Tight tendons behind my knee

[Tanglenose]

When I developpe derriere and sometimes a la seconde, tendons right behind my knee get really tight (until I bend my knee again). This is especially a problem with grande rond de jambe en l'air. Developpes devant are no problem, but for some reason developpes derriere really trigger that tightness. Any ideas about what this is, and how to solve it?

Edited December 21, 2010 by Tanglenose

[Victoria Leigh]

Actually, no, Tanglenose. This does not really make any sense to me, as when there is pain behind the knee, it should be there every time you straighten your knee, no matter what position.