Registration is due today for the Knoxville Recreation Center’s fall Body Fit Challenge. The intense four day a week workout schedule lasts 6 weeks and is designed to trim and tone and increase lean body mass. The challenge will take place Mondays-Thursdays September 13th through October 25th with the first three weeks of classes beginning at 6:30pm. In order to provide personalized instruction time, the program is open to just 12 registrants on a first come, first serve basis. Registrations completed at the recreation center, located at 800 South Park Lane in Knoxville.