The reasons are as follows:

1. Standing for a long time: hotel waiters need to stand for a long time in the middle shift to provide services for guests. Moving heavy objects and standing for a long time cause excessive pressure on their legs, resulting in leg injuries.

2. High-intensity work: The hotel industry needs rapid response and efficient work, and the middle shift needs waiters to run and lift heavy objects. High-intensity physical labor will lead to accidental leg injuries.