BACKGROUND: in the 1990s Russian cosmonauts performed six long-duration missions on Mir that went from 312 to 438 d. In 2015 a mission on the International Space Station that continued for 340 d, 8 h, and 47 min was successfully accomplished. It was a joint U.S./Russian mission completed by Scott Kelly and Mikhail Kornienko (KM).METHODS: The intensity of in-flight physical exercises and postflight motor changes were measured in KM and in the six cosmonauts who made shorter flights (173.3 ± 13.8 d) on ISS while using similar countermeasures against the adverse effects of microgravity.RESULTS: It was found that both parameters varied similarly in spite of the difference in the duration of ISS missions. KM maintained adequate physical performance throughout the entire flight; moreover, the level of postflight changes he displayed was comparable to that recorded in the group of cosmonauts who completed 6-mo missions on ISS.DISCUSSION: In summary, the 1-yr mission has clearly demonstrated the high efficacy of the countermeasures used by KM.Fomina EV, Lysova NYu, Kukoba TB, Grishin AP, Kornienko MB. One-year mission on ISS is a step towards interplanetary missions. Aerosp Med Hum Perform. 2017; 88(12):1094–1099.