Se eu estudar demasiado curvado, fico com dor no pescoço e na barriga por causa da tensão.

Here, estudar is functioning as the future subjunctive, not as a plain infinitive.

This is confusing at first because with regular -ar verbs, the eu/ele/ela form of the future subjunctive looks exactly the same as the infinitive.

After se when talking about a real possible future situation, Portuguese normally uses the future subjunctive:

• Se eu estudar, passo no exame.
• Se ele vier, falamos.

So Se eu estudar... means something like If I study... or If I happen to study... in a future or general conditional sense.

Here, demasiado means too or overly, not just very.

So:

• muito curvado = very bent / very hunched
• demasiado curvado = too bent / too hunched

That difference is important. The sentence is saying the posture is excessive or unhealthy, not just noticeable.

In European Portuguese, demasiado is very common in this kind of sentence.

Curvado means bent, curved, or more naturally here, hunched over / bent forward.

In this sentence, it describes the speaker’s posture while studying.

So estudar demasiado curvado means studying while being too bent over.

Yes. Curvado is an adjective, so it agrees with the person being described.

• male speaker: curvado
• female speaker: curvada

So a woman would normally say:

Se eu estudar demasiado curvada, fico com dor...

This is because the adjective refers back to the subject eu.

Yes, it is natural and understandable. It means too hunched over or too bent forward.

You could also hear alternatives such as:

• Se eu estudar muito curvado...
• Se eu estiver demasiado curvado a estudar...

But estudar demasiado curvado is perfectly fine and natural in everyday Portuguese.

Ficar com dor means to get pain, to end up with pain, or to start feeling pain as a result of something.

That fits this sentence well, because the idea is:

If I study in that posture, I end up getting pain.

By contrast, ter dor simply describes the state of already having pain:

• Tenho dor no pescoço. = I have pain in my neck.
• Fico com dor no pescoço. = I get pain in my neck.

So fico com dor is the more natural choice here because it focuses on the result.

Portuguese can use dor in the singular as a general symptom, even if more than one place hurts.

So fico com dor no pescoço e na barriga is fine.

You could also say:

fico com dores no pescoço e na barriga

That would sound a bit more like I get aches/pains in my neck and belly.

So:

• dor = pain, treated more generally
• dores = pains/aches, slightly more countable or distributed

Both are possible, but the singular works well here.

Because the nouns have different grammatical genders:

• o pescoço = masculine
• a barriga = feminine

And Portuguese contracts em with the definite article:

• em + o = no
• em + a = na

So:

• no pescoço
• na barriga

This is very normal in Portuguese, especially with body parts.

Barriga is an everyday word for the belly or stomach area.

Depending on context, English might translate it as:

• belly
• stomach
• abdomen

It is less anatomically precise than estômago or abdómen:

• estômago = the stomach organ
• abdómen = abdomen, more formal/medical
• barriga = everyday word for the front abdominal area

In this sentence, barriga sounds natural because it is talking about bodily discomfort in an everyday way.

Por causa de means because of.

So:

• por causa de tensão
• por causa da tensão

In the sentence, da is a contraction of:

• de + a = da

That happens because tensão is feminine and is being used with the definite article a.

Here tensão most likely means physical tension, muscle tension, or strain caused by posture. In other contexts, it can also mean stress or tension more generally.

Yes. Portuguese often leaves out subject pronouns when the verb form already makes the person clear.

So you could say:

Se estudar demasiado curvado, fico com dor no pescoço...

That is perfectly possible if the context already shows who is speaking.

Keeping eu is also fine. It can add:

• emphasis
• clarity
• contrast

So both versions are correct.

The present tense is very common here because it expresses a general result or habitual consequence:

If I study hunched over, I get pain...

It is like saying whenever that happens, this is the result.

You could use ficarei if you wanted a more specifically future-oriented meaning:

Se eu estudar demasiado curvado, ficarei com dor...

That is grammatical, but fico sounds more natural in everyday speech for a general cause-and-effect statement.