This 16-week XTERRA Training Plan is designed for the serious athlete, who wants to be competitive, or have a major jump in their training and performances for XTERRA. This plan works well for major XTERRA events that are on either a Saturday or Sunday. This plan has weekly training hours that average 12, but goes as high as 15, and as low as 9. The attached details document should answer all your questions about terminology and definitions. Best of luck!