Breakdown of Después de tantas horas sentada, me dolía la cadera y tuve que levantarme.
Questions & Answers about Después de tantas horas sentada, me dolía la cadera y tuve que levantarme.
Both are possible, but they are structured differently.
- Después de tantas horas sentada = after so many hours sitting / after so many hours being seated
- Después de estar sentada tantas horas = after being seated for so many hours
In the original sentence, después de + noun phrase is being used:
- después de tantas horas = after so many hours
Then sentada describes the speaker’s state during those hours.
This is a very natural, compact way to say it in Spanish.
Because sentada agrees with the speaker, who is understood to be female.
So:
- If a man says it: Después de tantas horas sentado...
- If a woman says it: Después de tantas horas sentada...
Spanish adjectives and participle-like forms often agree in gender and number with the person they describe.