Muscle development vs. CV; Importance of proper breathing for endurance athletes

Two good articles worth review: Discusses how muscle development - versus merely cardiovascular fitness - is essential to improving running speed. http://www.trifuel.com/training/triathlon-training/off-season-intervention-part-1-fitness-is-in-your-muscles-not-the-cardio. This matches my intuition regarding the absolute importance of incorporating tempo runs into your one's weekly workout plans. I found this article through the "Articles" link from Athlinks.com. Describes some important breathing and relaxation techniques which allow a runner to reduce their breathing rate, which has a beneficial effect of a reduced heart rate as well: http://www.trifuel.com/training/triathlon-training/breathing-relaxation-for-endurance-athletes