A mechanic injures their back while lifting a heavy box. What type of injury did they sustain if diagnosed with a "strain"?

A diagnosis of a "strain" indicates that the mechanic's injury involves a muscle or muscle tendon being stretched beyond its normal limits. A strain specifically refers to the overstretching or tearing of muscle fibers, which can occur when lifting heavy objects, particularly if proper lifting techniques are not employed. This type of injury is distinct from other conditions, such as fractures, where the bone itself is broken, or tendon ruptures, where the connection between muscle and bone is severed. Dislocations involve joints and their respective bones being forced out of position, which is also not applicable in this scenario. Therefore, the correct answer highlights the nature of a strain as a stretch or tear in the muscle tissue itself.