Learn Portuguese (Portugal): Por mais que eu me equilibre, a prancha vira. - No matter how much I balance myself, the surfboard turns.

The phrase por mais que introduces a concessive clause, which shows an obstacle that doesn't stop the main action. In Portuguese, this structure always triggers the subjunctive because it sets up a hypothetical or generalized scenario, rather than a simple concrete fact.

Could I use por muito que instead of por mais que in this sentence?

Yes, absolutely! Por muito que eu me equilibre means exactly the same thing. Both phrases translate to 'no matter how much' and both require the subjunctive verb form.

Why is the reflexive pronoun me placed before the verb in eu me equilibre?

The word que acts as a powerful 'magnet' in Portuguese. Whenever a verb immediately follows que, any object or reflexive pronouns are pulled right in front of the verb. If you were just stating 'I balance myself' as a normal sentence without the que, it would be eu equilibro-me.

Why is the second verb vira in the normal indicative tense when the first one is in the subjunctive?

The subjunctive is only triggered for the action tied to the 'no matter how much' phrase, because that part expresses a hypothetical effort. The second half, a prancha vira, is the factual result that actually happens despite the effort, so it stays in the normal indicative tense.