I have accepted a teaching job in China and my employer has requested that I have a medical.

I have accepted a teaching job in China and my employer has requested that I have a medical examination prior to leaving the UK. Is it necessary to complete this prior to applying for the visa? I ask as the employer wants me there quickly and waiting for the results before applying for the visa will delay my arrival in PRC. I understand that I will have to undergo another medical when I arrive in China anyway can anyone confirm this please?