Learn Hardcore Russian: Мне вредно и неудобно сидеть без движения весь день. - It is harmful and inconvenient for me to sit without movement all day.

Russian uses the dative to mark the experiencer in impersonal “state” sentences: it literally means “to me it is harmful/uncomfortable.” This is common with words like вредно, неудобно, нужно, можно, холодно, etc.

Examples: Мне холодно. Ему трудно работать по ночам. Детям вредно есть много сладкого.

What kind of sentence is this—where is the subject?

It’s an impersonal sentence. There is no grammatical subject. The predicative words вредно and неудобно act as the predicate, the affected person is in the dative (мне), and the action is expressed by an infinitive phrase (сидеть без движения весь день).

Are вредно and неудобно adverbs or adjectives?

They are predicatives (often listed as “category of state” words). They look like adverbs ending in -о, but they function as the main predicate in impersonal sentences and don’t modify nouns. You can’t say “вредный стул” with this form; that would be вредный, a normal adjective. Other common predicatives: нужно, можно, трудно, легко, плохо, хорошо, больно.

Could I say Для меня вредно instead of Мне вредно?

You can, but it’s less idiomatic here. With infinitives, Russian strongly prefers the dative experiencer: Мне вредно сидеть… You’ll hear для меня more when modifying a noun or a whole situation: Это вредно для меня. Сидеть без движения весь день вредно для меня (acceptable, a bit heavier in style). The most natural version is the original with мне.

Why is there no verb “to be” (есть) in the sentence?

Russian normally omits the present-tense copula. So “It is harmful” is just вредно. In the past or future you do use the verb: было вредно, будет вредно.

Can the word order change?

Yes. Russian word order is flexible:

Neutral: Мне вредно и неудобно сидеть без движения весь день.
Emphasis on the activity: Сидеть без движения весь день мне вредно и неудобно.
Another acceptable variant: Мне сидеть без движения весь день вредно и неудобно. All mean the same; word order shifts focus.

Why is сидеть an infinitive? Could I use сидя or a clause like “когда я сижу”?

After predicatives like вредно/неудобно, Russian typically uses an infinitive to name the action: мне вредно сидеть…

сидя is a gerund (“while sitting”) and is used to describe how another action is done, not as the subject of “is harmful.”
A clause works but changes structure: Мне вредно и неудобно, когда я весь день сижу без движения (fine, but more verbose and slightly different in focus).

What does без движения mean exactly, and why is движения in that form?

Без движения means “without movement,” i.e., “not moving.” Без takes the genitive case, so движение becomes genitive singular движения. Natural alternatives:

сидеть неподвижно (“to sit motionless”)
сидеть, не двигаясь (“to sit, not moving”)

What case is весь день, and what does it express? Could I say целый день?

Весь день is accusative and expresses duration (“for the whole day”). Целый день is a near-synonym; it can add a nuance of “the entire damn day”/“the whole long day,” often with a bit of emphasis.

Do I need any commas in this sentence?

No. Мне вредно и неудобно сидеть без движения весь день needs no commas:

вредно и неудобно is a compound predicate joined by и (no comma).
без движения весь день is a straightforward prepositional phrase plus time expression. If you use the gerund alternative, you normally set it off with commas: сидеть, не двигаясь, весь день.

Can I drop мне to make a general statement?

Yes: Вредно и неудобно сидеть без движения весь день. That means “It’s harmful and uncomfortable (in general) to sit motionless all day.” With мне, you make it personal: “for me.”

How do I say this in the past or future?

Past: Мне было вредно и неудобно сидеть без движения весь день.
Future: Мне будет вредно и неудобно сидеть без движения весь день.

What’s the difference between вредно and плохо here?

вредно = “harmful,” implying damage to health/well-being.
плохо = “bad/poor,” a general negative evaluation. Saying Сидеть без движения весь день плохо is a generic “It’s bad,” while вредно highlights harm (e.g., to health). Note: Мне плохо means “I feel unwell,” not “it’s bad for me.”

Does неудобно mean “uncomfortable” or “inconvenient”? Could I use некомфортно?

Неудобно can mean both “physically uncomfortable” and “inconvenient/awkward” depending on context. Некомфортно focuses on the feeling of discomfort (physical or psychological) and is a bit more bookish/modern. In this sentence both are possible; неудобно is the most idiomatic choice.

Could I say Мне нельзя сидеть без движения весь день instead of Мне вредно…?

Yes, but it shifts the nuance:

Мне вредно… emphasizes harm.
Мне нельзя… emphasizes prohibition or strong recommendation (e.g., doctor’s orders). They often overlap in practice.

How do I pronounce and stress the key words?

мне [mne] (one syllable)
вре́дно (stress on the first syllable)
неудо́бно (stress on до)
сиде́ть (stress on -де́ть)
движе́ния (stress on -же́-)
ве́сь день (stress on ве́сь and the single-syllable день)