После бега он тяжело дышит.

После means after, and it requires the genitive case.

The noun бег becomes бега in the genitive singular:

• nominative: бег = running, a run
• genitive: бега

So:

• после бега = after running / after the run

This is a very common pattern in Russian:

• после работы = after work
• после урока = after the lesson
• после дождя = after the rain

Russian often expresses this idea with a noun rather than a verb form.

So English after running is commonly rendered as:

• после бега = literally after running / after the run

Russian can also use a verbal construction in some contexts, but после + noun in the genitive is very natural and common.

For a learner, it helps to think of бег here as running in the general sense, just like an activity noun.

Here тяжело means heavily or with difficulty.

In the sentence:

• он тяжело дышит = he is breathing heavily

Even though тяжёлый / тяжело often means heavy / heavily, in Russian it can also describe something being physically difficult or labored. So with breathing, it means the breathing is hard, heavy, or labored.

Because тяжело is an adverb, and it modifies the verb дышит.

• тяжёлый = heavy (masculine adjective)
• тяжёлая = heavy (feminine adjective)
• тяжёлое = heavy (neuter adjective)
• тяжело = heavily / with difficulty (adverb, or short-form neuter in other contexts)

Here it answers the question How is he breathing?

• Он дышит как? — тяжело.
• How is he breathing? — heavily.

As for spelling: the standard spelling is тяжело. The letter ё is often omitted in ordinary writing, but in this word it is actually е, not ё.

Дышит is the 3rd person singular present tense of дышать = to breathe.

So:

• я дышу = I breathe / am breathing
• ты дышишь = you breathe / are breathing
• он/она дышит = he/she breathes / is breathing
• мы дышим = we breathe / are breathing
• вы дышите = you breathe / are breathing
• они дышат = they breathe / are breathing

In this sentence:

• он дышит = he breathes / he is breathing

In Russian, the present tense often covers both:

• he breathes
• he is breathing

Russian does not have a separate form like English is breathing. The exact meaning depends on context.

So:

• Он тяжело дышит can mean He breathes heavily or, more naturally here, He is breathing heavily.

Because после бега gives a specific situation, English usually translates it with the progressive:

• After running, he is breathing heavily.

Yes, Russian can often omit subject pronouns when the subject is clear from the verb form or context.

So both are possible:

• После бега он тяжело дышит.
• После бега тяжело дышит.

However, он is often kept when:

• the speaker wants to be clear about who is meant
• there is contrast with someone else
• the subject is being emphasized or newly introduced

Including он is completely natural.

Yes. Russian word order is more flexible than English, although different orders can slightly change emphasis.

The neutral order here is:

• После бега он тяжело дышит.

Other possible orders include:

• Он тяжело дышит после бега.
• Он после бега тяжело дышит.
• Тяжело дышит он после бега. (more marked, more stylistic/emphatic)

All of these can be grammatical, but the first one sounds very natural as a plain statement.

It can mean either, depending on context.

• after a run if you are thinking of one specific run
• after running if you are thinking of the activity in general

Russian does not always force this distinction in the same way English does. Бег can refer to:

• the activity of running
• a run as an event

So the English translation depends on the situation.

Grammatically, you can build sentences with после того как..., but in this exact case it sounds less natural because the tenses do not match the situation well.

A more natural version would be something like:

• После того как он побегал, он тяжело дышит.

But even that is heavier and less elegant than the simple:

• После бега он тяжело дышит.

Russian often prefers the shorter noun phrase when it is obvious and idiomatic.

Because после бега is just a prepositional phrase, not a subordinate clause.

• После бега он тяжело дышит. → no comma

Compare that with a real clause:

• После того как он пробежал, он тяжело дышит. → comma needed

So the difference is:

• после бега = simple phrase
• после того как... = full clause

A rough guide:

• тяжело ≈ tyi-zhi-LO
• дышит ≈ DY-shit

A few helpful points:

• The stress is on the last syllable of тяжело: тя-же-ЛО
• The stress is on the first syllable of дышит: ДЫ-шит
• The ж sound is like the s in measure
• The ы sound in дышит is a distinct Russian vowel that does not exist exactly in English

Yes, it is correct.

• Он тяжело дышит
• Он дышит тяжело

Both mean essentially the same thing: He is breathing heavily.

However, он тяжело дышит is the more neutral and common order. Putting тяжело after the verb can give it a slightly different rhythm or emphasis.

Дышать is an imperfective verb.

That makes sense because breathing is viewed here as an ongoing process or state:

• он тяжело дышит = he is breathing heavily

A perfective verb would not fit well for this basic description of an ongoing action. Russian uses the imperfective when describing what someone is doing or how something is happening over a period of time.

Yes, depending on context it can suggest either:

• breathes heavily
• is breathing with difficulty
• has labored breathing

If someone has just exercised, it usually means breathes heavily.
If someone is sick or injured, it may imply difficulty breathing.

So the exact nuance comes from the situation, not just the words themselves.