The IRFU will continue to use his expertise, particularly regarding his research into the advancement of player longevity, injury prevention and high performance.
Philip Morrow, the current IRFU head of fitness, will now be taking on the role of the Irish squad's strength & conditioning coach in the short to medium term, including the upcoming GUINNESS Series of games in November.
"I felt it was time to step down given the fact I want to spend more time with my family and concentrate on developing a high performance training centre at my home in France, while writing a second edition of my book, 'Complete Conditioning for Rugby'."
Ireland head coach Declan Kidney said: "I would like to thank Paul for his work during his time with the squad. The players certainly benefitted from his experience and I am sure his knowledge will see him continue to be successful.
"Myself and the rest of the management team wish him the very best for the future."