Run on the treadmills for as long as possible

(chapter originally by ? at writing.com)

"Deal!" Isabel agreed.

"Okay," was Kelly's response, "I'll take treadmill one and you can take number two."

I walk over to the treadmill next to the one Kelly was on, and Heather signals our start.

We start, both going at 5km/h as we agreed. Then Isabel's treadmill starts to slow down. While she is looking over her controls, Stephanie comes up behind Isabel and