"It was positive for me and I worked hard over there - it has been a long struggle, more than three months, but I am feeling more confident now," he says.
Although Fredi, who got injured against Chelsea in September, returned to start against Fulham on Boxing Day, it was a short-lived come back, and he explains: "I did come back at Christmas but I wasn't really comfortable with my leg. I needed to do something else and really focus on it to do the stengthening work.
"I just worked alone with someone who was just focused on me and nobody else - we had to work together twice a day and I think he brought good work specifically to me.
"I will play next week and hopefully I will have no more problems - but you never know.
"Paolo is coming back as well so I am looking forward to playing with him and the new lads."
He is happy with the signing of Les Ferdinand and adds: "We needed some force up front so that is good."
And his recipe for Premiership survival?
"We just have to fight - and that is it, nothing else."