22 KINESIOLOGIA SLOVE NICA 1995; 2 (1 ): 22-25 CHANGES IN LATENT MORPHOLOGIC STRUCTURE OF CHILDREN BETWEEN 7 AND 14 YEARS OF AGE Joie Šturna* Janko Strel* Franci Alnbroiič* SPREMEMBE V LATENTNI MORFOLOŠKI STRUKTURI OTROK MED 7. in 14. LETOM STAROSTI ABSTRACT Ona 1% sample of girls and boys of 7-14 years of age (in all 3163), representative for the Republic of Slovenia, changes in relations between morpholo- gic dimensions- measured with 15 anthropometric measures- and their latent structu re were analysed. Differences in latent structure were obtained through comparison of factor analyses, computed for ali the age groups and both sexes. This comparison shows a great instability of mor- phologic structure. The biggest changes occur be- cause of the distribution of circumference of ex- tremities and trunk on different dimensions, partly on skeleta! dimensionality and partly on subcuta- neous fat- with girls in the tenth and eleventh year and with boys from the twelfth to the fourteenth year. Fram the analysis of changes in the structure of the inter-correlation matrices, it is possible to con- dude that individual phases of changes of morpho- logic structure occur at a higher rate with boys, thus ensuring a more harmonious development, while with girls we find greater structural changes, special- ly between the seventh and eighth year and between the eleventh and twelfth year. Key words: morphology, structure, change, children, 7 to 14 years, males, fema/es *Faculty of Sport, University of Ljubljana, Slovenia IZVLEČEK Na, za RS reprezentativnem, 1 % vzorcu deklic in dečkov starosti od 7 do 14 let (skupno 3163 enot), so bile ugotavlja ne spremembe, ki nastopajo v tem ob- dobju v medsebojni povezanosti morfoloških značil­ nosti, izmerjenih s 15 antropometričnimi merami, in njihovi latentni strukturi. Spremembe v latentni strukturi so bile ugotavljane s primerjanjem rezulta- tov faktorskih analiz, izvedenih za skupine mer- jencev, dobljenih po spolu in starosti . Ta primerjava dokazuje veliko nestabilnost morfo- loške strukture. Največje strukturne spremembe nastajajo zaradi porazdeljevanja projekcij mer ob- segov ekstremitet in trupa na različne latentne dimenzije, deloma na dimenzionalnost okostja in deloma na podkožno maščevje - pri deklicah v de- setem in enajstem letu in pri dečkih od dvanajstega do štirinajstega leta. Iz analize sprememb v strukturi matrik interkorelacij je mogoče sklepati, da se posamezne faze v spremembah antropometričnih mer hitreje menjajo pri dečkih in tako zagotavljajo bolj skladen razvoj, medtem ko pri deklicah prihaja do večjih strukturnih sprememb, zlasti med 7. in 8 ., ter 11. in 12. letom. Ključne besede: morfologija, struktura, sprememba, šola, učenci, učenke Jože Šturm, Janko Strel. Franci Ambrožič CHANGES IN LATENT MORPHOLOGIC STRUCTURE OF C HI LOREN BETWEEN 7 ANO 14 YEARS OF AGE 23 INTRODUCTION There cannot be any doubt that great changes have occurred in life and work, both abroad, as well as in the R of Slovenia. It is therefore logical to expect a concurrent adaptation of the development of man in accord with these changes (see: Hmjelovec, Krstonijevic: 91; Kalošova, Riegerova: 88; Mo- mirovic, M rakovic, Hašek, Meti koš: 87). This is spe- cially true for the development of school youth (Bell: 93; Jensen: 88; Kurelic et al.: 75; Šturm, Strel: 83, 84, 85). On the basis of a comparative study of the years 1970 and 1983, drasticchanges werefo,und in the morphologic development of youth (Sturm, Strel, Ambrožič: 88). Acceleration of body height in some age groups ex- ceeds 3.8 cm, still greater changes are presentwhen separately viewing individual regions of differentso- cio-demographic characteristics, in rural areas we find even higher values. From the analyses it can be seen that the number of extremely short children has decreased by a factor of fou r and by the same factor we have an increase of extremely tali children. Changes in other parameters are also great and va- ried. The above-mentioned changes in the morphological development mean also changed relations in the psychosomatic development of youth and conse- quently a different relation towards movement ex- pression of youth (see also: Bischoff, Lewis: 87). Successfulness of youth in individual sports, special- ly in top competition sport, is also depend~nt on morphological development (Skrivasta: 90; Stihec, Kovač: 88, 90). Positive and also negative influences of individual anthropometric dimensions on move- ment efficacy are evident, therefore such informa- tion on the changes of morphologic development is a mustfor q uality direction of youth into sport. Such knowledge is also needed in programm i ng the trans- formation processes with which we develop move- ment abilities and facilitate the formation of motor programs. Beside changes in central and dispersion parameters of anthropologic variables (Šturm: 79; Šturm, Strel: 83, 84, 85), structural changes are equally important (Popovic, Drankovic, Bubanj, Stankovic, Popovic: 91; Szirovica, Momirovic, Hošek, Gredelj: 80). With this in mind we have attempted to find the factor structure of morphology of children between 7 and 14 years of age, as well as the changes in structure between these age levels. METHODS The subjects here presented represent a 1 % strati- fied sample of the whole populat ion of children between 7 and 14 years of age in Slovenia. In the year 1983, 3163 children were measured and di- vided into 16 sub-samples according to age and sex. The variable sample consists of 15 measures, best representing the following four latent dimensions: longitudinal skeleta! dimensionality, voluminosity, transversal skeleta! dimensionality and subcuta- neous fat. The measures used were: body height, length of leg, length of arm, body weight, circumfe- rence of lower arm, circumference of thigh, circum- ference of chest, breadth of pelvis, diameter of wrist, diameter of knee, diameter of ankle, upper arm skin fold, stomach skin fold, back skin fold and thigh skin fold. AII were measured according to international standards. The data was processed at the Institute for Kinesiology, Faculty of Sport, on the computer DEC 1091 of the University of Ljubljana computing cen- tre. The computer processing was done in two pha- ses. In the first phase the SPSS statistical package was used to compute the basic statist ical parameters and find the factor structures. The Hotelling principal component method was used, the Kaiser-Guttman criterion to establish the number of salient factors and the oblimin rotation to obtain the final oblique solution. In the second phase the TAMARI$ program in the GENSTAT statistical package was used to compare the correlations between individual variables in the two age groups. These comparisons were made for all the pairs of adjacent ages (7-8, 8-9 etc.). The changes in structure were analysed by the congru- ence of latent vectors, Schoenneman method, Flury congruence of factors, simple difference in correla- tion coefficients and standardised operator norm of difference matrix, which was used to assess the leve! of change in structure. AII the processing was done separately for both sex- es and all age groups (7 to 14 years). RESULTS AND DISCUSSION One of the possible strategies in finding changes in the morphologic structure in the process of growth and development between 7 and 14 years of age is the condensation of information emitted by the manifest anthropometric measures to latent dimen- sions with factor analysis (see also: Bosnar, Hošek, Prot: 87). 24 Jože Šturm, Janko Strel, Franci Ambrožič CHANGES IN 1.ATENT MORPHOLOGIC STRUCTURE OF CHILDREN BETWEEN 7 ANO 14 YEARS OF AGE Table 1: Factor structures by age - MALES N %KG %1 PC Measures, that define the factor 7) 185 66,8 43,2 1 = transversal + velurne (trunk) 2 = body fat + vol urne (thigh) 3 = longitudinal 8) 190 69,4 44, 1 1 = body fat + rnass + vol urne 2 = longitudinal 3 = transversal 9) 208 68,6 53,6 1 = body fat + rnass + vol urne 2= longitudinal + transversal 10) 185 75,2 51,4 1 = body fat + rnass + vol urne 2 = longitudinal 3 = transversal 11 ) 185 67, 1 52,0 1 = bodyfat + mass + velurne 2 = longitudinal + transversal 12) 190 65,0 49,4 1 = longitudinal + transv. + rnass + vol. 2 = body fat + vol urne + rnass 13) 209 64,0 46, 1 1 = longitudinal + transv. + rnass + vol. 2= bodyfat + rnass + velurne 14) 210 66,3 43,5 1 = longitudinal + transv. + rnass + vol. 2 = body fat + vol urne Legend: N nurnber of measured children percent of cornmon variance of the systern %KG % 1 PC % of explained variance by the 1 st cornponent Table 2: Factor structures by age- FEMALES N %KG %1PC Measures, that define the factor 7) 215 63,5 47,6 1 = bodyfat + rnass + velurne 2 = longitudinal + transversal 8) 207 73,9 51,2 1 = body fat + rnass + vol urne 2 = longitudinal 3 = transversal 9) 187 65.4 50,4 1 = body fat + rnass + vol urne 2 = longitudinal + transversal 10) 200 67,0 52,2 1 = longitudinal + transv. + rnass + vol. 2= bodyfat + rnass + velurne 11) 191 71,5 51 ,3 1 = body fat + rnass + vol urne 2 = transversal + vol urne 12) 190 70,6 44,1 3 = longitudinal 1 = body fat + rnass + volu me 2 = longitudinal 3 = transversal 13) 180 60,4 45,2 1 = body fat + rnass + vol urne 14) 194 65,3 38,9 2 = longitudinal + transversal 1 = body fat + rnass + vol urne 2 = longitud inal 3= transversal A comparison of the factor solutions in the individu- al age groups (tables 1 and 2) shows a great instability of the morphologic structure. Both the number and the nature of the latent dimensions of the morpho- logic characteristics asa rule d iffer in the consecu- tive age groups. On the basis of parallel and orthogonal projections of the manifest anthropometric measures on the in- dividual isolated latent dimensions, it is possible to state that four basic categories exist, which have been extracted also in previous studies o n different samples. These are: longitudinal skeleta! dimen- sionali ty, voluminosity, transversal skeleta! dimen- sionality and subcutaneous fat. In our case these categories coexist in different combinatio ns and therefore produce different latent dimensions. Both skeleta! dimensions are usual ly independent and separate-8 and 1 O year old boys, 8, 12 and 14 year old girls -or in unison - 9, 11 and 12 year old boys; 7, 9, 10 and 13 year old girls. Volu me, body mass and subcutaneous fat usually ap- pear together, with fatdominant - boys from age 8 to 11 and girls ali ages, except 1 O and 11. The greatest changes occur because of the oscilla- tion of the measures of voluminosity between different latent dimensions, on one side skeleta! dimensionality and on the other subcutaneous fat- boys from 12 to 14 and girls aged 1 O and 11 . Ali this causes that the factor structure at the different age groups and both sexes can be "cleaner" (the four categories se parate), or less clean (categories m ixed on factors). This is due to the variations of the corre- lations between individual variables. lf correlations between variables of the same category are signifi- cantly greater than correlations between variables of differentcategories, then we obtain a "clean" factor solution. A less clean solution is obtained if the cor- relations between variables of different categories are on par with those of the same category. Examples of less clean structure are specially evident with boys at the 7th and 14th year and with girls at the 10th and 11 th year. A second possible strategy that enables us to gather information on the changes in morphologic struc- ture is that which is based on the comparison of the correlation matrices of ali the variables. This infor- mation was given by the Tamaris program. One of the generated parameters of this program are the standardised operator norms of the correlation dif- ference matrix (table 3). Table 3: Standardised operator norms of difference matrix Age Male Fernale 7- 8 0.0421 0.0524 8- 9 0.0690 0.0199 9-10 0.0245 0.0297 10-11 0 .0312 0.0174 11 -12 0.0269 0.0426 12-13 0.0307 0.0276 13-14 0.0347 0.0289 Sum: 0.2591 0.2185 An inspection of table 3 leads us to believe that the greatest changes in morphologic structu re occur at the age of 7 and 8, that is, at the start of primary schooling. A similar situation - if somewhat less prominent - isto be found at the end of primary schooling (age 14). It seems to be possible to formulate the hypothesis that changes in morphologic structure are greater Jože Šturm, Janko Strel, Franci Ambrožič CHANGES IN LATENT MORPHOLOGIC STRUCTURE OF CHILDREN BETWEEN 7 ANO 14 YEARS OF AGE 25 with boys, are continually present and as a rule significant. W ith girls we find quite different changes of mor- phologic structure. Only at the 7-8 and 11 - 12 age levels do we find significant changes, otherwise we can see a quite stable evolution, specially between 8 and 9 and 1 O and 11 years of age. Ali the above-said enables us to formulate a hypoth- b is that individual phases of change of anthropo- metric measures pass quicker with boys and so en- able a more stable development, while with girls, be- cause of a somewhatslower pace of change, we find greater differences in morphologic structures, spe- cially between 7-8 and 11 - 12 years of age. From this we can conclude that changes with boys are more frequent than with girls. 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