[QUOTE=RoadMike;15661247] 4 weeks is not enough time to get any appreciable increase in VO2 max[/QUOTE]

Incorrect.

"Resting blood samples were also collected at the beginning of each pre and posttesting period, before and after the 4-week training program. The EXP group showed significant improvements in VO(2)max (+5.4%), peak oxygen pulse (+7.7%) and T(max) (+32.2%) compared with pretesting."

http://www.ncbi.nlm.nih.gov/m/pubmed/21849912/