We run for another five minutes and Catherine moves on to do the pec fly right in front of me. She comes pushing the bars with her legs wide open and I notice that she's got no panties under her shorts! A top with no bra under it, tiny shorts with no panties. Boy, that's a good uniform for a workout. Catherine is such a naughty one. I glance at a guy walking on the treadmill right next to me - he is obviously staring at Catherine. She has noticed it too, so she keeps on moving along the seat making her shorts stretch over her pussy even tighter. I can already see the silhouette of her pubis through them. The edges of her shorts are already wet with sweat.