pro-plodding along
http://www.time-to-run.com/training/methods/intervals/intensity.htm

pro-interval
http://www.dragondoor.com/articles/endurance-training-intervals-vs-long-slow/steady-distance/

http://www.ultralegends.com/interval-versus-tempo-training/

http://blog.nutribodies.com/15/interval-training-for-improved-sports-performance

http://www.jeffgalloway.com/

http://mikesworkout.blogspot.com/2009/09/interval-training-vs-long-slow-part-1.html

http://www.pponline.co.uk/encyc/0004.htm
But then why the unsupported assertion slapped on the end to only spend 10% on intervals??