Surrey manager Chris Adams says his players are on "a rollercoaster" trying to quickly adjust from one form of cricket to another this season.
He told BBC London 94.9: "If the fixtures are going to give us schedules like this then we need a few superhuman bodies in the dressing room.
"It's brutal at the moment. Players are being asked to challenge themselves both physically and mentally.
"It's been a rollercoaster from 50 overs cricket to Twenty20," he added.
Surrey were eliminated from the 50 overs Friends Provident Trophy at the group stage and are currently in fifth place in the Twenty20 Cup south division at the half-way stage.
The players now face a gruelling schedule in the County Championship although Adams accepts that his side have at least had some respite before embarking on the latest round of four-day games.
"We're fortunate in a way that we've got a few days off now but a lot of teams are still playing Twenty20 cricket," he said.
"We've got a few days off to get a rest in there for some very tired bodies and start thinking red-ball cricket again."
He added: " "We're about to embark on 12 days out of 14 [against Glamorgan and Northants] which is just going to be severely brutal, particularly if all games go to the wire and go to the last day.
Despite his concerns about the demands on his players, Adams has been encouraged with their progress so far this season.
"I think we're improving. Everywhere I go now people are starting to tell me that things are changing. They see a different Surrey side with more energy and more commitment," he added.
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