Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Knee-straining postures: a unsupported kneeling (roofer); b supported kneeling (tiler), c sitting on heels (installer), d squatting (reinforcement ironworker); and e crawling (floor layer). Subjects b–d are equipped with the CUELA measuring system
