The Heroes (1980)

Former Shaolin man Marshal Kao takes his former classmates prisoner and, instead of executing them, proposes to his Qing commander that he torture them until they're willing to fight on behalf of the Qings. The 'torture' comes to look increasingly like strenuous kung fu training with Kao putting the prisoners through their paces. The Qing governor and his aides become suspicious of Kao's motives, although the beautiful Princess Shao Lung develops her own ideas about him.