Treinamos na bicicleta ergométrica.

Treinamos comes from the verb treinar = to train or to work out.

In this sentence, it means we train / we work out.

A very important detail: treinamos can mean either:

• we train (present), or
• we trained (simple past / preterite)

So by itself, Treinamos na bicicleta ergométrica can mean either:

• We train on the exercise bike, or
• We trained on the exercise bike

Usually, the context tells you which one is meant.

For many -ar verbs in Portuguese, the nós form is the same in the present tense and the preterite.

For example, with treinar:

• nós treinamos = we train
• nós treinamos = we trained

This is completely normal in Portuguese.

If the speaker wants to make the time clearer, they often rely on context or add a time expression, such as:

• Hoje treinamos na bicicleta ergométrica. = Today we train / are training on the exercise bike.
• Ontem treinamos na bicicleta ergométrica. = Yesterday we trained on the exercise bike.

Portuguese often leaves out subject pronouns when the verb ending already shows who the subject is.

So instead of saying:

• Nós treinamos na bicicleta ergométrica.

it is very common to say simply:

• Treinamos na bicicleta ergométrica.

Because treinamos clearly matches nós (we), the pronoun is not necessary unless the speaker wants emphasis or contrast.

For example:

• Nós treinamos na bicicleta ergométrica, mas eles correram.
  = We trained on the exercise bike, but they ran.

Na is a contraction of:

• em
  • a = na

So:

• na bicicleta ergométrica literally comes from em a bicicleta ergométrica

Portuguese normally contracts these combinations:

• em + o = no
• em + a = na
• em + os = nos
• em + as = nas

Here, na bicicleta ergométrica means on the exercise bike or more literally in/on the exercise bike, depending on the natural English translation.

Portuguese often uses em where English uses on.

So English says:

• on the bike
• on the treadmill

But Portuguese commonly says:

• na bicicleta
• na esteira

This is just a normal difference between the languages. It is best to learn the Portuguese expression as a whole:

• treinar na bicicleta ergométrica = to train on the exercise bike

Bicicleta ergométrica means exercise bike or stationary bike.

Breaking it down:

• bicicleta = bicycle / bike
• ergométrica = an adjective used for fitness/exercise equipment, roughly related to ergometric or exercise-testing/training equipment

In everyday Brazilian Portuguese, bicicleta ergométrica is the standard way to say exercise bike.

You may also hear people say just:

• bike ergométrica

especially in casual speech.

Because ergométrica agrees with bicicleta, which is a feminine singular noun.

In Portuguese, adjectives usually match the noun in gender and number.

So:

• bicicleta = feminine singular
• therefore ergométrica = feminine singular

Compare:

• um aparelho ergométrico = an ergometric/exercise device
• uma bicicleta ergométrica = an exercise bike

Portuguese uses definite articles more often than English.

So na bicicleta ergométrica literally includes the:

• on the exercise bike

But depending on context, English might translate it more naturally as:

• on an exercise bike
• on the stationary bike
• using the exercise bike

Portuguese often sounds more natural with the article, even where English might leave it out or choose a different article.

Normally, no. Em bicicleta ergométrica without the article sounds unnatural here.

The usual phrasing is:

• na bicicleta ergométrica

because Portuguese generally wants the article in this kind of expression.

So for a learner, the safest choice is:

• Treinamos na bicicleta ergométrica.

That would not be the normal choice here.

De bicicleta usually means by bike or on a bicycle in the sense of transportation or manner:

• Vou ao trabalho de bicicleta. = I go to work by bicycle.

But for exercise equipment, Portuguese normally says:

• na bicicleta ergométrica

So if you mean we worked out on the exercise bike, use:

• Treinamos na bicicleta ergométrica.

Treinar is completely natural, especially in fitness or sports contexts.

Depending on the situation, Brazilians might also say:

• malhar na bicicleta ergométrica = to work out on the exercise bike
• fazer exercício na bicicleta ergométrica = to exercise on the exercise bike
• pedalar na bicicleta ergométrica = to pedal on the exercise bike

Each one has a slightly different feel:

• treinar = train/work out
• malhar = work out, more casual and gym-oriented
• fazer exercício = exercise
• pedalar = pedal, focusing on the action

Yes, it is fairly similar:

• Treinamos = We train / trained
• na bicicleta ergométrica = on the exercise bike

So the structure is basically:

• verb + prepositional phrase

Portuguese does not need to state we, so the sentence can start directly with the verb.

If you include the pronoun, it becomes:

• Nós treinamos na bicicleta ergométrica.

That is also correct.

A simple approximate pronunciation for Brazilian Portuguese is:

• trei-NAH-moos nah bee-see-KLEH-tah ehr-go-MEH-tree-kah

A few useful notes:

• trei sounds somewhat like tray
• the stress in treinamos falls on na
• bicicleta is stressed on cle
• ergométrica is stressed on mó, which is marked by the accent: ergométrica

That accent mark is important because it shows the stressed syllable.

Because treinamos can mean both we train and we trained, you can add context words to make the present meaning clearer.

For example:

• Hoje treinamos na bicicleta ergométrica. = Today we train / are training on the exercise bike.
• Geralmente treinamos na bicicleta ergométrica. = We usually train on the exercise bike.
• Estamos treinando na bicicleta ergométrica. = We are training on the exercise bike.

That last one, estamos treinando, is especially clear if you want the idea of we are training right now.

You can make the past meaning clear by adding a past-time expression, such as:

• Ontem treinamos na bicicleta ergométrica. = Yesterday we trained on the exercise bike.
• Na semana passada, treinamos na bicicleta ergométrica. = Last week, we trained on the exercise bike.

You could also use another tense if needed, but in many everyday situations, a time word is enough to remove the ambiguity.