I just read an excellent article by Kevin Maggs of Active Spine and Sport and Running Reform. In the article Kevin summarizes the work of Dr. Roger Kram of the University of Colorado. Kram has spent much of his career dissecting the many factors that contribute that contribute to the energetic cost of running, and Kevin does a great job summarizing a bunch of different studies (that use some interesting contraptions!).
In a nutshell, he Kevin writes that “You can account for nearly 90% of the metabolic costs with 3 factors: vertical body weight support, forward propulsion and leg swing.”
Read the full article here: http://activespineandsport.net/news/break-down-of-energic-cost-for-each-component-of-running/