Keah et al, 2009 reported a rhabdomyolisis case on a 33 year old, sedentary woman, that during a company motivation course was instructed by the speaker to do 90 push-ups as a penalty for losing in one of the events.
@jamesm1978 I'm not 100% sure but I'm reading it as pushups are basically like doing 40% of your 1RM bench press but they use your core muscles more than just flat benching.