Commuters could soon get their exercise fix on the train to work, thanks to a new double-decker carriage design that includes onboard spin bikes.

German rail firm DB Regio and the Bavarian Railway Company (BEG) have unveiled their “Idea Train”, a life-size model of a double-decker train car that features sports and premium compartments, as well as public viewing areas and a play area for children including game consoles.

The train, which is equipped with exercise bikes and a digital fitness trainer, has been in development for a year and is now available to customers in Nuremberg, Germany, to test out.

Developers believe that once self-driving cars become a reality, rail transport will need to come up with innovative ways to attract customers.

“Passengers expect comfort, convenience and individuality, and want to be able to make good use of their time,” said Dr Johann Niggl, BEG managing director.

“Trains will need to be built for mass transport and be highly reliable, but they'll also need to be comfortable, convenient and customised.”

The train will have special work areas to make phone calls or hold meetings, as well as a cabin for power naps.

However, keeping fit on a train may not be just around the corner.

Dr Jörg Sandvoß, chief executive of DB Regio, said: “When developing such concepts, it's not about implementing a train with all the creative ideas at once, but rather taking individual approaches into consideration for new trains, depending on the respective requirements.”

As reported last year, a boat is being developed in France that will harnesses energy from passengers’ workouts.