'n Kinantropometriese en asimmetriese profiel van internasionale manlike elite-spiesgooiers

Abstract

The importance of studies on a complete anthropometric profile is stressed due to the lack of literature and due to the fact that athletes' morphological composition is one of the factors that contribute to performance. The purpose of this study was firstly to describe the body composition and somatotypes of international male elite javelin throwers and to identify which variables distinguish the world's elite javelin throwers (n=6) (Group A) from the sub elite throwers (n=13) (Group B) and which variables contribute to their performance. The anthropometrical variables are primarily as described in Norton et al. (1996). Elite javelin throwers were found to have an average body mass of 97.0 kg, stature of 187.5 cm, percentage body fat of 11.9% and percentage muscle mass of 40.4%. The javelin throwers had an average value of 11.2 kg for skeletal mass and expressed as a percentage, an average of 11.7%. The average acromial-radial length (humerus) was 35.5 cm with the radial-stilion length (forearm) 28.7 cm. The javelin throwers had an average bi-iliocristale breadth of 31.9 cm, bi-acromiae breadth of 45.5 cm, A-P chest depth of 21.9 cm and a chest breadth of 33.8 cm. The average wrist breadth was 6.0 cm, ankle breadth 8.1 cm, femur breadth 10.2 and humerus breadth 7.4 cm. The javelin throwers had an average flexed arm girth of 38.3 cm, forearm girth of 30.5 cm, thigh girth of 64.1 cm and calf girth of 40.8 cm. The average somatotypes for the javelin throwers were 2.5-5.9-1.4. Seven variables that best discriminate between the javelin throwers in Group A and the javelin throwers in Group B were determined by using discriminant analysis. The variables were age, body mass, mesomorph, muscle mass, A-P chest depth, chest breadth and arm-span. The forward step-wise discriminant analysis found the variables that best discriminate between the two groups to be age (F=10.53, P<0.05), body mass (F=3.97) and percentage muscle mass (F=2.33). After the classification matrix was completed, 100% of the javelin throwers in Group A were classified back into their different groups and 92% of the remaining throwers in Group B were classified back to their group. One of the javelin throwers not originally in Group A, was classified back into the A group. The prevalence of morphological asymmetry amongst sports participants have been well documented. The importance of studies on this topic is stressed due to the indication of its negative effect on health and performance. The second aim of this study was to determine the degree of upper-body asymmetry in elite male international javelin throwers. Twelve (12) anthropometrical variables (3 skin/olds, 5 circumferences, 3 segment lengths and I diameter) were measured according to the methods described in Norton et al. (1996). The percentage of morphological asymmetry was determined by making use of Wolanski's Relative Indices of Assymetry (RIA). Statistically significant differences were found between the dominant and non-dominant sides of the relaxed arm circumference, forearm circumference, half-chest circumference (p<O.05), acromial-radial length and midstilion-dactilion length (p<0.001). The greatest degree of asymmetrical development occurred at the tricep skinfold (5.9%), half-chest circumference (4.9%), forearm circumference (3.9%), subscapular skinfold (-2.9%), biceps skinfold (2.5%), sum of the 3 skinfolds (2.2%) and the relaxed arm circumference (1.8%). Therefore the conclusion is that significant levels of morphological asymmetry occur in the upper body of javelin throwers and that some of their dominant values, compared to their non-dominant values, are significantly greater.