THE SCIENTIFIC BASES OF MODERNSTRENGTH TRAININGBy Gilles Cometti, French Atletism Federation UEREPS, Dijon

This article, originally published in “The Throws –Official Report of the EuropeanAthletic Coaches Association Congress, 1987” examines modern strength developmentmethods and reviews the strength development methods proposed by various expertsin the field. Re-printed with permission from the European Athletic Coaches Association.

This exposé aims at discussing methods of strength training and correspondingscientific knowledge. It will be made up of four parts:

In a first part, we will deal with strength mechanisms: among them we will mostlydevelop the phenomena of synchronization of motor units and that of elasticity.

We shall then see the methods of development of strength.

In a third part, we will deal with the principle of alternation of types of contractionwhich strikes us as being the focus point of modern strength training.

We shall end with the principle of variation of strength in movement with anappliance called “Sportonic”.

1) Mechanisms of strength

In figure 1, you see the different known mechanisms that exist in strength development.

The best known mechanism is that of hypertrophy and it has been known for manyyears with Zatsiorski, that the best method to increase the muscular volume consists inmaking repetitions of series of 10 with weights you can only lift ten times. The number ofseries must be relatively high, about 10 series. But the most important factors forstrength development are nervous. They number three: the recruitment of motor units

ruled by the Henneman law, the synchronization of motor units which we will developlater and the intermuscular co-ordination.

The recruitment of the motor units deals with the strength developed between 0 and 80% of the maximum, and explains the quick gains of strength at the beginning of atraining period. For us it is not the determining mechanism in the case of high strengthtraining. The inter-muscular co-ordination is explained as the movement training, whichis to say with good timing of the concerned muscle contractions.

Moreover there exists a third group of phenomena which come into focus when themuscle is submitted to stretching. They are the myotatic reflex and muscular elasticity.We shall develop this phenomenon of elasticity.

Synchronization of motor units

As is shown on figure 2, this mechanism was already noticed by Zatsiorski some 20years ago. He said that for experienced weight lifters, the number of synchronizedmotor units could reach 80%, whereas for beginners it is only 20%.

Let us take a simple picture to explain the principle of synchronization: let us imagine aroom full of spectators who would be asked to shout a sound all together. The first timethey would be surprised and would not react at the same moment; the sound would thusbe long and not very strong. After many rehearsals, the answer would be shorter butalso stronger; they would then be synchronized.

The same thing happens due to the training of motor units. However this fundamentalphenomenon has not yet found a coherent explanation which explains the questionmark on figure 2.

We are going to try and find an explanation thanks to the work of French researchworkers.

With Paillard we thus learn that the motor-neurons (motoneurons) are at the beginningsystematically in phase, thus synchronized; which is paradoxical in comparison withwhat was claimed previously. In fact, noticed Paillard, this phenomenon ofsynchronization is unfavorable for everyday life because it would engender violent andtrembling movements. Fortunately there is for everyday life a de-synchronizationphenomenon which is the Renshaw circuit.

This cell starts contact with a collateral of the motor- neurons and ends at the differentneighboring motor- neurons, and as each Renshaw cell acts in the same way, we thusget a jamming of the different impulses originally synchronized. The de-synchronizationis thus the result of an inhibition sent by the Renshaw circuit. How is this possible?Another French research worker— Pierrot Desseilligny— showed that the Renshawcell was under the control of nervous centers which could send inhibitor impulses. Thisinhibition made it possible to regain the initial synchronization. We thus note in this casethat improvement in strength is considered as due to the removal of an inhibition.

In order to solicit this mechanism, as already stated by Zatsiorski, you must haveweights or muscular tensions superior to 80 % of the maximum. In our opinion themechanism of concentration fits this explanation.

We can now deal with the second mechanism which interests us, that is to saymuscular elasticity.

Muscular elasticity

This is generally represented by Hill’s illustration which is shown in figure 3. A differentiation is made between an elasticity in series and an elasticity in parallel. Theseries-elastic was classically located in the tendons and in the muscular sheathes.However, for some years, research-workers have also located it in the contractile part ofthe muscle, more precisely in the actin-myosin pons.

Figure 4 schematizes the different representations of the myosin molecule. Firstly weshow a simple schema with a head and a tail (fig. 4,A), then we introduce a spring at thetail level of myosin(fig. 4,B); you can find these representations in Bosco’s works, after Huxley.

Finally nowadays research-workers such as Goubel in France base themselves onHuxley and Simon’s schema which add to the spring of the myosin tail therepresentation of different anchoring points for the head; these anchoring points havingalso a role to play during stretching (fig. 4,C). You can note that things develop at theelasticity level.

Basically you see a new idea appear, particularly regarding tests. You can thus find inBosco two new tests for elasticity. They are the Squat-jump and the Countermovementjump. The Squat-jump consists of measuring the elevation of the centre of gravity froma low knee 90° bend; the athlete can thus only solicit the contractile aspect (of course ina schematic way). Then he does the countermovement jump which consists ofbeginning in a standing position then in bending, then immediately extending; theathlete soliciting this time twice his elasticity. The difference of performance betweenthe two tests is a significant measure of the elastic qualities of the athlete. This is a veryefficient method of control for training.

2) Methods for developing strength

Still thanks to Zatsiorski, we know that to develop strength you must create maximumtension in the muscle. This in order to solicit synchronization of the motor units. Thesetensions may be obtained:

either in mann ways the weight is maximum and you then have the method ofmaximum efforts

or the weight is sub maximum and you must then compensate either withmaximum fatigue or maximum speed. You then discover the method of repeatedefforts, and the method of dynamic efforts, as shown on figure 5.

For a long time these three methods and their combinations have been the majorconstituent of the variety of strength training.

With Schmidtbleicher there has been a new distinction which deals with all kinds ofmuscular contractions.

You can distinguish 4 types of muscular contractions as shown in figure 6. Theisometric contraction where there is no movement of the muscular insertions, and theanisometric contractions where the insertions move. The most current contraction in thisgroup is the concentric contraction: the muscular insertion points approach one another,

the muscle shortens. More recently used, you may find the eccentric contraction wherethe insertions move away from one another. This type of work is one of the discoveriesof modern strength training, applied with care it is a method with a surprising efficiency.

Finally since Zanon, we have talked of plyometric work when a muscle sollicited in aneccentric manner immediately produces concentric work. In figure 6 you can notice theopening of possibilities brought by these kinds of contractions. With Schmidtbleicher wecan make an inventory of the possibilities offered if we attribute to the three methods of

Zatsiorski the 4 types of contraction. The variety of work is thus much improved; butmodern strength training has found something even better, a combination at these typesof contractions as we are going to see right now.

3) Alternation of types of contraction

The phenomenon against which the development of strength fights is habit. Againsthabit you should then use the alternation of efforts. The first alternation which appearedin strength training— as shown in figure 7— is the alternation of weights; this methodis known in France under the name of method of contrasts, or the Bulgarian method. Itconsists of alternating in the session heavy and light weights. But thanks in particular toPletnev and Komi, the alternation applies nowadays with the type of contraction of themuscle.

In figure 8 we have schematized the results of these two authors. Komi’s work dealt with 3 different groups. One of the exercises taken as a support is bench press. Komi madea group work in concentric only, a group in eccentric only (but still with 25% concentricfor safety’s sake) and a mixed group with 50% concentric and 50% eccentric. You cansee in the diagram the progress of work over 12 weeks. The mixed group is far above

as far as its progression is concerned. Pletnev had the same idea but this time with anew parameter, i.e. isometric work. He thus had 4 groups: one working in concentric,one in isometric, one group in eccentric and a mixed group with the three parameters.The mixed group also had the best results. Pletnev then wanted to know more about thebest possible combination of these 3 types of contraction and he did a secondexperiment with 3 groups: one working 50% in eccentric, 25% in isometric and 25% inconcentric; a group with 50% isometric, 25% eccentric and 25% concentric; and a group50% concentric, 25% eccentric and 25% isometric. The group with 50% eccentric workperformed best. Since then other studies have been made in the same direction. Theseexperiments show the interest in this type of alternation. We think that nowadays oneshould investigate all the possibilities of combinations as suggested by figure 9, takinginto account the fact that one can combine the types of contraction either in the samesequence or in the same series. Moreover we can combine the types of contraction 2 by2, 3 by 3, or even 4 by 4. You can thus note the great variety introduced. But thesubtleness of modern musculation does not stop there. Why not vary strength and thetype of muscle solicitation in the same repetition!

4) The modification of strength in the same repetition

This idea is shown in figure 10. Already some methods exist which go this direction.They are the stato-dynamic method and the 120-80 % referred to by Tschiene. Thestato-dynamic method consists of making a halt with a bar (about 2 seconds), thenfinishing the movement very quickly. The movement is thus both isometric andconcentric. The 120-80 % method is even more ingenious as it proposes in the samemovement, to go down at 120 % and up at 80% . Of course with classical equipmentsthis supposes a way of loading the bar during the movement. This is a rather riskyoperation. In this case it is better to have an appliance enabling a change of load duringthe movement, as with the Sportonic.

This revolutionary appliance offers the following possibilities: it can be linked to acomputer and thus has an entry and an exit. In the entry— as shown on figure 11—you can programme the developed strength according to the movement both for the inand return movement; the Sportonic having a motor to take the place of weights.

We can note immediately the possibilities. Moreover, thanks to force sensors fixed tothe bar, it is able to supply information in the manner the movement has been executed.It thus gives the speed of the bar, its movement and the force applied. It is with this kindof appliance and with the preceding methods that modern strength training will improve.