Further proof that physical fitness has gotten less and less fun over the ages: this Popular Science article from August, 1931:
One of the newest of exercising devices is a mechanism that somewhat resembles a hobbyhorse without rockers. Seated in its saddle and operating this odd contrivance, the user can exercise and develop all the principle muscles of his body. A pair of pedals work a crankshaft device which imparts an up and down motion to the saddle similar to that experienced in riding a horse at a trot. Assuming different positions on the machine while working it develops legs, back, stomach, or neck muscles. The machine is designed for the use of invalids as well as for those who wish to reduce with the aid of scientific exercise.