I found this recent review interesting, in large part because 1) it echoed some of the comments that I made in the 30 s intervals thread and 2) some of their conclusions parallel the "training adaptations by levels" table that I put together:
http://www.ncbi.nlm.nih.gov/entrez/..._uids=16464121&query_hl=3&itool=pubmed_DocSum
http://www.ncbi.nlm.nih.gov/entrez/..._uids=16464121&query_hl=3&itool=pubmed_DocSum