Introduction

Gymnastics has moved over the last 25 years into an era characterised by ahtleticism, agility and small body size. Through the 1970's with Olga Korbet and Nadia Comanichi and into the 80's with Oksana Omilianchik and Mary-Lou Retton, contemporary gymnastics certainly witnessed the 'child champion'. Small and strong; the body shape these athletes had led them to bring the complexity of women's gymnastics to a level never witnessed before.

Recently, for application in the current Olympic Cycle, the Federation of International Gymnastics raised the minimum age of senior women gymnasts from 15 to 16 years. This change acknowledged that young girls with small bodies often achieved higher levels of performance early in their careers and was an attempt to reward girls who stay in the sport to physical maturity.

Contrary to this, during the last decade we have witnessed some taller, more linear, gymnasts such as Svetlana Boginskia and current World Champion Svetlana Chorkina; both substantially taller women have been able to work the Code of Points to their advantage. But now moving into the new millennium, all available information indicates that the next 'Code of Points' will possess an acrobatic bias. This bias will encourage those athletes with the acrobatic athletic structure currently being characterised by American - Vanessa Atler; an athlete who is compact in body size, explosive and dynamic in performance and displays complex acrobatics. A new open ended judging criteria, similar to that used in diving, will be implemented and more difficult and complex routines will be rewarded with higher scores.

Taking this into consideration, smaller gymnasts with a high strength to weight ratio are better able to handle their own weight during complex skills, particularly those involving rotation around one or more axis of the body. Biomechanical principles underlie this trend in both physique and style. Selection of the appropriate body type prior to training is critical to be successful in elite gymnastics in this day and age.

Selection of Athletes

Of all female sports, gymnastics has one of the most obvious trade-mark body images. Research suggests that female gymnastics is more dependent on genotype, with participants already possessing the basic physique of small stature, short limbs, broad shoulders, and narrow hips. If body type is so critical to successful performance in gymnastics, it seems logical to encourage girls with inappropriate morphology into alternative sports in which they can have success. Lack of success and lack of skill improvement can be factors leading to attrition of children from sport. This will limit attrition by female participants from sport as they experience enjoyment from and commitment to a suitable activity.

Successful performance depends upon the delicate interplay between the inertial properties of the body segments and the external and internal forces which act on those body segments (Jensen, 1978). Segmental inertias represent direct constraints on the efforts of the sportsperson to develop linear and angular momentum. Consequently, those with large segmental inertias require large forces in order to maintain movement patterns similar to a sportsperson with smaller segmental inertias. Hence the tendency is for people with low segmental inertias to be successful in sports requiring rapid rotational sequences, such as gymnastics.

Body Growth

When the overall body size of an individual changes due to growth, it is the interplay between the changes in each individual body segment which affects the ability of the athlete to perform. Jensen (1981) reported that as the moments of inertia of the individual segments of the human body increased due to growth, there was an increased compensation in the force patterns in order to maintain or improve the performance of rotational movements. There is also evidence to suggest that, as a girl passes through puberty, there is a substantial decrease in performance of rotational movements due to large increases in the body segment moments of inertia (Jensen, 1981). These changes in inertia represent constraints to which the body must adapt if the level of motor performance is to be maintained or improved.

Training

In order to achieve an internationally competitive level of gymnastics performance an extraordinary amount of training is required. The effect that this training has on the delicate balance of the developing body is difficult to measure. Girls who are initially identified as having the necessary potential to be included in a intensive gymnastic training centre often already possess a smaller, stronger and leaner morphology than the average. It appears that body lengths are strongly influenced by heredity, while body widths and girths can be more influenced by training (Malina, 1978; Salmela, 1979).

Self selection for gymnastics and training may result in a decreased intensity of growth, delayed onset of the symptoms of sexual maturation and altered rhythm of the consecutive stages of development (Ziemilska, 1985). The often found delay in menarche has been attributed to: net caloric deficit with exercise over time, low weight to height ratio, critical body weight, and the composition and altered hormonal levels.

The inverse relationships between skill level and physical characteristics such as adipose tissue, weight and body size, along with the direct relationship between high power to weight ratios and extremely high skill levels, indicate the need for regular intensive training. In general, the body responds in a normal manner when the level of training is reduced. Hence it appears important that girls need to possess the small body prior to beginning training and grow slowly.

An (unpublished) study recently completed by Richards, Elliott, and Ackland, assists in the understanding of the relationship between morphology and intensity of growth experienced by subjects who participated in training for gymnastics. Thirty seven females, aged initially between 10 and 12 years of age, completed a mixed longitudinal study conducted over 3.3 years. Testing sessions at four-monthly intervals comprised measures of structural growth including height, mass, skinfolds and segment lengths and determination of the inertial parameters of the leg, thigh and trunk segments using the elliptical zone modelling technique. Tests of functional development comprised the assessment of gymnastics performance (front and back saltos, a twisting vertical jump and a v-sit action), a vertical jump, as well as lower limb, upper limb and trunk strength assessments. The sample was divided into two training groups to distinguish between elite and moderately trained gymnasts.

The results indicated that the sample was smaller in body size than the general population. Furthermore, the elite gymnasts were smaller than the moderately trained gymnasts and other results were similarly consistent across the gymnastics performance tests. High levels of angular momentum did not enhance the resultant performance. Performance of the back salto was not so dependent upon leg strength as were the front salto and the twisting jump; the former relying more on technique than strength for a good performance. The power to mass ratio was a very strong predictor of jump height on the vertical jump test, though this test related little to gymnastics performance. Vertical jump height was shown to be a poor predictor for successful gymnastics performance.

Subjects of smaller height and slimmer build performed better on the gymnastics activities. Those girls who grew substantially during the course of the study were less likely to perform well on the gymnastics activities. The subjects who grew a lot during the study and had an absolute larger body size were also those who displayed high levels of leg power and strength, though this did not enhance their performance. Those athletes who had a high strength to mass ratio were better able to take-off in a closer to vertical position to perform the saltos more successfully, particularly the back salto. The trunk strength for mass ratio appeared to be the strength measure that was most affected, in a negative direction, by large changes in body size.

The level of training undertaken by the subjects during the course of the study significantly affected their ability to perform the gymnastics activities successfully. The highly trained gymnasts were able to produce higher levels of trunk velocity on both the front and back saltos, higher amounts of longitudinal rotation on the twisting jump and produce a faster v-sit action.

The performance of both training groups improved with increasing age and this improvement affected the highly trained and moderately trained gymnasts in a similar pattern. The amount of angular momentum able to be produced on take-off significantly increased with the age of the gymnast. This was caused by a parallel increase in whole body moment of inertia. High levels of angular momentum had a detrimental effect on the success of the front salto. Higher levels of leg power were produced by the moderately trained gymnasts and this variable also increased with age. This finding was contrary to the results for the trunk and upper limb strength measures as well as strength to mass ratios, which displayed increases for both training intensity and with age. The only exception was leg strength, which was found to be similar between the moderate and elite trained gymnasts.

In order to facilitate greater understanding of the relationships between structural growth and functional development, actual growth and performance histories were examined for four case histories. Case one, an elite gymnast, experienced a low level of growth thus maintaining a small body size, which, combined with her level of training, improved gymnastic performance. Although case two was particularly strong, her high level of growth, particularly in body mass and moment of inertia, did not enable her to maintain her performance. This, coupled with reducing her training during the course of the study resulted in a deterioration in performance. A low growth rate and small actual body size enabled case three to achieve a high level of skill although she only performed a moderate amount of gymnastics training. Case four had a large actual body size and grew quickly, which combined with a moderate level of training, resulted in a reduced level of gymnastics performance, although she maximised her technique and performed at a level above what would have been predicted for her morphology.

Summary