To adapt the dogs to the confines of the tiny cabin of Sputnik 2, they were kept in progressively smaller cages for periods of up to 20 days. The extensive close confinement caused them to stop urinating or defecating, made them restless, and caused their general condition to deteriorate. Laxatives did not improve their condition, and the researchers found that only long periods of training proved effective. The dogs were placed in centrifuges that simulated the acceleration of a rocket launch and were placed in machines that simulated the noises of the spacecraft. This caused their pulses to double and their blood pressure to increase by 30–65 torr. The dogs were trained to eat a special high-nutrition gel that would be their food in space.