The treadmill

Isabel walked over to the treadmill and put her towel over the arms, turning the speed up to 12 and beginning to jog. Kelly, as competitive as ever, walked up to the treadmill next to Isabel, setting her speed to 13. The two girls jogged alongside each other in silence, occasionally shooting glances at each other.

It was Isabel that made the next move, setting her speed up to 14. This was quicker than she'd ordinarily like, but she had been working out a lot recently and this wasn't causing her too many problems. Kelly reacted instantly, setting her speed to 15, moving towards a sprint at this stage.

"Is this supposed to impress anyone?!" Isabel asked.

"The only thing anyone here is impressed about is that you've managed to keep your clothes on for this long!" shouted Kelly, loudly enough for the people working on the machines around to hear.

"Oh fuck off Kelly, at least there's someone that might want to see me naked!"

Quick as a flash, Kelly reached over and upped the speed on Isabel's treadmill to 20. Isabel tried desperately to keep up with the new pace, but found herself drifting towards the back of the treadmill, the button to slow the speed down getting slowly further and further out of reach. Kelly stopped her treadmill to watch the action unfold as Isabel lunged forward to reach for the speed button, falling just short and tripping, catching herself on the arms of the treadmill. As she did so, her feet slid towards the back of the treadmill, pulling her towards the ground. Her knees made the initial contact with the rubber, and she felt a slight burn as she held on for dear life. Another few seconds and her feet slipped off the back, her hips just about touching the rubber of the treadmill as she held onto the bars. The front of her pants rubbed against the treadmill for a few seconds before they were shucked down to her knees, her panty-clad bottom on show for everyone in the gym with Isabel having no way of pulling her pants back up..