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PubMed2001

The experience of back pain in young Australians.

The usual activity level and history of low back pain was determined by questionnaire in 614 young Australians (9-27 years); dancers (25%), gymnasts (5%) and a control group who did not participate in dance or gymnastics for > or =6 hours/week during the previous three months (70%). These groups demonstrated significantly different activity levels (dancers >gymnasts >controls). Of all respondents, 34% experienced pain of more than two days duration in the previous year, and 50% in all previous years. The incidence and magnitude of pain in the previous year was significantly greater in the dancers and gymnasts (P<0.05) compared to the controls. The incidence of pain was not linked to the average total hours of activity until this exceeded 30 hours per week. There was no significant difference in the incidence of pain in the previous year between control group respondents who did and did not undertake regular activity. The average hours of activity per incident was approximately 20 hours for the dancers and approximately 5 hours for the other groups. This study has demonstrated that back pain in active and inactive adolescents presents a significant challenge for health-care practitioners involved in the management and prevention of symptomatic spinal disorders.

Adolescent↗
PubMed1990

Eating problems and calorie intake levels in Swiss adolescent athletes.

The purpose of this study was to investigate the incidence of eating disorders (ED), calorie intake levels and body fat measures in Swiss female athletes. Thirty athletic and 34 non-athletic adolescent Swiss females were assessed for tendencies toward eating disorders and weight preoccupation using the Eating Disorders Inventory (EDI). Calorie intakes were calculated from 7-day intake records. Body compositions were determined using skin-fold measures. The athletes were divided into two groups: Those whose activities emphasize leanness (12 gymnasts, means age = 12.5 +/- 1.1 yrs), and those whose activities do not emphasize leanness (18 swimmers, mean age = 12.8 +/- 0.9 yrs). The non-athletic school-girls (mean age = 13.4 +/- 1.2 yrs) served as controls. ANOVA indicated that the gymnasts had lower body fat levels (p less than 0.01) and consumed fewer total calories (p less than 0.05) than swimmers or controls, but all groups consumed similar calories per kg/body weight. Chi square analysis indicated that similar numbers of swimmers (11%), gymnasts (1%) and controls (6%) were exceptionally preoccupied with weight (p greater than 0.05). However, more swimmers (38%) scored high on the body dissatisfaction subscale of the EDI than the gymnasts (1%) or control (9%) (p less than 0.01). In fact, more swimmers scored high on 3 subscales of the EDI compared to the other groups (p less than 0.05). It appears that disturbances in eating behaviors are not limited to sports that emphasize leanness.

Adolescent↗
PubMed2006

Hitting the vault board: implications for vaulting take-off--a preliminary investigation.

Gymnastics vaulting relies on a specialized take-off board for propulsion during the take-off phase of the vault. There is little information on the vault board and its behaviour. The aim of this study was to characterize the behaviour of the vault board during handspring drill take-offs of young male gymnasts (n = 36). The side of the top surface of the vault board and the wooden base were marked with three reflective markers, placed at the end of the vault board nearest the vault table and the centres of the two rearmost coil springs. The vault board surface was divided into two areas, rear and middle, based on marker location. The gymnasts' groups were determined from the location of the gymnast's lateral malleolus at vault board contact. Landings with the malleolus directly above or behind the rearmost marker were considered rear landings; landings with the malleolus forward of the rearmost marker were considered middle landings. Marker movements were automatically digitized and the right malleolus was hand digitized at 120 Hz. The maximum vertical displacement, vertical deflection time, and vertical velocity at take-off of the vault board markers did not differ statistically between board contact groups (all p > 0.05). The lateral malleolus velocity components also did not differ between board contact groups. Some low to moderately strong correlations were observed between the various marker displacements, durations and take-off velocities. Modest correlations were obtained between board markers and right malleolus velocities. The results indicate that foot contact on the vault board, as defined here, did not result in differences in board marker behaviour or right lateral malleolus velocities. This information does not support the idea that vault board contacts at the rear of the vault board are worse than contacts near the middle of the vault board. More research is needed to ascertain the role of the vault board's vibration characteristics to whole body actions that are observed in the subsequent preflight phase.

Adolescent↗
PubMed2001

The role of vision in control of orientation in a back tuck somersault.

During a back tuck somersault, the angular velocity of the head is thought to surpass the visual system's ability to maintain a distinct and continuous picture of the environment. The primary objectives of this research were to determine if differences existed with regard to trunk and lower body kinematics, as well as landing balance, when gymnasts perform back tuck somersaults under different vision conditions. Ten female gymnasts (age = 11.6 +/- 2.67 years, competitive level = 8 +/- 1.15, and training time in gymnastics = 5.9 +/- 1.63 years) performed back tuck somersaults under 4 vision conditions while wearing electromagnetic sensors that allowed automatic digitizing. Although no significant differences were found between vision conditions with regard to timing, joint angles, and joint angular velocities, gymnasts were more stable at landing under conditions that allowed vision during either the entire somersault or the last half of the sumersault.

Acceleration↗
PubMed2005

Body movements on the men's competition mushroom: a three dimensional analysis of circular swings.

OBJECTIVES: To develop a method for the three dimensional analysis of body movements and body positions during the performance of circular swings on the competition mushroom, an apparatus used by young gymnasts for pommel horse training. METHODS: Five experienced male gymnasts, all of national level, performed three series of 10 circular swings on the competition mushroom. An optoelectronic instrument was used for the detection of the three dimensional movement of 13 body landmarks. From landmark trajectories, several technical measurements were obtained: diameters of ideal circles of ankles, hips, shoulders; deviation of the ankle diameters from circularity and from the horizontal plane; angle between the shoulder, hip, and ankle. The values were used for a quantitative assessment of performance of the five gymnasts. RESULTS: During the exercise, each ankle should follow a nearly horizontal circular path (deviation from circularity ranged from 3.6% to 6%, deviation from horizontality was 9.4-19.7%), there should be an angle of about 180 degrees at the hips (actual values 146-153 degrees ), and the shoulders should move as little as possible, and only in the lateral plane, without major anteroposterior movements (shoulder movement was 27-31% of ankle movement, hip movement was 16-20%). CONCLUSIONS: The method could help coaches and gymnasts to determine which parts of the body are not repeating a selected movement with sufficient accuracy and to quantify improvements made after a specific training programme.

Adolescent↗
PubMedDate not supplied

Homolateral hand and foot coordination in trained older women.

BACKGROUND: Age-related deterioration in homolateral hand and foot coordination might be due to the combined effects of aging and a sedentary lifestyle. Unfortunately, there is a lack of information regarding the effects of training programs on coordinated inter-limb behavior with advancing age. OBJECTIVE: The aim of the present study was to verify differences in homolateral hand and foot coordination between trained and untrained older women. METHODS: Fifteen sedentary older women were matched in age (61-70 years) with 15 older women who had trained for at least 7 years with 3 one-hour sessions/week of rhythmic gymnastics. The subjects performed simultaneous flexions and extensions of the homolateral wrist and ankle in the sagittal plane at a 1:1 ratio. Two homolateral conditions (preferred and non-preferred limbs) were tested in two coordination modes: in-phase (isodirectional) and anti-phase (non-isodirectional) at three test frequencies (80, 120, and 180 bpm, respectively). The time of correct execution within a maximum of 60 s was recorded for each test condition. RESULTS: Sedentary older women maintained the required movements for a shorter time than older gymnasts, especially with increasing execution frequency and in the anti-phase condition. Older gymnasts showed no negative effects of increasing frequency on coordination performance in the in-phase mode, and frequency-related performance decrements of lower magnitude than sedentary older women in the anti-phase mode. CONCLUSION: The present results indicate that the beneficial effects of rhythm-based training can be better understood when both the spatial and temporal constraints of the inter-limb coordination performance are considered. In fact, trained women largely succeeded in maintaining temporal constraints of in-phase inter-limb coordination even at the highest execution frequency, whereas sedentary women performed worse than trained women already at the lowest frequency. Furthermore, only trained women still succeeded in the anti-phase conditions. Thus, it appears that regular and prolonged practice of rhythmic gymnastics enhances inter-limb performance over both a sedentary lifestyle as well as ageing.

Aged↗
PubMed2003

Evidence of sustained skeletal benefits from impact-loading exercise in young females: a 3-year longitudinal study.

UNLABELLED: The skeletal effects from intensive exercise throughout puberty are undefined. Forty-five female gymnasts and 52 controls were studied over 3 years, including a heredity aspect. The effects of size, maturity, exercise, and diet were identified using a multilevel regression model. Results demonstrated sustained skeletal benefits resulting from exercise throughout all stages of pubertal development. INTRODUCTION: Weight-bearing exercise is beneficial for peak bone mass development. However, whether skeletal benefits achieved with exercise are maintained if training remains intensive throughout the pubertal years is not entirely clear. The influence of familial resemblance for bone mass remains undefined in physically active versus inactive children. The aim of this study was to investigate the long-term influences of impact-loading exercise on bone quantity and quality in young females after controlling for growth, maturation, and hereditary factors. MATERIALS AND METHODS: At baseline, 45 gymnasts (G) and 52 normally active controls (C) 8-17 years of age were recruited. Anthropometry, diet, physical activity, and quantitative ultrasound (QUS) were measured annually for 3 consecutive years. DXA scans of total body (TB) and lumbar spine (LS) bone mineral content (BMC) and density (BMD) were taken three times at 1-year intervals. A multilevel regression model was fitted, and the independent effects of body size, maturity, physical activity, and diet were identified over time. To assess heredity influences, 27 G mothers and 26 C mothers volunteered for cross-sectional measurements of anthropometry, QUS, and BMC/BMD. RESULTS AND CONCLUSIONS: Gymnasts were smaller and lighter (as were their mothers) than controls, but they had significantly higher QUS and axial and appendicular BMC and BMD, with > 170 g more bone mineral in TB across puberty (after adjustment for maturity [years from peak height velocity], height, weight, energy, and protein intake). Gymnasts had up to 24-51% higher BMC and 13-28% higher BMD, depending on skeletal site. These results provide evidence of sustained skeletal benefits from impact-loading exercise, which are unlikely to result entirely from heredity, throughout pubertal years.

Absorptiometry, Photon↗
PubMed2004

Influence of type of mechanical loading, menstrual status, and training season on bone density in young women athletes.

Bone mineral density (BMD) variables were compared in 2 groups of women Division I collegiate athletes-gymnasts (GYM) and cross-country runners (CC)-during the preseason and during the competitive season. An osteogenic advantage may exist in women athletes involved in impact loading (gymnastics) over those women in active loading sports like long-distance running. The effects of menstrual status and the time of the training season on BMD also were examined. Dietary intake, menstrual status, BMD, and serum estradiol levels were measured during the preseason and during the competitive season in 26 women athletes (18-22 years of age). GYM had significantly higher BMD (p < 0.05) at all sites for both the pre- and posttests compared to CC. Neither group experienced a significant change (p > 0.05) in BMD between trials for any site; however, CC showed slight decreases at all BMD sites from baseline to the posttest. GYM had a higher prevalence of self-reported menstrual cycle disturbances than CC. No significant difference (p > 0.05) in BMD was found between the eumenorrheic and menstrual dysfunction groups (oligo/amenorrheic). In conclusion, the gymnasts had significantly higher (p < 0.05) BMD than the runners, suggesting BMD is influenced by the type of mechanical loading. Menstrual status did not significantly affect BMD in these women athletes. Cross-country runners were determined to be at greater risk than the gymnasts for low bone mass; thus, it is recommended that these athletes include more high-impact activities in their training regimen to optimize their bone health.

Adolescent↗
PubMedDate not supplied

A heterologous radioimmunoassay system for human osteocalcin. Applications in performance sports girls.

Taking into account the involvement of the measurement of osteocalcin, a protein-containing gamma-carboxyglutamic acid (Gla), in investigating the physiopathology of bone and calcium metabolism, a radioimmunoassay (RIA) method useful in human clinics was developed. The reagents for the RIA of human osteocalcin namely, the radioiodination preparation, the reference preparation and the antiserum were obtained starting from bovine bone on account of the structure similarities between bovine and human osteocalcin. The reagents were incubated at 4 degrees C for 48 h followed by the polyethylene-glycol (PEG) separation technique. The sensitivity of the osteocalcin RIA method is 2.0 ng/ml, the intraassay precision is 3-5% and the interassay precision, 8-12% (coeficient of variation). Osteocalcin was measured in the sera of 3 groups of performance sports girls under basal conditions and being of more or less similar ages: rowing girls (n = 10, mean age 16 yr 6 mos), gymnast girls (n = 13, mean age 14 yr 8 mos) and table tennis girls (n = 9, mean age 16 yr). The same samples were used for the measurement of myoglobin. Osteocalcin quantification showed similar levels in the rowing and the table tennis girls, i.e. 11.91 +/- 3.39 ng/ml (X +/- SD) and 9.50 +/- 4.15 ng/ml, respectively. By contrast, in the gymnast girls, the osteocalcin levels were about 4 times higher (44.31 +/- 7.27 ng/ml) than in the other two groups. Myoglobin measurements showed lower levels in the gymnast group, than in the rowing and the table tennis groups, the latter two having similar levels. The multiplicative increase of osteocalcin in the gymnast girls is interpreted and commented in relation to their age and sexual development.

Adolescent↗
PubMed1980

Experimental evidence of a strategy for a beat swing prior to a kip.

Throughout a beat swinging motion prior to a kip the gymnast changes the relative orientation of his legs and head-torso with respect to his arms. It was observed that if these changes occurred in a correct order he could rapidly increase his swing with his limited strength. If changes in orientation of the body parts did not take place in a correct phase, the person would immediately begin to lose any height gained. Previous measurements of the filmed motion of a gymnast performing this motion and his anthropometric dimension and were used to compute from the Dempster-Hanavan model the gymnast's center-of-mass (CM) and polar moment-of-inertia (I) at each instant throughout the maneuver. A simple mechanical model should be able to reproduce the time history of the CM. This model provides some insight into what might be required to increase one's swing. From filmed motion of "good" and "bad" beat swings leading to a kip and this simple model a simple strategy was devised. Graphs are presented which show that the simple strategy is related to the gymnast's radius-of-gyration. The simple strategy is only for the swinging motion. It was concluded that the strategy of the final, small segment of the kip was not the same as that during the swinging segment but a complex one of largely utilizing the accumulated angular momentum.

Anthropometry↗
PubMed2002

Validation of the Godin-Shephard questionnaire in prepubertal girls.

PURPOSE: This study was designed to provide validation of the Godin-Shephard questionnaire for the assessment of habitual activity in prepubertal children. METHODS: Twenty-nine female competitive gymnasts and 32 recreational and nongymnasts, aged 7-11 yr, underwent multiple measures of physical activity over a 15 month period. The Godin-Shephard questionnaire (G-S) was completed once, in the middle of the study period. The Physical Activity Checklist Inventory (PACI) was completed 6 times, at intervals throughout the study, for 2 weekend days and 4 weekdays. Caltrac activity monitors (Hemokinetics, Madison, WI) were worn by each subject in two waves consisting of 2 weekdays and 1 weekend day each. Self-reported activity (h/wk) was recorded by the gymnasts in daily logs and for the nongymnasts through quarterly queries regarding participation in organized activities. A rank order was assigned to each subject for each tool. Spearman rank order correlations assessed the relationship between the G-S versus each measure and combination of measures. Subjects were also divided into gymnast and recreational/nongymnast groups, and alternately into 7-9 yr old and >or= 10 yr old groups, re-ranked and re-analyzed. RESULTS: The average rank of combined PACI, Caltrac and h/wk scores showed only moderate correlation with ranked G-S scores for the overall group and for the 7-9 yr old subset, rho = 0.380 (P = 0.003) and rho = 0.422 (P = 0.043), respectively. The average rank of combined PACI and Caltrac scores also showed only moderate correlation with the ranked G-S scores for the gymnast subset, rho = 0.423 (P = 0.025). No measure or combination of measures correlated significantly with the ranked G-S scores for the >or= 10 yr old subset or the nongymnast subset. CONCLUSION: Based upon comparison with multiple single day measures of activity, the G-S did not provide a good estimate of habitual activity in preadolescent females.

Child↗
PubMed2004

Once a week is not enough: effects of a widely implemented group based exercise programme for older adults; a randomised controlled trial.

OBJECTIVES: To determine the effects of gymnastics on the health related quality of life (HRQoL) and functional status of independently living people, aged 65 to 80 years. Gymnastics formed part of the More Exercise for Seniors (MBvO in Dutch) programme, a group based exercise programme for older adults in the Netherlands. It has been widely implemented since 1980. DESIGN: Randomised controlled trial with pretest and post-test measurements. INTERVENTION: The exercise programme given by experienced instructors lasted 10 weeks and was given weekly (MBvO1; n = 125, six groups) or twice weekly (MBvO2; n = 68, six groups). The control group (n = 193) was offered a health education programme. SETTING: Community dwelling of older people, with a comparatively low level of fitness as assessed with the Groningen Fitness test for the Elderly. RESULTS: No significant effects were found on the HRQoL (Vitality Plus Scale, TAAQoL, and RAND-36) and the functional status (Physical Performance Test and the Groningen Activity Restriction Scale). The MBvO2 group, with a low level of physical activity at baseline, showed the only improvement found on the Vitality Plus Scale (F = 4.53; p = 0.01). CONCLUSIONS: MBvO gymnastics once a week did not provide benefits in HRQoL and functional status after 10 weeks. However, participants with a low level of physical activity may benefit from MBvO gymnastics if they participate twice a week. To improve the health of the general public, sedentary older adults should be recruited and encouraged to combine MBvO with the health enhancing physical activity guidelines.

Activities of Daily Living↗
PubMed1987

A scale for measuring persistence in children.

Persistence and its assessment have been studied since the 1920s. One common approach in measuring persistence has been through testing the subject's ability to solve difficult or monotonous problems. Another approach has been through questionnaires. Although persistence is very important in academic achievement and in the general development of personality, no questionnaires have been developed for measuring persistence in children. The present research concerns the development of such a scale. It includes 40 items and was tested on 322 Israeli children aged 7-13. The internal reliability of the scale (Cronbach alpha) was .66, and the test-retest reliability after 6 months was .77. The scale differentiated active gymnasts from non-gymnasts as well as persistent gymnasts from dropout gymnasts. In addition, significant correlations were found between the scale and the need-persistence measure of the Rosenzweig Picture Frustration Study, Locus of Control, and other measures. We discuss these findings along with the significance of persistence in everyday life.

Journal Article↗
PubMed2000

A 1-year prospective study on the relationship between physical activity, markers of bone metabolism, and bone acquisition in peripubertal girls.

We conducted a 1-yr prospective study to evaluate the association between physical activity and biochemical markers of bone formation and resorption with bone mineral acquisition in 155 peripubertal Caucasian girls (51 gymnasts, 50 runners, and 54 nonathletic controls). The bone mineral density (BMD) of the femoral neck, the greater trochanter, and the lumbar spine were measured by dual energy x-ray absorptiometry. Serum biochemical markers of bone formation (osteocalcin, bone-specific alkaline phosphatase, amino-terminal propeptide of type I procollagen) and bone resorption (degradation product of C-terminal telopeptide of type I collagen) were measured. The 1-yr increase in BMD (adjusted for age, height, Tanner stage, BMD at baseline, and increases in height and weight) of the femoral neck was 0.037 g/cm2 x yr [95% confidence interval (CI), 0.019-0.051 g/cm2 x yr), and that of the greater trochanter was 0.020 g/cm2 x yr (95% CI, 0.003-0.039 g/cm2 x yr) greater in gymnasts than in controls. The corresponding figures for gymnasts compared with runners were 0.038 g/cm2 x yr (95% CI, 0.009-0.041 g/cm2 x yr) and 0.033 g/cm2 x yr (95% CI, 0.006 to 0.043 g/cm2 x yr). The figures for the lumbar spine did not differ significantly between study groups. The baseline serum concentrations of formation markers and resorption marker accounted for 2.3-12.8% (P < 0.05) of the variation in the 1-yr increase in BMD at the femoral neck and lumbar spine. However, there was no significant difference between the levels of adjusted baseline bone turnover markers of the gymnasts, runners, and controls. The present data add considerable support to the argument that high impact mechanical loading is extremely important and beneficial for the acquisition of BMD of the hip during peripubertal years. Our results indicate also that a high rate of bone turnover, reflected as elevated bone markers, is only weakly associated with the 1-yr bone gain in peripubertal girls.

Adolescent↗
PubMed2003

Strength training vs. aerobic training: cardiovascular tolerance in elderly adults.

The aim of the present study was to evaluate cardiovascular tolerance to two different types of exercise (strength training vs. aerobic training) in healthy elderly subjects. Nineteen healthy elderly subjects aged 65-81 were studied. All the subjects participated in a 6-month combined physical activity program of gymnastics (2 times/week; 50 min.) and strength training (2 times/week; 40-50 min.). The gymnastics sessions consisted of general physical activity that is usually offered to elderly people and included warm-up, aerobic exercises, strength training, some balance and coordination exercises, recreational games and cool-down. The strength training consisted of two sets of 10 to 12 repetitions at 70% of one repetition maximum (1 RM) for "women's double chest"; "leg extension"; "overhead press; "seated leg curl"; "lateral raise"; "leg press" and "abdominal machine". Cardiovascular tolerance was evaluated both by measuring heart rate (HR) continuously (Polar Vantage NV) during the sessions and by measuring systolic (SBP) and diastolic blood pressure (DBP) with an electronic sphygmomanometer at five different times (baseline, after warm-up, 15-20 min., 30-40 min. and after cool-down). Moreover, in order to measure the response according to the type of exercise, in strength training sessions, SBP and DBP were also evaluated in different machines (legs vs. arms). Comparison between the two different types of exercise (gymnastics vs. strength training) and between different machines was performed by an unpaired Student's t test. The level of significance was set at p < 0.05. The results showed no significant differences in HR, SBP and DBP values between the two training types. Both sessions were performed at appropriate intensity without exaggerated cardiovascular response. In strength training, exercises that involved the legs presented higher rises in SBP and DBP values than those performed with the arms. These data suggest that, if appropriate techniques are used, strength training as well as gymnastics can be performed by healthy older subjects so long as basic rules for exercise in this population are followed. Furthermore, the data indicate a greater cardiovascular hemodynamic response after strength exercises with the legs than with the arms.

Age Factors↗
PubMed2004

Maximal dismounts from high bar.

In men's artistic gymnastics the triple straight somersault dismount from the high bar has yet to be performed in competition. The present study used a simulation model of a gymnast and the high bar apparatus (J. Appl. Biomech. 19(2003a) 119) to determine whether a gymnast could produce the required angular momentum and flight to complete a triple straight somersault dismount. Optimisations were carried out to maximise the margin for error in timing the bar release for a given number of straight somersaults in flight. The amount of rotation potential (number of straight somersaults) the model could produce whilst maintaining a realistic margin for error was determined. A simulation model of aerial movement (J. Biomech.23 (1990) 85) was used to find what would be possible with this amount of rotation potential. The model was able to produce sufficient angular momentum and time in the air to complete a triple straight somersault dismount. The margin for error when releasing the bar using the optimum technique was 28 ms, which is small when compared with the mean margin for error determined for high bar finalists at the 2000 Sydney Olympic Games (55 ms). Although the triple straight somersault dismount is theoretically possible, it would require close to maximum effort and precise timing of the release from the bar. However, when the model was required to have a realistic margin for error, it was able to produce sufficient angular momentum for a double twisting triple somersault dismount.

Acceleration↗
PubMed2004

Effect of head position and visual condition on balance control in inverted stance.

This study analyzed the effect of head position and visual condition on the control of balance in handstand, a gymnastics posture that necessitates adaptation of sensory information processing. Five expert gymnasts participated. Centre of pressure trajectories and kinematics of different body segments were recorded. The gymnasts were instructed to maintain three handstands as long as possible in four head positions, with and without vision. Performances and postural stability was much better in the standard and dorsiflexion positions than in the aligned and ventroflexion positions under the two conditions of vision. Performances were lower without vision in the standard and dorsiflexion position. If vision clearly plays an important role, yet the tonic neck reflexes also seem to contribute greatly to control body sways during inverted posture.

Adult↗
PubMed2001

Mechanical demand and multijoint control during landing depend on orientation of the body segments relative to the reaction force.

The purpose of this study was to determine how diverse momentum conditions and anatomical orientation at contact influences mechanical loading and multijoint control of the reaction force during landings. Male collegiate gymnasts (n=6) performed competition style landings (n=3) of drop jumps, front saltos, and back saltos from a platform (0.72 m) onto landing mats (0.12 m). Kinematics (200 fps), reaction forces (800 Hz) and muscle activation patterns (surface EMG, 1600 Hz) of seven lower extremity muscles were collected simultaneously. Between-task differences in segment orientation relative to the reaction force contributed to significant between-task differences in knee and hip net joint moments (NJM) during the impact phase. During the stabilization phase, ankle, knee, and hip NJMs acted to control joint flexion. Between-task differences in muscle activation patterns indicated that gymnasts scaled biarticular muscle activation to accommodate for between-task differences in NJM after contact. Activation of muscles on both sides of the joint suggests that impedance like control was used to stabilize the joints and satisfy the mechanical demand imposed on the lower extremity. Between-subject differences in the set of muscles used to control total body center of mass (TBCM) trajectory and achieve lower extremity NJMs suggests that control of multijoint movements involving impact needs to incorporate mechanical objectives at both the total body and local level. The functional consequences of such a control structure may prove to be an asset to gymnasts, particularly when required to perform a variety of landing tasks under a variety of environmental constraints.

Adult↗