Після тренування тепла ванна допомагає розслабити м’язи.

Після always takes the genitive case.

So in this sentence:

• після тренування = after training / after the workout

The noun тренування is a neuter noun, and in the singular its nominative and genitive forms happen to look the same:

• nominative: тренування
• genitive: тренування

So even though the form does not change, it is still functioning as genitive here because після requires it.

Because ванна is a feminine singular noun, and here it is the subject of the sentence, so it is in the nominative case.

The adjective must agree with the noun in:

• gender
• number
• case

So:

• тепла = feminine singular nominative
• ванна = feminine singular nominative

That gives:

• тепла ванна = a warm bath

Why not the other forms?

• теплий is masculine nominative, so it does not match ванна
• теплу ванну is feminine accusative, which would be used if bath were the direct object, not the subject

The subject is тепла ванна.

It is the thing doing the action of helping:

• тепла ванна допомагає... = a warm bath helps...

So the structure is:

• Після тренування = time phrase
• тепла ванна = subject
• допомагає = verb
• розслабити м’язи = infinitive phrase

М’язи is the direct object of розслабити, so it is in the accusative plural.

The singular is:

• м’яз = muscle

The plural is:

• nominative plural: м’язи
• accusative plural: м’язи for inanimate nouns

Because muscles are grammatically inanimate, the accusative plural looks the same as the nominative plural.

So:

• розслабити м’язи = to relax the muscles

This is a question of aspect.

• розслабити = perfective
• розслабляти = imperfective

In this sentence, розслабити is used because the focus is on the result:

• a warm bath helps relax the muscles

It suggests reaching the state of relaxed muscles.

If you used розслабляти, it would emphasize the process or repeated action more:

• допомагає розслабляти м’язи = helps with relaxing the muscles / helps relax muscles in general

Both can be possible in some contexts, but розслабити sounds very natural here.

Because Ukrainian often uses допомагати / допомогти + infinitive to mean help do something.

So:

• допомагає розслабити м’язи = helps relax the muscles

This is a very common pattern.

Other examples:

• Це допомагає заснути. = This helps you fall asleep.
• Вправи допомагають зміцнити спину. = Exercises help strengthen the back.

So the infinitive after допомагає is completely normal.

Yes. Ukrainian word order is fairly flexible.

The original sentence:

• Після тренування тепла ванна допомагає розслабити м’язи.

This sounds natural and puts the time/context first: after training.

You could also say:

• Тепла ванна після тренування допомагає розслабити м’язи.
• Тепла ванна допомагає розслабити м’язи після тренування.

These versions are also understandable, but the emphasis changes slightly.

In the original sentence, після тренування is set up first as the situation in which this statement is true.

Because Ukrainian has no articles.

English distinguishes between:

• a warm bath
• the warm bath

Ukrainian simply says:

• тепла ванна

The exact meaning depends on context. In this sentence, English would most naturally translate it as a warm bath.

So learners should get used to the idea that Ukrainian usually leaves definiteness and indefiniteness unstated.

Yes. Ванна can mean:

• bath as in the tub itself
• a bath as the act of taking one, depending on context

In this sentence, тепла ванна clearly means a warm bath.

For bathroom, Ukrainian more often uses:

• ванна кімната
• or colloquially ванна in some contexts, depending on speech and region

So here there is no ambiguity once you see тепла ванна допомагає...

Putting після тренування first gives the sentence a natural topic-first structure:

• As for after training, a warm bath helps relax the muscles.

This is very common in Ukrainian. Time expressions often appear early in the sentence to frame the statement.

English can do something similar:

• After training, a warm bath helps relax the muscles.

So the Ukrainian order is not unusual at all.

In many contexts, тренування already covers workout, training session, or exercise session.

So the original sentence can naturally mean:

• After a workout, a warm bath helps relax the muscles.

If you want, you can think of тренування as a broad word that often corresponds to:

• training
• workout
• exercise session
• practice session

The exact English translation depends on context, but the Ukrainian is perfectly natural as written.