Muscles: National Geographic investigates the science of muscle by taking a journey inside the bodies of two remarkable humans with startling muscular disorders. 31-year old Jason Dunn lives with Dystonia, a rare disease that causes his brain to send faulty messages to his muscular system. Every waking moment his muscles flex out of his control, twisting his body into unusual positions. Ami Ankileweitz has Spinal Muscle Atrophy, a gene
