Ao correr ao sol, a Ana ficou com a testa quente e o queixo cheio de suor.

Ao correr is a very common Portuguese structure meaning while running, when running, or upon running, depending on context.

It is built like this:

• a + o = ao
• followed by an infinitive: correr

So:

• ao correr = while running

In European Portuguese, this kind of structure is often preferred where English might use while + -ing.

In this sentence, Ao correr ao sol means While running in the sun.

Ao sol is the usual expression for in the sun or under the sun / exposed to sunlight.

Here:

• sol is masculine singular
• a + o = ao

So ao sol literally looks like to the sun, but idiomatically it means in the sun.

This is just the normal Portuguese expression:

• estar ao sol = to be in the sun
• sentar-se ao sol = to sit in the sun
• correr ao sol = to run in the sun

You should learn ao sol as a set phrase.

In European Portuguese, it is very common to use the definite article before a person’s first name:

• a Ana
• o João
• a Maria

So a Ana simply means Ana, but with the article that Portuguese normally uses.

This is much more common in Portugal than in English, where we normally do not say the Ana. It does not mean the Ana in translation; it is just standard Portuguese usage.

Here ficou com means something like ended up with, got, or was left with.

So:

• ficou com a testa quente = her forehead got hot
• ficou com o queixo cheio de suor = her chin ended up covered in sweat

This is a very common pattern in Portuguese:

• ficar com fome = to become hungry
• ficar com medo = to become afraid
• ficar com dores = to end up with aches/pains

So ficar com often expresses a resulting state.

Portuguese often uses the definite article with body parts when it is already clear whose body part is meant.

So instead of saying:

• a sua testa
• o seu queixo

Portuguese very naturally says:

• a testa
• o queixo

Because the sentence is about Ana, it is obvious that these are her forehead and her chin.

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

• Levantei a mão = I raised my hand
• Ela lavou o rosto = She washed her face
• Ele magoou o braço = He hurt his arm

English uses possessives more often; Portuguese often does not need them.

Quente is an adjective meaning hot or warm, and here it describes a testa.

So:

• a testa quente = the hot forehead

In Portuguese, adjectives often come after the noun, especially in ordinary descriptive use.

Also, quente has the same form for masculine and feminine singular:

• o chá quente
• a testa quente

Only the plural changes:

• quentes

So here quente matches testa in number, and its form already works for feminine singular.

Cheio de means full of or, in many contexts, covered in.

So:

• o queixo cheio de suor = the chin full of sweat / the chin covered in sweat

This is a very natural way to describe visible sweat on part of the body.

You can think of it as a result description:

• ficou com o queixo cheio de suor = her chin ended up covered in sweat

Because cheio agrees with o queixo, and queixo is masculine singular.

Agreement works like this:

• o queixo cheio
• a cara cheia
• os braços cheios
• as mãos cheias

So in this sentence:

• o queixo = masculine singular
• therefore cheio

This is a very important point in Portuguese: adjectives agree with the noun they describe.

Yes, suado is possible in some contexts, but it is not exactly the same in feel.

Compare:

• o queixo cheio de suor = the chin covered in sweat
• o queixo suado = the sweaty chin

Cheio de suor gives a slightly more visual, concrete image, as if you can really see the sweat there. It sounds very natural in this sentence.

So suado is possible in general Portuguese, but cheio de suor is a good choice here because it is vivid and specific.

Ficou is the pretérito perfeito of ficar. It shows a completed event or change:

• she ran in the sun
• as a result, her forehead became hot and her chin got sweaty

So ficou focuses on the change of state.

Compare:

• ficou com a testa quente = her forehead got hot
• estava com a testa quente = her forehead was hot

The first one emphasizes the result of what happened; the second one just describes the state.

In a sentence like this, the normal interpretation is that Ana is the one doing the running.

So:

• Ao correr ao sol, a Ana ficou...
• understood meaning: While Ana was running in the sun, she ended up...

In Portuguese, an initial infinitive phrase like this usually connects naturally to the subject of the main clause unless something else is clearly stated.

So yes, a learner should normally read it as Ana was running in the sun.

The phrase Ao correr ao sol is an introductory adverbial phrase, and the comma separates it from the main clause:

• Ao correr ao sol,
• a Ana ficou...

This is very natural and helps readability.

In Portuguese, commas are often used after introductory elements like this, especially when they are a bit longer or when the writer wants the sentence to be clearer.

Yes, in meaning it is similar.

• Ao correr ao sol... = While running in the sun...
• Correndo ao sol... can also suggest running in the sun...

But in European Portuguese, the ao + infinitive structure is especially common and very natural in this kind of sentence.

So for a learner of Portuguese from Portugal, ao correr is a very useful pattern to notice and learn well.