EXPLOSIVE ISOMETRIC MUSCLE FORCE OF DIFFERENT MUSCLE GROUPS OF CADET JUDO ATHLETES IN FUNCTION OF GENDER

e aim of this paper is to determine the di erences in general and speci c explosive isometric muscle force in male and female cadet judo athletes. e results of the measured contractile characteristics were obtained by application of a standardized test battery using the isometric dynamometry method for the following ve muscle groups: exor muscles of the le (ŠL) and the right hand (ŠD), back (MRT) and leg extensor muscles (NOGE) and the ankle joint plantar exor muscles (LIST). e testing included a sample of 14 participants who were competing in the system of individual national championship of the Republic of Serbia for the given age category. On the basis of the obtained results, it can be argued that a general, statistically signi cant, di erence exists between tested judo athletes in the function of gender, both for the absolute values of the variables of basic and speci c explosive isometric muscle force (Wilks’ Lambda Value 0.000, F=898.61, p=0.000), as well as between the partialized (relative) values of the measured variables (Wilks’ Lambda Value 0.001, F=325.71, p=0.000). e highest level of di erence between male and female athletes in relation to the absolute values of the obtained results was determined for the variables of the speci c explosive isometric muscle force of the le hand exor muscles (RFDmax_ŠL, p=0.001), leg extensor muscles (RFDmax_NOGE, p=0.003) and right hand exor muscles (RFDmax_ŠD, p=0.005). In relation to the relative values obtained by partialization of absolute values in relation to skeletal muscle mass (SMM) the highest level of di erence was determined for variables of speci c isometric explosive muscle force for the le and the right hand, respectively (RFDmax_ŠLSMM, p=0.000; RFDmaxŠDSMM, p=0.003). e summarized value of the gender dimorphism index (IPD) is at the level of 71.55 and 53.09% for both absolute basic (RFDFmax) and speci c (RFDmax) explosive isometric muscle force, respectively. is indicates that the tested girls reached 71.55% and 53.09% of the given contractile characteristics compared to the tested boys. However, when the measured variables are partialized relative to the skeletal muscle mass (SMM), the fore mentioned di erences are lowered to 101.98% and 71.58%, respectively. On general level, the obtained results have shown that there are methodological indications of scienti c justi cation in relation to the partialization of the results of explosive isometric muscle force as a measure of development of contractile muscle potential directly responsible for the intensive manifestation of muscle force in the unit of time, in relation to skeletal muscle mass.


INTRODUCTION
Judo is an Olympic martial sport in which the performance is determined by the optimal integration of various components of the athlete's preparation that are jointly manifested in the changing conditions of the competition.It can be described as a high-intensity sport, in which athlete attempts to throw his opponent on the back or control him during groundwork combat (Franchini et al., 2007).According to the applicable Judo rules we can distinguish several age categories where in the system of long-term athletes development, and in the system of the selection of perspective athletes, the cadet and junior age categories are distinguished in their importance, while the signi cance of the senior age category is primarily in the materialization of the maximal competitive performance through the achievement of results in competitions of international signi cance.In each of the age categories, competitors are further divided into clearly de ned weight categories, which is common in martial sports disciplines.Within the overall development of their competitive capacities, in order to be successful at international competitions, judo athletes during their training must achieve an exceptional level of physical preparedness (Franchini et al., 2011) where, from a physiological point of view, anaerobic power and capacity, aerobic power and muscle strength/power are considered the main abilities to be developed in judo competitors ( omas et al., 1989).Consequently, these characteristics were in the primary focus of previous research.
An analysis of judo fighting points to the differences in the manifestation of muscle force and power among judo athletes of different weight categories (Franchini & Sterkowicz, 2000).This specificity further influences tactical setting of the match and the dominance of use of particular techniques, or groups of techniques specific to each of the weight categories.However, the undeniable fact is that the optimal level of development of the dimensions of isometric muscle force largely determines the competition performance, whereby explosive isometric muscle force (RFD -rate of force development) can be singled out as one of the important predictors of competition performance (Monteiro, 2016;Monteiro et al., 2011).Although modalities of muscle force and power have been in focus of a large number of papers (Detanico et al., 2012;Franchini et al., 2011), regardless of the age category, there is a lack of available data considering basic and specific explosive isometric muscle force.Considering the fact that a sports career is a multi-year process aimed at achieving maximum results, within which three main stages with the corresponding sub stages can be distinguished (Koprivica, 2013), and considering the fact that cadet age is consistent with the first stage of the development of a sports career -basic preparation stage, it can be concluded that at this age it is necessary to provide all conditions for the unobstructed and multidimensional development of the psycho-physical potential of the athlete as a precondition for later specialization.Cadet age is also characteristic because of the phenomenon of accelerated biological development which, due to the specificity of the growth of each individual, causes the heterochronism of biological development in general, as well as the heterochronism of the development of different abilities, from both the aspect of the age and the gender aspect.In the modern concept of the technology of development of a top athlete, along with the course of the selection process, the process of testing and evaluation of the obtained results in relation to the standards established for each individual age and competitive level should start and run (Koprivica, 2013;Dopsaj, 2015).It is also necessary to point out the fact that the positive impact of systematic training on the morphological characteristics and motor skills of children involved in judo sport is documented even in younger age categories (Ilić et al., 2012), so in this respect early involvement of children in systematic judo training can be considered justified and even desirable.
In accordance with the previous, this paper presents one of the initial quantitative research aimed at de ning the descriptive characteristics as well as the parameters of the di erences in the explosive isometric muscle force in systematically trained and selected cadet age category judo athletes, both from the aspect of absolute and from the aspect of values partialized in relation to skeletal muscle mass (SMM).Partialization of the results was enabled by the application of a new methodology for measuring the body composition of the participants using the InBody 720 system, which operates on the measurement principle of multichannel multisegmental bioelectric impedance (Dopsaj et al., 2015).
e secondary aim of this research consists in obtaining the initial values of the measured contractile characteristics, which can serve as initial standard values in the function of evaluation and de ning qualitative assessments of a given level of preparedness of tested athletes.
is will signi cantly contribute to the increase of the knowledge base in the system of long-term sport preparation of young judo athletes, i.e. it will improve the existing technology of sports preparation in judo sport.

METHODS
e method used in this research was laboratory testing.All data sampling was performed by dynamometry method, using tensiometric probes.e research sample e research sample in this study consisted of 14 cadet age judo athletes, of which 10 boys and 4 girls.e basic descriptive characteristics of the sample are shown in Table 1.All subjects were members of Judo team "Vinča" and were competing in Republic of Serbia system of national championship for cadet age category.Of the overall sample, two participants were members of Republic of Serbia cadet national team.

Measurement methods
Testing of muscle force characteristics was performed using dynamometry method, by application of isometric tensiometry, by means of tensiometric probes (Isometrics SMS All4Gym, Belgrade).All tests were performed on University of Belgrade Faculty of sport and physical education in Methodological research laboratory (MIL).
All tests were carried out in the morning (between 09:00 and 11.30 AM) by application of standardized testing procedure and standardized test battery described in previously published literature (Dopsaj et al., 2000;Dopsaj et al., 2001;Dopsaj et al., 2004;Dopsaj et al., 2007).
According to the testing procedure requirements, all participants performed 10 minute individual warm-up and stretching.A er that the testing was carried out according to the following procedure: e testing procedure was thoroughly explained to the participants.Each subject had two trial attempts performed in high and sub-maximal intensity for the purpose of familiarization with the testing procedure.A er having at least 5 min pause, the testing was carried out using trial-to-trial method, where the break between testing attempts was 3 minutes (Tanner & Gore, 2013).
Better test result was taken for statistical processing.Pictures 1 to 4 show the measurement procedures for the applied test battery.

Variables
For the purposes of this research contractile characteristics of isometric muscle force were examined from the aspect of intensity of its manifestation.In other words characteristics of explosive muscle force were examined.Explosive muscle force was analyzed in relation to basic (RFDF max ) and speci c (RFD max ) value.All tests were performed on the following muscle groups: exor muscles of the le (ŠL) and the right hand (ŠD), back extensor muscles (MRT), leg extensor muscles (NOGE) and ankle joint plantar exors (LIST), by application of following variables: Following variables were used for the assessment of basic explosive isometric muscle force (basic explosiveness): -RFDF max _ŠL -basic explosive isometric muscle force of exor muscles of the le hand expressed in N/s -1 -RFDF max _ŠD -basic explosive isometric muscle force of exor muscles of the right hand expressed in N/s -1 -RFDF max _MRT -basic explosive isometric muscle force of back extensor muscles expressed in N/s -1 -RFDF max _NOGE -basic explosive isometric muscle force of leg extensor muscles expressed in N/s -1 -RFDF max _LIST -basic explosive isometric muscle force of ankle joint plantar exors expressed in N/s -1 Following variables were used for the assessment of speci c explosive isometric muscle force (speci c explosiveness): -RFD max _ŠL -speci c explosive isometric muscle force of exor muscles of the le hand expressed in N/s -1 -RFD max _ŠD -speci c explosive isometric mus-cle force of exor muscles of the right hand expressed in N/s -1 -RFD max _MRT -speci c explosive isometric muscle force of back extensor muscles expressed in N/s -1 -RFD max _NOGE -speci c explosive isometric muscle force of leg extensor muscles expressed in N/s -1 -RFD max _LIST -speci c explosive isometric muscle force of ankle joint plantar exors expressed in N/s -1 All absolute values of the examined variables were partialized relative to the pure skeletal muscle mass (SMM) in order to obtain relevant data in relation to the used component of the body composition, which is directly responsible for the manifestation of the contractile potential of skeletal muscles.All calculations were performed using the standard calculation formula as follows: VAR_CCrel = VAR_CCmax / SMM, where VAR_CCmax represents the measured value of the isometric explosive muscle force characteristic for the given muscle group, SMM represents skeletal muscle mass expressed in kg, while VAR_ CCrel represents the value of the variable derived.
Both absolute and partialized results of muscle explosiveness, i.e. explosive isometric muscle force, are also shown in the function of gender, that is, they are represented in terms of gender dimorphism, where the gender dimorphism index (IPD) is calculated as a ratio of the given result of the girls relative to the given result of the boys, multiplied by 100 (Dopsaj et al., 2015).

Statistical analysis
For the purposes of this paper, in the rst step of the analysis all raw data obtained by laboratory testing were subjected to descriptive statistical analysis in order to de ne the basic measure of central tendency (MEAN), indicators of data dispersion -standard deviation and coe cient of variation (SD, cV%) and results span indicators -minimum and maximum (MIN, MAX).For the purposes of determining the di erences between the tested variables in the function of gender, the methods of multivariate (MANOVA) and univariate (ANOVA) statistical analyses were used.All analyses were carried out using Microso O ce Excel 2007 and IBM SPSS Statistics v23.0 so ware packages, while the statistical signi cance level was de ned based on the 95.0% probability criterion for p ≤ 0.05.

RESULTS
Table 2 shows the descriptive statistics in relation to the tested variables by gender of the participants Table 3 shows the results of analyses of di erences (MANOVA & ANOVA) between the tested groups in the function of gender.Based on the presented results of MANOVA, it can be argued that there is a statistically signi cant di erence between the absolute values of basic and speci c explosive isometric muscle force variables (Wilks' Lambda Value 0.000, F = 898.61,p = 0.000), as well as between the partialized values of the basic and speci c explosive isometric muscle force (Wilks' Lambda Value 0.001, F = 325.71,p = 0.000), for the tested cadet age judo athletes in the function of gender.
e highest level of di erence between the male and female athletes in relation to the absolute values was determined for the variables of the speci c explosive isometric muscle force of the le hand ex-or muscles (RFD max _ŠL, p = 0.001, Eta 2 = 0.618, i.e. 61.8%), for the leg extensor muscles (RFDmaxNO-GE, p = 0.003, Eta 2 = 0.527, i.e. 52.7%), and for the right hand exor muscles (RFD max ŠD, p = 0.005, Eta 2 = 0.493, i.e., 49.7%).
In relation to the values of the variables partialized based on the pure contractile tissue, i.e. skeletal muscle mass, the highest level of di erence was determined for the variables of the speci c explosive isometric muscle force for the le hand (RFD max _ŠL SMM , p = 0.000, Eta 2 = 0.657, i.e. 65.7%), for the right hand (RFD max _ŠD SMM , p = 0.003, Eta 2 = 0.523, i.e. 52.3%), and for leg extensor muscles (RFD max _NOGE SMM , p = 0.022, Eta 2 = 0.367, i.e. 36.7%), while other variables did not show statistically signi cant di erences.

DISCUSSION
Based on the results of descriptive statistical analysis, it can be concluded that all the measured values of the tested variables are in the acceptable range of variation of results because the coe cient of variation (cV%) for the absolute values is in the range of 1.48% (RFD max _LIST) up to 5.19% (RFDF max _NOGE) for boys, while in girls it the ranges from 5.16% (RFD max _ ŠL) up to 49.18% (RFDF max _ŠL) (Table 1).Since most variables, that is 75.0% of the variables, have extremely low level of variation, i.e. an extremely high level of homogeneity (15 variables have a variation below 10% or below 30%, for both males and females), while the other 25.0% have a coe cient of variation below 60.0%, at the general level it can be concluded that the measured results are homogeneous and representative in terms of valid scienti c interpretation.
In relation to the achieved levels of development of the basic explosive isometric muscle force, i.e.RFDFmax variable, it can be argued that for the boys subsample a maximum average value of 425.70 and 458.51 N/s -1 has been measured for the le and right hand, respectively.For the girls subsample basic explosive isometric muscle force of the le and right hand at the level of 272.69 and 378.34 N/s -1 respectively, has been measured (Table 2).
ANOVA has shown that in the case of these results there was no statistically signi cant di erence between the absolute characteristics of the basic explosive isometric muscle force in relation to gender (Table 3, RFDF max _ŠL -F value = 2.19, p=0.164;RFD-F max _ŠD -F value = 0.61, p=0.452).
If the obtained average value is analyzed in the context of gender dimorphism, it can be argued that the ratio of girls and boys results of the measured variable for the le and right hand is at the level of 64.05 and 82.52%, respectively (Chart 1), i.e. the value of the gender dimorphism index (IPD) is at an average level of 73.63%.In other words, the general level of muscle explosiveness of the hand exor muscles in girls is at about 3/4 of the score achieved by boys.
For the back extensor muscles (Dead li test), as one of the very important muscle groups from the aspect of judo sport, average RFDF max value of 935.49N/s -1 in boys subsample and 585.78 N/s -1 in girls subsample was measured (Table 2).e results of ANO-VA have shown that there is a statistically signi cant di erence between the aforementioned absolute characteristics of explosiveness in relation to gender (Table 3, RFDF max _MRT -F value = 4.95, p=0.046).
e girls achieved a lower level of basic explosiveness by as much as 349.71N/s -1 , with the achieved IPD level of 62.62% (Graph 1).In other words, the basic level of muscle explosiveness of the back extensor muscles in girls is at about 2/3 of the results achieved by boys.
e average value of the basic explosive isometric muscle force of the leg extensor muscles was at the level of 1059.57N/s -1 in boys and 724.21N/s -1 in girls (Table 2).e results of ANOVA have shown that there was no statistically signi cant di erence between the measured explosiveness in relation to gender (Table 3, RFDF max _NOGE -F value = 1.41, p = 0.258).As with the back extensor muscles, for the leg extensor muscles it was found that girls achieved a lower score for as much as 335.36 N/s -1 , with IPD level of 68.35% (Chart 1).For this muscle group, the basic explosiveness of the leg extensor muscles in girls was at the level of about 2/3 in relation to the boys.
For the ankle joint plantar exor muscles the mean value of basic explosive isometric muscle force at the level of 2839.53N/s -1 in boys and 2277.07N/s -1 in girls was measured (Table 2).e results of ANOVA have shown that there was no statistically signi cant di erence between the above mentioned absolute characteristics of explosiveness in relation to gender (Table 3, RFDF max _LIST -F value = 1.41, p = 0.257).For the ankle joint plantar exor muscles it was found that girls achieved a lower score for 562.46 N/s -1 , with the achieved IPD level of 80.19% (Chart 1).In case of this muscle group, the result achieved by girls is at the level of about 4/5 in relation to the results found in boys.
In relation to the achieved levels of development of the basic explosive isometric muscle force, but from the aspect of values partialized in relation to the skeletal muscle mass, for the handgrip test the results at the level of 11.60 and 12.73 N/s -1kgSMM for the boys subsample, and 10.65 and 13.2 N/s -1kgSMM for the girls subsample were measured, for le and right hand, respectively (Table 2).e results of ANOVA have shown that there is no statistically signi cant di erence between the mentioned relative characteristics of explosiveness in relation to gender (Table 3, RFDF-max_ŠLSMM -F value = 0.10, p = 0.750; RFDFmax_ ŠDSMM -F value = 0.03, p = 0.858).It was found that female subjects for the le hand achieved 0.95 N/s -1kgSMM lower partialized value of basic explosive isometric muscle force compared to boys, reaching the IPD level of 91.81%, while the partialized values achieved for the right hand grip were 0.49 N/s -1kgSMM higher than those found in boys, with an IPD level of 103.69% (Chart 2).ese results indicate that a er partialization in relation to the pure skeletal muscle mass, i.e.SMM, the gender di erence in relation to the basic explosive isometric muscle force of the exor muscles of the le and right hand is lost, that is, they are in the IPD summarized interval of 97.75%.
For the back extensor muscles (Dead li test) the measured mean value of RFDF max _MRT SMM in boys was at the level of 25.93 N/s -1kgSMM while in girls it was at the level of 22.31 N/s -1kgSMM .When it comes to leg extensor muscles (Leg extension test), the measured relative value of the basic explosive isometric muscle force was at the level of 28.68 N/s -1kgSMM in boys and 27.05 N/s -1kgSMM in girls (Table 2).e results of ANOVA have shown that in both tests there was no statistically signi cant di erence between the aforementioned relative characteristics of explosiveness in relation to gender (Table 3, RFDF max _MRT SMM -F value = 0.59, p=0.457;RFDF max _NOGE SMM -F value = 0.6, p=0.806).In this test, the tested girls achieved 3.62 N/s -1kgSMM lower relative values of the basic explosive isometric muscle force, with the IPD reaching a level of 86.04 %, that is, the tested boys in the given test achieved 1.63 N/s -1kgSMM better result compared to girls, with the IPD of 94.32%, respectively (Chart 2).In this respect, it can be said that for the back extensor muscles, from the aspect of relative values, boys achieved about 1/6 better results than girls, while partialized results for the leg extensor muscles were very similar.
e results of partialized values of the basic explosive isometric muscle force for the ankle joint plantar exor muscles (Sitting plantar exion test) showed that this characteristic is at the level of 61.85 N/s -1kg- SMM for the boys subsample and 82.80 N/s -1kgSMM for the girls subsample (Table 2).e results of ANOVA have shown that there is no statistically signi cant di erence between the aforementioned relative characteristics of explosiveness in relation to gender (Table 3, RFDF max _LIST SMM -F value = 0.259, p=0.620).Nevertheless, on this test girls achieved, on average 20.95 N/s -1kgSMM higher results, with the IPD at the level of 133.82%.In other words, when observed from the aspect of partialized values relative to the skeletal muscle mass (SMM), girls achieved about 1/3 better results than boys on the sitting plantar exion test.
e achieved level of development of speci c explosive isometric muscle force, i.e. variables (RFD max ), for the exor muscles of the hand (Handgrip test) was at the average level of 2253.89 and 2369.22N/s -1 in boys and 990.67 and 1177.33N/s -1 in girls, for the le and right hand, respectively (Table 2).In relation to the partialized values the achieved results were at the level of 61.85 and 64.80 N/s -1 in boys and 36.90 and 43.36 N/s -1 in girls, for the le and right hand, respectively (Table 2).e results of ANOVA have shown that a statistically signi cant di erence exists between the aforementioned characteristics of explosiveness in relation to gender for the absolute as well as for the partialized values of the obtained results (Тable 3, RFD max _ŠL -F value = 19.44,p=0.001;RFD max _ŠD -F value = 11.68,p=0.005;RFD max _ŠL SMM -F value = 22.949, p=0.000;RFD max _ŠD SMM -F value = 13.17,p=0.003).Based on the presented results, it was found that the boys achieved 1263.22N/s -1 better results for the le hand, i.e. 1191.89N/s -1 for the right hand, and that the IPD value was 43.95% and 49.69%, respectively.In this respect, it can be said that the results achieved by boys are more than twice higher than the results achieved by girls.
For the back extensor muscles (Dead li test) speci c explosive isometric muscle force mean value at the level of 6231.00N/s -1 and 3322.33N/s -1 was measured for the boys and girls subsample, respectively (Table 2).e results of ANOVA have shown that there was no statistically signi cant di erence between the absolute characteristics of explosiveness in relation to gender (Table 3, RFD max _MRT -F value = 3.48, p=0.087), that is, the di erence is at the boundary level for the 90.0%probability.e absolute mathematical di erence of the measured results of the given variable of 2908.67 N/s -1 in favor of the boys, and the IPD value of 53.31% indicates that in the case of this muscle group, boys achieved approximately double the results compared to girls.
For the leg extensor muscles (Leg extension test) the measured mean value of speci c explosive isometric muscle force is at the level of 4919.67 N/s -1 and 2298.00N/s -1 for boys and girls, respectively (Table 2).e results of ANOVA have shown that there is a statistically signi cant di erence between the aforementioned absolute characteristics of explosiveness in relation to gender (Тable 3, RFD max _NOGE -F value = 13.38,p=0.003).From the aspect of absolute indicators, the boys on average achieved 2621.67N/s - 1 better results, with the IPD at the level of 46.71%.In other words, in this case, the di erence achieved indicates about twice the better results in boys.
For the ankle joint plantar exor muscles (Sitting plantar exion test) the measured mean value of speci c explosive isometric muscle force was at the level of 12314.40N/s -1 in boys and 8840.33N/s -1 in girls (Table 2).e results of ANOVA have shown that there is a statistically signi cant di erence between these results (Тable 3, RFD max _LIST -F value = 8.183, p=0.014).Girls achieved a lower level of absolute value of speci c explosive isometric muscle force for 3474.07N/s -1 , with the achieved IPD level of 71.78% (Graph 1).In other words, the achieved RFD max values for the girls subsample were 2/3 of the values achieved by boys.
For the back extensor muscles (Dead li test) the mean partialized value of speci c explosiveness at the level of 167.75 N/s -1kgSMM was measured in boys, while for the girls measured mean value was at the level of 124.91 N/s -1kgSMM (Table 2).
e results of ANOVA have shown that there was no statistically signi cant di erence in relation to gender (Табела 3, RFD max _ MRT SMM -F value = 1.765, p=0.209), although girls of a given age achieved a lower level of speci c explosiveness for 42.84 N/s -1kgSMM , with the achieved IPD level of 74.45% (Chart 2).e speci c level of explosiveness of the back extensor muscles partialized in relation to the skeletal muscle mass (SMM) found in girls was at about 3/4 of the results measured in boys.
For the leg extensor muscles (Leg extension test) partialized value of speci c explosiveness in boys was at the level of 136.42 N/s -1kgSMM , while for the girls it was at the level of 136.42 N/s -1kgSMM (Table 2).A statistically signi cant di erence was found between these results (Таble 3, RFD max _NOGE SMM -F value = 6.95, p=0.022).As in the case of back extensor muscles, for the leg extensor muscles girls achieved lower relative value of a given variable for 50.08 N/s -1kgSMM with the achieved IPD value of 63.29% (Chart 2).In the case of this muscle group, the relative value of speci c explosiveness in girls was approximately 2/3 relative to the results measured in boys.
e average value of the speci c explosive isometric muscle force of the ankle joint plantar exor muscles (Sitting plantar exion test) was 341.04 N/s -1kgSMM in boys, and 319.09N/s -1kgSMM in girls (Table 2).ere was no statistically signi cant di erence between these relative explosiveness characteristics in relation to gender (Table 3, RFD max _LIST SMM -F value = 0.815, p=0.384).e girls achieved a 21.95 N/s -1kgSMM lower value, with the achieved IPD level of 93.56% (Graph 2).However, in the case of this muscle group, the average value of the relative level of speci c explosiveness of the ankle joint plantar exor muscles in girls was very similar to the values found in boys.
On the basis of all of the fore mentioned, it can be concluded that, in all tested muscle groups, boys have signi cantly higher absolute values of basic explosive isometric muscle force than girls.e results of this study have shown that IPD values range from 62.62% for the back extensor muscles up to 82.52% for the nger exor muscles of the right (dominant) hand.On a general level girls on average achieved 71.55% of basic explosiveness in realtion to boys (Graph 1).
ese results are very similar to the results of previously published research that dealt with inter gender power di erences of di erent muscle groups (Chen et al., 2012), where it has been found that girls at the general level account for 37-68% of the muscle power achieved by men, with lower results achieved for all of the tested muscle groups.In the context of the results obtained by this study, it is important to point out the fact that smaller inter gender di erences in exerted power have been found in the extensor muscle groups of the lower extremities, where girls achieve results at the level of 65% of the value of the results achieved by men (Chen et al., 2012) which, although concerning di erent properties, somewhat correlates with the ndings of our study.However, when the results are considered from the aspect of values partialized relative to the skeletal muscle mass (SMM), the observed di erences between the tested boys and girls are drastically reduced, indicating a relatively equal contractile potential in the function of pure muscle mass, regardless of the gender of the participants.In this respect, the absolute values total IPD of 71.55% (IPD RFDF max _ ALL), and relative IPD value of 101.98% (IPD RFDFmax _ALL SMM ) can be indicative (Graph 2). is can be explained by the higher percentage of muscle mass in the body composition of boys (PSMM% = 54.66±1.42)compared to girls (PSMM% = 49.99±3.81),and by the fact that girls have lower total body mass, and hence, lower absolute muscle mass.Also, these results correlate with the previously determined fact that men and women have relatively small di erences in RFD in conditions of maximal voluntary contraction (Kent-Braun & Alexander, 1999), i.e. explosive isometric muscle force exerted without involving the external muscle electro stimulation in terms of increasing the level of achieved activation.
It is necessary to considering that even with relative indicators of the basic explosive isometric muscle force of the ankle joint extensor muscles (plantar exors), it has been established that the IPD is at the level of 133.82%, indicating that the tested girls on average achieved 1/3 better results than boys in the given test.Also, one of the possible explanations for the determined di erences in the parameters of basic and speci c explosive isometric muscle force, regardless of the muscle group observed, relates to the previ-ously established di erences in the percentage of di erent type muscle bers and the di erences in the overlapping area of myo laments in muscle bers in favor of men (Staron et al., 2000; Kent-Braun & Alexander, 1999), which could have caused an absolute higher potential for expressing explosiveness in boys.Second potential cause of the inter gender di erences can be the established di erence in the distribution of contractile tissue between the upper and lower part of the body.A higher percentage share of contractile tissue in the lower part of the body in women (Janssen et al., 2000) was determined, but also a higher percentage of muscle mass in the male body composition and an absolute higher skeletal muscle mass in boys.
Possible reason for the determined values of the speci c explosive isometric muscle force of the ngers exor muscles of the le and right hand, both from the aspect of absolute and relative values, in addition to the greater distribution of muscle mass in the cranial part of the body in men (Janssen et al., 2000 ), most likely indicate the presence of a speci c adaptation as a consequence of judo training, given the fact that the absolute values of RFD max at the level of 4623.1 N/s -1 for both le and right hand have been found.e average absolute values of speci c explosive isometric muscle force at the level of 5197.6 N/s -1 and 4040.4N/s -1 for both hands have been determined by previous study which examined adult trained wrestlers and moderately active subjects (Marković et al., 2016).Based on the comparison of the previous results with the results of this research, it can be argued that cadet judo athletes on the handgrip test achieve results at the level of 88.94% compared to adult wrestlers and 114.42% compared to adult moderately active participants.is can be interpreted as the direct in uence of judo training.

CONCLUSION
e aim of this paper is to de ne descriptive characteristics as well as the parameters of the di erence in explosive isometric muscle force in systemically trained and selected cadet age judo athletes, both from the aspect of the absolute values and from the aspect of the values partialized relative to the skeletal muscle mass (SMM).e basic method used in this research was the laboratory testing method using tensiometric probes.e research sample in this study consisted of 14 cadet age judo athletes, of which 10 boys and 4 girls.Explosive isometric muscle force was analyzed in relation to its basic (RFDF max ) and speci c (RFD max ) dimension, while the following ve muscle groups were tested: exor muscles of the le (ŠL) and the right hand (ŠD), back (MRT) and leg extensor muscles (NOGE) and the ankle joint plantar exor muscles (LIST).
On the basis of the obtained results, it can be argued that a general, statistically signi cant, di erence exists in the tested cadet age judo athletes in the function of gender, both considering the absolute values of the variables of general and speci c explosive isometric muscle force (Wilks' Lambda Value 0.000, F = 898.61,p = 0.000), as well as between the partialized (relative) values of basic and speci c explosive isometric muscle force (Wilks' Lambda Value 0.001, F = 325.71,p = 0.000).
e total value of the gender dimorphism index (IPD) for absolute basic (RFDF max ) and speci c (RFDmax ) explosive isometric muscle force was at the level of 71.55 and 53.09%, respectively, which means that the tested girls reached 71.55% and 53.09% of the given contractile characteristic relative to the tested boys.However, when the measured variables are partialized relative to the SMM, the di erences in the function of the gender are reduced to 101.98 and 71.58%.
ese results have shown that there are methodological indications of scienti c justi cation in relation to the partialization of the results of explosive isometric muscle force, as a measure of development of the contractile muscle potential responsible for the most intensive expression of muscle force in the unit of time, in relation to skeletal muscle mass i.e. the mass of pure contractile tissue in the organism.In this way, the level of sensitivity of the variable itself is increased in terms of determining the real functional di erences between the genders.e assumption is that this method of partialization of the results could be more sensitive in relation to determining the di erences in contractile abilities and in relation to other criteria such as age, competitive e ciency, training period, etc.
Generally speaking, the results of this research present the initial quantitative values of the measured contractile characteristics, which can serve as initial standards in the function of evaluation and in function of de ning qualitative assessments for assessing the level of tness of athletes, which will increase the knowledge base in the system of preparation of young judo athletes, i.e. it will contribute the improvement of the existing technology of sports preparation in judo sport.

Limitations
is study was conducted on a relatively small sample of participants consisting of 10 male and 4 female judo athletes who were all members of the cadet selection of the same judo team. is somewhat diminishes the possibility of generalization of the ndings and points to the need for further systematic investigation of the characteristics of explosive isometric muscle force, and muscle force in general, with the inclusion of a larger number of subjects in the sample.

e
results of the obtained gender dimorphism index (IPD) values in relation to the absolute and partialized (relative) values of the measured explosiveness (basic and speci c) for the applied tests are shown in Chart 1 and Chart 2. Based on the obtained absolute values, it can be argued that a greater di erence in speci c explosiveness between males and females (IPD RFD max _ALL = 53.09%)was determined, compared to the level of basic explosiveness (IPD RFDF max _ALL = 71.55%).

Graph 1 .Graph 2 .
IPD in relation to the absolute values of the explosive isometric muscle force (explosiveness) IPD in relation to the partialized (relative) values of the explosive isometric muscle force (explosiveness) As in the case of absolute IPD values (Graph 1), based on the obtained results of the partialized (relative) values of the explosive isometric muscle force (explosiveness) (Graph 2), it can be argued that a greater di erence in speci c explosiveness between males and females was determined (IPD RFD max _ ALL SMM = 71.58%)comparing to the basic explosiveness di erences (IPD RFDF max _ALL SMM = 101.98%).

Table 1 .
Basic descriptive characteristics of examined subsamples in relation to gender

Table 2 .
Basic descriptive indicators of the tested sample in relation to gender

Table 3 .
Results of MANOVA and ANOVA for the tested variables in relation to gender