Jack Kelly – A Fresh Look at Take-off – 2

A fresh look at take-off – the plot thickens

In my first contribution to GymCraft I took a close look at the peculiar nature of the trampoline take- offs and landings. I emphasised the need for coaches to concentrate on the landing phase (touch down to full depression) and the take-off phase (full depression to final departure) and to educate the gymnast’s awareness of the resultant delay factor. I make no apology for remaining at this fundamental level and will attempt to develop the theme.

There is a perception among trampoline coaches that advanced or high performance coaching is about teaching and coaching the more complex moves. Indeed this is reinforced when you read the BG syllabus. The higher the coaching award, the more complex are the moves the coach is qualified to work with. I have no argument with this, but there is a risk that the coach loses sight of the essential techniques which contribute to the performance of these high level elements.

My view is that advanced coaching is not about coaching advanced moves but rather the coaching of fundamental techniques with an advanced understanding of their significance. Complex moves have a modular structure, being constructed from a series of simpler elements which should be part of the gymnast’s existing repertoire. Complex moves generally break down because of a failure in the performance of one of the basic modules. The failure of the module can usually be traced to faulty technique or timing during the take-off. I can hardly believe that I feel the need to write this, as it should be screamingly obvious to all coaches that the effectiveness of the take-off will determine the outcome of the skiII to follow. My experience of coach education at all levels however, tells me that too many coaches focus on what they see happening in the air rather than concerning themselves with the timing and direction of the forces produced during the take-off phase.

What then does a trampolinist do during a basic take-off? When you jump from the floor there is a very clear feeling of driving the legs straight against the firm floor surface. When I ask trampolinists (up to international standard) what they feel they do during a basic take-off, they describe the feeling as similar to the one they experience in jumping off the floor. In other words they feel they are jumping “off” the trampoline. This is very strange because the two methods of becoming airborne are totally different and the performer who submits to this misunderstanding is likely to have a problem when trying to harness the power of the trampoline for all take-offs from straight jumping to multiple somersaults.

It is obvious that the floor remains static as the leg power is directed against it, whilst the trampoline bed sinks in response to the applied force. (Not to complicate matters with thoughts of sprung floors or tumble tracks!). Let us now examine the sequence of actions the performer must make in order to produce a single jump from a motionless trampoline bed. For the sake of simplicity, I shall concentrate on the feet, legs, trunk and head, omitting all reference to the arms for the time being.

The gymnast stands on flat feet which are parallel and no more than hip width apart; indeed, many top performers keep their feet together which has both advantages and drawbacks. The trunk is upright with the head in normal alignment. The eyes however will be looking downwards towards the bed and/or end frame. The bed is set in motion by a slight flexion of the hips and knees followed by an extension of the legs delivering force through the flattened feet to the bed. Throughout this initial “press” there should, be no bending forward of the trunk or movement of the head. The initial head and trunk posture is maintained (Fig la).

Fig 1 a & b

Any dipping of the shoulders to help initiate the first “press” as one might do in a standing jump from the floor, is likely to cause balance problems when the bed is fully depressed (Fig 1 b).

The legs are now straight and the trunk erect with the result that the bed wilI have been depressed and the gymnast must now wait in this standing posture for the bed to deliver its stored energy (Fig 2a). We now have the performer as the “human arrow” with the trampoline acting like a bow to fire the gymnast into the air (Fig 3). (It will be appreciated that following the initial “press” the performer is only likely to leave the bed by a matter of centimetres). Should the gymnast fail to maintain their arrow-like posture throughout the bed’s recoil period, then a loss of power will result along with the possibility of accidental rotation and/or travel away from the start position (Fig 2b).

Fig 2a
Fig 2b

The inability to maintain Arrow-like posture during the depression and recoil of the bed is a major source of spinal injury among trampolinists ranging from simple aches and pains to more serious damage, and should therefore further motivate coaches to insist on correct technique during this stage.

Fig 3a & b

Having used the simple ”press and go” technique as a vehicle for describing the process of making a single jump from the trampoline, the subsequent jumps will increase in height due to the body weight depressing the bed further and the performer deliberately exerting greater force as the legs are driven straight. Coaches should encourage a gradual build up of height and discourage the performer who tries to gain too much height in too few jumps. The landing from each jump will start with a flattening of the feet just before the initial touchdown and a repetition of the hip and knee flexion described earlier. This is the start of the landing phase which ironically involves the forceful extension of the legs normally associated with a takeoff from the floor!

The foot flattening and hip and knee flexion must occur before initial touch down but should be delayed as long as possible otherwise the gymnast will stamp the bed, failing to deliver the leg power efficiently. The timing of this process is crucial and is characterized by a barely audible impact on the bed, unlike the less skilled performer who will strike the bed noisily. Listen to your trampolinists, don’t just watch them and you maybe surprised how much you can learn about their timing.

With each successive jump the gymnast must wait longer in the arrow posture for the bed to deliver it’s stored energy as clearly the deeper the depression, the greater will be the time lapse before the performer is shot into the air. As the bed reaches the bottom, the stresses being applied to the performers body can increase to many times body weight, depending on the height of the jump, thus it is important that these potentially destructive forces are absorbed by a body in strong upright posture.

I have stressed the need for maintaining flat feet throughout contact with the bed, but this is over simplified, as the feet play a very important part in producing a powerful takeoff. Readers of my first article may recall I that I quoted “it ain’t what you do it’s the time that you do it, that’s what gets results. ” The ankles must move forcibly into plantar flexion but it is crucial that this happens at the right time.

Pointing the toes too early will disturb the power transmission and balance function of the flat feet, whilst leaving it too late (or failing to plantar flex at all) will result in a serious lack of power, not to mention form marks! If the gymnast carries out the sequence described during the landing and takeoff phases they will become airborne with the trunk upright, head in normal alignment, legs straight and toes pointed. In short, they are now exhibiting ”good form”. This ”good form” is not simply a bit of ”style” to impress the judges but the logical outcome of a sequence of work performed in the right order whilst in contact with the trampoline bed.

Isn’t it strange how some things from your past make a lasting impression? I remember vividly performing a handspring when I was a student at the Scottish School of Physical Education in 1958. The tutor yelled “Kelly! Don’t try to straighten your legs after you’ve taken off. Good form must be the result of efficient technique!” Nothing has happened in the last forty five years to change that principle and I commend it to all who aspire for excellence.

Let me close by giving some food for thought and the assurance that I am not arrogant enough to think that I have all the answers. I have already indicated some uncertainty when stating that many trampolinists feel that they jump ”off” the bed, contrary to the technique I have described. George Rackham in his definitive book ”Diving Complete” tells us that the springboard diver depresses the board as much as I have described but rather than waiting with straight legs for the board to shoot him upwards the legs remain bent in order to jump as the board recoils.

“When the board reaches it’s lowest point ……………… with the knees bent and the heels down.”

If we think about it carefully, driving the legs straight during the landing phase will depress the bed/board farther, but as the bed/board is recoiling upward it is effectively as firm as the floor and it is totally conceivable that a re-bending and straightening of the legs could take place so that the gymnast/diver does actually “jump off” the bed/board to supplement the stored energy within the equipment. Indeed there is likely to be individual variations of technique used by different performers.

Why is there this uncertainty with all the video and film analysis which has taken place over the years? The divers seem to know what is happening on take-off so why isn’t the trampoline community so sure? Quite simply because the movements to be analysed are hidden within the depression of the bed whereas the depression of the springboard is clear for all to see. I have asked BG to invite Professor Fred Yeadon at Loughborough to undertake some detailed work on this. In the meantime coaches should work with the principles set out earlier in this article, but believe me the jury is still out!

Next article.

© Jack Kelly