High Intensity Training & VO2max: The Science

For those endurance athletes tired of the long, slow distance training (LSD), this study suggests that your cardiovascular fitness can greatly benefit from a period of shorter, less frequent training with a greater intensity.

55 fit individuals were put to the test over a 6 week period to measure increases in VO2 max. During the last four weeks, the moderate intensity group exercised for 60 minutes, 4 days a week, the vigorous intensity group exercised for 40 minutes 4 days a week, and the near-maximal intensity group exercised for 35 minutes, 3 days a week.

All controls were considered and the results indicated that:

"...VO2max significantly increased in all exercising groups by 7.2, 4.8, and 3.4 mL·min-1·kg-1 in the near-maximal-, the vigorous-, and the moderate-intensity groups, respectively. Percent increases in the near-maximal- (20.6%), the vigorous- (14.3%), and the moderate-intensity (10.0%) groups were all significantly different from each other."— Shannan E. Gormley, David P. Swain, Renee High, Robert J. Spina, Elizabeth A. Dowling, Ushasri S. Kotipalli, Ramya Gandrakota, 2008

Source: Effect of Intensity of Aerobic Training on VO2max - Med Sci Sports Exerc. 2008