pinch, twist, wring, determined
擰 centers on applying force with the hand to twist, pinch, or wring something. The sense of being determined likely extends from the idea of firmly gripping or twisting one's resolve.
擰 combines 扌 (hand) with 寧, which likely contributes the sound and may relate to twisting or pressing. The exact historical development is uncertain.
The hand radical 扌 beside 寧 suggests a hand firmly twisting or pinching something. Imagine gripping a cloth and wringing it out with determination.
For ドウ, picture a determined hand twisting a dough: dough -> ドウ, and the hand wrings it firmly.