enhancing its capacity for protein synthesis.
4. The increased protein synthesis leads to muscle hypertrophy, where the muscle fibers grow thicker and stronger.

Copilot Chat GPT

Certainly! Let’s delve into the fascinating world of muscle contraction and building. 🏋️‍♂️

Muscle Contraction Mechanism:

At the cellular level, muscle contraction primarily involves the interaction between two key proteins: actin and myosin.

When you perform a movement like a push-up or squat, nerve impulses from your brain travel to the muscle fibers.

These impulses trigger the release of calcium ions within the muscle cell, which bind to troponin (a regulatory protein) and cause a conformational change in tropomyosin (another regulatory protein).

This conformational change exposes the binding sites on the actin filaments.

Myosin heads (part of thick myosin filaments) then attach to these exposed binding sites on actin, forming cross-bridges.

ATP (adenosine triphosphate) provides energy for myosin heads to pull the actin filaments toward the center of the sarcomere (the basic contractile unit of muscle).

This sliding of actin and myosin filaments results in muscle contraction.

Muscle Building Mechanism (Hypertrophy):

During strength training, such as CrossFit workouts, muscle fibers experience microscopic damage due to the intense contractions.

In response, the body activates satellite cells, which fuse with existing muscle fibers.

These fused cells contribute additional nuclei to the muscle fiber, enhancing its capacity for protein synthesis.

The increased protein synthesis leads to muscle hypertrophy, where the muscle fibers grow thicker and stronger.

Key factors for muscle growth include protein intake, adequate rest, and progressive overload (gradually increasing resistance during workouts).

Energy Systems for Muscle Activity:

Muscles rely on different energy systems during exercise:

Phosphagen System: Provides rapid energy for short bursts of intense activity (e.g., sprinting, heavy lifting). Creatine phosphate stores are rapidly broken down to regenerate ATP.

Glycolysis: Breaks down glucose to produce ATP. It’s essential for moderate-intensity activities lasting several minutes.

Oxidative Phosphorylation: Utilizes oxygen to generate ATP from stored carbohydrates and fats. It’s crucial for endurance activities (e.g., long-distance running).

Remember, these processes occur simultaneously, allowing you to perform those challenging CrossFit workouts and build stronger muscles! 💪🔥12