There's a fairly decent 12 part series on "Official Fitness" on the paid portion of this site that was written, in part, with the cooperation of Dr. P.Z. Pearce, Medical Advisor to the Hawaiian Ironman Triathlon ( and seven time finisher of the event) a team phsysician to the Seattle Seawhawks, advisor to Gonzaga University athletic department, member of US Olympic medical and drug committee, Medical Advisor to the US Marathon Association...among other positions.
Dr. Pearce sugests that one warm up the body prior to stretching. He also states that flexibility, cardio/vascular fitness, strength, endurance and balance/agility should all be part of any fitness program.
He points out that injuries to athletes and officials usually are caused by what he refers to as "novel action", meaning a movement that is unexpected or that which the body has not been prepared to undertake.
While including all the elements of fitness in a home program sounds daunting, with some simple workouts and 30 to 40 minutes six days a week, I've found it easy to do.
http://allsports.officiating.com/x/article/5244