The human body is an amazing machine. It can do a huge variety of difficult, complex and unique physical tasks. However, the human body is also limited in what it can do. Pains and strains/MSDs occur where the demands of the job exceed the capabilities of the person doing the job.
Each person in a workplace is unique. This diversity shows up in many ways including:
Because of these differences, the fact that one person can perform a job without suffering an MSD does not mean that everyone will be able to. Jobs should be designed for a variety of workers.