Benefits of Interval Training:
http://www.outsideonline.com/fitness/outside-fitness-center/The-Right-Way-to-Interval-Train.html?page=2
Why Am I Slow?
http://www.outsideonline.com/fitness/fitness-coach/Why-Am-I-a-Slow-Athlete.html
Oxon Hill Bicycle and Trail ClubP.O. Box 81 Oxon Hill, MD 20750-0081