It may be lonely up there on the International Space Station (ISS), but astronauts don't strength train regularly in space to pass the time. They're fighting bone loss, and now they've got a new piece of equipment to try.

On average, astronauts lose one to two percent of their bone mass per month in zero-G. Just imagine how serious this loss could be on a two-year round-trip journey to Mars. To help slow down bone loss, the ISS was recently shipped an advanced Resistive Exercise Device called aRED. By utilizing a system of vacuum cylinders, astronauts can perform a wider variety exercises on aRED than the previous device, at workloads up to 600 pounds.

If only we would all exercise like astronauts. ISS crew lift, run on a treadmill and/or bicycle up to two hours a day. Expedition 14 astronaut Sunita Williams even ran a marathon on the ISS treadmill in April 2007.