Antes de correr, estiro los músculos en el parque.

Before running, I stretch my muscles in the park.

Breakdown of Antes de correr, estiro los músculos en el parque.

• yo: I
• en: in
• de: of
• el parque: the park

Questions & Answers about Antes de correr, estiro los músculos en el parque.

Why does the sentence use de after antes (antes de correr)?

In Spanish, antes almost always needs de when it’s followed by a noun or an infinitive:

• antes de + infinitive: antes de correr = before running
• antes de + noun: antes de la cena = before dinner

So antes de correr is the standard structure.
Without de (antes correr) it sounds wrong in this context.

Why is correr in the infinitive and not a conjugated form like corro or corra?

After a preposition (like de, en, a, por, etc.), Spanish uses the infinitive, not a gerund or a conjugated verb:

• antes de correr = literally before to run → before running
• después de comer = after eating
• sin dormir = without sleeping

So because correr comes after de, it must be in the infinitive: antes de correr.
You would only conjugate the verb if you change the structure, e.g. antes de que yo corra (subjunctive).

Could I say Antes de correr, yo estiro los músculos? Why is yo omitted?