involuntarily

He shivered involuntarily as the cold wind blew through his thin jacket.

(Chinese) 寒风吹过他单薄的外套时，他不由自主地打了个冷颤。

The muscles in my leg began to twitch involuntarily after the long run.

(Chinese) 长跑后，我腿部的肌肉开始不由自主地抽动。