Changing Posture: Destination over Location
When you talk about changing your physical posture—like sitting down, lying down, or standing up—Russian treats this as directional movement rather than a stationary state.
Because you are directing your body onto or into a space, you must use the prepositions на (onto) or в (into) followed by the Accusative case (the case of destination), rather than the Prepositional case.
Lying Down: ложиться and лечь
To say "to lie down," use the verbs ложиться (imperfective) or лечь (perfective).
Remember that in the Accusative case, inanimate masculine nouns (like матрас or пол) and neuter nouns do not change their forms. Use на for lying on top of a surface, and в for lying into something that envelops you, like a hammock (гамак).
| This is my mattress, you cannot lie down on it. | Это мой матрас, нельзя ложиться на него. |
| I want to lie down on this mattress. | Я хочу лечь на этот матрас. |
| May I lie down in this hammock? | Можно лечь в этот гамак? |
You can also use this structure to talk about lying on a specific side of your body (бок):
| The doctor told me to lie down on my right side. | Врач сказал мне лечь на правый бок. |
Sitting Down: садиться and сесть
To say "to sit down," use the verbs садиться (imperfective) or сесть (perfective). You will often see this paired with на for open surfaces (like a deckchair or stool) and в for enclosed seating (like an armchair).
| Why do you always sit down on my deckchair? | Почему ты всегда садишься на мой шезлонг? |
| He slowly sat down in the armchair. | Он медленно сел в кресло. |
When your destination is a feminine noun ending in -а, such as табуретка (stool), its Accusative ending changes to -у. Any adjectives describing it must change accordingly.
| Grandfather sat down heavily on the stool. | Дедушка тяжело сел на табуретку. |
Neuter nouns, such as бревно (log), stay identical to their Nominative dictionary form in the Accusative case.
| The children sat down on a large log. | Дети сели на большое бревно. |
Standing Up: вставать and встать
To say "to stand up" or "to get up," use the verbs вставать (imperfective) or встать (perfective).
Beyond simply getting out of bed, this verb is used when you physically position yourself onto a surface or put your weight onto a specific limb.
| Why did you stand up on the stool? | Зачем ты встал на табуретку? |
| The athlete cannot stand up on his right leg. | Спортсмен не может встать на правую ногу. |
