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The International Space Station (ISS) is a space laboratory and construction site that orbits around the Earth at an altitude of about 390 kilometres. Astronauts usually live on the ISS for six-month periods, although some sojourns last up to a year.

On the ISS, the astronauts’ work can be both difficult and diverse: tasks include challenging repair jobs and lengthy spacewalks. Therefore, it is important that the astronauts prepare themselves with specially designed routines before arriving at the space station. Such a regimen might include lifting weights, moving heavy objects, doing push-ups and pull-ups, running and cycling. This constant variation prepares astronauts for all the stresses and challenges they will encounter in space.

Once aboard the space station, these men and women need to continue their workouts, this time in little to no gravity. This situation presents some unique challenges, but scientists have developed many innovations to help astronauts stay in good shape. These include special shoes and new types of weight-lifting machines, treadmills and exercise bikes that all work without gravity. This physical activity is important because it helps address the detrimental effects of zero gravity, such as premature ageing and the loss of muscle mass and bone density.