L''importance de l''articulation temporo-mandibulaire pour la performance athlétique.
The Temporo-Mandibular Joint involvement in sports events.
by: Gilles G. Brisson D.C.
A forcefull hypercontraction of the T.M.J. causing a malocclusion interferes with the mechanics of the movement and the performance during an activity involving the dominance of one side of the body.
During the examination and treatment for various injuries of several of the throwers on the Canadian Track and Field team, as well as athletes participating in other sports involving the utilisation of an implement, I found that even after having stabilised the different musculo-skeletal components, some of the athletes seemed to develop the same erroneous patterns during the execution of their movement, which eventually brought back the pain.
Knowing the importance of the Temporo-Mandibular Joint, and its influence upon the biomechanics of the body, this element was evaluated with relation to the execution of the whole movement.
It is evident that several other components may influence poor biomechanics during the execution of a movement. The case which I am about to present is just one of these elements.
Before starting any discussion about the T.M.J. involvement, it is important, for the purpose of this study to define a unilateral event or sport.
A unilateral activity or sport could be defined as: any activity involving the dominance of one side of the body taking part in the major execution of the movement; e.g. throwing events, or racket sports.
In this particular study, I have decided to analyse the example of javelin throwing. It is possible to apply the results of this study to any other sport where an implement is utilized, and or power is needed to execute any phase of the movement. e.g: tennis, golf, hockey, etc.
First of all, it is very important to look at the movement in its entirety, as well as the different transfers of force during the execution of the throwing action.
Technique of the Javelin Throw:
For the purpose of the description we will used a right handed person . (7 )
- APPROACH RUN.
- The FRONT LEG blocks (heel-toe movement) and initiates the transfer of velocity from the run to the leg and thigh which is added to the power generated by the LEG and THIGH.
- Forward acceleration of the right hip ( pelvic girdle) adding to the power already accumulated, while the right foot drags on the ground in order to control this action. The pelvic girdle should not at any time sag posteriorly during this action .
- Transfer of accumulated velocity and power to the trunk , which begins accelerating via forward rotation .
- Acceleration of the right shoulder (scapular belt) commences, while the actions on the ground (foot dragging,left foot blocking ) continue, as well as the forward rotation of the right hip. This transfer of acceleration from the trunk to the right shoulder further amplifies the velocity and power which will eventually be transfered to the javelin itself.
- Acceleration of the forearm and release of the javelin : The ground motions are maintained, while the right hip has rotated forward to the point of being at the same level as the left hip .
Meanwhile, the right shoulder continues its forward rotation until it catches up with the left shoulder and in fact passes it . At the same time the right elbow begins its flexion . The elbow pivots slightly and continues moving forward toward the direction of the throw , while the forearm begin accelerating and generating more power through vigorous extension.
The javelin is released via the vigorous flexion of the wrist and the extension of the fingers outwards . At this moment, all velocity and power which as been generated and conserved is transfered directly to the implement . If all movements in these preceeding phases were executed in the axis of the throw ,with no biomechanical errors or deceleration , then the accumulation of velocity and power should have been conserved right up until the moment of release .
The summation of all forces generated in the preparatory phase of the movement, if correctly applied to the implement to be thrown, give it the maximum propulsion . Any changes or imbalances in the musculo-skeletal structure such as poor body positioning, or contraction of the wrong muscles will bring about either a loss of power, or an incorrect transfer of force towards another area of the body. Such errors directly affect the optimal execution of the movement.
During observation and discussion with athletes on the National Throws team in track and field, as well as the National Throws Co-ordinator(8), it was noted that in the final phase of the throwing action, especially from the moment the athlete initiates the release movement at the scapular belt, followed by the transfer of force to the implement, and finally the execution of the throw itself, many athletes had a tendency to clench their teeth in an ultimate effort to bring more power into the throw. This contraction of the T.M.J. is not an addition of power, but rather an inhibitor to the transfer of the force accumulated in the preparatory phase. We can calculate this as a loss of power, which, instead of being utilized to throw the implement, is lost in the jaw. It was also noticed that this contraction is more accentuated on the side of the body where the implement is held, due to the fact that all forces are directed towards the side where the execution of the movement is to take place.
If you execute this movement repeatedly, (the throwing action)100-150 times every training session, with the same erroneous pattern as explained before, one will develop a unilateral hypercontraction of the temporo-mandibular joint. This results in what we would call a forcible mal-occlusion on that same side, which might not show up upon normal evaluation of the T.M.J. .
This unilateral hypercontraction at the jaw level is a loss of energy (negative) which could be used otherwise (more positively) for the optimal execution of the movement,in such a way as not to alter the balance of the musculo-squelettal system during the last phase of the throw.
This imbalance occurs more in the pelvic and scapular belt area. At the pelvic level, one will notice a lowering of the pelvis accompanied by sagging, with retraction of the buttock muscles. At the shoulder level we will observe the same pattern, meaning a dropping of the whole scapular belt accompanied by retraction of the shoulder joint, and a loss of force by the rotator cuff. This deviation from the normal will displace the center of gravity, thus modifying the whole approach of the throw by changing the body alignment, resulting in a poor transfer of force from the leg to the trunk, trunk to the shoulder, and shoulder to the arm .
The procedure used to verify the interaction of the musculature of the temporo-mandibular joint during the execution of the throwing movement is as follows: Ask the patient to forcefully contract the muscles of the temporo-mandibular joint on the side suspected of "closing mal-occlusion" (normally on the side where the implement is held ) and at the same time, test a previously strong indicator muscle which is located on the side where the implement is held ( it could be from the shoulder, or even the pelvic area ). If a forcible mal-occlusion is present, a weakness in the indicator muscle will appear. If one performs the same procedure on the opposite side, no weakness will be apparent . I must emphasise here that a normal closure of the jaw without forcefull contraction of the muscles involved in the action (masseter, buccinator, temporalis), would not give a positive response regarding the weakness of the strong indicator muscle .
Treatment approach :
The treatment approach for the correction of this forcible mal-occlusion is :
First of all, one must put a tongue depressor between the last two molar teeth on the side which is involved . Normally, the width of two tongue depressors is necessary, in order to annihilate the positive response illicited upon performing the same muscle test as previously described. If you need more than two tongue depressors to cancel the positive therapy localisation, you might need to seek the help of other professionals to rebalance the mal-occlusion .
The treatment itself, for the stabilisation and the equilibrium of the temporo-mandibular joint is well documented and explained by Doctor George J Goodheart(6), Doctor David S. Walther(3), and Doctor David W. Leaf(1), in their various research papers and lectures.
We must investigate , before carrying out this type of evaluation of the forcible mal-occlusion, any structural imbalances which could influence the temporo-mandibular joint and correct them.
-Dural sheath involvement
-Muscle imbalances: especially the Sterno-cleido mastoid , Upper trapezius , Masseter, Buccinator, Temporalis, External and internal Pterygoid.
-Any muscles related to the action of throwing.
Thus, it is of utmost importance to properly stabilize all the musculo-squelettal imbalances that you find before evaluating for a forcible mal-occlusion of the temporo-mandibular joint during a specific action (such as javelin throwing as discussed in this paper).
It is quite possible that the athlete may have to perform what we can call "tongue depressor therapy". This means that the athlete will have to practice his throwing action while holding the tongue depressor(s) between his teeth (without clenching) in the back of his mouth, (this being on the side of closing mal-occlusion), until he can consciously perceive the adequate positioning of his jaw. This conscious perception has to become an automatism recorded by the brain as part of the procedure in the execution of the whole throwing action.
Subsequently, when the athlete executes his whole throwing pattern, he/she will be able to feel if there is any closing of the jaw which could disturb the musculo-squelettal balance needed to complete the generation and transfer of maximal force to the throw. In addition, he/she will be able to proceed with the correction of this incorrect gesture through relaxation of the jaw by bringing it to the the neutral position.
It is interesting to go directly onto the practice field , so that we may observe the athlete during his training session, and discuss the different problems which might appear during the execution of the whole movement with him/her and the coach. With this information, plus the knowledge and comprehension of the biomecanics of the throw, we can proceed with the correction of musculo-squelettal imbalances, and have a direct feedback of our intervention . For example, the tongue depressor therapy can be evaluated directly with the athletes while they are performing their throws, followed by the correction of the T.M.J. imbalances, thus enabling us to observe the immediate biomechanical changes .
During the execution of a movement which involves the dominance of one side of the body over the other, as in throwing, we notice that all of the muscles associated with the occlusion of the jaw very often go into hypertension, thus bringing about an imbalance of the Temporo-mandibular joint in the form of a closed mal-occlusion on the dominant side. This problem changes the whole biomecanics of the execution of the movement, resulting in a loss of power .
It is quite possible to find a bilateral hypercontraction of the musculature of the T.M.J. with the sport which sollicites both sides of the body, like gymnastics or weight lifting. The same procedure of examination and treatment is used to alleviate the problem. However, regardless of the fact that you can find a bilateral forcible closed mal-occlusion, it will exist on the side which is more involved than the other, and will correspond to the more prominant side that the person uses in his normal daytime activities .
Ideally, during the action of throwing or any other sporting activities, the jaw should be kept in a neutral position whereas all muscles related to the temporo-mandibular joint should not at any time be in hypercontraction.
It is important throughout the execution of any given movement to not only properly utilise the required components; but also to sollicit them in a precise order.
The repetitive hypercontraction of the musculature of the jaw , causes a forcible mal-occlusion of the T.M.J. leading to a loss of power, as well as negatively affecting certain biomechanical components of the movement.
The evaluation of the Temporo-Mandibular Joint is of prime importance during the examination of an individual who practices a sports activity an order to eliminate any components having a negative influence upon the execution of the movement in question, so that the athlete may develop his full potential.
1. Leaf, David, D.C. Seminars in Essentials and advanced Applied Kinesiology, Montreal, Canada
2. Leaf, David, D.C. Applied Kinesiology Flowcharts , 1990
3. Walther, David, D.C., Applied Kinesiology ,Volume II ,System DC . ,1983
4. Walther, David, D.C., Applied Kinesiology, Synopsis System DC. , 1988
5. Goodheart, George, D.C., Research Tapes,# 28, 32, 77,108,111.
6. Goodheart, George, D.C., Collected Published articles & reprints, pp.184-188 .
7. Didier, Poppe , E.P.S. Professor ,Le double appui au lançer du Javelot , CTR Nouvelle-Calédonie ,Wallis & Futura .
8.Baert, Jean-Paul, National Coordinator and Olympic coach of throwing events for Canadian Track and Field Association (Athletics Canada).
Coordonnée pour communiquer avec le Dr.Gilles Brisson