The prime minister called the action “dangerous and utterly irresponsible” on Wednesday, amid fears the health service could be overwhelmed after flu-case admissions hit a record high last week for this time of year.
This is the 14th walkout by resident doctors, the new name for junior doctors, in the long-running pay dispute.
Mr Miller, who joined the picket line at the Royal Stoke University Hospital on Wednesday, said resident doctors did not want to strike, but he felt there was no other option.
“There is a crisis going on here, our pay is still down significantly, 21% down compared to 2008 and we’ve got a crisis of training posts as well.
“We want to be at work, we want to see patients, we enjoy our job, but this is the measures we’ve had to take in order to get the changes that we need,” he said.