Ο αγκώνας μου είναι καλύτερα σήμερα, αλλά προσέχω ακόμα όταν ανοίγω βαριές πόρτες.

Greek usually keeps the definite article with body parts and with possessive expressions.

So:

• ο αγκώνας = the elbow
• ο αγκώνας μου = my elbow

This is very normal in Greek. English often drops the when using possessives, but Greek usually does not.

μου is the weak form of the personal pronoun meaning my / of me.

In this sentence, it shows possession:

• ο αγκώνας μου = my elbow

Greek commonly places this weak possessive pronoun after the noun. You will see this pattern all the time:

• το χέρι μου = my hand
• η πόρτα σου = your door
• το σπίτι του = his house

Grammatically, μου is a genitive form, but for a learner it is often easiest to think of it as the normal post-noun way to say my.

Because καλύτερα is being used in the common expression είμαι/είναι καλύτερα, which means to be feeling better or to be in better condition.

So:

• Ο αγκώνας μου είναι καλύτερα σήμερα = My elbow is better today

Here καλύτερα does not describe the noun the way an adjective would. It works more like better in I feel better.

Compare:

• είμαι καλύτερα = I am feeling better
• είμαι καλύτερος = I am better (as an adjective, usually about a masculine person or thing, not the normal way to talk about how you feel physically)

So in health or condition contexts, καλύτερα is the natural choice.

Because the subject is singular:

• ο αγκώνας = the elbow = one elbow

So the verb must also be singular:

• ο αγκώνας μου είναι... = my elbow is...

If the subject were plural, the verb would be plural too:

• Οι αγκώνες μου είναι καλύτερα = My elbows are better

It can mean several related things, and here it means I am careful or I watch out.

So:

• προσέχω ακόμα = I am still being careful / I still watch out

The verb προσέχω is very common and flexible. Depending on context, it can mean:

• pay attention
• be careful
• watch out
• take care

In this sentence, because the speaker is talking about an elbow and heavy doors, the sense is clearly I am still careful.

ακόμα here means still.

So:

• προσέχω ακόμα = I am still being careful

It shows that the situation continues. The elbow is better, but the speaker has not completely stopped being cautious.

You may also see the spelling ακόμη. In most everyday contexts, ακόμα and ακόμη mean the same thing.

Because όταν ανοίγω here expresses a repeated or habitual situation: when/whenever I open heavy doors.

That is why the present tense fits well:

• όταν ανοίγω βαριές πόρτες = when(ever) I open heavy doors

This suggests something general, not one single future event.

A useful contrast:

• όταν ανοίγω... = when/whenever I open... (habitual, repeated)
• όταν ανοίξω... = when I open / when I have opened... (one future occasion, more specific or completed)

So the present tense here matches the idea of an ongoing precaution in repeated situations.

In this sentence, whenever is often the best way to understand it, even though English may simply say when.

• όταν ανοίγω βαριές πόρτες literally looks like when I open heavy doors
• but the sense is really whenever I open heavy doors

That is because the Greek present tense here describes a repeated action, not a single moment.

Because adjectives in Greek must agree with the noun in gender, number, and case.

Here:

• πόρτες = feminine plural
• so the adjective must also be feminine plural

The dictionary form is:

• βαρύς = heavy (masculine singular)

But here it becomes:

• βαριές = feminine plural

So:

• βαριές πόρτες = heavy doors

This kind of change is very normal in Greek adjectives.

It is the direct object of ανοίγω (I open), so it is in the accusative.

• ανοίγω πόρτες = I open doors

In this particular noun type, the feminine plural nominative and accusative look the same:

• nominative plural: οι πόρτες
• accusative plural: τις πόρτες

So even though the form πόρτες looks the same, its job in the sentence is accusative because it is the object.

Because Greek, like English, can leave out the article when speaking in a general or indefinite way.

Here the meaning is not the heavy doors but heavy doors in general.

So:

• ανοίγω βαριές πόρτες = I open heavy doors

If the speaker meant specific doors already known in the conversation, Greek could use the article:

• ανοίγω τις βαριές πόρτες = I open the heavy doors

Greek word order is more flexible than English word order, although some versions sound more natural in a given context.

The original sentence is completely natural:

• Ο αγκώνας μου είναι καλύτερα σήμερα, αλλά προσέχω ακόμα όταν ανοίγω βαριές πόρτες.

But you could also move some parts for emphasis:

• Σήμερα ο αγκώνας μου είναι καλύτερα...
• Αλλά ακόμα προσέχω όταν ανοίγω βαριές πόρτες.

The basic meaning stays the same, but the emphasis changes slightly. Greek often uses word order to highlight what is most important or most contrastive.

Yes. σήμερα is an adverb of time, and Greek allows some flexibility with adverb placement.

These are all possible, with slightly different emphasis:

• Ο αγκώνας μου είναι καλύτερα σήμερα.
• Σήμερα ο αγκώνας μου είναι καλύτερα.
• Ο αγκώνας μου σήμερα είναι καλύτερα.

The version in your sentence is very natural. Putting σήμερα later often feels smooth and conversational.

Yes, it is natural.

Greek often uses είμαι/είναι καλύτερα where English might prefer:

• is better
• feels better
• is doing better

So you should not expect a word-for-word match with English. The Greek structure is idiomatic and common for talking about recovery or improvement.

In other words, even if English focuses on feels, Greek can simply use είναι καλύτερα.