Learn Hardcore Ukrainian: Після тренування болять м’язи, але це приємно. - After the workout the muscles hurt, but it feels pleasant.

Після тренування в мене болять м’язи. – After training, my muscles hurt.
Після тренування болять мої м’язи. – grammatically correct, but sounds more emphatic/contrasty, like it’s my muscles that hurt (not something else).

Leaving out the possessive is very normal with body parts, especially with verbs like боліти (to hurt, ache):

У мене болить голова. – I have a headache (literally: At me hurts head), no “my” needed.

What case is тренування in, and why does it look the same as the basic form?

Тренування here is in the genitive singular, required by the preposition після.

Rule: після + genitive case

після тренування – after (the) training/workout
після уроку – after the lesson
після роботи – after work

The noun тренування is a neuter noun ending in -ння. Many such nouns have the same form in nominative and genitive singular:

Nom. sg.: тренування – training
Gen. sg.: тренування – of training

So it looks like the dictionary form, but its role in the sentence (and the preposition після) tells you it’s genitive.

What’s the difference between болить and болять?

Both come from the verb боліти – to hurt / to ache.
The form depends on whether the subject is singular or plural:

болить – 3rd person singular
- У мене болить голова. – My head hurts.
- Живіт болить. – The stomach hurts.
болять – 3rd person plural
- Після тренування болять м’язи. – After training, (my) muscles hurt.
- Болять зуби. – My teeth hurt.

In your sentence, м’язи (muscles) is plural, so the verb must be болять.

Could I say “М’язи болять після тренування” instead? Is that the same?

Yes, that’s perfectly correct and very natural:

М’язи болять після тренування, але це приємно.

Ukrainian has fairly flexible word order. Both:

Після тренування болять м’язи…
М’язи болять після тренування…

are fine and mean the same thing. The difference is just slight emphasis:

Starting with Після тренування emphasizes the time/situation: After the workout, the thing that happens is...
Starting with М’язи emphasizes what hurts: The muscles (specifically) hurt after the workout...

Semantically, for most contexts, they’re interchangeable.

How would I explicitly say “After the workout, *my muscles hurt*” in a very clear, learner-safe way?

The most natural, explicit version is:

Після тренування в мене болять м’язи.

Breakdown:

Після тренування – after the workout
в мене – in/at me → idiomatically “I have”
болять м’язи – muscles hurt

This structure “в мене болять …” is very common and sounds more natural than forcing a possessive pronoun like мої unless you need emphasis:

Після тренування в мене болять м’язи. – neutral
Після тренування болять мої м’язи, а не спина. – My muscles hurt after the workout, not my back. (contrast)

What does це refer to in але це приємно? Is it like English “it”?

Yes. Here це functions like the dummy “it” in English:

але це приємно – but it is pleasant / but it feels good.

It doesn’t refer to a specific neuter noun; it refers to the whole situation just mentioned: the fact that the muscles hurt after training.

This pattern is very common:

Це добре. – That’s good / It’s good.
Це важко. – That’s hard / It’s difficult.
Це дивно. – That’s strange.

So це приємно is “That/It is pleasant.”

Is приємно an adjective? Why not приємний?

Приємно is not an adjective; it’s used as a predicative adverb / “category-of-state” word and means “pleasantly / (it is) pleasant”.

Compare:

приємний – an adjective: pleasant (modifies a noun)
- приємний запах – a pleasant smell
- приємний день – a pleasant day
приємно – used to describe a state or feeling, often with це or мені/тобі:
- Це приємно. – It is pleasant.
- Мені приємно. – It’s pleasant for me / I’m pleased.
- Було дуже приємно. – It was very pleasant.

So але це приємно literally: but this is pleasant → but it feels good.

Why is there a comma before але?

In Ukrainian punctuation, the conjunction але (“but”) usually joins two clauses, and a comma is placed before it, just like in English:

…болять м’язи, але це приємно.
– …the muscles hurt, but it’s pleasant.

Other examples:

Він втомився, але продовжував працювати. – He got tired, but continued working.
Я хотів піти, але передумав. – I wanted to go, but changed my mind.

You can also start a new sentence with Але for stylistic reasons:

Після тренування болять м’язи. Але це приємно.

That’s more emphatic in writing, like: After the workout, my muscles hurt. But it feels good.

What’s the apostrophe (’) doing in м’язи?

The apostrophe (ʼ) in Ukrainian shows that:

The preceding consonant is not softened (not palatalized), and
The following я / ю / є / ї keeps its [j] (“y”) sound.

So in м’язи:

м – [m]
’ – separates the м and я
я – [ja] (like “ya” in yard)
з – [z]
и – [ɪ] (like the “i” in sit)

Approximate pronunciation: [ˈmʲjazy], often simplified for learners as “MYA-zy”.

Without the apostrophe, the spelling would suggest a different sound, so it’s important in words like:

м’ясо – meat
п’ять – five
об’єкт – object

What exactly does тренування mean? Is it “training” in general or “a workout”?

Тренування covers both meanings, depending on context:

A workout / training session (countable)
- Після тренування болять м’язи. – After the workout, my muscles hurt.
- У мене сьогодні два тренування. – I have two training sessions today.
Training / practice in a more general sense (uncountable or abstract)
- Він потребує більше тренування. – He needs more training.
- Регулярне тренування корисне для здоров’я. – Regular training is good for your health.

So in your sentence, it’s naturally understood as “after (a/the) workout” or “after training” in the gym/sport sense.

Can I drop це and just say “але приємно”?

Yes, that’s also possible and quite natural in spoken Ukrainian:

Після тренування болять м’язи, але приємно.

This sounds a bit more casual and elliptical, like English:

My muscles hurt after the workout, but (it’s) nice.

Including це (але це приємно) feels a bit more complete and neutral, especially in writing.
Both are correct; the difference is mainly in style and fullness of the sentence, not in meaning.

Why is the verb болять in the present tense if we’re talking about “after” something?

Because we’re describing a current state that results from a past action:

You trained (in the past or just now).
As a result, now your muscles hurt.

So болять is present tense: hurt / are hurting.
This is similar to English:

After the workout, my muscles *hurt.* (present simple)

If you wanted to refer to a past situation (for example, yesterday’s workout), you would use past tense:

Після вчорашнього тренування боліли м’язи.
– After yesterday’s workout, my muscles hurt / were hurting.

In your sentence, the focus is on a general or current experience, so the present tense болять is appropriate.