Muscles power health inEssential ways

how muscles work

Muscle function is essential to life. It is necessary for both voluntary movements (such as walking, eating, dressing, or speaking) and involuntary movements (such as the pumping functions of your heart or respiratory functions of your lungs). There are three types of muscle: skeletal, cardiac, and smooth, and when muscle function is impaired, critical organs may be affected and quality of life may meaningfully decline.

An impaired diaphragm—the skeletal muscle that supports the movement of air by the lungs—can result in difficulty breathing and eventually respiratory failure.1 If cardiac muscle in the heart is unable to pump sufficiently to maintain proper blood flow throughout the body, a patient may suffer from fluid overload, shortness of breath, dizziness, and fatigue.2 Many diseases—such as ALS and heart failure—that affect muscle function result in muscle weakness either through diminished signaling between nerves and muscle or through other mechanisms, and this leads to limited performance of vital muscle systems. Increasing muscle function may alleviate the impact of these diseases, and may also improve a person’s prognosis and quality of life.

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The key to muscle function is contraction

The principal functionality of muscle is rooted in its ability to contract and relax. The foundation for muscle contraction is the sarcomere. Sarcomeres contain a motor protein called myosin, which powers the muscle to contract by “grabbing” onto another protein called actin and “flexing.” When the myosin releases the actin, the muscle relaxes. This process is regulated by another protein called troponin.

At Cytokinetics, we have focused on these crucial proteins within muscle cells as the keys to unlock the treatment of diseases that are caused by impaired muscle function. Our potential therapies are engineered to impact muscle function and contractility. By targeting the interacting proteins of the sarcomere, our cardiac muscle activators and inhibitors modulate heart function either by powering up or powering down cardiac muscle contractility, potentially increasing lifespan in patients with heart failure. Our skeletal muscle activators are designed to work by directly binding the form of troponin unique to that muscle type which then amplifies the magnitude of skeletal muscle contraction. We are dedicated to applying our expertise in the mechanics of muscle contractility to pioneer new therapies for people whose lives are impacted by severe and debilitating muscle diseases.

  1. Heart Failure | National Heart, Lung, and Blood Institute (NHLBI). 2019. Available at: Accessed March 22, 2019.
  2. Amyotrophic Lateral Sclerosis (ALS) Fact Sheet | National Institute of Neurological Disorders and Stroke. 2019. Available at: Accessed March 22, 2019.