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PubMed1993

Hand placement techniques in long horse vaulting.

In this study, the effects of two different hand placement techniques used by gymnasts to perform Tsukahara and Kasamatsu long horse vaults were examined. Selected linear and angular flight descriptors were calculated to determine whether those gymnasts making initial hand contact on the end of the horse gained additional lift, range or rotation when compared to those gymnasts making the more traditional initial hand contact on top of the horse. Three-dimensional cine-film analysis using the Direct Linear Transformation (DLT) was used to obtain data on 17 elite gymnasts competing in the 1991 World Student Games at Sheffield, UK. The gymnasts were divided into two groups according to the techniques used: group E in which the first hand contact was made on the vertical surface of the near end and the second on the top of the horse, and group T in which both hands were placed on top of the horse. The vertical and horizontal motion of each gymnast's mass centre and the somersault rotation during pre-flight (board take-off to horse contact) and post-flight (horse take-off to ground landing) were determined. The projections of linear displacements of each gymnast's mass centre onto a vertical plane were determined from the three-dimensional mass centre co-ordinates, and somersault angles were calculated using the line joining the midpoints of each gymnast's shoulders and knees. Whole body mass centre linear velocity and somersault angular velocity were determined using quintic splines.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed2005

Differences in sole arch indices in various sports.

BACKGROUND: There are controversial data about the relation between foot morphology and athletic injuries of the lower extremity. Studies in soldiers have shown some relationship, whereas those involving athletes have not shown any significant relationship. The reason for these differences is not clear. OBJECTIVE: To determine the effect of various sports on sole arch indices (AIs). METHOD: A total of 116 elite male athletes (24 soccer players, 23 wrestlers, 19 weightlifters, 30 handball players, and 20 gymnasts) and 30 non-athletic men were included in this cross sectional study. Images of both soles were taken in a podoscope and transferred to a computer using a digital still camera. AIs were calculated from the stored images. RESULTS: The AI of the right sole of the gymnasts was significantly lower than that of the soccer players, wrestlers, and non-athletic controls (p<0.01). The AI of the right sole of the wrestlers was significantly higher than that of the soccer players, handball players, weightlifters, gymnasts, and non-athletic controls (p<0.03). The AI of the left sole of the gymnasts was significantly lower than that of the wrestlers and non-athletic controls (p<0.001). The AI of the left sole of the wrestlers was significantly higher than that of the soccer players, handball players, and gymnasts (p<0.007). The AI of both soles in handball players was significantly lower than those of the non-athletic subjects (p = 0.049). The correlation between the AI of the left and right foot was poor in the soccer players, handball players, and wrestlers (r = 0.31, 0.69, and 0.56 respectively), but was high in the gymnasts, weightlifters, and non-athletic controls (r = 0.96, 0.88, and 0.80 respectively). CONCLUSION: The AIs of the gymnasts and wrestlers were significantly different from those of other sportsmen studied, and those of the gymnasts and handball players were significantly different from those of non-athletic controls.

Adolescent↗
PubMedDate not supplied

Osteochondrosis of the humeral capitellum.

Seven cases of osteochondrosis of the capitellum occurring in five high performance female gymnasts between the ages of 11 and 13 are presented. Two of the patients were treated by surgical excision of the loose osteochondral fragment in three elbows. Four of the five gymnasts, including the two who underwent surgical treatment, were able to return to full workouts without recurrence of symptoms within the 3 year followup. All conditions in gymnasts were detected after symptoms had presented. A survey of 37 actively competing gymnasts at a nationally known gymnastics academy was performed, including a detailed history and physical examination and radiographic examination. No other cases of osteochondrosis were detected. It was postulated that this condition represents a lateral compression injury because of repetitive valgus overload. Investigation of the capitellar blood supply indicates that the common factors in osteochondrosis of the capitellum are repetitive or prolonged trauma to a vulnerable epiphysis on a basis of vascular interruption. Gymnastics maneuvers require forceful weight-bearing through the upper extremities. Medical personnel and coaches associated with gymnastics need to be aware of the condition of osteochondrosis of the capitellum so that any gymnast who presents with a painful, tender, swollen or locked elbow is appropriately investigated and treated.

Adolescent↗
PubMed1995

Differential effects of swimming versus weight-bearing activity on bone mineral status of eumenorrheic athletes.

To examine the role of skeletal loading patterns on bone mineral density (BMD), we compared eumenorrheic athletes who chronically trained by opposite forms of skeletal loading, intensive weight-bearing activity (gymnastics, n = 13), and nonweightbearing activity (swimming, n = 26) and 19 nonathletic controls. BMD (g/cm2) of the lumbar spine, femoral neck, trochanter, and whole body was assessed by dual energy X-ray absorptiometry (DXA). Subregion analysis of the whole body scan permitted BMD evaluation of diverse regions. Swimmers were taller (p = 0.0001), heavier (p < 0.005), and had a greater bone-free lean mass (p < 0.001) than gymnasts and nonathletic controls. When adjusted for body surface area, there was no difference in lean mass between swimmers and gymnasts, and both were higher than controls (p < 0.01). Gymnasts had a lower (p < 0.005) fat mass than swimmers and controls. There were no group differences for spine or whole body BMD, but gymnasts had higher spine BMD corrected for body mass than either swimmers or controls. Gymnasts (1.117 +/- 0.110) had higher femoral neck BMD than controls (0.974 +/- 0.105), who were higher than swimmers (0.875 +/- 0.105) (p = 0.0001). This result still applied when BMD was normalized for body weight and bone size. Trochanter BMD of gymnasts (0.898 +/- 0.130) was also higher than controls (0.784 +/- 0.097) and swimmers (0.748 +/- 0.085) (p = 0.0002), and remained higher when corrected for body mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed2003

Optimised performance of the backward longswing on rings.

Many elite gymnasts perform the straight arm backward longswing on rings in competition. Since points are deducted if gymnasts possess motion on completion of the movement, the ability to successfully perform the longswing to a stationary final handstand is of great importance. Sprigings et al. (1998) found that for a longswing initiated from a still handstand the optimum performance of an inelastic planar simulation model resulted in a residual swing of more than 3 degrees in the final handstand. For the present study, a three-dimensional simulation model of a gymnast swinging on rings, incorporating lateral arm movements used by gymnasts and mandatory apparatus elasticity, was used to investigate the possibility of performing a backward longswing initiated and completed in handstands with minimal swing. Root mean square differences between the actual and simulated performances for the orientations of the gymnast and rings cables, the combined cable tension and the extension of the gymnast were 3.2 degrees, 1.0 degrees, 270N and 0.05m respectively. The optimised simulated performance initiated from a handstand with 2.1 degrees of swing and using realistic changes to the gymnast's technique resulted in 0.6 degrees of residual swing in the final handstand. The sensitivity of the backward longswing to perturbations in the technique used for the optimised performance was determined. For a final handstand with minimal residual swing (2 degrees) the changes in body configuration must be timed to within 15 ms while a delay of 30 ms will result in considerable residual swing (7 degrees).

Arm↗
PubMed1999

Mechanical energetic processes during the giant swing exercise before dismounts and flight elements on the high bar and the uneven parallel bars.

The purposes of this study were as follows: (1) To study the energy exchange between the body of the gymnast and the high bar and uneven parallel bars during forward and backward giant swings. (2) To examine the differences between the mechanical energy produced and the mechanical energy absorbed by the muscles during forward and backward giant swings on the high bar and the uneven parallel bars. The data were gathered during the gymnastic world championships in 1994. The experimental set up consisted of two video cameras (50 Hz) and two force measurement bars (500 Hz). A total of 101 giant swings before dismounts and flight elements performed by 33 male and 34 female gymnasts were analyzed. There are characteristically two main phases during forward and backward giant swings before dismounts and flight elements. During the first phase energy is transferred from the gymnast's body into the bar. During this phase of the backward giant swing the energy of the system decreases because the amount of energy decrease of the gymnast's body is more than the energy transferred into the high bar. An exception can be seen during the giant swings in which the gymnast used the power technique. During forward giant swings the energy of the system increases during the first phase. This occurs through active flexion of the hipjoint which produced the extra muscular energy. During the second phase energy is transferred from the bar back into the gymnast's body whose total energy increases. An increase in the energy of the system can only be achieved through muscular work. During the second phase of the backward giant swing the energy of the system increases. The forward giant swings performed on the uneven parallel bars showed a large energy loss during this phase. The energy deficit seen during the first phase of the backward giant swing can be improved by using the power technique. To achieve this the athlete must be in a bent position at the start of the giant swing exercise. Through extension at the shoulder and hip joints muscular energy can be put into the system.

Biomechanical Phenomena↗
PubMed1985

Nutrition of premenarcheal athletes: relation with the lipid and apolipoprotein profiles.

The lipid and apolipoprotein profiles in plasma and the nutritional intake were investigated in 25 female elite gymnasts, 23 recreational gymnasts, 21 girl swimmers, and 16 controls. The girls were matched for sexual development, assessed by means of breast development. The age of the girls varied from 10.0 to 15.0 years. The recreational gymnasts and the girl swimmers had the highest levels of HDL-C, while those of the elite gymnasts and the controls were equally low (P less than or equal to 0.05). The same trend was seen in the case of the HDL-C/TC, HDL-C/LDL-C, and HDL-C/apo A-I ratios (P less than or equal to 0.05). The swimmers and the controls had similar high levels of apo A-I, and the swimmers also had a low apo B level. The differences with the elite group reached statistical significance (P less than or equal to 0.05). The recreational gymnasts had a lower level of apo E than the elite gymnasts and the swimmers had (P less than or equal to 0.05). The composition of the diet, expressed in energy %, was similar for all groups. The recreational gymnasts had a higher P/S ratio than the controls. It is concluded that the differences in lipid and apolipoprotein profiles found between young, female athletes and controls are not associated with differences in dietary intake and may be due to differences in physical activity. Also, genetic factors may have contributed to the variation found in the mentioned profiles. Yet, in this pediatric population, the nutritional intake played a small but significant role relative to the plasma lipids and apolipoproteins.

Adolescent↗
PubMed1999

Comparison of calcaneal ultrasound and DXA in young women.

PURPOSE: The purpose of the study was to assess quantitative ultrasound (QUS) parameters in collegiate female gymnasts, a population whose training incorporates high-impact loading, which is particularly osteogenic, and to determine the discriminative capacity of this relatively new radiation-free technique compared with bone densitometry in a young healthy population. METHODS: We studied 19 collegiate gymnasts and 23 healthy controls undergoing regular weight-bearing activity, matched for age (gymnasts 19.2 +/- 1.2, controls 19.9 +/- 1.6 yr) and body weight (gymnasts 56.7 +/- 3.7, controls 57.7 +/- 7.8 kg). QUS parameters of the calcaneus (broadband ultrasound attenuation (BUA), bone velocity (BV), and speed of sound (SOS)) were measured by a Walker Sonix UBA 575+. Bone mineral density (BMD; g x cm(-2)) of the lumbar spine, hip (femoral neck, trochanter, Ward's triangle) and whole body was assessed by dual energy x-ray absorptiometry (DXA, Hologic QDR 1000/W). Data analysis included unpaired two-tailed Student's t-tests, analysis of variance, Pearson product-moment, and Spearman rank-order correlations. RESULTS: Regional and whole body BMD of gymnasts was greater than controls (P < 0.001), with the difference being 7-28%. Average QUS parameters of the right and left calcaneus were also higher (P < 0.001) in the gymnasts. BUA, BV, and SOS were significantly (P < 0.001) correlated to each bone site with r = 0.54-0.79. Analysis of receiver operating characteristic (ROC) curves indicated no significant difference in sensitivity and specificity for QUS and DXA measures. CONCLUSIONS: These results indicate that QUS parameters of the calcaneus are higher in young women gymnasts compared to individuals who undergo regular weight-bearing activity and that QUS parameters are able to discriminate between these two groups in a similar manner as does regional and whole body BMD.

Absorptiometry, Photon↗
PubMed1988

[Lipids, lipoproteins, apoproteins and physical exercise in young female athletes].

Body composition, lipid, lipoprotein and apoprotein profiles were evaluated in 38 female adolescents, with ages from 11.5 to 15.0 years, and arranged in three groups: controls, swimmers and rhythmic gymnasts. Body composition showed evident differences when comparing gymnasts with controls and swimmers. Lowest levels for NEFA corresponded to gymnasts. HDL-C was higher in sports girls with respect to controls, mainly in gymnasts. Gymnasts appeared to have significantly higher Apo A1 differences when comparing them with controls and swimmers. HDL-C/CT, HDL-C/LDL-C, HDL-C/Apo A1/Apo B ratios demonstrated higher levels in sports girls, and mostly in gymnasts. Most significative correlations were found between body composition and Apo A1 and Apo A1/Apo B in control and swimming groups. Thus, physical activity at early ages has a beneficial effect on HDL-C and Apo A1 concentrations. Differences between sports girls and controls are more significantly revealed by lipid, lipoprotein and apoprotein relating ratios. Rhythmic gymnasts do seem to have a different lipidic pattern when compared to controls and swimmers.

Adolescent↗
PubMed1985

Socio-economic factors in relation to lipid profiles in young girl athletes.

The influence of socio-economic factors on blood lipid values was studied in 4 groups of young female athletes. Based on type of sport (gymnastics and swimming) and of training intensity, the participants were subdivided into 25 talented, high achievement gymnasts (age 12.3 +/- 1.6 (SD) year), 42 non-talented, low achievement gymnasts (age 12.0 +/- 1.2 (SD) year), 12 high achievement swimmers (age 10.3 +/- 1.6 (SD) year), and 24 low achievement swimmers (age 10.8 +/- 1.6 (SD) year). With respect to socio-economic factors, no significant differences were observed between the two gymnastic groups nor between the two swimming groups. The blood lipid values revealed a significantly higher low density lipoprotein-cholesterol level and significantly lower high density lipoprotein-cholesterol/total cholesterol and high density lipoprotein-cholesterol/low density lipoprotein cholesterol ratios in the talented gymnasts as compared to the non-talented gymnasts. In the high achievement swimmers, low density lipoprotein-cholesterol and triglyceride levels were significantly lower and high density lipoprotein-cholesterol/total cholesterol was significantly higher as compared to the other swimmers. The Spearman rank order correlation coefficients for the relationships between socio-economic factors and blood lipid values were mostly weak or inconsistent. Therefore, no major influence of socio-economic factors on blood lipid values could be demonstrated in the groups investigated.

Adolescent↗
PubMed1997

Influence of high impact loading on ultrasound bone measurements in children: a cross-sectional report.

Evidence suggests that weight-bearing exercise during the growing years may enhance peak bone mass. The purpose of this study was to compare ultrasound bone measurements, serum alkaline phosphatase (S-ALP), serum osteocalcin (S-OC), and dietary calcium in highly active and normal healthy male children. Subjects were 33 elite and subelite male gymnasts and 40 normoactive controls matched for age (9.4 +/- 1.1 years), height (133.9 +/- 5.9 cm), and weight (30.1 +/- 3.8 kg). Measurements of broadband ultrasound attenuation (dB/MHz) through the calcaneus (CBUA) and ultrasound velocity (m/s) through the calcaneus (CVOS), distal radius (RVOS), and proximal phalanx of the index finger (PVOS) were performed using a Contact Ultrasonic Bone Analyzer (CUBA Research). Gymnasts had significantly greater CVOS (P < 0.001), RVOS (P < 0.0001), and PVOS (P < 0.05). There were no differences in CBUA, S-ALP, or S-OC between groups. RVOS correlated significantly with dietary calcium intake in all subjects (P < 0.05) and training time in the gymnasts (P < 0.05). Though gymnasts had significantly greater calcium intakes than controls (P < 0.05), whose mean value was below the RDA, after controlling for calcium intake in the gymnasts alone, RVOS was still significantly correlated with training time (P < 0.05). These preliminary results suggest that the heavy musculoskeletal loading inherent in gymnastics training produces positive adaptive responses in the growing skeleton. Furthermore, ultrasound appears to provide a safe, noninvasive means of comparing the skeletal status of exercising and normal healthy children, whereas single samples of biochemical markers did not discriminate between the groups.

Bone Density↗
PubMed1994

Prospective study of psychological development of adolescent female athletes: initial assessment.

PURPOSE: This study aimed at assessing the impact of physical training on psychological functioning at the onset of a prospective study of psychological and somatic maturation of adolescent female athletes. METHODS: Twenty-seven highly trained gymnasts aged 12.7 +/- 1.1 year (mean +/- SD, training load = 18-26 hr/week) and 16 age-matched but moderately trained swimmers (13.0 +/- 0.9 yr, training load 4-15 hr/wk) were submitted to standardized somatic and psychiatric examinations during training camps. RESULTS: Gymnasts were significantly shorter, lighter and thinner (p < 0.001) than swimmers. Their bone age was moderately but significantly retarded (-1.42 +/- 0.99 yr, p < 0.001) in contrast with swimmers in whom it was adequate for chronological age (+0.28 +/- 0.94 year, ns). Only 7.4% of gymnasts had already had menarche in contrast with 50% of age-matched swimmers (p = 0.003). Psychological functioning was considered as normal in all subjects. However, seven athletes including 3/27 gymnasts and 4/16 swimmers (p = 0.394) were considered as subjects "at risk" to develop a manifest mental disorder over time. Ten gymnasts (41.7%) presented with a global delay in psychological maturation, whereas no such case was observed among swimmers (p = 0.015). No correlation could be established between psychological delay and pubertal retardation (p = 0.210). CONCLUSION: Strenuous training in gymnastics for more than 1 yr has so far no detectable interference with the normal maturational events of adolescence. The outcome of athletes at risk to develop psychopathology as well as those with a global delay in psychological maturation who presented as if they were still in the latency period, remains uncertain.

Adolescent↗
PubMed2001

Mechanical energetic processes during the giant swing before the Tkatchev exercise.

The goal of this study was to examine the possibility of the utilization of high bar and uneven parallel bar elasticity by the gymnasts through muscular work during the giant swing before the Tkatchev exercise on the high bar or uneven parallel bars. The performances were gathered during the Gymnastic World Championship in 1994. The set up consisted of two video cameras (50Hz) and two force measuring bars (500Hz). Twenty giant swings before the Tkatchev exercise, nine giant swings before the Tkatchev exercise after Tkatchev on the high bar and 15 giant swings before the Tkatchev exercise on the uneven parallel bars were analyzed. The giant swings were performed by 20 male and 15 female gymnasts. There are three phases during the giant swing exercise before the Tkatchev in which the systems (high bar-human body) total energy can be changed. During the first phase, energy is transferred from the gymnast's body into the bar. A clearly effective use of the bar's elasticity during the first phase could not be found. During the second phase, energy is transferred from the bar's back into the gymnast's body whose total energy increases. An increase in the energy of the system can only be achieved through muscular work. During the second phase of the various giant swing techniques no significant (p<0.05) difference in the energy increase through muscular work could be found. During the third phase, energy is once again produced by the gymnast through extension at the hip and shoulder joints.

Adult↗
PubMed1993

Kinetics of the lower extremities during drop landings from three heights.

In this study, the landing preferences of gymnasts (n = 6) and recreational athletes (n = 6) were determined by comparing the changes in lower extremity kinetics of drop landings performed from three heights (0.32-1.28 m). Net joint moments and work done on the extensor muscles of the ankle, knee, and hip were selected as variables representative of the demand placed on the muscles responsible for controlling flexion and dissipating the load. Kinematic and kinetic two-dimensional data were acquired simultaneously using high-speed film (202.4 fps) and a force plate (1000 Hz). Reaction forces and lower extremity joint motions were used to calculate net joint forces, net joint moments powers, and work done on the extensor muscles of the ankle, knee, and hip. Results indicated that the extensor joint moments tended to peak earlier after contact with increases in velocity, but the temporal sequence of events was maintained independently of velocity or group. As impact velocity increased, net peak extensor moments and work done on the extensor muscles significantly increased. Significantly larger ankle and hip peak extensor moments were observed for the gymnasts across velocities as compared to the recreational athletes. No significant differences in work done on the extensor muscles were noted between groups. Significant interaction effects indicate that gymnasts chose to dissipate the loads at contact by using larger ankle and hip extensor moments at higher impact velocities than the recreational athletes, whereas recreational athletes chose to adjust their strategy by using greater degrees of hip flexion (McNitt-Gray, Int. J. Sport Biomech, 7, 201-204, 1991) and longer landing phase durations than the gymnasts. The greater demands placed on the ankle and hip extensors by the gymnasts, as compared to the recreational athletes, may be explained by the need to maintain balance during competitive gymnastics landings or, perhaps, by the inability of recreational athletes to produce larger extensor moments at the ankle or hip during landings from great heights.

Ankle Joint↗
PubMed1984

The influence of strenuous muscle stimulation on the menarche.

Nowadays, the average age at which menarche begins is lowering by three to four years every century, that is, four months every decade, according to both Japanese, and European and American annual changes of the average age. It emerged that the menarche shows a tendency to occur later in female gymnasts, because of the influence of strenuous muscle stimulation, and the fact that a higher level of technic is required in gymnastic games each year. These conclusions have been drawn from replies submitted to a questionnaire distributed among a relatively small number of gymnasts who participated in the competitions including the Inter High School Championship and the World Cup Championship. For example, at the age of 14, the percentage of women who had menstruated is almost 100% among women in general, but only 24% among World Cup Championship gymnasts, the average age at menarche of the latter being later than that of the former by as many as 3 years. At the age of 16, the percentage of women who had menstruated is 100% among women in general, but on the other hand, it is only 60% among World Cup Championship gymnasts, in other words, only a low percentage of women, of the latter group, had menstruated. Finally in our study, we established that the age at menarche of gymnasts is three or five years later than that of women in general. From our study, we concluded that the excessive burden imposed on muscles might cause an abnormal menstrual cycle, and the influence on menstruation would be considerable.

Adolescent↗
PubMed2003

A correlative study between prevalence of chondromalacia patellae and sports injury in 4068 students.

OBJECTIVE: To study the prevalence of chondromalacia patella among college students and the correlation with sports injury. METHODS: 354 students from gymnastic department and 429 from nongymnastic department with knee joint pain were selected. 184 students from gymnastic department and 342 from nongymnastic department were checked randomly by a surgeon. 77 patients (37 males, 40 females) from gymnastic department and 119 patients (62 males, 57 females) from nongymnastic department were diagnosed as chondromalacia patellae. The amount of exercise and the occurrence of sports injury were investigated in each student. All data were analyzed with SPSS 10.0 statistical software. RESULTS: The prevalence of chondromalacia patella was 20.1% in female students and 11.6% in male students from gymnastic department, and 5.61% in female students and 4.92% in male students from nongymnastic department. The amount of exercise and the occurrence of sports injury to the knee joint in students from gymnastic department were greater than those from nongymnastic department. CONCLUSIONS: In both female and male students, the prevalence of chondromalacia patella is higher in gymnastic department than nongymnastic department. Sports injury is an important cause of chondromalacia patella.

Adolescent↗
PubMed1984

Sex hormone profiles of premenarcheal athletes.

Female gymnasts have a delayed onset and probably retarded progression of puberty. The aim of this study was to test the hypothesis that the delay in onset of puberty in gymnasts as compared to girl swimmers is modulated by a lower estrone level due to a smaller amount of body fat. The sex-hormone and gonadotropin levels of 46 gymnasts and 37 girl swimmers of the same biological maturation (breast development: M = 1 or M = 2) were studied. In each subject the following hormones were measured in plasma: estrone, 17-beta-estradiol, DHEAS, testosterone, androstenedione, LH, and FSH. In prepubertal children (M = 1) the levels of estrone, testosterone, and androstenedione were lower in the gymnastic group as compared to the swimming group. In the early pubertal (M = 2) gymnastic and swimming groups these hormone levels were no longer different. The other hormone levels were not significantly different in either the prepubertal groups or the early pubertal ones. Within the total prepubertal group there is a clear relationship between the estrone levels and the levels of testosterone and androstenedione, but not between estrone and 17-beta-estradiol, nor between the calculated fat mass and any of the hormone levels. It appears that the androstenedione and testosterone levels are responsible for the difference in estrone level, rather than the amount of body fat.

Adolescent↗
PubMed1998

Effect of physical training on bone mineral density in prepubertal girls: a comparative study between impact-loading and non-impact-loading sports.

Physical activity is known to have an anabolic effect on bone tissue. It has been shown to increase the bone mineral density (BMD) in young adults, as well as in teenagers. But there is little information about the effect of intensive physical activity in childhood, particularly at the prepubertal stage. To examine the influence of an early intensive physical training on BMD, we have studied a group of elite prepubertal girls, at the starting phase of their peak bone mass acquisition. Subjects were engaged either in sport requiring significant impact loading on the skeleton, or in sport without impact loading. Forty-one healthy prepubertal girls took part in this study. The sport group consisted of 10 swimmers (10.5 +/- 1.4 years old) and 18 gymnasts (10.4 +/- 1.3 years old), who had performed 3 years of high-level sport training (8-12 h per week for swimmers, 10-15 h per week for gymnasts). Thirteen girls (10.7 +/- 1 years old) doing less than 3 h per week of physical activity served as a control group. BMD measurements were done using dual-energy X-ray absorptiometry. There was no statistical significant difference between groups as regards age, body height and weight, and body composition. There was no statistical significant difference between swimmers and controls for all the BMD measurements. Mean BMD in gymnasts was statistically higher than in the control group for mid-radius (+15.5%, p < 0.001), distal radius (+33%, p < 0.001), L2-4 vertebrae (+11%, p < 0.05), femoral neck (+15%, p < 0.001) and Ward's triangle (+15%, p < 0.01). Moreover, in gymnasts, BMD at radius, trochanter and femoral neck was above normative values. We conclude that physical activity in childhood could be an important factor in bone mineral acquisition in prepubertal girls, but only if the sport can induce bone strains during a long-term program: gymnastics has such characteristics, unlike swimming. Such acquisition could provide protection against risks of osteoporosis in later life, but this remains debatable.

Bone Density↗