Final answer:
High armrests can cause poor posture by misaligning the spine and elevating the shoulders, leading to back strain and muscle fatigue due to improper positioning of the body's center of gravity.
Step-by-step explanation:
When armrests are too high, they can affect your posture, which, in turn, can lead to back strain and muscle fatigue. This concept is related to the body's center of gravity (CG) and the resulting torque that the muscles need to exert to maintain equilibrium. Good posture is described as the body's CG being directly above the pivot point at the hips, creating no torque and needing minimal muscle effort to maintain. However, armrests that are too high can cause the shoulders to elevate and the spine to be misaligned, resulting in a posture where the body's CG is not optimally positioned. This misalignment can cause the muscles in the back and neck to exert excessive force, leading to discomfort and potential strain.