Birmingham's goalkeeping coach Dave Watson admits Ben Foster's injury problems mean he cannot play non-stop football for 12 months.
Watson was responding to criticism of Foster for taking a temporary break from making himself available for England duty.
He believes Foster needs to take such action at this juncture after suffering back, thigh and thumb setbacks this season.
Watson said: "We are having to nurse Ben through because of his previous injury record and this is the first time he's played a full season for three or four years.
"Ben is very patriotic. He wants to play for his country and enjoys playing for his country.
"But he simply can't sustain the daily requirements throughout 12 months at present.
"Not everyone knows how difficult it has been for Ben. The strains are just too much at the moment, simple as that."
Watson added: "This decision will hopefully enable him to play first-team football throughout a season or two.
"It will allow us and Ben to manage his body and condition - and ultimately extend his career.
"Ben is certainly good enough for England and, if things go well, who knows in the future?"