Astronaut Sunita Williams completed first simulated triathlon in space this past weekend on ISS.

Astronaut Sunita Williams completed the first simulated triathlon in space this past weekend on ISS.

After “swimming” half a mile (0.8 km), biking 18 miles (29 km), and running 4 miles (6.4 km), Williams finished with a time of one hour, 48 minutes and 33 seconds, she reported. The space station has its own treadmill and stationary bike, which use harnesses and straps in place of gravity to keep astronauts from floating away. To simulate the swimming portion of the race, Williams used what’s called the Advanced Resistive Exercise Device (ARED) to do weightlifting and resistance exercises that approximate swimming in microgravity.