From U Zagreb-Croatia: Pre-exercise static stretching

http://www.ncbi.nlm.nih.gov/pubmed/22316148

Scand J Med Sci Sports. 2012 Feb 8. doi: 10.1111/j.1600-0838.2012.01444.x. [Epub ahead of print]
Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review.
Simic L, Sarabon N, Markovic G.
Source
Motor Control and Human Performance Laboratory, School of Kinesiology, University of Zagreb, Zagreb, Croatia.

Abstract
We applied a meta-analytical approach to derive a robust estimate of the acute effects of pre-exercise static stretching (SS) on strength, power, and explosive muscular performance. A computerized search of articles published between 1966 and December 2010 was performed using PubMed, SCOPUS, and Web of Science databases. A total of 104 studies yielding 61 data points for strength, 12 data points for power, and 57 data points for explosive performance met our inclusion criteria. The pooled estimate of the acute effects of SS on strength, power, and explosive performance, expressed in standardized units as well as in percentages, were -0.10 [95% confidence interval (CI): -0.15 to -0.04], -0.04 (95% CI: -0.16 to 0.08), and -0.03 (95% CI: -0.07 to 0.01), or -5.4% (95% CI: -6.6% to -4.2%), -1.9% (95% CI: -4.0% to 0.2%), and -2.0% (95% CI: -2.8% to -1.3%). These effects were not related to subject's age, gender, or fitness level; however, they were more pronounced in isometric vs dynamic tests, and were related to the total duration of stretch, with the smallest negative acute effects being observed with stretch duration of ≤45 s. We conclude that the usage of SS as the sole activity during warm-up routine should generally be avoided.