The term 'track shapes, often' can be solved by the word 'ovals', which is a five-letter word. Ovals are a type of shape that is characterized by its curved lines and lack of sharp angles. They are often used in track and field events, such as running and hurdling, to mark the boundaries of the track. Ovals are also commonly used in other sports, such as cycling and motor racing, to mark the boundaries of the course.