Pope says recent Canada pilgrimage shows he needs to slow down, no plan to retire but 'door is open'

Pope Francis reportedly acknowledged Saturday that he can no longer travel like he used to because of his strained knee ligaments.

He told reporters that his recent, week-long Canadian pilgrimage was "a bit of a test" that showed he needs to slow down and one day possibly retire, according to the Associated Press.

The pope spoke to reporters while flying home from northern Nunavu.

The 85-year-old pope said he hasn't thought about resigning but said "the door is open" and it's OK for a pope to step down.

"You can change the pope," he said while sitting in an airplane wheelchair. "I think at my age and with these limitations, I have to save (my energy) to be able to serve the church, or on the contrary, think about the possibility of stepping aside," he said.

Francis strained his right knee ligaments earlier this year, the wire service also reports.

In the six-day Canada trip, Francis reportedly appeared to be in pain as he got up and down from chairs.