Intramuscular fat refers to the fat that is found within the muscles of animals or humans. It is also known as marbling, and it contributes to the tenderness, flavor, and juiciness of meat. Full definition
Like its cousin, the tenderloin, it's low on intramuscular fat and very tender. (prevention.com)
In addition, reducing intramuscular fat could help improve muscular strength and mobility, particularly in older people with diabetes. (sciencedaily.com)