COMPARISON OF BIOMECHANICAL ASPECTS OF PERFORMANCE IN ELITE MALE AND FEMALE TRACK ATHLETES
AbstractIt is generally thought that the technique of skilled male and female athletes is identical; that elite females will perform a skill almost exactly the sane as elite males. A common belief is that skilled athletes have uniform technique, and over time top athletes will develop similar technique, regardless of their sex. Females do have some unique structural factors such as: wider pelvis, shorter legs, more oblique femurs, larger ratio of leg weight to body weight, greater fat deposition on the thigh, and greater carrying angle of the arm (Wells, 1991) which may affect technique. If there are differences in technique based on sex-related structural factors, then these technique differences need to be emphasized by coaches and teachers of sport skills. The vast majority of published research describing skilled athletic performance has been based only on the techniques of male athletes. Very few studies have described only the techniques of skilled female throwers (Terauds, 1984) but several studies described skilled male and female throwers, including shot, discus and javelin throwers (Bartlett, 1992; Bartlett & Best, 1988; McCoy, Gregor, Whiting, Rich & Ward, 1984, McCoy, Gregor, Whiting, Rich & Ward, 1985; Rich, Whiting, McCoy, Gregor & Ward, 1985). Those studies which have exmined female throwers sometimes suggest that temporal and anthropometric variables related to performance in females are different from those related to male performances (Ballreich, 1983; Schulter, 1983). The extent and implications of these possible differences in performance have not yet been fully examined, nor even acknowledged by most researchers in sport biomechanics. An extensive search of the sport biomechanics literaturn revealed no specific discussion of male-female differences in biomechanical variables of sports The field event of shot putting is a controversial event in modem track and field, as many male world class throwers have been banned from competition for steroid use at some point in their careers (Noden, 1993). The three medalists at the 1992 Barcelona Olympic Games had all been previously suspended for drugs and had served a suspension, and a recent article suggested that all throws over 21.3 m (70 feet) were likely produced by athletes on steroids (Noden, 1993). In an extensive review of available literature, only a few studies (McCoy et al., 1984; Terauds, 1984) were located which described the techniques of elite female shot putters, or attempted to compare these techniques to those of male throwers. In the shot event, the shot thrown by male athletes is 16 lb (7.26 kg), while that thrown by females is 8 lb 9 oz (3.88 kg). Since there are differences in the dimensions and weight of the equipment used, it may not be possible to make comparisons of performance in the throwing disciplines between males and females (Kenntner, 1983). In shot putting, women now achieve similar distances to men, with implements which are only 53% as heavy. The progression in Olympic performances in the shot put between male and female athletes is illustrated in Figure 1, which shows that females have only recently attained sh$lar distances to those achieved by male throwers. Where there is the same speed of projection of the point of release, the thrusting force must be 30-49% lower due to the lighter shot (Ke~tner1,9 83). In a study of elite male and female shot putters McCoy et al., 1984 reported that the males had significantly greater distance thrown, kight of release and velocity of release, but these differences were not related to the differences in stature between male and female throwers. They noted that release height is determined by the vertical position of the body in space, and the angle of the arm at release. The major objective of the present research was to determine the relative importance of certain measured mthropometric, strength, and technique variables to throwing performance in elite male and female track athletes. Previous research (Alexander, 1989) has suggested that there may be differences in the types of variables that affect performance of female athletes, as compared to those of males in skilled sprinting. For example, the =lationship between the strength values at a joint, as measured by joint torques, and the resultant angular velocities produced at that joint during a skilled performance, are different for male and female athletes. As well, while many elite male throwers are very tall with long limb segments, elite female throwers are often relatively short with correspondingly shorter limb segments (Korni & Mero, 1985). However, female throwers may be able to generate superior angular velocities of some body segments, as reported for the knee and elbow joints of several javelin throwers (Komi & Mero, 1985). Very little research has been located that has attempted to determine if there are different variables which can predict success in male and female athletes in a particular sport. This paper will examine the important research question 'Are the physical attributes and biomechanical techniques used by male and female elite athletes to perfom a particular skill similar, or are there substantial differences between these variables?' These findings may also have some application to the training and performance of elite throwers, as any differences found may suggest more appropriate training procedures. Females training hard on 'male-important' aspects may spend their time better on 'female-important' factors to improve performance. The anthropometric variables of elite males and females are also very different, as females are on average 10 - 12 cm shorter and 10 kg lighter, have a relatively longer trunk and shorter leg length and arm span (Kemtner, 1983). Females also have a slightly lower center of gravity relative to their standing height, slightly wider hips and narrower shoulders relative to their standing height, and a slightly greater Q-angle (Atwater, 1988). However, it has been suggested that due to the greater inclination of the femur, a female is better able to transfer leg strength to the shot than a man (Kemtner, 1983) although no rationale for this belief was presented. The carrying angle of the elbow joint is often described as being larger for females (Kemtner, 1983) leading to less skilled throwing patterns, but Atwater, 1988 reported that there were no significant differences between the sexes on this variable. A larger canying angle (elbow valgus) leads to less skilled throwing patterns because the lever arm for spinal rotation and hip rotation (distance from axis through the spine and left hip to shot at release) is decreased if the elbow is in slight valgus at release. A shorter lever arm for throwing may lead to a decreased release velocity of the implement. A brief article describing how the rotation style of shot putting is particularly suited to the female physiology, noted the following (Durant, 1977): females have a lower center of gravity than males- both at rest and in motion- because of heavier hips, shorter legs, smaller upper bodies, lighter musculature and 20 to 30% more body fat females are less capable of rapid, forceful muscular activity than males because of lighter musculature agd a lower basal metabolic rate the female cannot set her body into motion as fast as males can- a fact only exacerbated by adding a 4 kilo shot to her body weight In a recent study to compare performance between sexes, the shot put performance of skilled male and female collegiate throwers was examined to determine the similarities and differences in technique between the sexes. The overall objective of the study was to determine whether the same group of independent variables could predict performance in the shot event for both male and female subjects. If the same variables predict performance in both sexes, then it may be concluded that the factors affecting performance are similar betwen the sexes. Sixtyone athletes (males = 30, females = 31) were fdmed from a sagittal view while competing in a shot competition, and seventy two variables were measured or calculated from film data. Although some of the variables were related to distance thrown, such as length of the glide, other variables such as angle of release and height of release were not found to be significant predictors of distance. The findings may be related to the skill level of this group of subjects, who were elite university throwers, but not international or world class athletes. However, the study does suggest that there are different aspects of technique which should be emphasized for female throwers, including knee extension during the glide, elbow velocity during the delivery, and a greater angle of shoulder flexion at release. For the male throwers, the CG velocity during the glide, the vertical acceleration of the CG during the delivery, and the trunk angle at the start of the glide are all important for producing longer throws. 36 REFERENCES Alexander, M. J. L. (1989). The relationship between muscle strength, sprint kinematics and sprinting speed in elite sprinters. Can J Sport Sci, 14(3), 148-157. Atwater, A. E. (1988). Biomechanics and @e female athlete. In J. L. Puhl, C. H. Brown, & R. 0. Voy (Eds.), Sport Science Perspectives for Women, (pp. 1-12). Champaign, IL: Human Kinetics Publishers. Ballreich, R. (1983, ). Biomechanical aspects of the motor technique of elite men and women athletes. 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