I recently was working with our gym's level 3's and 4's after being out of the gym for a while and noticed that we seem to be drastically lacking in the hollow body department. Even my tightest girls seemed to be having trouble maintaining the tight, rounded-back form (especially on bars) that is so essential in this sport. They're constantly either arching their backs or just plain loose and all over the place core-wise. I want to really start pushing form and training hollow bodies in conditioning, especially this summer with our new up and comers from preteam. So...I'd like opinions from fellow coaches. How long do you think a (new) level 3 should be able to hold a plank and/or the hollow body, "rocker" position (on back, feet up, arms by the ears, rounded back). Just curious here. I know answers will vary from gymnast to gymnast, but I would love to have a "baseline" requirement to start working towards. I want to make sure they all have the strength to perform well without risking back injuries and such, but I'd rather not kill them by pushing them too hard for their level, if you know what I mean. Thanks, guys! 