How do muscles work?

Muscles are fascinating biological structures responsible for the movement of our bodies. They work through a complex process involving the interaction between muscle fibers, nerve impulses, and energy production.

I’m gonna start with 5 fun facts about muscles:

  • 600 Muscles in the body.
  • Muscles are 40% of the body weight.
  • Largest Muscle – Gluteus Maximus (buttocks).
  • Smallest Muscle – Tensor Tympani (inner ear).
  • Strongest Muscle is in the jaw.

Now let’s break down the basics of how muscles work:

  1. Muscle Structure: Muscles are composed of individual muscle cells called muscle fibers. These fibers are grouped together into bundles called fascicles, and multiple fascicles form a whole muscle. Muscles are connected to bones via tendons, and when they contract, they pull on the tendons, causing movement at the joints.
  2. Muscle Contraction: Muscle contraction is the process by which muscles shorten or generate tension. It occurs when the muscle fibers contract and the sarcomeres within them shorten. Sarcomeres are the basic units of muscle contraction and are composed of two main proteins: actin and myosin. When the muscle receives a signal from the nervous system, calcium ions are released, enabling the interaction between actin and myosin.
  3. Sliding Filament Theory: The sliding filament theory is the fundamental principle explaining muscle contraction. During contraction, myosin (thick filaments) and actin (thin filaments) slide past each other, causing the sarcomeres to shorten. The myosin heads attach to the actin filaments and pull them towards the center of the sarcomere, shortening the overall length of the muscle fiber.
  4. Nerve Control: Muscle contraction is initiated by nerve impulses sent from the brain or spinal cord. When the brain decides to move a particular muscle, it sends an electrical signal through motor neurons. These neurons release a chemical neurotransmitter called acetylcholine at the neuromuscular junction, which bridges the gap between the motor neuron and the muscle fiber. Acetylcholine binds to receptors on the muscle cell membrane, initiating the release of calcium ions and triggering the sliding filament process.
  5. Energy Production: Muscle contractions require energy in the form of adenosine triphosphate (ATP). ATP is produced through various metabolic processes, primarily using oxygen (aerobic metabolism) or in the absence of oxygen (anaerobic metabolism). During low-intensity activities, the muscles rely on aerobic metabolism, while high-intensity activities depend on anaerobic metabolism, producing lactic acid as a byproduct.
  6. Muscle Relaxation: After the nerve signal ceases, the calcium ions are pumped back into the sarcoplasmic reticulum (a storage structure within muscle fibers), and the actin and myosin filaments separate, allowing the muscle to relax and return to its original length.

Overall, the coordinated action of thousands of muscle fibers within a muscle allows us to perform a wide range of movements, from simple tasks like typing on a keyboard to more complex activities like running or lifting heavy objects.

After menopause, there are several hormonal changes that can affect various aspects of the body, including muscles. The primary hormonal change during menopause is the decrease in oestrogen production by the ovaries. This decline in oestrogen can lead to various effects on muscles and overall musculoskeletal health. Here are some of the ways muscles change after menopause:

  1. Muscle Mass and Strength: oestrogen plays a role in maintaining muscle mass and strength in women. After menopause, the decrease in oestrogen levels can contribute to a gradual decline in muscle mass, a condition known as sarcopenia. Sarcopenia is a natural part of aging, but it may occur more rapidly after menopause due to hormonal changes. As a result, women may experience a decrease in muscle strength and overall physical performance.
  2. Muscle Fatigue: Some women may notice increased muscle fatigue or reduced exercise tolerance after menopause. This could be related to hormonal changes impacting the muscle’s ability to generate energy efficiently. The decline in oestrogen may affect energy metabolism in the muscles, leading to quicker fatigue during physical activities.
  3. Bone-Muscle Interaction: Oestrogen also plays a crucial role in bone health, and after menopause, the decline in oestrogen levels can lead to a reduction in bone density, increasing the risk of osteoporosis. Bones and muscles have a synergistic relationship, and changes in bone density can affect muscle function. Weaker bones may lead to a decrease in muscle support, stability, and overall function.
  4. Connective Tissues: oestrogen also influences the connective tissues in the body, such as tendons and ligaments, which are essential for maintaining joint health and stability. The hormonal changes during menopause can affect these tissues, potentially increasing the risk of injuries or joint-related issues.
  5. Body Composition: Due to the changes in muscle mass and bone density, women may experience shifts in body composition after menopause. They may notice an increase in body fat and a decrease in lean muscle mass, which can have implications for overall health and metabolic function.

It’s important to note that individual experiences can vary widely. Not all women will experience the same extent of muscle changes after menopause, and lifestyle factors, such as diet, exercise, and overall physical activity, can significantly influence muscle health during this stage of life.

Engaging in regular strength training exercises and maintaining a balanced diet with sufficient protein intake can help mitigate muscle loss and support overall musculoskeletal health after menopause. If you’re concerned about muscle changes or overall health during menopause, it’s advisable to consult with a healthcare professional for personalized guidance and recommendations.