Warn out places.
Her feet hit the ground harder than she intends, so she pauses for a brief second, hissing in pain. This, is the reason she free runs all the time. She has to be smarter, make better judgement, work harder, be faster—
She needs to be capable of outrunning everything.
"…stupid. That was so amateur." She scolds herself, brushing her hair away from her face. A couple of seconds off on the jump. Just a few. And now her ankle hurt. It was barely there, but she focuses on it, telling herself it was so stupid, and she wouldn’t be in pain if she’d counted properly.
If she hadn’t been so absorbed in this, she might’ve heard the footsteps.