The Klingon calisthenics program was a holodeck program favored by Lieutenant Worf for recreation when he served on board the USS Enterprise-D. The participants fought "to the death" against one or more holographic characters in a jungle-like setting among ruined structures using melee weapons. There were several levels of difficulty for the program.
Most humanoids other than Klingons found the program excessively violent, but William T. Riker was known to have participated in at least one of Worf's calisthenics programs. (TNG: "Where Silence Has Lease")
Jadzia Dax created a similar program on Deep Space 9 and found a surprised Worf running the program. Rather than a jungle settings, Jadzia's version of the program featured similar opponents in a drier, rockier setting that lacked the abandoned ruins. (DS9: "The Way of the Warrior")
In 2369 while treating Commander Riker in sickbay, Doctor Beverly Crusher thought the two deep cuts on his head were caused by a Parrises squares game, but Riker said he'd not played this game. Another suggestion of Crusher was Worf's calisthenics program but Riker revealed that this wound was caused by Data's cat Spot. (TNG: "Timescape")