McFadden missed Birmingham's pre-season tour of the Far East for family reasons, as he stayed behind with his wife for the birth of their son.
He has been doing solitary fitness work at Blues' Wast Hills training ground in preparation for their season opener against Sunderland on August 14.
The Scotland international has featured in Birmingham's last two outings against Derby and Northampton and insists he will be fully fit for their trip to the Stadium of Light.
"From what I gather, the tour was tough and not that great in terms of some of the organisation but with the games the guys played, they are probably ahead of me in that respect," he told the Birmingham Mail.
"Saturday was my first game but I trained hard here. I feel fine, I just need games. I will be ready for when the season starts.
"I went in every day and was training with a few of the young reserve players. But obviously I was not getting any match time.
"We've got a game Tuesday, then Saturday, then I have a friendly with Scotland.
"The games are coming thick and fast and hopefully I can play a few 90 minutes and get the tiredness you need to feel, because that's when you get the fitness and sharpness, from when you're absolutely knackered."