I think Chi Running is as near to TI running as you can get, and it has the stamp of approval of Terry himself. I bought the book last year when I decided to take part in the Aquathlon run by the local triathlon club. The race consisted of a 400 swim in a pool ( 4 x 100m, each swum in a different lane) and then a 5k run, about half of which I walked using the old Baden Powell scout's pace or something similar. I came second (of two) in my super vet age group, the winner being an accomplished marathon runner and about ten years younger. The age groups are quite wide in triathlon, it seems. I also bought Chi Walking, but concluded that there wasn't much wrong with my walking technique. I still can't run worth a damn but I intend to enter for the Aquathlon again this year.
My bike is a rusty heap that hasn't been ridden for thirty years or so. I keep thinking of buying a modern job but the roads are not very safe round here - narrow and twisty and populated by lunatics.