Arthur Jones (November 22, 1926 – August 28, 2007) was an inventor, and founder of Nautilus and MedX, now known as MedX Fit Tech; and was also an aviation enthusiast. Arthur Jones is famous for discovering and introducing exercise concepts, and is considered a pioneer Jones was a pioneer in the field of physical exercise, especially weight training and strength training.

He is considered the inventor of cams, inventor pulleys, in exercise machines, that adjusted resistance along the range of motion of an exercise by use of the variable radius of the cam, compared to the consistent radius of a pulley. A large radius on the cam improved leverage at a specific point in the range of motion, and made that portion of the lift easier. A short radius, decreased leverage, and made the lift more difficult at that point of the range of motion.

These variable radii on the cam were designed to provide optimal resistance that varied along the variable force output generated by human muscular structures due to angle changes of muscles with the skeletal system during the full range of motion of an exercise.

The Nautilus machines made use of the cam and became popular in fitness centers in the early 1970s through the 1980s. Arthur Jones held numerous patents for a variety of exercise machines and methods.

The Nautilus logo showing the shell of a marine mollusc Nautilidae and the cam of similar shape are inter-related in concept and inspiration of the function of the cam.

The Nautilus machines and the Nautilus company were profitable to the point of grossing an estimated $400 million annually. Jones made the list the of Forbes 400 richest people. At one point, financial analysts estimated that Nautilus was grossing $400 million annually. As Nautilus faced competition from numerous exercise machine companies, Arthur Jones sold Nautilus Inc. in 1986 for $23 million.

Arthur Jones is also known for discovering that different people had different capability for recovering from maximum isometric contraction at several points of joint range of motion. He found that some people recovered in a day, and were just as strong in 24 hours. Other people might take three days to recover before they are capable of repeating the initial force output. The concept was part of the basis of MedX Corporation, which Arthur Jones transitioned to after he sold Nautilus. MedX was initially focused on the development of spinal rehabilitation equipment involving spinal extension, and premium excise equipment.

Jones also sold MedX Corporation in 1996 and then retired.

Arthur Jones worked with Casey Viator, Eddie Robinson, Mike Mentzer, Ray Mentzer, Sergio Oliva, Boyer Coe, and Dorian Yates.

Arthur Jones was married to Teri Jones, but the couple divorced in the late 1980s.

Arthur Jones was born in Arkansas, and grew up in Seminole, Oklahoma.