Learn Hardcore French: Nous aimons nous détendre au parc après le travail.

The first nous is the subject pronoun: Nous aimons = We like.
The second nous is the reflexive pronoun used with the verb se détendre (to relax): nous détendre = to relax (ourselves).

So the structure is:

Nous (subject) aimons (verb) nous (reflexive pronoun) détendre (infinitive verb).

You cannot drop the second nous, because se détendre always needs its reflexive pronoun.

What does se détendre mean exactly, and why is it reflexive?

Se détendre is a reflexive verb that means to relax or to unwind.

Literally, it is to relax oneself, which is why it uses a reflexive pronoun (me, te, se, nous, vous, se).
In the infinitive:

se détendre = to relax
nous détendre = to relax (ourselves)
je veux me détendre = I want to relax

In modern English we just say relax, but French keeps the reflexive structure.

Why is it Nous aimons nous détendre and not Nous aimons à nous détendre?

With aimer followed by a verb, French normally uses a bare infinitive (no preposition):

J’aime lire. = I like to read.
Nous aimons voyager. = We like to travel.

So with a reflexive verb it’s the same:

Nous aimons nous détendre. = We like to relax.

Adding à (Nous aimons à nous détendre) sounds old‑fashioned or incorrect in modern everyday French.

Could you say Nous aimons nous relaxer instead of nous détendre?

You can say Nous aimons nous relaxer, and people will understand you.

However:

se détendre is the most natural, common everyday verb for to relax.
se relaxer is also used, but can sound a bit more informal or influenced by English to relax. It is accepted but less "classic" than se détendre.

For a learner, se détendre is the safest and most idiomatic choice.

Why is it au parc and not à le parc?

Au is simply the contraction of à + le:

à + le parc → au parc
à + le cinéma → au cinéma
à + le restaurant → au restaurant

French always contracts à + le into au in standard writing and speech.
So au parc literally means at/to the park.

What is the difference between au parc and dans le parc?

Both can be correct, but there’s a nuance:

au parc = at/to the park in a general sense
- Nous aimons nous détendre au parc.
  → We like relaxing at the park (somewhere in the park area).
dans le parc = inside the park, emphasising being inside the space.
- Nous aimons nous détendre dans le parc, près du lac.
  → We like relaxing in the park, near the lake.

Often they overlap, and au parc is very common as the neutral choice.

Why is it après le travail and not just après travail?

In French, general activities or concepts like le travail, l’école, le déjeuner often keep the definite article le / la / l’, even when English doesn’t use the.

après le travail = after work
à l’école = at school
après le dîner = after dinner

Without the article (après travail) would sound incomplete or ungrammatical in standard French.

Could the time expression go at the beginning? For example: Après le travail, nous aimons nous détendre au parc.

Yes. Putting the time expression at the beginning is very natural:

Après le travail, nous aimons nous détendre au parc.

Both word orders are correct:

Nous aimons nous détendre au parc après le travail.
Après le travail, nous aimons nous détendre au parc.

French is quite flexible with time expressions, just like English.

Why is the verb aimons in the present tense instead of something like nous aimons de nous détendre or a different tense?

Here:

aimons is the present tense of aimer for nous:
- nous aimons = we like / we love

The present tense in French, like in English, is used for habits and general preferences:

Nous aimons nous détendre au parc.
= We like relaxing at the park (general habit).

You don’t need any extra preposition such as de here; aimer + infinitive is the standard pattern.

Why is it Nous aimons nous détendre and not Nous nous aimons détendre?

Object pronouns in French (including reflexive pronouns) usually go:

before the conjugated verb, or
before the infinitive, when there is one.

In this structure, aimons is conjugated, and détendre is in the infinitive form. The reflexive pronoun belongs to se détendre, so it goes right before détendre:

Nous aimons nous détendre. ✅
- nous (subject) … nous détendre (reflexive + infinitive)

Nous nous aimons détendre ❌ is wrong because it separates the reflexive pronoun from its infinitive verb in the wrong way.

Can I leave out nous before détendre and just say Nous aimons détendre au parc?

No. Se détendre is a reflexive verb and must have its reflexive pronoun.

✅ Nous aimons nous détendre au parc.
❌ Nous aimons détendre au parc.

Détendre without se is a transitive verb meaning to loosen / to relax something:

Cette musique détend les gens.
= This music relaxes people.

But when the subject is relaxing itself, you use the reflexive form se détendre: nous détendre, me détendre, etc.

Is there any emphasis or special meaning because nous appears twice?

No special emphasis is intended here.

The first nous = subject (we)
The second nous = reflexive pronoun of se détendre

Unlike English, you must repeat it because French grammar requires both roles to be expressed separately. It does not mean “we ourselves really like to relax”; it just means “We like to relax.”

How would this sentence change if you use on instead of nous?

With on (informal we / people / you), you would say:

On aime se détendre au parc après le travail.

Changes:

nous aimons → on aime (3rd person singular)
nous détendre → se détendre (because the infinitive goes back to its base form se détendre)

Meaning is essentially the same, but on is more common in everyday spoken French than nous.