When body parts are put into awkward positions, i.e. at the extreme of the available range of motion, the efficiency of the muscles attached to those body parts goes down and the loads in the connective tissues goes up.
Any position held statically invites fatigue to set in quickly, and is potentially injurious.
Repetition - Numerous movements of body parts performed over a long period of time. When repetition rates are high, the time necessary for tissues to recover from forceful exertions may not be available, leading to fatigue and loss of efficiency in the muscles. Force - High muscle loads caused by forceful exertions or movement in awkward positions. High muscle loads results in high loads in connective or structural tissues, which over time, can lead to the breakdown of these tissues. Donald L. Morelli is a Certified Professional Ergonomist with over 20 years of business experience, primarily in ergonomics and safety.