most in-depth account of his comeback so far. Here it is in its entirity:
From BBC Sport
By Ian Thorpe
We have a rule of thumb in swimming: for every month you have off it takes about three months of training to get back to your previous condition.
I'm not sure what the time frame is when you've been out of action for five years like me, but it can't be too good!
I first decided to return to competitive swimming during a flight from Chicago to London last September. It was a decision made with the heart and not the head.
For a while I constantly tried to persuade myself that it was a bad idea but after a couple of months I realised that it was something that I really wanted to do.
I actually started swimming on 13 October, the day I turned 28, and had to do so in secrecy. I used seven or eight different pools so that I was not seen at any one too frequently.
The head coach of Swimming Australia wrote some sessions for me and at first I was effectively being coached by text message. I would go to the pool, do the session, get out and receive some feedback, positive or negative.
Nobody knew what I was doing and it was nice because it was a very personal experience for a while but I got busted after about six weeks. I knew the low-key aspect of it would come to an end but it was great while it lasted.
Recently I have been training in Switzerland and I am enjoying working with my new coach Gennadi Touretski.
I have always enjoyed the process of training, and I have never been afraid of hard work, but it does seem to be more stimulating than I remember when I was younger.
When I was not swimming I used to do six hours of training every week in the gym, mainly cardio work. Now I am doing 30 hours a week, 20 in the pool and a further 10 doing weights and other exercises. These hours are not what I would describe as a huge amount.
There are tangible things happening in the pool that allow me to seexactly how I am progressing. Do I want to tell anyone about them? No, I don't. I don't really want people to know what I am doing at the moment - how well or how badly...
Some days are hard, particularly when I do not swim as well as I would like. There are days when I want to do something and I can remember how it is done but my body won't let me. I probably might only be a week away from being able to do it but it is frustrating at the time.
I'm enjoying that struggle. It's not like I'm slogging away, it's something that helps me. I wouldn't have it any other way.
I still think that the greatest value I can give to the Australian team is on the relays. Beyond that I don't know; it's too early to even think about it.
However, if I am swimming well then I might be able to do an extra race or two. Certainly, the 200m and 100m freestyle remain the two most competitive events in men's swimming at the Olympics.
I will make my return to competitive swimming in Singapore in November, while the Australian Olympic trials will take place in March 2012. Nobody knows whether I will race enough before the Games but it is what it is and it has to be this way. There is no other choice.
When I do return to competition I will look very similar in the water to when I retired in November 2006, but I should have more front-end speed and maybe a few tricks. There are a few things that I am working on, skill-based things that I should probably do well but have not done before.
It might actually be fantastic that I do not race in many competitions before the Olympics, because that will ensure that I am fresh when they come around.
The London Olympics will be an exciting event. Whether I was going to be involved or not I would have made sure that I was there. I don't think Londoners realise how much they will enjoy it and how much they will want it back when it's over. That is what happened to us Australians after Sydney in 2000.
People often ask me if I think there will be a rerun of the 200m freestyle final at Athens in 2004, the so-called race of the century when I defeated Michael Phelps. It is only a possibility - it may not happen.
I am assuming that Michael will swim the race but I have to qualify first and that is going to be a lot harder than people realise. Even if we both do swim then one of the likely outcomes is that neither of us actually wins. For example, German Paul Biedermann will do very well in that race. It will be very interesting - if I am swimming it.
However, that is looking much too far ahead. I have been training in England this week ahead of my trip to the Great Salford Swim on Sunday. It is part of the Big Splash campaign aimed at inspiring the UK to swim.
One in five adults cannot swim and one in five children leave primary school without being able to swim. That is far too high and I think it is important to increase participation rates in the UK.