Με πονάει το μπράτσο μου όταν σηκώνω βαριά κουτιά.

Because Greek often expresses physical pain as something hurts me rather than I hurt.

So Με πονάει το μπράτσο μου is literally closer to:

My arm hurts me.

Here:

• με = me
• πονάει = hurts
• το μπράτσο μου = my arm

This is a very common Greek pattern with body pain:

• Με πονάει το κεφάλι μου. = My head hurts.
• Με πονάνε τα πόδια μου. = My legs hurt.

Because the grammatical subject is το μπράτσο μου.

So the verb agrees with το μπράτσο μου:

• το μπράτσο = singular
• therefore πονάει = third person singular

Even though English says My arm hurts, Greek structures it as My arm hurts me, so the verb matches arm, not me.

Compare:

• Με πονάει το μπράτσο μου. = My arm hurts.
• Με πονάνε τα μπράτσα μου. = My arms hurt.

Yes. That is also correct.

Both are natural:

• Με πονάει το μπράτσο μου.
• Το μπράτσο μου πονάει.

The version with με is especially common when talking about body pain, because it highlights the experiencer: it hurts me.

The difference is not huge here. Greek word order is flexible, and both sentences can be used in everyday speech.

Greek normally uses the definite article with body parts and with possessive clitics.

So:

• το μπράτσο μου = my arm
• literally something like the arm of mine

This is very normal Greek structure:

• το κεφάλι μου = my head
• το χέρι μου = my hand / arm
• τα πόδια μου = my legs

In English, we do not say the arm my, but in Greek the article is usually required.

Because Greek possessive pronouns in this pattern are usually weak pronouns placed after the noun.

So:

• το μπράτσο μου = my arm
• το σπίτι μου = my house
• η φίλη μου = my friend

This is the normal way to say possession in everyday Greek.

Not exactly.

• μπράτσο usually means arm, especially the arm as a limb, often the upper arm
• χέρι can mean hand, but in everyday Greek it can also refer more broadly to the arm depending on context

So in this sentence, μπράτσο makes it clearer that the pain is in the arm, not specifically the hand.

A learner will often hear:

• χέρι in many everyday situations
• μπράτσο when the speaker wants to be more specific about the arm

Because this sentence describes a habitual or repeated situation:

whenever / when I lift heavy boxes

Greek often uses the present tense after όταν for repeated actions or general truths.

So:

• όταν σηκώνω βαριά κουτιά = when/whenever I lift heavy boxes

This does not mean one specific future event. It means this happens generally.

If you were talking about a single future action, Greek might use a different structure, for example with subjunctive:

• όταν σηκώσω... = when I lift... / when I have lifted... in the future

But here the meaning is habitual, so σηκώνω is right.

Σηκώνω is the first person singular present active form of the verb σηκώνω.

Here it means:

• I lift
• I raise
• sometimes I pick up, depending on context

So:

• σηκώνω βαριά κουτιά = I lift heavy boxes

Other forms:

• σηκώνεις = you lift
• σηκώνει = he/she/it lifts
• σηκώνουμε = we lift
• σηκώνετε = you lift
• σηκώνουν = they lift

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

Here:

• κουτιά is neuter plural
• so βαριά is also neuter plural

Agreement:

• βαρύ κουτί = heavy box
• βαριά κουτιά = heavy boxes

The adjective βαριά can look confusing because the same form can also appear elsewhere, but here it is the neuter plural form matching κουτιά.

It is in the accusative plural, because it is the direct object of σηκώνω.

You are lifting what?

• κουτιά = boxes

With neuter nouns, the nominative plural and accusative plural often have the same form, so κουτιά looks the same in both cases.

Singular:

• το κουτί = the box

Plural:

• τα κουτιά = the boxes

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

So:

• βαριά κουτιά = heavy boxes
• τα βαριά κουτιά = the heavy boxes

In this sentence, the speaker means heavy boxes in general, not some specific boxes already identified, so no article is needed.

No, Greek word order is fairly flexible.

The given sentence is natural:

• Με πονάει το μπράτσο μου όταν σηκώνω βαριά κουτιά.

But you could also hear:

• Το μπράτσο μου με πονάει όταν σηκώνω βαριά κουτιά.
• Όταν σηκώνω βαριά κουτιά, με πονάει το μπράτσο μου.

The core grammar stays the same, but the order can shift for emphasis, rhythm, or topic.

Yes. In everyday Greek, many speakers use both forms.

So you may hear:

• Με πονάει το μπράτσο μου
• Με πονά το μπράτσο μου

Both are common and correct in speech. The -άει form is very common in standard written and spoken Greek, but the shorter form πονά is also widely used.

Here, whenever is often the better explanation, even though English may simply say when.

That is because the sentence describes a repeated pattern:

• every time I lift heavy boxes, my arm hurts

So όταν here has the sense of:

• when
• whenever
• every time that

This is a very common use of όταν in Greek.