ESA astronaut Alexander Gerst running on the International Space Station as part of every astronaut's 90-minute exercise routine. In microgravity astronaut's bones and muscles waste away. An effective way of counteracting this is by keeping fit, however floating in weightlessness makes running difficult. Elastic bands keep Alexander in place and push his body down on the treadmill.
The International Space Station circles our planet at 28 000 km/h, 400 km high.
Alexander Tweeted this image with the text: "Just ran 16 300 km on the treadmill (35 minutes at 28 000 km/h"
Read more about his mission at http://www.esa.int/Our_Activities/Human_Spaceflight/Blue_dot
Follow Alexander here: http://alexandergerst.esa.int/