"A marathon is like life with its ups and downs, but once you've done it you feel that you can do anything." -unknown
Stretching. Good or bad?
Our muscles are like springs. The tighter the spring the more elastic energy is returned and therefore the more running economy. However like most things we have to find the right balance. Too little flexibility may cause injuries. Also best to use dynamic stretching before a key session or race.
Research: Int J Sports Med. 2002 Jan;23(1):40-3. Running economy is negatively related to sit-and-reach test performance in international-standard distance runners. Jones AM. Department of Exercise and Sport Science, Manchester Metropolitan University, Alsager, United Kingdom.