Muscular adaptations induced by training and de-training * - a review of biopsy studies

bv Günter Tidow

[ p ^ © by IAAF

10:2; 47-56, 1995

^ V This conlributitm is ba.sett <m tt leclure at the EACA Conference 1995 on combined events, edited hy the aulhor.

'Speed .strength' is defined as the ability of die ncurtmiuscular system to realize a maxi­mal impulse wiihin a period which is limited ucct>rding to the respective movemeni. A .synopsis f>f mediott-specijlcpiiysiotogicat finttings will he given us retaietl lo speed-slienglh training, and the way in which speed-strenglh can be carried oul in a more eciJntmiical antl effeclive way will be exam-inetl. Ttw influence of hvpertrffptiy iraining meihods (HM), ffte melhod tif maximum Slrenglh efforts againsi high and muximtan resisiances (neuronal activulitm Iraining I NAM), orihodox .speed-strength Iraining. .speed training, deloading, and die so-called time-controlled .speetl strength method (TCSSM) f}n the fibre speclrum is tlescribed. In the second pan the results tjfa pilot study ofthe reproducibility tif acyclic velocity maxima depending on lite amounl of resis­tance anil the tluraiion tif intra-set inten-ats are presenied. The results .show thai the exptosivc-btillisiic load characteristics ofthe TC.SS.M allow a gradual apprti.ximatiim lo die tpHdiry of .special slrength iraining mctli-oils (SSTM). By using the reactive varialion of TCSSM (TCSSMr) the effectiveness can even he increaseil. 1lius Ifte sequence HM ^ NAM ^ TCSSM ^ TCSSMr - tdlcrnaling wilh SSTM in each case -promises die great­est gain in iransformtttion of tfie fibre spec­trum. A *

f^rof Dr Günter Tidtnv is tfie Head of tlie Dcptatmeni ofMtivetnciit antl Training .Science al the HumboUh University in licrlin.

(Translated from ifie original German by .Jürgen Schiffer)

1 Revievi of muscle bictp.sy literulure

1.1 Introduetiun From ihe point of view of physiology,

training is a process consisting of a series of stresses bringing about or preserving adapta­tions. Consequently, ihe exact knowledge of the responses of differeni organ syslems lo defined load stimuli is the key tc» a systemat­ic and effective iraining as well as. generally, to a well-founded iraining control, In this regard iraining science can be defined as a '.science of meifioti-induced atlaplaliims'.

Analyses of tissue samples, taken from the muscles prior to or after iraining. provide imporlant indications of stress-induced (in­ternal) adaptation mechanisms. In the fol­lowing, a synopsis of method-specific physio­logical findings will be given as relaled to speed-strength iraining. and ihe way in which speed-strength training can be carried out in a more economical and effeclive way will be examined. In this context, 'speed-strenglh' is defined as the ability of ihe neuromuscular system to realize a maximal impulse wiihin a period which is limited acct)rding lo the re­spective movemeni.

Figure I shows that, under ballistic condi­lions. Ihree influencing factors determine Ihe relalive degree of the force level, which can be quanlified using a force-time curve relat­ed to instants of time: • Firstly, the degree of activation of the

motor neiinme pind and ils corresponding efferenl range t}ffrequencies:

• secondly, the sum lotal of ihe contraction force of the motor units, which is primarily deiermined bv the muscle"s cross-section area, and

• thirdly, ihe given fibre spectrum with fibre-tvpe-relaled divergent coniraclion veloci­ties.

• A complete cessation of iraining (see Michael KHNT: The Oxford Diet ion nai rj' of Sports Science and Medicine. Oxford el al.i Oxft)rd University Press 1*W4. p. 126. 47

Motor-neuron pool

Frequency spectrum

Total cross section

^ Force of contraction

Type I - mn 30N

TypaJla-mn: 30N

Jype.lÜ) - mn: 30N

(100% Fibre spectrum

I Contraction time

100%

Type I: I40- I80n is

.lYRe!!a:tO0-l2Oms

TYpB_!|b 60-eOms

120 ms 180 t

C o m p l e x

fo rce - t ime curve

Figure 1 : Ballistic force development of a skeletal muscle

If all motor units (MU) are activated synchronously and if the relation between fibre type and force is identical, the course of the force-time curve is determined by the fibre distribution. If Ihe time limit of impulse development is 120ms, only type lib and type lla motor units can realize their full contraction force, whereas, in the case of a time limit of 60ms only lib motor units can do this.

Fibre type

Contractility

Myosin

Innervalion-frequency

heavy chains: •HC

light chains: •LC-

- ^ IIB

high

F-A.SX CK, C

Model

of

myiisin-molecules (a variation

of fibre type)

- 10/s

S

sl+s2 (fl)

(fl + C) (n + f2 + f3)

~25/s

sl+s2 fl + f2 + Q

-40/s

FA

f l + £ 2 + f3

>5Vs

FB

n+ü + a

48

Figure 2: Fibre spectrum of the skeletal muscles with an increase In contractility from left to right

The shaft of the myosin molecules is formed by different (type-determining), heavy chains, while the head consists of double-paired (slow/fast) light chains and globular regions with type-variable activity of myosin LC kinase or ATPase. According to RAYMENT et al. (1992) there are two clefts within the globular regions indicating the actin and the ATP binding sites.

It would be opiimal to influence all compo­nents in a positive way by a corresponding training regulation, i.e. to increase the cross-section of Ihc muscle, to improve the neu­ronal activation and to transform the fibre spectrum in the direclion of a higher propor­tion of lype Mb motor unils.

1.2 Hypertrophy truinin)> and Ihe fibre spectrum

When using hypertrophy methods ('HM') the possibili ty of achieving a seleelive increase of the a reas of type II fibres (RoKHZKi el al. 1991) or even an increase of tbe proportions of lype II fibres (ZEMAN et al. 19K8) Ihrough Ihc administration of ana­bolic steroids or beia|-reeepIor ag<misis must be ruled out because of doping controls. Gains in eoniraciile poieniial . which are achieved in fast muscles in a physiological way - and which can be measured very pre­cisely by means of nuclear magnetic reso­nance imaging ( N A R I C I et al. 1988} - are accompanied by a iransformalion of Ihe fibre speclrum to Ihe lefi.

The arrows in Figure 2 show thai this means a decrease of the proportion of type l ib fibres to Ihe advantage of Ihe neighbour­ing fibre fractions: After a 13 lo 20 week hypertrophy training of Ihe vasius laier-alis muscle, S I A R O N el al. (1991) could delect hardly anv ivpe Mb fibres. The dynamics of Iransformation to the lefl was 5 to 7% per week. Similar findings were made by KLITGAARD el al. (1990) in ihe biceps brachii muscle.

1.3 Neuronal activation training i 'NAM') and the fibre spectrum

Thc method of maximum slrength efforts against high and maximum (a '•){)%) resis­tances CNAM") is usually applied after hy­pertrophy Iraining ('MM') in order lo reduce slrenglh deficits. The model in Figure 3 shows ihal in 'mixed" skeletal muscles ihis is only possible by increased "rale coding", because Ihc recruiiing limii of these muscles is nor­mally around 8(1% of maximum slrength.

This means thai only in Ihe case of resis­tances higher than S()% is ihe voluntary cen­tral-efferent excitation so high that in each attempt longer lasting ma.Ktmal activations of higher-ranking moior neurones are enforced. Thus NAM demands loads which are higher than 90%. If one performs squais at 100% of maximal strengih. there are tension limes of 3 to 6sec per allempi (HÄKKINEN 1993). In spite of maximal activation or calcium release, ihe rale of cross bridge cycles/sec is very much reduced. CAIOZZO et al. (1992) examined the influence of high k)ads on the fibre speclrum of fast animal muscles. Even 4 sels of 10 repe­titions againsi resisiances of 90 (concenlric

As hypertrophy Iraining is characterized by only a slow cross bridge cycling because of resistance and aclivalion. the inirinsic coniraclion ve­locitv of ihe fibres is also re­duced (Ei)MAN 1979), These effecis of coniractiliiy reduc­tion, which are a conci)mi-lani to hypertrophy, can only partly be compensated for by a higher strength maxi­mum. Consequen l ly . HM leads to a reduction of speed strength.

Fibre distribution

Neuronal activaliorv of tfie motor units

~1^ Rale coding

Type lltj: 30

Typella 10

Type I: 60

Figure 3: Model of recruitment and rate coding In the case of low slrength demands only a few type I motor neurones are activated, according to Ihe size principle of recruitment. Higher strength efforts lead to the increasing integration of greater motor units (of types lla and lib). In this model, ihe recruiting limit is reached at 80% of maximal strength. Further strength increases are only pos­sible by even higher frequencies. 49

50

coniraction) to 120% (ecceniric ctmlraclion), performed on every second day wilh intra-set recovery intervals of 8 sec duration and inler-set resl intervals of 10 min duralion. led to a pron(junced reduction ofthe ivpe lib fraction after only one month of Iraining. As far as perceniage is concerned, this transtormalion to the lefl. which was accompanied by a cor­responding reduclion of ATPase activity -and therefore also of contraclilily - was only slighily more pronounced wiih 4sec duralion (per repelilion) Ihan with 2sec duralion.

1.4 Orthodox speed-strength truining and the fibre spectrum

The invesiigalions by St HMIDIBLEICHER & BüHRLE (1987) in parlicular show ihat the effect of maximal dynamic slrenglh efforls against low or medium resisiances - 30 to 45% of maximal slrenglh with 8 to 10 repeti­tions per set - performed according to the speed-strenglh method does not correspond wilh the training goal. Allhough a signifleanl increase of maximal strengih as well as of the total cross-section could be verified, there was no change of the explosive slrenglh para­meters. Although here no muscle specimens were taken. Ihe mere hyperirophv of lhc muscles trained by means of hench-press exercises is evidence of a fibre transformation to the left. It may be assumed that Ihe cause of this was the energetic "overtaxing" of the fast triceps brachii muscle, which has a high proportion of type tib motor units (JOHNSON et al. 1973). b>' the rhythmic-serial exercise. The study by C A I O Z / O el al. (1992) men­tioned above shows thai fasl muscles •reaci" to deficits in energy balance caused by (slrength) loads primarily by a transforma­tion of their originally high proportion of type lib fibres. Only the prolonged duration of the exercise (from 2 sec to 4 sec) - the stress being otherwise absolutely identical -led Io a hypertrophy only in second plaee.

1.5 Speed training and the fibre spectrum

Wilhoul muscle strength no anti-gravita-lion movemeni is possible. This applies even to the levator muscle of the upper eyelid. In this regard the borderline belween acyclic strength and speed loads is diffuse. RAPP & WEICKKR (1982) examined the adaptations of ihe fasi running muscles of animals during iraining with an emphasis on strength or speed. The main effecl was thai a ireadmill wilh a steep angle of inclination and a rela­tively low velocity produced a difterent distri­

bution proportion of ihe fast light chains than one wilh a fiat angle of inclination and a sig­nifieanlly higher velocity. Therelore. running t ra ining with an emphasis on strengih reduced the proport ion of LCf3 while it increased LCfl . In agreement with ihis. SwEhM Y el al. 1988 showed that diverging inirinsical contraction velocilies of lype lib fibres, measured in fibre lengihs/sec. are deiermined by the LCI:LC3 ratio. Conse­quently it may be assumed that the efficiency of speed training, apart from an improved co-ordinalion and energv flow rale, is mainly dependent on relalivelv low external resis­tances and complete rest intervals. Only then can maximal cross bridge cycling be realized. Furthermore, the activation of the muscle musl be very short. Obviously, type lib fibres in particular react to longer tension limes and/or higher load volumes so sensitively because 'naturally' ihey are activated only intermit tent ly via 'shori bursts". Conse­quently, as far as energetics is concerned, they are "specialized" only lo ballislic loads. The findings published by HtNMG & LoMo (1985). EKEN & Gl. NDLRSEN (1988) as wel! as Ai:soNi el al. (1990) showed ihat even shorl-time. high-frequency stimulations - analo­gous lo nalural lype lib impulse patterns -only then led to a righl iransformalion of the fibre speclrum of fasl animal running mus­cles, which had been considerably shified lo ihe lefl by wav of denervation. if a low vol­ume and long rest intervals were given. These results are corroborated bv human biopsy findings of BAIMANN cl al. (1987). at leasl as far as lendency is concerned. According lo Ihese results, an 11 week sprini Iraining led to an increase of the type lib fraction of ihe vas­lus lateralis muscle from 10 to 18%. which can be interpreted as a relransformation of the fibre speclrum which had been shified lo the lefl by previous endurance training.

1.6 Ueluading and the fibre spectrum

There is a considerable range of "deloading methods'. These meihods include, for exam­ple, rcduced training, complele rests from iraining of different durations, immobilisa­tion, reduction or even elimination of gravita­tion. When STARON ei al. (1991) re-examined the hyperlrophy-lrained sample meniioned above after an 8 month "deiraining". ihey found an almosl complete rel runsformufion to the original fibre speclrum. Contrary to ihis. a greal extent of the training-induced hvper-Irophy remained. Presumably this finding is due lo the everyday anii-gravilalion function of ihe analvsed vastus lateralis muscle.

Research findings by HATHER et al. (1991) corroborate ihis rest-induced relransforma­tion. More accenlualed meihods of deloading - such as the hindlimb suspension' in four-legged animals ( I ) I I I H E el al. I993a/b) or space flight (DI-SI'LANCHES el al. 1990) - lead to a more pronounced and atrophy-accompa­nied iransformalion to the rigfit: Then Ihe per­centage type lib as well as lype lla propor­tions even surpass the original fibre distribu­tion.

Conclusion: The often quoted phenome­non of performance-increasing 'late inmsfor-maiions' is normally based on timely relrans-formations caused by deloading.

1.7 Implications for training practice

This synopsis has shown that hypertrophy training ("HM") leads lo a transformation to the left and that neuronal aclivalion meihods againsi high and maximum resisiances ('NAM") al leasl retards the reiransforma-lions intended. Therefore, it appears lo be useful lo apply the time-controlled speed-strenglh method CTCSSM". T IDOW 1990) after using HM and NAM. The time-con­trolled speed-strenglh method demands loads of 40 lo 60% of maximal strengih which the athlete can jusl manage in a (reactive) ballis­tic way. The movement execution is explosive and dynamic.

It is important lo supervise - and feedback (!) - both the qualily (Ume/velocity) of each allempi as well as Ihe inter-set and especially the intra-set rest interval duration. As a result, the lime-controlled speed-sirengib method virlually consisls of single attempts. As in the repelilion melhod. load-induced performance decrements of lhc neuromuscular system are minimized by using adequate resl inlervals. If one proceeds in this way, it is generally possi­ble to achieve a relransformation to the right of a fibre speclrum shified to the lefl of a muscle which is hyperlrophied and can be activated in an optimal way. Then, in spite of an almost ideniical cross-section, the result­ing improvemenl of contraclilily allows even higher rates of strengih increase.

2 The reproducibihty of acyclic velocity maxima - a pilot study

2.1 Preliminary remarks

rhe effect of speed-sirenglh methods, which has given ihem Iheir name, is slill dis­puted. This stalement is confusing because ihe specificity of all other Iraining methods is widely accepled. A look al the dosages of

speed-strength loads published by various authors (e.g. HARRE el al. 1969: H, LETZEL­TER 1985; TIDOW 1985: SCHMIDTBEEICHER & BL'HRI.E 1987: POPRAWSKI 1988; GROS.SER 1991; MARTIN/CARL & LEHNERTZ 1991) pro­vides first keys: While there is a relatively high agreement regarding the loads (30 lo 70% of maximum strength = "Smax"), which, with one exception, have lo be moved in a rhythmic-serial way. there is a variation of the presei number of repetiiions per set (3 lo 10 reps) as well as of Ihe duration of ihe rest intervals between the sets (2 to 5min).

Finally, in none ofthe comparative training experimenls (H. LETZELTER 1985; SCHMIDT-BLEK HER & BuHRLE 1987) was there a con­irol of the quality ofexercise e.\ecuii<m. It is possible thai ihis is Ihe key lo ihe facl that the efficiency of orthodox" speed-strength methods does nol correspond wilh the de­mands of the training goal. C'onsequenily it seems to be useful to examine Ihe intra-set reproducibility of the maximal speed of single movemenis againsi resistances which are con­sistent wilh the method. This examinalion is the central intention of this study.

2.2 Material and methods

The "bench press" was chosen for the lest exercise. Altogether 50 subjects look pari in this experimeni: 40 physical educalion stu­dents of bolh sexes as well as 10 competitive athletes, among whom there were two 20m shot putters, iwo 60m discus ihrowers and two German Champions in the bench press.

After having tested the absolute movement speed with a barbell weighing 15kg (men) and 9kg (women). Ihe subjects had to acceler­ate barbells of increasing weighl on five con­secutive days starling with 30% of the indi­vidual best performance in the bench press. The increment was 10% per day up to 70% of the individual maximum strength. By way of introduction (after a standardized warm-up) the maximal speed which could be achieved reaciively using Ihe respective amounl of resislance was determined in three individual attempts.

Then the subjecls performed 5 sets of 10 repetiiions, with resl intervals of 5min dura­tion belween the sets. In each following set the duralion of the intra-set rest inlervals was systematically reduced by 3sec each: froml5 sec (only wilh 70% of Smax) or I2see at the beginning to 9sec, 6sec and 3sec. up lo. final­lv. a continuous, rhythmic mode of working. Figure 4 shows the setup of the experiment. 51

Figure 4: Experimental setup for the bench press

The experimental conditions on the test days were kept constant by controlling the height of the lower uprights, the position of these uprights in relation to the subject, the grip width and the laser barriers, which were adjusted to the subject's individual reaching height.

A control and measur ing appara tus ("D IV). developed solely for this experimeni. conlrolled the rest inlervals belween both the sets and Ihe repetiiions and recorded the time needed for pushing the barbell through two laser harriers posilioned veriicallv on top of one another. The laser beams were orient­ed lo the subject's individual reach height, in such a way thai the lime needed for covering tbe last 25cm of the total acceleration path could be measured. On the sound of the starl­ing signal from the D II. each altempi had lo be made immedialely in an explosive and bal­listic way. i.e. with a maximal effort of will. The lime was measured in ten thousands of a

second and was fed back al once. An acoustic countdown prepared the respecli\e subject for the beginning of each set as well as for the next repetition. Each attempt was followed by the immediale lowering and placing tif Ihe barbell back onto the lower pair of uprighis. whose heighl had previously been adjusled exactly to Ihe subjects's thorax deplh (barbell contact afler having breathed in). On Ihe one hand Ihis excluded the use of thc elastic read­justment forces of the thorax while, on the other hand, a short relaxaiion phase during the inira-sei rest intervals was guaranteed. As. according to MORITANI (1993). ballistic movements are preceded by a "quiescent

110

IOS

TOO X of total samples

resislance EU < Shg SOK.Smn EOKSmax

DuiBtion o< Ihe mtra.s« interval | I5s Q >2s Q 9t Q3S S <

52

Figure 5: Complete overview of the mean progression of fatigue

The heights of the columns represent the percentage time differences between the first and the tenth repetition within a set, which depend on both the intra-set rest intervals and the load.

period', the creaiion of the prerequisites for such a relaxation opportunity seemed lo be essenlial.

2.3 Results

The results are presenied in Figure 5.

This figure shows that there is a highly sig­nificantly varying progression of fatigue direclly depending on the toad (% of Smax) to be moved and the duralion of the intra-set rest inlervals. As far as the mean limc differ­ence belween tbe first and the tenth repeli­lion of each set is concerned, ihe athletes suc­ceed in staying below a velocity reduclion of 5% when exercising wiih a barbell weighing 15 ov 9kg, respeclively. even in Ihe case of a rhythmic mode of working - see black col-umn(s). On the other hand, the reproducibili­ty of the maximum movemeni velocity was lowesi when performing al 70% of Smax. as had been expecled. Here, Ihe subjecls look more than twice as Umg on average to cover the 25cm measuring distance in the tenth rep­etition, i.e. the barbell velocitv was reduced by 50%.

Between these extremes there are intra-set slowing-down effecis induced by method-typ­ical loads (40 to 60%). By way of example. this will be i l luslraled using the results obiained al 50% of Smax (see Figure 6). For

differenlialed judging, that perceniage in­crease in lime is given here which occurred within each set wilh a varying duralion of the intra-repetititm resl inlervals during the sec­ond Io tenth repelilion. Reference crilerion: the respeclively firsl. i.e. lhc fastest attempt of the same set. Il becomes cibvious that, in Ihe case of the traditional, rhythmic mode of working, there was an increase in lime of less than 5% only up to the third repeti t ion. There is a slowing-down of ihe barbell veloci­ty by more than 10% already during Ihe sixth repetition, while in the tenth repetition Ihe time increase is approx. 27%!

If one looks al the points of intersection of Ihe fatigue curves wilh the 5% and 10% Ihresholds. it can be seen that seven repeti­tions can be performed within the 5% zone with an intra-set rest interval of 12 sec dura­tion, while 6 repeiitions can be performed wilh a 9 sec resl interval, and 4 repeiitions wilh a 6 or 3 sec resl inierval. However, espe­cially with very wide ranges of dispersion, as in Ihis experiment, statistically determined central trends conceal individual reaction pa t te rns . As shown in Figure 7 with the example of three subjecls. three groups with a differeni fatigue behaviour can be identi­fied within the tolal sample. The difference of fatigue progression when performing explo­sive, rhythmic-serial strength efforts againsi

1 ot pressli^g tirne

[%1

30 -1

0 ->

X of total samples

10 • 10

_/>'"

. ' '4 5 • ' 3

Y^-—/ . / ' • 2

S e l l : 12s Sei 2: 93 I ' T ' T T r I T T I I 1 I I I I I I

Sei 3: 6s Set4: 3s Sei 5: rhy I T I I I M M I M F I M M 1 r 1 I 1 n '

Duration of the Intra.set rest Interval

Figure 6: Mean change (,At%) of tbe nine pressing times, as compared with the first attempt of each set In the case of a varying duration of Inter-set rest Intervals (load: 50% of Smax) 53

1 of pfestun^ um«

1%) t i o - |

-100 -

-90 -

-so -

' 0 -

-eo -

50 -

~ ta -

-30 -

20 -

. 10 -

-0 -

f=«nale diACUS IhrrwoF J

Irilr«-»»! t w t lnl»rv»li rtrythmic ,

/ ^ • ^ Type lit). prwXimtrilinf i

-• M H .* Typnlla-pnacvmnanz > gnof

T y p t l i liit'Dieoonvnani / ,

/ .' / /

/ ; J '

y , y

/' A / y >

X A y , -J» - B«noh

^ , ' y * nr»o»f

•̂ • / W - ' /

<̂ . ' - / X , ' / • , ' ^___.-̂

^ *' *̂'—"""""̂ t ^ ^

,* ' ^^^'^ *" ' ^ : T — " 1 1 1 1

a iSKg 30% S m » . 4 0 ^ S m a i 5 0 * Small eo* . Smai 7 0 S Smai

Amount a l rvftlitancc

Figure 7: Load behaviour (in At% between the 1 st and 10th repetition) of a female discus thrower {silver medallist in the 1994 Junior World Championships), a 20m shot putter and a German Champion In the bench press (PB: 185kg with a body weight of 67.5kg)

54

loads which are ideniical as far as percentage is concerned seems remarkable. In the case of 50 or 70% of Smax. the inter-individual degree of velocity reduclion of Ihe barbell during the 10th repelilion is in some subjecls Ihree or four limes as great as in other sub­jects!

2.4 Discussion

The results shown give rise to tbe assump­tion Ihal up lo now not enough attention has been paid to the load characleristic of 'ortho­dox speed-slrength training". Both the ener­gy consumption induced by explosive-rhyth­mic work during orihodox speed-strength training and the limiled faligue resislance of Ihe lype II alpha motor neurones must be considered. The dependence of the inira-set impulse decrease on the load and intra-set resl inierval duralion "as a sum lolal" reflecis the lime-relaied dynamics of the biochemical or neuronal micro-regenerat ion. Il must remain open which of these two infiuencing faclors is the primary determinant of fatigue progression. At least fatigue progression can­nol be explained by cumulative serial effects: a crossover experiment, which was character­

ized by a rhythmic nunle of work during ihe first set and a prolongation of the inlra-sel resl interval in each subsequenl set by 3 sec each, led to intra-serially congruent trends of slowing-down in Ihc case of 50% of Smax. In this context the direclion of the change of intra-set resl interval duralion had no influ­ence on the first allempi of the subsequent sets. A resl inierval between tfie sets of 5 min duration was sufficient for the reproducibility of the individual PB (al 50% of Smax at leasl) even when, prior to this. 10 attempts had been performed in an explosive-rhythmic way. However, it remains ques t ionable whether such rest inlervals between the sets allow ibe complele replenishment of the phosphocreatine siores (PCr). The load-dependent increase of contraction duralicm and ATP consumpiion speaks againsi such a complele replenishment. In any case, an intra-set potenliation of the slowing-down effecis might occur in all sets with shorter rest intervals (2 to 3min).

NMR-spectroscopy as well as muscle-biop­sy findings by MizuNO ei al. (1994) suggest the marked effect of energy provision: In the case of a progressive increase of load, sub-

jects with a high proportion of type lib fibres in particular show a significantly greater increase of inorganic phosphate (Pj). and thus an increase of the PJPCv ratio', ihan subjects with mixed muscles or even a predominance of ivpe I fibres. Here, an analogy to the reac­tion tvpes presenied in Figure 7 suggests it­self: The pH value, which shows a high corre­lation wilh ihe fibre-lype-dependenl lactale accumulation in the muscle cell, dramalically decreases in Ihe fasi(esi) motor unils - as the ATP consumption is highesi here - and caus­es an increasing •impairment' of the contrac­tion of Ihese motor units. The rapid fatigabili­ty demonstrated bv the voung female discus ihrower, who was nol very much strength-trained, indicales a slill high type lib propor­tion in the activated muscles. Shot putters and bench pressers. however, have under­gone many years of intensive slrenglh train­ing. Their varying fatigue behaviour implies a type lla pred(tminance (in the shoi puller) or a type I/type lla speclrum which rather lends to endurance slrenglh. Considerably diver­gent load-velocity relat ions belween the female discus thrower and the bench presser are proof of the antagonism of speed and fatigue resislance: they suppori the differeni fibre disiribulion (LARSSON & Moss 1993) postulated in this article.

Since there are considerable slowing-down effects even at 40% of Smax. changes of the training effect in the direction of endurance strengih are unavoidable. If one considers that a release velocity of the shol which is reduced by only 5% turns a shol pul of 22m into one of 20m. reductions of 10%. are unac­ceptable from the point of view of "speed strength".

In order to guarantee an effect specificity which conforms with the training goal, it seems to be absolutely essenlial to regulate the load in speed-strength training in an indi­vidual and muscle-specific way: In ihe case of inier-sel rest intervals of 5 min duralion. wilh immediale feedback of the limes achieved, bolh the number of repetitions as well as the duration of the intra-set rest inlervals should be varied in a load-related way: lo such an extent that in the preparatory period the speed reduclion should remain below 10% and below 5% during the compeiition period. Only then is il possible to avoid a contractili-iv-redueing transformation of the fibre spec­trum or to guarantee a coniractllily-increas-ing relransformation of the spectrum of origi­nally fast muscles, which has been shifted to ihe left by previously used hypertrophy meth­ods (HM: cf. SIARON el al. 199-1) or neuronal

activation meihtxis (NAM: cf. CAIOZZO el al. 1992).

The explosive-ballistic load characleristic of the titne-cinitrolted speed-sirength method (TCSSM: TIDOW 1994) allows a gradual approximat ion to the quality of special strength-training methods (SSTM). By using the i-eticiive varialion of TCSSM (TCSSMr). which leads lo velocilies being 3 lo 5'Xi higher ihan during an aciive mode oi work, ihe effectiveness can even be increased. Thus the sequence HM m NAM m TCSSM m TCSSMr - a l le rna l ing with SSTM in each case -pnmiises the greatest gain in iransformalion.

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