According to Wikipedia
"A podcast is a digital medium that consists of an episodic series of audiodigital radioPDF, or ePub files subscribed to and downloaded through web syndication or streamed online to a computer or mobile device. The word is a neologism and portmanteau derived from "broadcast" and "pod" from the success of the iPod, as audio podcasts are often listened to on portable media players."

Personally I listen to podcasts while riding the spin bike, cleaning house, often on long commutes, you get the idea. 
Here are must listen to podcasts:

Jorge Rodriguez teaches physical education in Texas. On Voxcast Jorge, with a host of other physical educators interview and converse with some PE superstars.

 in this podcast Joey Feith and Nathan Horne chat about physical education.

  Actually a blog site but if you scroll down through the written blog, it is also available in podcast form. Ash covers the research end of physical education. What does the latest research tell us?

#Physedagogy Great podcast group interviewing innovative physical education teachers and hosting free webinars.

Created to provide physical education professionals with quality blog posts in a podcast format.  P.E. teachers are encouraged to email their articles tolynn.hefele@gmail.com in written or audio format to be included in the broadcast.  Each session features two blogs and a commercial product that benefits the educational community.

 Jarrod Robinson, the PE Geek discusses his latest teaching experiences and reviews a variety of technology tools and apps.