Can apparent changes in muscle extensibility with regular stretching be explained by changes in tolerance to stretch?

Folpp H et al Aus J of PT (52) 2006

This study is one of several which over the last decade have given fuel to the fire that stretching doesn’t really make muscles “longer”. Recent studies have also concluded stretching (static) can have a negative effect on activities requiring power such as vertical leap, sprints and weight lifting. The authors used 20 participants each performing 20 minutes of hamstring stretches 5 days a week for four weeks. Exact measures of control vs. stretched limb were used regarding torque and subjective tolerance-to-stretch. The conclusions were very interesting in that no objective measures could show an actual increase in muscle length per se or muscle extensibility. What did change or improve was the subjects’ tolerance-to-stretch; this increase in tolerated stretch was matched by the increase in torque tolerated; 12 Nm. Additionally these findings matched several other studies in terms of degree of “increased stretch/tolerance” (~8 degrees) however some of the previous studies used much less time and effort than the 20 minute 5x per week of this study. An “increase” in straight leg motion should be assumed to about 5-10 degrees with a dedicated hamstring stretching routine over 4 weeks but the maintenance of this “increase” is likely lost rapidly without continued application.