Muscles: How They Work and Why They Matter in Grand Rapids, MI

There are about 600 muscles in the human body. These muscles help pump blood, support movement, lift heavy objects, maintain posture, and even assist with childbirth. Muscles work by contracting (tightening) and relaxing to create movement.

In Grand Rapids, Michigan, understanding how your muscles function is especially important if you’re active outdoors year-round—whether you’re shoveling snow in winter, biking the White Pine Trail, or walking along the Grand River. Cold Michigan winters can increase muscle stiffness and the risk of strains, making muscle health a key part of overall wellness.

How Muscles Work

Muscle movement can be:

  • Voluntary – movements you control consciously (like walking, lifting, or typing).
  • Involuntary – movements that happen automatically without conscious thought (like your heart beating or your intestines moving food along).

Muscles use glucose from carbohydrates in your diet as their main fuel source. To work properly, muscle tissue also needs:

  • Calcium
  • Magnesium
  • Potassium
  • Sodium
  • Adequate water and electrolytes

Staying hydrated is especially important during hot, humid West Michigan summers and when exercising indoors at local gyms or recreation centers in Grand Rapids.

Types of Muscle in the Human Body

There are three main types of muscle:

1. Skeletal Muscle

Skeletal muscle is the specialized tissue attached to bones by tendons. It:

  • Allows you to move your arms, legs, head, and trunk
  • Helps maintain posture and balance
  • Is under voluntary control (you decide when to move it)

Skeletal muscles and bones together form the musculoskeletal system (also called the locomotor system). These muscles are often arranged in opposing pairs, such as:

  • Biceps and triceps in the upper arm
  • Quadriceps and hamstrings in the thigh

Under a microscope, skeletal muscle looks striped, or striated, which is why it is sometimes called striated muscle.

2. Smooth Muscle

Smooth muscle is found in many internal organs and structures, including:

  • Digestive tract (stomach, intestines)
  • Uterus
  • Blood vessels, such as arteries
  • Bladder and airways

Smooth muscle is arranged in layers that contract in waves along the length of the structure. This helps move substances like food, blood, or urine through the body.

Smooth muscle is involuntary, meaning it works automatically without conscious control. For example, you don’t have to think about moving food through your intestines—your smooth muscles do it for you.

3. Cardiac Muscle

Cardiac muscle is the specialized muscle that makes up the heart. It:

  • Contracts and relaxes rhythmically to pump blood throughout the body
  • Works involuntarily, without conscious control
  • Has a unique structure that allows it to work continuously throughout your life

Cardiac muscle shares some features with both skeletal and smooth muscle but is structurally and functionally unique.

What Muscles Are Made Of

Although skeletal, smooth, and cardiac muscles have different roles, they share a similar basic structure.

Each muscle is made of thousands of elastic fibers bundled tightly together. Each bundle is wrapped in a thin, transparent membrane called the perimysium.

An individual muscle fiber contains:

  • Myofibrils – long strands made of protein blocks
  • Myoglobin – a specialized protein that stores and carries oxygen in the muscle
  • Molecules that provide energy for contraction

Within each myofibril are filaments that slide and fold together when the muscle receives a signal to contract. When enough fibers contract at the same time, the entire muscle shortens, creating movement.

The Neuromuscular System: How Your Brain Moves Your Muscles

The brain, nerves, and skeletal muscles work together to produce movement. This system is called the neuromuscular system.

A typical skeletal muscle is connected to the nervous system by 50 to 200 or more branches of specialized nerve cells called motor neurons.

  • The tip of each nerve branch is called a presynaptic terminal.
  • The point where the nerve meets the muscle fiber is called the neuromuscular junction.

How Movement Happens

  1. The brain sends a signal down the spinal cord to the motor neurons.
  2. Motor neurons release a chemical messenger called acetylcholine at the neuromuscular junction.
  3. The muscle responds to acetylcholine by contracting.
  4. When the signal stops, the muscle relaxes.

Conditions that affect the neuromuscular system can cause muscle weakness, fatigue, or loss of movement. If you notice these symptoms, local specialists in Grand Rapids—such as neurologists at Spectrum Health or Trinity Health Grand Rapids—can evaluate your neuromuscular function.

Shapes of Skeletal Muscles

Skeletal muscles come in several main shapes, which relate to how they function:

  • Spindle-shaped – wide in the middle and tapering at both ends
    • Example: Biceps in the upper arm
  • Flat – thin and sheet-like
    • Example: Diaphragm, the muscle that separates the chest from the abdominal cavity and helps with breathing
  • Triangular – broad at one end and narrow at the other
    • Example: Deltoid muscles of the shoulder
  • Circular (sphincter muscles) – ring-shaped muscles that surround openings in the body
    • Examples: muscles around the mouth, eyes, and anal sphincter

These different shapes allow muscles to perform a wide variety of movements, from fine control (like writing) to powerful actions (like jumping or lifting).

Common Muscle Disorders and Problems

Muscle disorders, collectively called myopathies, can lead to:

  • Muscle weakness
  • Pain or tenderness
  • Loss of movement
  • In severe cases, paralysis

Common Muscle Problems

  • Injury or overuse

    • Sprains and strains
    • Muscle cramps
    • Tendonitis
    • Bruising or contusions
    • Often seen in people who shovel snow, play sports, or work in physically demanding jobs common in West Michigan

  • Genetic muscle conditions

    • Muscular dystrophy and other inherited muscle disorders

  • Inflammatory muscle diseases

    • Myositis and related conditions

  • Nerve-related diseases that affect muscles

    • Multiple sclerosis (MS)
    • Peripheral neuropathies
    • Motor neuron diseases

  • Conditions that cause muscle weakness

    • Metabolic disorders
    • Endocrine disorders, such as thyroid or adrenal gland diseases
    • Toxic causes, including:
      • Long-term alcohol use
      • Pesticide poisoning
      • Certain medications (for example, some steroids and statins)
    • Autoimmune conditions, such as myasthenia gravis

  • Cancers

    • Soft tissue sarcomas and other tumors that affect muscle or surrounding tissues

If you experience persistent muscle pain, weakness, or unexplained fatigue, it’s important to seek medical care. Early diagnosis and treatment can prevent complications and improve quality of life.

Muscle Health in Grand Rapids, MI

Living in Grand Rapids and the greater West Michigan area brings some specific muscle health considerations:

  • Cold winters can increase the risk of:
    • Muscle strains while shoveling snow or walking on ice
    • Stiffness from reduced activity and lower temperatures
  • Active outdoor lifestyle in warmer months:
    • Hiking, running, biking, and water sports on nearby lakes can lead to overuse injuries if muscles are not properly warmed up and conditioned
  • Indoor work and technology use:
    • Office jobs and remote work can lead to neck, back, and shoulder muscle tension without proper ergonomics and stretching

Maintaining strong, flexible muscles through regular exercise, stretching, and proper nutrition is essential for staying active year-round in Grand Rapids.

Local Resources for Muscle and Movement Care in Grand Rapids

If you have concerns about muscle pain, weakness, or movement problems, you can access many high-quality healthcare resources in Grand Rapids, Michigan:

Medical Providers

  • Primary Care Physicians & Internists

    • Available through major health systems such as:
      • Corewell Health (formerly Spectrum Health)
      • Trinity Health Grand Rapids
      • Metro Health – University of Michigan Health
      • Mercy Health clinics in the region

  • Specialists

    • Physiatrists (physical medicine and rehabilitation doctors)
    • Neurologists (for nerve and neuromuscular disorders)
    • Orthopedic surgeons (for bone, joint, and some muscle injuries)
    • Sports medicine physicians

Rehabilitation and Exercise Professionals

  • Physiotherapists / Physical Therapists

    • Available at hospital-based rehab centers (Corewell Health, Trinity Health Grand Rapids, Metro Health) and private clinics across the city

  • Exercise Physiologists & Athletic Trainers

    • Often found in sports medicine centers, cardiac rehab programs, and university-affiliated clinics in the Grand Rapids area

  • Chiropractors and Osteopathic Physicians (DOs)

    • Some focus on musculoskeletal alignment and manual therapy

Public Health and Community Resources

  • Kent County Health Department

    • Offers health education, chronic disease programs, and referrals to local services

  • Grand Rapids Public Health and Community Centers

    • May offer fitness programs, fall-prevention classes, and wellness education for adults and seniors

If you’re unsure where to start, contacting your primary care provider within a Grand Rapids health system is a good first step. They can evaluate your symptoms and refer you to the appropriate specialist or rehabilitation service.

Key Points to Remember

  • Muscles work by contracting and relaxing to produce movement.
  • There are three main types of muscle:
    • Skeletal muscle – attached to bones and under voluntary control
    • Smooth muscle – found in organs and blood vessels, works involuntarily
    • Cardiac muscle – found only in the heart, works involuntarily
  • The brain, nerves, and muscles work together as the neuromuscular system to control movement.
  • Muscle disorders (myopathies) can cause weakness, pain, loss of movement, or paralysis.
  • Local healthcare providers in Grand Rapids, MI—including Corewell Health, Trinity Health Grand Rapids, Metro Health, and Mercy Health—offer diagnosis, treatment, and rehabilitation for muscle and movement problems.
  • Seasonal changes in Michigan, especially cold winters, make warming up, stretching, and safe movement practices especially important for protecting your muscles.

If you have ongoing muscle pain, weakness, or difficulty with daily activities, schedule an appointment with a Grand Rapids healthcare provider for a thorough evaluation and personalized treatment plan.