Complete five max sets of pull-ups at five minute intervals. Perform sets at 0, 5, 10, 15, and 20 minutes.
These are max sets but not to muscle failure. Perform the maximum number of repetitions possible while maintaining good form, but stop short of actual muscle failure (you may go to failure on the last set if you prefer).
Advanced: Pull-ups and/or Chin-ups
Intermediate: Partial or Assisted Pull-ups or Body Rows
Basic: Body Rows