However, his absence is not likely to cast doubt on his participation in the upcoming series in Australia, according to fellow batsman Ian Bell.
Cook chose to skip England's scheduled session at the Floreat Oval in Western Australia in order to receive treatment on the complaint.
Paceman Stuart Broad was also an absentee, believed to be due to a similar problem, as England continued to build towards their opening three-day test against a Western Australia Chairman's XI at the WACA later this week.
The captain's omission in particular drew plenty of interest from the gathered media, but Bell insisted that Cook's complaint was nothing serious.
"I'm sure he'll be fine," he said.
"He's had the odd little niggle with the back, which I suppose we all have certain areas we have to keep working on.
"Obviously a long flight isn't always easy. I'm sure he'll be right in the next week or so."
