Why Do My Legs Shake So Much During 90 Degree Wall Sit Exercises?

Introduction

For many individuals, performing a 90-degree wall sit, a strength training exercise, can result in shaking legs. This article explores the underlying reasons behind this phenomenon and provides insights into how to address it effectively.

Understanding Muscle Fatigue

Muscle Fatigue: Holding a position like a wall sit engages your quadriceps, hamstrings, and glutes. As these muscles tire from maintaining tension, they may start to tremble. This is a common response to the demands placed on your body during sustained muscle activity.

The Role of Muscle Activation

Muscle Activation: The shaking can also be a sign that your muscles are working hard to maintain stability. This occurs especially if you are new to the exercise or pushing your limits. Your muscle fibers are adapting to the increased demand, which can lead to tremors.

Nervous System Response

Nervous System Response: Shaking can occur due to the nervous system's recruitment of muscle fibers as some tire. As your body recruits more fibers to compensate, this can lead to the shaking effect. This is a natural compensatory mechanism to keep your muscles working efficiently.

Lack of Strength or Endurance

Lack of Strength or Endurance: If you haven't built up enough strength or endurance in the targeted muscles, they may struggle to sustain the effort, leading to shaking. Gradual progression in your training can help improve stability and control.

Hydration and Nutrition

Hydration and Nutrition: Dehydration or low electrolyte levels can also contribute to muscle cramps and shaking. Ensuring proper hydration and electrolyte balance is crucial for maintaining muscle function. (Reference to sources on hydration and electrolyte balance)

Understanding Muscle Function

What are Muscles and How Do They Work?

At the microscopic level, muscle fibers are composed of millions of small tubes called sarcomeres, which are bunched together in muscle groups. Sarcomeres are made up of thin filaments known as actin surrounding thick filaments known as myosin. When a muscle is activated by nerve signals, calcium bonds to the actin, causing it to reveal an area for the myosin to grab onto. The myosin has an ADP molecule and a phosphate molecule attached to it, the myosin attaches to the actin, creating a cross-bridge. The phosphate molecule is released, and the ADP causes the myosin to move the actin closer together. The ADP is then released. When it's time to release the myosin from the actin, a new ATP molecule attaches to the myosin. It is then broken down into ADP and phosphate, ready for the next go-around. This action enables muscles to work.

The ATP Energy Source

Where Does ATP Come From?

A small amount of ATP is initially stored in the muscles. ATP is fairly sparse and not very stable in water. ATP needs to be regularly regenerated. When you contract your muscles, blood flow is temporarily restricted, leading to oxygen deprivation. Your muscle cells start to use the glycogen stored glucose, a process known as anaerobic glycolysis. This is required for bursts of activity due to oxygen deprivation. This process is part of the Cori Cycle.

Metabolic Byproducts and Electrolyte Imbalances

Byproducts and Electrolyte Imbalances:

During anaerobic glycolysis, metabolic byproducts such as inorganic phosphate, ADP, and ammonia can accumulate, preventing the release of calcium necessary for muscle contraction. Additionally, hydrogen ions and reactive oxidative species can interfere with muscle function, leading to fatigue and cramps. Electrolytes, including calcium, chloride, and potassium, are essential for passing signals through the nerves to the muscles. Depletion or imbalances in electrolytes can cause unusual muscle behavior and pain.

Conclusion

The shaking in your legs during a 90-degree wall sit is often a combination of muscle fatigue, energetic byproducts, and electrolyte imbalances. Proper training, balancing electrolytes, and maintaining good hydration can help address these issues and improve your overall performance. Consult with a healthcare professional or a fitness expert if your legs continue to shake severely or are accompanied by pain.