Igoe, who signed a new one-year contract in the summer played in last night's friendly against Charlton Athletic despite his injury.
The former Portsmouth player, who faces a race against time to be fit told readingfc.co.uk: "I'm still struggling with my stomach a bit and it's affecting my groins now.
"After training sessions I feel stiff for a couple of days, but it's getting better gradually and hopefully I'll be fit for the start of the season."
Igoe went on to talk about his assist for James Harper's goal in the Charlton friendly: "I've got to be honest, I didn't really see Harps, I just thought I'd pull it back across the goal in the hope that somebody would be there, and fortunately he was.
"The lads looked fit (during the Charlton game), we've nearly finished pre-season now and we haven't got many injuries thank God, and we do look good. We'll be working on the sharper stuff now for the next week, ready for the start of the season at Derby."