Skeletal muscle tissue is the largest body mass in the human body, accounting for 45% of total body weight. Muscle injury is one of the most common injuries in the athletic population and often occurs during training, warm-ups, or competition. Most sports-related muscle injuries consist of strains, contusions, and, less commonly, tears. These injuries are responsible for a large portion of the time lost in competitions and are the most challenging injuries to return to the field, especially in elite athletes. Ultrasound, which is dynamic, inexpensive, and more convenient to use in follow-up examinations, and magnetic resonance imaging (MRI), which provides better anatomical definition, are the leading diagnostic imaging techniques. In the initial phase, rest-ice-compression-elevation (RICE) therapy and nonsteroidal anti-inflammatory drugs (NSAIDs) are often used. Following this initial phase, ultrasound therapy, strengthening and stretching, and pain-free range of motion exercises are used in clinical treatment. This chapter presents an overview of the etiology, risk factors, classification, treatment, and possible complications of common types of muscle injuries.