Final answer:
Mr. Jamison likely has a back strain due to overexertion from lifting heavy boxes. Lifting with the back instead of the legs can lead to muscle strain and damage to spinal discs, since the back muscles have to exert large forces and have mechanical advantages less than 1.
Step-by-step explanation:
Mr. Jamison complains of back pain, likely because he has been moving and carrying heavy boxes. You suspect he has a back strain due to overexertion. This is a common issue that arises when people lift heavy objects using their back rather than their legs, which can cause muscle strain and damage to discs and vertebrae. The back muscles and spine endure abnormally large forces during such activities, leading to potential injuries. It is essential to lift objects properly to avoid such strains.
Back muscles must exert very large forces, which are borne by the spinal column. Improper lifting techniques can easily lead to discs being crushed by mere exertion. Proper lifting techniques, such as bending the knees and keeping the back straight, help distribute the weight more evenly and prevent injury. In general, it's important to avoid lifting with the back, as the back muscles have mechanical advantages less than 1, making them prone to injury when subjected to heavy loads.