Monark pendulum balance ergometers are the worlds most used test cycle for fitness testing. Established in 1910, Monark Exercise AB is a Swedish based company specializing in making Ergomedic Test Cycles. Monark is the only exercise bike approved for the measurement of VO2 by the US Air Force and US Fire Department. They are heavily favored in medical and rehab clinics, and they are heavily used by universities and professional sports teams. Only Monark Eromedic Bikes are used by professionals.