Reality is that females should train with heavy weights just like their male counterparts often do and no it won't make you «bulky» and deepen your voice. (simplyshredded.com)
So how should you train your core, given its basic functions? (fitnessandpower.com)
Individuals should train for 15 + repetitions for 1 — 3 sets with increasing volume for more advanced individuals. (simonsterstrength.com)