Beginning with the 2007-2008 season, schools following National Federation of State High School Associations (NFHS) guidelines, which includes most junior high and high schools, will not be allowed to perform or compete on spring floors. This rule was implemented as a safety measure preventing schools from using height increasing apparatus.
Please visit the NFHS website for complete information.
http://www.nfhs.org/web/2007/01/nfhs_spirit_rules_changes_20070.aspx