FACTORII CARE INFLUENTEAZA CRESTEREA FORTEI MUSCULARE, CA URMARE A ANTRENAMENTULUI SPORTIV

Abstract

The natural question coming to the mind of any theorist, but especially of any practitioner, is: "how is it possible to initiate, support and optimize an action involving a more or less important strength effort?" By taking into account the functionality of the system that meets this desideratum, there aren't too many answers, the final solution keeping to many factors: a structural factor, related to the muscle intimate composition, a nervous factor, that refers to the motor unit way of functioning and using, and a spatial factor which, depending on the movement amplitude, is or is not able to sustain a certain motion. Beside these ones, the factors influencing the muscular strength development, as a result of sports training, are also particularly important. And, to have a complete image of them, they will be related to other factors, such as the practitioner's age, gender and diet. [PUBLICATION ABSTRACT]

Tudor VIRGIL1,

Doru loan CRIÇAN2,

1ANEFS Bucureçti

Universitatea Balamand, Liban

Cu vinte cheie: forja, factorii condizionali, faeton structurali, faeton nervosi, antrenament sportiv.

Rezumat

În aparenta, cresterea forjei poate parea rezultatul unui singur factor, ci anume crearea tensiunilor musculare maximale la nivelul muschiului solicitât sau al grupului de muschi solicitati. Ceea ce încercam noi sä demonsträm, este nuanjarea acestei idei care a dominât multa vreme conjinutul si structura metodicii de antrenament pentru dezvoltarea forÇei musculare.

Aläturi de factorii neurofuncjionali, relativ independent de conduita adoptatä în programarea si desfasurarea antrenamentului, o multitudine de alji factori de ordin intern sau extern pot influença, într-o mäsurä importantä, valoarea câstigurilor de forta.

* Durata procesului de antrenament

* Nivelul inifial al subiectului

* Calitatea antrenamanetului

* Frecvenfa antrenamentelor

* Metode utilizate în antrenament

* Unghiul în care lucrezä articulaba solicitatä

* Efectul de controlateralitate si de contracte a antagonistilor

întrebarea fireascä, pe care si-o pune orice teoretician dar mai ales orice practician, este: "cum se poate declansa, susjine si optimiza o acjiune care implica un efort de forja mai mult sau mai pujin considerabil?"

Tinând cont de funcjionalitatea sistemului care asigurä acest deziderat, nu exista prea multe variante de räspuns, soluta tinaia depinzând de mai mulfi factori: un factor structural, vizând compoznjia intima a muschiului, un factor ñervos, ce are în vedere modul de funcionare si utilizare a UM si un factor spafial care, în funere de amplitudinea miscarii, poate sau nu sä potenjeze o anumitä ñuscare. Pe langa acestia de foarte mare importanza sunt si factori care influenjeazä cresterea forjei musculare, ca urmare a antrenamentului sportiv. Iar pentru a avea imaginea completa acestia vor fi coroboraji si cu alji factori cum ar fi: vârsta si sexul practicantului, alimentaria.

In lucrarea de faja ne propunem sä facem o analiza a factorilor care due la optimizarea forÇei si care sunt apanajul antrenamentului sportiv.

În aparenta, cresterea forjei poate pärea rezultatul unui singur factor, si anume crearea tensiunilor musculare maximale la nivelul muschiului solicitât sau al grupului de muschi solicita^. Ceea ce încercam noi sä demonsträm, este nuanjarea acestei idei care a dominât multa vreme conjinutul si structura metodicii de antrenament sportiv pentru dezvoltarea forjei musculare.

Aläturi de factorii neurofuncjionali, relativ independenti de conduita adoptatä în programarea si desfasurarea antrenamentului, o multitudine de alti factori de ordin intern sau extern pot influenza, într-o mäsurä importantä, valoarea câstigurilor de forja.

Durata procesului de antrenament

O estimare relativa conduce, conform unei vechi expresii a ínjelepciunii populare, la concluzia cä "ceea ce se castiga usor se pierde usor". Astfel, un anumit nivel al forjei maximale objinut íntr-un ciclu scurt de pregätire se va menjine pe o perioadä aproximativ dubia faja de cea necesarä ajungerii la acest nivel. La polul opus, ameliorärile progresive, objinute de-a lungul unor ani de pregätire, asigurä pästrarea unui nivel al forjei maximale pe o perioadä de timp mult mai ìndelungata.

Trebuie totusi subliniat cä, ìn conformitate cu studiile lui Verchosanski (1974), câstigurile de forjä objinute ìn urma hipertrofiei musculare pot fi pästrate o perioadä mai ìndelungata, in comparale cu câstigurile realízate ìn urma ameliorärii coordonärii intramusculare sau intermusculare.

Nivelul iniziai al subiectului

Gradui de crestere a valorilor de forjä ale unui sportiv sunt diferite, în funche de nivelul general sau specific al forjei pe care îl prezintä la o evaluare iniziala, înainte de începerea unui program sistematic de ameliorare a forjei sale generale si spécifiée. în raport eu acest nivel initial al forjei, constatäm cä, în cazul debutanjilor, rata progresului este foarte mare în prima fazä a pregätirii, însa pe mäsurä ce sportivul se apropie, în timp, de valoarea forjei sale limita, rata progresului scade.

Interpretarea evolujiei nivelului de forja în cadrul procesului de antrenament, asa cum este ea prezentatä de Müller (1965) si Groh (1972), permite o evaluare ragionala a dezvoltärii forjei în procesul de antrenament.

Cei doi autori vorbesc despre:

- un nivel inifial alforfei, care reprezintä nivelul forjei maximale ìn debutul procesului de antrenament specific pentru dezvoltarea forjei;

- un nivel relativ al forfei, care reprezintä valoarea forjei maximale la un anumit moment al procesului de antrenament;

- nivelul for fei-limitä, care reprezintä nivelul maximal accesibil individuai la sfarsitul unui ciclu de antrenament de pregätire de forjä sau la sfarsitul carierei sportive.

Calitatea antrenamanetului

Calitatea antrenamentului (ìn general, nu numai a celui specific dezvoltärii forjei) poate fi definita, printre aitele, de raportul volum-intensìtate. Caracteristic ameliorärii calitäjilor de forjä este faptul cä atingerea valorii forjei-limitä se poate objine ìntr-un timp mai scurt, in situajia ìn care amplitudinea contracjiei musculare (intensitatea) este dominante in raport cu volumul de antrenament.

Experienja realizatä de Mellerowicz (1972) pe doi gemeni nu face decât sä intäreascä cele afirmate mai sus, deoarece cresterea valorii forjei maximale a fost cu mult mai ìnsemnata ìn cazul utilizarli unor intensitäji mari, cu volum de lucru redus, decât in cazul invers, in care intensitäjile au fost reduse si volumele foarte mari.

Frecventa antrenamentelor

Datoritä studiilor efectúate de Hattinger (1966), s-a putut evidenzia cä, în cazul unui antrenament izometric efectuat zilnic, câstigul de forjä poate fi cuprins ìntre 1 ci 4% din valoarea forjei maximale relative, ìn funcjie de muschiul solicitât. Acest câstig global se repartizeazä astfel: 56% chiar ìn ziua antrenamentului, 39% in ziua imediat urmätoare si doar 0,6%) dupa o säptämanä de la efectuarea antrenamentului.

Concluziile sunt remarcabile sub aspectul aplicativitäjii in practica, ele obligând la o reevaluare conceptúala a organizärii antrenamentului, în general, si a antrenamentului pentru dezvoltarea forjei, ìn particular.

Un astfel de studiu ar putea sä convingä o bunä parte a antrenorilor (în special, de sporturi colective), cä atunci când specificul disciplinei solicita parametri de forjä deosebiji, objinerea lor se poate face numai daca se acjioneazä în spiritul legilor ce guverneazä activitatea.

Un antrenament pe säptämanä, pentru dezvoltarea forjei, íi poate induce sportivului o anumitä stare de obosealä, dar de aici si pana la a considera oboseala ca unica expresie a eficienjei antrenamentului este un drum lung care, din pacate, nu conduce la amelioräri efective ale parametrilor de força.

Metode utilizate în antrenament

Obiectivul urmärit de orice program specific pentru dezvoltarea forjei este sä se ajungä la valoarea forjei-limitä individuale (aceasta reprezintä un nivel estimât al forjei maximale, individual accesibil la fínele unei etape de pregätire specifica sau a carierei). Drumul de parcurs pana la atingerea acestui deziderat poate fi mai lung sau mai scurt, ìn funere de regimul de contraete utilizai si de metoda cu care se intervine.

De exemplu, daca în pregätire se folosesc metode ìn care regimul de contracte este exclusiv izotonic, durata necesarä pentru a se ajunge la valoarea forjei-limita individuale este de 10-12 säptämani, în funche de muschiul sau de grupul de muschi vizat (Weineck, 1992); ìn regim izometric, ìnsa, timpul necesar pentru a se ajunge la nivelul forÇei-limita se scurteazä considerabil (la 6-8 säptämani).

Probabil cä acesta a fost si motivul pentru care, la ìnceputul anilor '60, lucrul ìn regim izometric constituía soluta cea mai uzitatä pentru cresterea forjei musculare. Ulterior, metodele de antrenament s-au diversificat, iar criteriile de apreciere a eficienjei utilizarli unei anumite metode s-au schimbat si eie, preocupärile orientându-se, in esenta, spre transferul câstigurilor de forjä în gestul sportiv specific.

Unghiul ìn care lucrezà articularía solicitatà

In principiu, Hettinger (1966) este eel care determina unghiul optimal de objinere a forjei maximale pentru miscarea de flexie a antebrafului pe braj, ajungând la concluzia cä acesta este cuprins ìntre 80 si 100°.

Deci, cresterea valorii forjei nu reprezintä o funche liniarä în raport cu deschiderea unghiularä a segmentelor participante la ñuscare, ea fiind legata mai degrabä de variala raporturilor unghiulare dintre brätele de pârghie si de faptul cä, într-un anumit moment al miseärii, unghiurile formate de suporturile osoase nu solicita aceleasi pärji ale muschiului efector, si nici chiar acelasi muschi (în cazul participärii mai multor muschi la realizarea miseärii).

Asa cum am väzut în capitolul care prezintä cei mai importanti muschi ai corpului uman si adunile pe care acestia le realizeazä sau le susjin, o anumitä miscare poate fi efectuatä, în principal, de unul sau doi muschi, fiind susjinutä, în anumite faze, si de alci muschi.

în mäsura în care este posibil, la stabilirea parametrilor unghiulari ai unui exereijiu de antrenament pentru dezvoltarea for^ei, prima opjiune si cea mai importantä este aceea care asigurä desfasurarea miseärii la parametrii unghiulari ai gestului sportiv.

Efectul de controlateralitate §i de contraente a antagoni§tilor

Aplicarea stimulilor de antrenament pentru dezvoltarea for^ei la nivelul brajului drept va determina, dupä Shaver (1970), o crestere a valorilor de forja ale brafului stâng, farà ca asupra acestuia sä fie aplicaji stimuli de antrenament. Fenomenul se poate explica prin faptul cä 8-10% din fibrele nervoase nu se ìncrucisaza ìn bulbul rahidian, ci influen|eazä, în mod direct, un anumit numär de fibre musculare de aceeasi parte.

Verhosanski (1974) pune in evidenza, ìn cazul antrenärii flexorilor brajului stâng, de exemplu, o crestere substancíala a tensiunii flexorilor acestuia, in situala ìn care sunt simultan pusi sub tensiune si extensorii brafului drept.

Concluzii:

1. Pe langä factorii structurait si factorii nervosi de foarte mare importanza pentru practicanjii sportului de performanjä si nu numai sunt si factori care influenjeazä cresterea fortei musculare, ca urmare a antrenamentului sportiv.

2. Faeton care influenjeazä cresterea forjei musculare, ca urmare a antrenamentului sportiv cei mai importanti sunt: calitatea acestuia, nivelul initial al celor cuprinsi în acesta, durata lui, freevenja antrenamentelor, metodele utilizate, unghiul în care lucreazä articulaba, efectul de colateralitate si de contracte a antagonistilor. Toji acesti faeton trebuiesc cunoscuji si stapâniji de orice antrenor. în funche de ramura de sport practicatä, antrenorii si sportivii trebuie sä se Jina cont de particularitäjile acesteia, pentru a avea o eficienjä corespunzätoare în dezvoltarea fonjei.

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FACTORS INFLUENCING THE MUSCULAR STRENGTH DEVELOPMENT, AS A RESULT OF SPORTS TRAINING

Virgil TUDOR1,

Doru loan CRISAN2,

1 ANEFS Bucharest

2 University of Balamand, Lebanon

Key words: strength, conditional factors, structural factors, nervous factors, sports training

Abstract

The natural question coming to the mind of any theorist, but especially of any practitioner, is: "how is it possible to initiate, support and optimize an action involving a more or less important strength effort?"

By taking into account the functionality of the system that meets this desideratum, there aren't too many answers, the final solution keeping to many factors: a structural factor, related to the muscle intimate composition, a nervous factor, that refers to the motor unit way of functioning and using, and a spatial factor which, depending on the movement amplitude, is or is not able to sustain a certain motion. Beside these ones, the factors influencing the muscular strength development, as a result of sports training, are also particularly important. And, to have a complete image of them, they will be related to other factors, such as the practitioner's age, gender and diet.

In this paper, we aim at analyzing the factors that lead to the strength optimization and that exclusively belong to sports training.

Apparently, the strength development results from a single factor, namely the creation of a maximal muscular tension at the exerted muscle or muscular group level. But we are trying here to make some specifications about this idea that has longtime been prevailing in the content and structure of the sports training methods.

Together with the neurofunctional factors, relatively independent of the adopted behavior in the training programming and performing, a multitude of other internal or external factors may influence, to a great extent, the strength gain value.

* Duration of the training process

* The subject 's initial level

* The training quality

* The training frequency

* Training methods

* The exerted joint work angle

* The antagonists ' counter-laterality and contraction effects

The natural question coming to the mind of any theorist, but especially of any practitioner, is: "how is it possible to initiate, support and optimize an action involving a more or less important strength effort?"

By taking into account the functionality of the system that meets this desideratum, there aren't too many answers, the final solution keeping to many factors: a structural factor, related to the muscle intimate composition, a nervous factor, that refers to the motor unit way of functioning and using, and a spatial factor which, depending on the movement amplitude, is or is not able to sustain a certain motion. Beside these ones, the factors influencing the muscular strength development, as a result of sports training, are also particularly important. And, to have a complete image of them, they will be related to other factors, such as the practitioner's age, gender and diet.

In this paper, we aim at analyzing the factors that lead to the strength optimization and that exclusively belong to sports training.

Apparently, the strength development results from a single factor, namely the creation of a maximal muscular tension at the exerted muscle or muscular group level. But we are trying here to make some specifications about this idea that has longtime been prevailing in the content and structure of the sports training methods.

Together with the neurofunctional factors, relatively independent of the adopted behavior in the training programming and performing, a multitude of other internal or external factors may influence, to a great extent, the strength gain value.

Duration of the training process

A relative estimation leads, according to an old popular saying, to the conclusion that "what is easily gained is easily lost". Thus, a certain maximal strength level gained within a short training cycle will be maintained for an approximately double period, as compared to the period necessary to reach this level. At the opposite side, the progressive improvements obtained during many years of training assure the maintaining of a maximal strength level for a considerably longer period.

But we have to emphasize that, according to the studies made by Verchosanski (1974), the strength gains due to the muscular hypertrophy can be preserved for a longer period, as compared to the gains due to the intramuscular or intermuscular coordination improvement.

The subject's initial level

The athlete's degree of increasing his strength values are different, depending on his strength general or specific level at an initial testing, before he starts a systematical program meant to improve his general and specific strength. As compared to this strength initial level, we find out that, in the beginners, the progress rate is very high in the first preparation phase, but, as the athlete gets closer to his limit-strength value, the progress rate diminishes.

The interpretation of the strength level evolution, as presented by Müller (1965) and Groh (1972), allows a rational evaluation of the strength development within the training process. These two authors speak about:

- a strength initial level, representing the maximal strength level in the beginning of the training process specific to strength development;

- a strength relative level, representing the maximal strength value at a certain training moment;

- the limit-strength level, representing the maximal individual level by the end of a strength training cycle or of the sports career.

The training quality

The training quality (in general, not only of the training specific to strength development) can be defined, among others, by the ratio between volume and intensity. A characteristics of the strength quality improvement consists in the fact that the limit-strength value can be reached within a shorter time interval, if the muscular contraction amplitude (the intensity) is prevailing, as compared to the training volume.

The experiment made by Mellerowicz (1972) on twins confirms our above-mentioned assertions, because the increase of the maximal strength value was more significant by far when using some great intensities and a reduced work volume than when the intensities were reduced and the volumes very great.

THE TRAINING FREQUENCY

The studies made by Hattinger (1966) emphasized that, in the case of a daily isometric training, the strength gain may be comprised between 1 and 4% out of the relative maximal strength value, depending on the exerted muscle. This global gain is distributed as follows: 56% in the training day, 39% in the next day and only 0.6% a week after the training performing.

The conclusions are remarkable under the practical aspect, they imposing a conceptual révaluation of the training organizing, in general, and of the training for the strength development, in particular.

Such a study might persuade most of the coaches (mainly those involved in team sports) that, when the discipline specificity requires particular strength parameters, these ones are possible to be reached only if the actions keep to the laws governing the activity.

A weekly training session for the strength development may induce to the athlete a certain fatigue state, but to consider that fatigue is the unique expression of the training efficiency is an idea that doesn't lead to real improvements of the strength parameters.

Training methods

The objective of any specific program for the strength development is to reach the individual limit-strength value (which represents an estimated level of the maximal strength, individually accessible by the end of a specific preparation stage or of the sports career). The way to be covered, in order to fulfill this desideratum, may be longer or shorter, depending on the used contraction and on the intervention method.

For instance, if the training is based on methods using exclusively isotonic contractions, the necessary duration to reach the individual limit-strength value is 10 to 12 weeks, depending on the aimed muscle or muscular group (Weineck, 1992); but, under isometric conditions, the necessary time to reach the limit-strength value considerably diminishes (6 to 8 weeks).

This might have been the reason for which, in the early '60, the work under isometric conditions represented the most used solution for the muscular strength increase. Subsequently, the training methods became more diversified and the criteria to evaluate the efficiency of a certain method also changed, nowadays the concerns being essentially oriented towards the strength gain transfer to the specific sports gesture.

The exerted joint work angle

In 1966, Hettinger determined the optimum angle for the maximal strength gaining in the flexion movement of the forearm on the arm and he concluded it was comprised between 80 and 100°.

Therefore, the strength value increase doesn't represent a linear function, as compared to the angular opening of the segments participating in the movement, it rather being related to the variation of the angular ratios among the lever arms and to the fact that, at a certain moment of the motion, the angles formed by the bony supports don't exert the same parts of the effector muscle, not even the same muscle (if many muscles participate in the movement performing).

If possible, when establishing the angular parameters of a training exercise for the strength development, the first and the most important option is that one able to assure the movement performing at the sports gesture angular parameters.

The antagonists* counter-laterality and contraction effects

The training stimuli applying, in order to develop strength at the right arm level, will determine, according to Shaver (1970), an increase of the left arm strength values, in the absence of the training stimuli. The phenomenon could be explained by the fact that 8 to 10% out of the nervous fibers don't cross in the spinal cord, but they directly influence a certain number of muscular fibers on the same part.

Verhosanski (1974) emphasizes that, when the left arm flexor muscles, for instance, are exerted, their tension considerably increases, if the right arm extensors are simultaneously tensed.

Conclusions

1. Besides the structural and the nervous factors, those influencing the muscular strength development, as a result of sports training, are particularly important for the performance athletes.

2. The most important factors influencing the muscular strength development, as a result of sports training, are: its quality, the athlete's initial level, its duration, its frequency, the used methods, the joint work angle, the antagonists' counter-laterality and contraction effects. All these factors have to be known and controlled by any coach. Depending on the practiced sports branch, coaches and athletes must take into account its particularities, in order to get efficiency in the strength development.