The injured worker should give a valid and consistent effort when doing the physical tests required by the FCE. These tests have built in mechanisms to try to spot someone who is not giving their best effort and/or is trying to manipulate the test. If you have a non-valid test or show inconsistent effort, this can seriously negatively impact your case and how the employer's insurance company, and even the SC Workers Compensation Commissioner hearing your case, views your disability.
Report any and all pain and or limitations you have during the FCE to the person giving the test
Yes you must give valid and consistent effort but you also need to report any and all pain an limitations that you have while doing the activities required during the test. Otherwise, the test administrator will not know how these tasks affect you and your ultimate work restrictions need to be based upon the whole story; not just how hard you tried.