Chelsea's squad are in the midst of a gruelling start to pre-season under new boss Mauricio Pochettino.
The Argentinian coach started work last week after his appointment was officially confirmed back in May.
He has several tasks on his hand, not least restoring the club to former glories after they finished last season in the bottom half of the table for the first time since 1995-96.
However, interim boss Frank Lampard also insisted towards the end of the campaign that the squad needed 'some physical work', suggesting their levels of fitness were inadequate.