Clarifications for the level 1 and 2 trampoline coach syllabus Page 25 Saying “Body Vertical at...

1
Clarifications for the level 1 and 2 trampoline coach syllabus Page 25 Saying “Body Vertical at max depression means you obtain the maximum height” is meaningless. What does it mean? Vertical and straight, vertical and body bent, vertical and leg bent, vertical and leg straight? None of the drawings in the resource pack support this statement. If it means, the body line (feet through the COM) must be vertical, then that is true as otherwise you would Travel and lose height. Page 32 Teaching an arm set in the way drawn with progression from arms up to arm swing to arm set is 1. Illogical and 2. Possibly too premature depending on the performer. To get your arms vertical from an arm swing requires core strength and bounce height. Leave it until much later to teach this. You don’t need an arm set to be able to do simple skills. Page 35 Seat drop body position too upright along with many other drawing inaccuracies in the rest of the sports specific sections. Page 36 What does “So that the hips are not almost on the feet” mean? Page 38 What is the benefit of looking at the ceiling in a back drop? It just means you have to change your focal point. Looking down your body means that as soon as you are returning to feet you can sight the end deck. Page 38 Back drop- Arms above the head has no relevant lever effect. In any lever, the long lever needs to be the one creating the force. The reactive force is always the shorter one for the lever to be efficient. In a back drop, the body is behaving as a 1 st class lever like a see-saw. In all class 1 levers, the direction of the reactive force changes direction, eg arm of see-saw moves down the other arm moves up. This means that as the legs move outside the Base of support, the body reacts by moving off the bed. Energy is always conserved so what the legs put in will come out the same whether you have your arms up down or where ever you have them. The speed of rotation is then set by the body shape and will be slower with arms raised. In the back drop the bit that is forced down into the bed is the lever fulcrum, that is the hips not the shoulders! One might require arms above the head for ball out (level 3), but it is a moment of inertia reason not a lever reason. Forward momentum in the bed is not present in a back drop until the legs move outside the base of support, but it is in a ballout from ¾ front somersault because of residual rotation from the somersault. So the Ball out benefits from a large moment of inertia to slow in-bed rotation that keeps the legs more vertical and so reduces ball out travel. The back drop does not benefit in the same way. It is not necessary to teach a back drop with arms above the head in order for someone to learn ¾ Font ss to ball out with arms above head. They are not the same skill anymore than landing on feet from back somersault or landing on feet from front SS are the same. Page 40 Casting of Seat ½ twist to feet. Don’t lean sideways! May be related to vision as people do odd things when they don’t see where they are going. What are they looking at? Page 40 Landing both hands on same side. Not common, but caused by hip twisting. Teach a shoulder turn. Revise standing twist. Page 42 ½ twist to front drop. Not turning shoulders enough has nothing to do with alignment along the centre line . It is a confusion resulting from simultaneous rotation and twist that has two possible causes. 1. The twist happens (turning while standing) before the hips have moved, so the body/hip direction has re-orientated away from the centre line. The performer then rotates around the lateral axis. The feet will move towards the direction of twist in this case. This is not a common fault. 2. Simultaneous rotation around all 3 axes of rotation. Feet could move to either side, but the most common is away from the direction of twist. In push and go attempts, turning the shoulders more may result in the body aligning with the centre line as the skill is turned more into a pre-twisted front drop rather than a back drop take off with half twist to front. In more advanced attempts however, the 2nd mechanism is more likely to be the cause so

Transcript of Clarifications for the level 1 and 2 trampoline coach syllabus Page 25 Saying “Body Vertical at...

Page 1: Clarifications for the level 1 and 2 trampoline coach syllabus Page 25 Saying “Body Vertical at max depression means you obtain the maximum height” is.

Clarifications for the level 1 and 2 trampoline coach syllabusPage 25 Saying “Body Vertical at max depression means you obtain the maximum height” is meaningless. What does it mean? Vertical and straight, vertical

and body bent, vertical and leg bent, vertical and leg straight? None of the drawings in the resource pack support this statement. If it means, the body line (feet through the COM) must be vertical, then that is true as otherwise you would Travel and lose height.

Page 32 Teaching an arm set in the way drawn with progression from arms up to arm swing to arm set is 1. Illogical and 2. Possibly too premature depending on the performer. To get your arms vertical from an arm swing requires core strength and bounce

height. Leave it until much later to teach this. You don’t need an arm set to be able to do simple skills.Page 35 Seat drop body position too upright along with many other drawing inaccuracies in the rest of the sports specific sections.Page 36 What does “So that the hips are not almost on the feet” mean?Page 38 What is the benefit of looking at the ceiling in a back drop? It just means you have to change your focal point. Looking down your body means that as

soon as you are returning to feet you can sight the end deck.Page 38 Back drop- Arms above the head has no relevant lever effect. In any lever, the long lever needs to be the one creating the force. The reactive force is

always the shorter one for the lever to be efficient. In a back drop, the body is behaving as a 1st class lever like a see-saw. In all class 1 levers, the direction of the reactive force changes direction, eg arm of see-saw moves down the other arm moves up. This means that as the legs move outside the Base of support, the body reacts by moving off the bed. Energy is always conserved so what the legs put in will come out the same whether you have your arms up down or where ever you have them. The speed of rotation is then set by the body shape and will be slower with arms raised. In the back drop the bit that is forced down into the bed is the lever fulcrum, that is the hips not the shoulders! One might require arms above the head for ball out (level 3), but it is a moment of inertia reason not a lever reason. Forward momentum in the bed is not present in a back drop until the legs move outside the base of support, but it is in a ballout from ¾ front somersault because of residual rotation from the

somersault. So the Ball out benefits from a large moment of inertia to slow in-bed rotation that keeps the legs more vertical and so reduces ball out travel. The back drop does not benefit in the same way. It is not necessary to teach a back drop with arms above the head in order for someone to learn ¾ Font ss to ball out with arms above head. They are not the same skill anymore than landing on feet from back somersault or landing on feet from front SS are the same.

Page 40 Casting of Seat ½ twist to feet. Don’t lean sideways! May be related to vision as people do odd things when they don’t see where they are going. What are they looking at?

Page 40 Landing both hands on same side. Not common, but caused by hip twisting. Teach a shoulder turn. Revise standing twist.Page 42 ½ twist to front drop. Not turning shoulders enough has nothing to do with alignment along the centre line . It is a confusion resulting from

simultaneous rotation and twist that has two possible causes.1. The twist happens (turning while standing) before the hips have moved, so the body/hip direction has re-orientated away from the centre line. The performer

then rotates around the lateral axis. The feet will move towards the direction of twist in this case. This is not a common fault. 2. Simultaneous rotation around all 3 axes of rotation. Feet could move to either side, but the most common is away from the direction of twist. In push and go

attempts, turning the shoulders more may result in the body aligning with the centre line as the skill is turned more into a pre-twisted front drop rather than a back drop take off with half twist to front. In more advanced attempts however, the 2nd mechanism is more likely to be the cause so telling to performer to turn shoulders more will not result in a successful outcome.

As long as the hips move down the centre line (rotation just around the lateral axis) that is where the body will align with, so it can be corrected by focussing on hip/feet direction.

Page 43 Casting on ½ twist to feet from back is caused by the centre of mass of the legs moving sideways. The Base of support is the body in this case. This happens if the body twists too early. The Intervention suggested is correct.

Level 2Cradle Why teach a cradle with the coach manually twisting the body? It shouldn’t be necessary! Twist is the easy bit. Revise back to front drop straight and

Feet half twist to back. Learn this intervention for the course then forget it!