Nos bañamos después de hacer ejercicio.

Because bañarse is a reflexive verb. It means something like to bathe oneself or, in many everyday Latin American contexts, to take a bath/shower.

• bañamos by itself = we bathe / we bathed something or someone
• nos bañamos = we bathe ourselves / we take a bath or shower / we bathed

The pronoun nos matches nosotros/nosotras and shows that the action is being done to ourselves.

It can mean more than one thing depending on context.

Nos bañamos can be:

• we bathe
• we shower
• we are bathing (less direct, depending on context)
• we bathed
• we showered

This happens because the nosotros form of the present tense and the preterite for many -ar verbs looks the same:

• present: bañamos
• preterite: bañamos

So context tells you which meaning is intended.

For example:

• Normal routine / habit: Nos bañamos después de hacer ejercicio. = We shower after exercising.
• Past event: Ayer nos bañamos después de hacer ejercicio. = Yesterday we showered after exercising.

Spanish often leaves out subject pronouns because the verb ending usually tells you who the subject is.

So:

• Nos bañamos already tells you we bathe / we bathed
• adding nosotros is possible, but usually unnecessary

You could say:

• Nosotros nos bañamos después de hacer ejercicio

But that sounds more emphatic, like:

• We shower after exercising
• or to contrast with someone else

In neutral everyday Spanish, dropping nosotros is more natural.

In much of Latin America, bañarse is often used in everyday speech for to bathe or to shower, depending on context.

So Nos bañamos may naturally mean:

• We bathe
• We shower
• We take a shower

If you want to be more specific about shower, many speakers also use:

• ducharse = to shower

So:

• Nos bañamos después de hacer ejercicio
• Nos duchamos después de hacer ejercicio

Both can work, though usage depends on region and personal preference.

Because después is followed by de before a noun or infinitive.

So the correct pattern is:

• después de + noun
• después de + infinitive

Examples:

• después de clase = after class
• después de comer = after eating
• después de hacer ejercicio = after exercising

Without de, it would be incorrect in this structure.

Because hacer ejercicio is the most common everyday way to say to exercise in Spanish.

It works like this:

• hacer = to do
• ejercicio = exercise

Together:

• hacer ejercicio = to exercise

There are other possibilities, but hacer ejercicio is the most natural and widely used expression in general conversation.

For a learner, this is the safest phrase to use.

Because hacer ejercicio is a fixed expression meaning to exercise in general.

Compare:

• hacer ejercicio = to exercise
• hacer el ejercicio = to do the exercise or to do the assignment/exercise

So in your sentence:

• después de hacer ejercicio = after exercising

If you said hacer el ejercicio, it would sound like a specific exercise, task, or school assignment, not physical exercise in general.

Yes. That is completely natural.

Both are correct:

• Nos bañamos después de hacer ejercicio
• Después de hacer ejercicio, nos bañamos

The second version puts more focus on the time sequence:

• After exercising, we shower

Spanish word order is flexible, especially with time expressions like this.

Yes, but it changes the meaning slightly.

• después de hacer ejercicio specifically means after exercising
• luego means later / then

So:

• Nos bañamos después de hacer ejercicio = specifically after working out
• Luego nos bañamos = then/later we shower

If you want to keep the same full meaning, después de hacer ejercicio is better.

Yes. After de, Spanish commonly uses an infinitive when English often uses -ing.

So:

• después de hacer ejercicio literally looks like after to do exercise
• but it naturally means after exercising or after doing exercise

This pattern is very common:

• antes de salir = before leaving
• después de comer = after eating
• sin hablar = without speaking

This is something English speakers often need to get used to.

Yes, depending on context, bañarse can also mean to go swimming or to bathe in water, especially with places like rivers, lakes, or the sea.

For example:

• Nos bañamos en el río = We bathed / swam in the river

But in your sentence:

• Nos bañamos después de hacer ejercicio

the most natural interpretation is usually we shower / bathe after exercising, not we go swimming.

Context is what decides the meaning.

Yes, it is very natural.

A speaker in Latin America would easily understand:

• Nos bañamos después de hacer ejercicio

It sounds like a normal everyday sentence about routine or hygiene after working out.

Depending on the country, some people might prefer:

• Nos duchamos después de hacer ejercicio

But nos bañamos is still very common and natural in many places.

You would change the reflexive pronoun and verb form.

Examples:

• Me baño después de hacer ejercicio. = I shower after exercising.
• Te bañas después de hacer ejercicio. = You shower after exercising.
• Se baña después de hacer ejercicio. = He/She showers after exercising.

So for we, Spanish uses:

• nos + bañamos

That is why your sentence is:

• Nos bañamos después de hacer ejercicio.