stiffly

adverb2

1. •
   With stiffness; lacking a smooth flow of movement, or lacking movement altogether.

   • When Handy had gone, Bert Barricue sagged in, unwashed, unshaven. He sat down stiffly. — 1949
2. •
   In a stiff manner.

   • 'Very well, Clara,' she said stiffly, 'but I shall also speak to your father.' — 1956