The word “strike” as used herein shall mean a cessation or deliberate slowing down of work by a combination of persons as a means of enforcing compliance with a demand upon the employer, but shall not include protected activity under Article 16 of this Chapter: Provided, however, that nothing herein shall limit or impair the right of any public employee to express or communicate a complaint or opinion on any matter related to the conditions of public employment so long as the same is not designed to and does not interfere with the full, faithful, and proper performance of the duties of employment. (1981, c. 958, s. 1.)