Before addressing musculoskeletal injury, an overview of the subject is in order. The history of ergonomics (or human factors engineering as it was originally known in the USA) is a history of performance improvement in human-machine systems. Attempts to improve human performance date back to the beginning of recorded history (mostly tool and weapon design changes to improve hunting and warfare performance). Modern ergonomics developed out of military necessity during WWII. Much like today where the miner is blamed for making a mistake and getting injured, early in the war it was common practice to blame the pilot/operator for crashed airplanes and ship/tank failures. By wars end however, it was clear to all concerned that when there was a mismatch between the operators abilities and the equipments operational characteristics, the resulting failure was beyond the operators control. It was time to design military equipment around the operator.
Eventually, the desire for better human-machine performance spread to the industrial world. This included the need to reduce injuries, and impact of person-task mismatch on injury events began to be understood. Much of the early work on human physical capability was done in Europe, but by the 1970s, the goal of limiting musculoskeletal injuries through job/task design was being carefully researched here in the USA. Back injuries were the prime initial focus of this effort because they were the most frequent and costly injuries. Later, as the relationship between human physical/psychological capacity and job/task induced external load became better understood, the focus spread to all forms of musculoskeletal injury.
This then became and remains the focus of ergonomics. What is reasonable to expect from people? How much can they safely lift, push, pull without being overloaded? How does this vary with body posture and time on task? How variable is that within the individual (day-to-day variability due to fatigue, yesterdays activity, etc.), and between individuals (the large young active male versus the small elderly sedentary female)? How long can they focus on a task and what factors affect their focus? What can people hear/see/feel/perceive about their job, and how does that change with time on a task? As we understand these and other similar factors, we can design jobs that are within peoples capacity and as a result we will get better, more consistent performance with fewer musculoskeletal complaints and injuries.