Body mechanics refers to the safe and efficient use of the body during movement and activity. It involves proper body alignment, balance, and coordinated movement. Prolonged immobility can lead to complications like pressure ulcers, bone demineralization, negative nitrogen balance, orthostatic hypotension, increased cardiac workload, contractures, thrombus formation, and stasis of respiratory secretions. Nurses implement measures to prevent these complications through frequent position changes, range of motion exercises, proper nutrition, and encouraging early mobility.