noobar wrote: ... it has nothing [to do] with the swing, its a takeoff problem and as kirk said that the bubka drill is good to learn remaining the leg straight, but how can u do the straight take off, can u suggest any exercises
Noobar, I didn't actually mean the Bubka Drill. I meant my own "Whip Hinge Drill", where I emphasize the downswing ... rather than the upswing.
In this highbar drill, you start in the C (the pre-stretch that "finishes" the takeoff), and vigorously swing your trail leg down and forwards, until you feel the power of the whip as you pass under the bar. You then coast to a stop ... without emphasizing a "Bubka" ... and repeat. Have your kids do about 20 reps per day (2 sets of 10 ... but start with 4 sets of 5), and they'll soon forget how to hunch the top arm or bend the trail leg prematurely. Until they get good at it, I recommend you hold their starting (C) body positions for them ... else they'll swing out of synch. Sorry ... no vids.
In contrast, the Bubka Drill emphasizes the gymnastic action of inverting on the highbar ... just like on the pole. Done right, that's a simulation of the upswing, but it more often becomes a power (muscular) excercise. By "done right" I mean that it needs a powerful DOWNSWING (a la the "hinge whip drill") to get it right.
Some may think that this is an Advanced drill, but done with a coach holding the athlete in the starting C position, it's a very basic drill ... ideal for high-schoolers learning how to swing with a long, powerful trail leg (and a fully stretched top arm).
Kirk