The 41-year-old, who made almost 200 career appearances for Millwall and Wimbledon, was previously conditioning coach at Reading and has also worked with the Republic of Ireland international squad.
"Jon is a fitness coach," explained manager Brian McDermott. "He is a good lad, he will be a real asset to us. He will work with Matt Pears, who is a good guy.
"Jon was at Reading in 2005/06 when we got 106 points and came out of the Championship. He was there in the Premier League when Reading finished eighth, and then he set up his own business.
"He has massive respect out there from all the sports scientists and fitness coaches. He lectures on that. I asked him if could help us out. It might be for a short period, it might be for a longer period, but he's going to work with Matt Pears.
"This isn't a reflection on Chris Short and what he has given to the club. This is more about how I felt we needed to go and I know Jon very, very well. He's popular and he's one of life's good guys."
One of Goodman's first tasks will be to link up with Pears in readiness for individual summer programmes for the playing squad.
"The next eight or nine days are very important," added the manager. "Jon and Matt will prepare a programme for each player so when we come back on June 27 we can get the balls out straight away.
"If they've done the right things we'll be up and running and hit the ground running."http://www.leedsunited.com/news/20130425/jon-joins-up-at-thorp-arch_2247585_3156873