Abstract The sections in this article are: Basic Concepts—Review of Muscle Mechanics Muscle Fiber Types Mechanics of Muscle Electrical Properties of Skeletal Muscle Individual Respiratory Muscles and Their Properties General Considerations Diaphragm Intercostal Muscles Sternocleidomastoid and Scalenus Muscles Abdominal Muscles Other Respiratory Muscles Altered Respiratory Muscle Mechanical Properties in Disease Obstructive Lung Disease Diseases Characterized by Stiff Lungs Neuromuscular Diseases Severe Obesity