Skeletal maturation, fundamental motor skills and motor coordination in children 7-10 years.

Relationships between skeletal maturation and fundamental motor skills and gross motor coordination were evaluated in 429 children (213 boys and 216 girls) 7-10 years. Skeletal age was assessed (Tanner-Whitehouse 2 method), and stature, body mass, motor coordination (Körperkoordinations Test für Kinder, KTK) and fundamental motor skills (Test of Gross Motor Development, TGMD-2) were measured. Relationships among chronological age, skeletal age (expressed as the standardised residual of skeletal age on chronological age) and body size and fundamental motor skills and motor coordination were analysed with hierarchical multiple regression. Standardised residual of skeletal age on chronological age interacting with stature and body mass explained a maximum of 7.0% of the variance in fundamental motor skills and motor coordination over that attributed to body size per se. Standardised residual of skeletal age on chronological age alone accounted for a maximum of 9.0% of variance in fundamental motor skills, and motor coordination over that attributed to body size per se and interactions between standardised residual of skeletal age on chronological age and body size. In conclusion, skeletal age alone or interacting with body size has a negligible influence on fundamental motor skills and motor coordination in children 7-10 years.

Does ulnar variance change with age and what is the influence of training and biological characteristics in this change? A short-term longitudinal study in Portuguese artistic gymnasts.

OBJECTIVE: To analyze the variability and longitudinal stress-related changes in ulnar variance (UV) in a group of immature artistic gymnasts. The relationship between UV and a group of biological and training variables was also investigated. DESIGN: Prospective cohort study. SETTING: Portuguese Federation of Gymnastics. PARTICIPANTS: Twenty-five Portuguese skeletally immature gymnasts competing nationally. ASSESSMENT OF RISK FACTORS: Skeletal age (Tanner-Whitehouse 3 method), stature, body mass and body mass index (BMI) (Seca stadiometer), fat-free mass and percentage of body fat mass (Tanita BC 418), handgrip strength (Takei dynamometer), and training data (interview). MAIN OUTCOME MEASURES: To determine UV stress-related changes over time, left UV was obtained using Hafner procedure. Ulnar variance values and biological characteristics were tested twice (at baseline and after 18 months of training). RESULTS: Analysis of covariance analysis presented a significant interaction between age and time effect in UV at baseline. Each category of UV reacted differently to the interaction between age and training time. Significant relationships between UV and biological and training variables (chronological and skeletal age, body mass, BMI, handgrip strength, hour per week, and years of training) were evident in at least one of the moments of data collection. CONCLUSIONS: The gymnasts showed significant longitudinal UV changes toward less negative UV over the training period. Nevertheless, we could not find a significant correlation between UV and the majority of the researched variables. Thus, although UV has been broadly studied, this phenomenon is complex because it depends on different intrinsic and extrinsic factors that are difficult to control, making necessary additional research on this topic. CLINICAL RELEVANCE: The gymnast's wrist has been associated with a high incidence of painful symptomatology and injuries, leading to the formulation of several hypotheses related to the UV ethiology. Knowledge about the possible intrinsic or extrinsic factors related to UV changes and/or different UV categories (negative, neutral, and positive), as well as their consequent specific injuries in gymnasts' wrists may contribute to a primary prevention or reduction in the occurrence, recurrence and severity of pain, functional disability, or injuries in radius-ulnocarpal joint, thereby improving gymnasts' performance.

Internal social processes of discipline formation: the case of kinanthropometry.

In 1972, the term 'kinanthropometry', derived from the Greek words 'kinein' (to move), 'anthropos' (human) and 'metrein' (to measure), was launched in the international, Francophone journal Kinanthropologie by the Canadian William Ross and the Belgians, Marcel Hebbelinck, Bart Van Gheluwe and Marie-Louise Lemmens. The authors defined this neologism as 'the scientific discipline for the study of the size, shape, proportion, scope and composition of the human being and its gross motor functions'. Presenting a theoretical framework for the analysis of the internal social processes of discipline formation - derived from the social history-of-science tradition - this article critically examines whether kinanthropometry was indeed promoted and developed by its community members as a scientific discipline. Therefore, the focus will be on its conceptualisation and positioning within the field of kinanthropology/kinesiology and on its development by a scholarly association, i.e. the International Working Group on Kinanthropometry (IWGK). The strong emphasis of the kinanthropometry community on the standardisation of measurement techniques and its practical and professional application hampered its disciplinary development. Findings of this study could serve as a basis for future 'fundamental' investigations addressing questions of disciplinary development within the field(s) of physical education, kinesiology and sport science(s).

The left hand second to fourth digit ratio (2D:4D) is not related to any physical fitness component in adolescent girls.

INTRODUCTION: The second to fourth-digit-ratio (2D:4D), a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with fitness and sports performance, although results are not univocal. Most studies however focus on a single aspect of physical fitness or one sports discipline. METHODS: In this study the 2D:4D ratio of 178 adolescent girls (age 13.5-18 y) was measured on X-rays of the left hand. The relation between 2D:4D digit ratio and multiple aspects of physical fitness (balance, speed of limb movement, flexibility, explosive strength, static strength, trunk strength, functional strength, running speed/agility, and endurance) was studied by correlation analyses and stepwise multiple regression. For comparison the relation between these physical fitness components and a selected number of objectively measured anthropometric traits (stature, mass, BMI, somatotype components and the Bayer & Bailey androgyny index) are presented alongside the results of 2D:4D digit ratio. RESULTS: Left hand 2D:4D digit ratio (0.925±0.019) was not significantly correlated with any of the physical fitness components nor any of the anthropometric variables included in the present study. 2D:4D did not enter the multiple stepwise regression for any of the physical fitness components in which other anthropometric traits explained between 9.2% (flexibility) and 33.9% (static strength) of variance. CONCLUSION: Unlike other anthropometric traits the 2D:4D digit ratio does not seem to be related to any physical fitness component in adolescent girls and therefore most likely should not be considered in talent detection programs for sporting ability in girls.

Digit ratio (2D:4D) and competition level in world-class female gymnasts.

In this study the relationship between the digit ratio (2D:4D) and artistic gymnastics performance and competition level was investigated in a sample of Caucasian world-class female gymnasts (n = 145). The sample was divided into three competition events (compulsories, free work, final score). Within each event three performance groups (lowest, middle, and highest) were based on the competition scores gathered at the World Championships at Rotterdam, the Netherlands, in 1987. Lengths of the digits were measured on X-rays of the left hand. Several anthropometric dimensions were measured and from those measurements an androgyny index (Bayer & Bayley) and somatotype components (endomorphy, mesomorphy, ectomorphy) were calculated. Although significant differences in some anthropometric characteristics between the performance level groups within each competition event were observed, no significant differences in the 2D:4D ratios were found between the performance level groups, varying from 0.918 ± 0.020 to 0.924 ± 0.020. Also, no significant correlations were observed between the 2D:4D ratio and anthropometric, androgyny, and somatotype characteristics, r varying from r = -0.11 to r = +0.12. It can be concluded that in this sample the 2D:4D digit ratio, unlike other anthropometric characteristics, is not a discriminating factor for the performance in artistic gymnastics performance on a world-class level.

The left hand second to fourth digit ratio (2D:4D) does not discriminate world-class female gymnasts from age matched sedentary girls.

INTRODUCTION: The second to fourth-digit-ratio (2D:4D), a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with sports performance, although results are not univocal. If this relation exists, it is most likely to be detected by comparing extreme groups on the continuum of sports performance. METHODS: In this study the 2D:4D ratio of world-class elite female artistic gymnasts (n = 129), competing at the 1987 Rotterdam World-Championships was compared to the 2D:4D ratio of sedentary age-matched sedentary girls (n = 129), alongside with other anthropometric characteristics including other sexually dimorphic traits such as an androgyny index (Bayer & Bayley) and Heath-Carter somatotype components (endomorphy, mesomorphy, ectomorphy) using AN(C)OVA. 2D:4D was measured on X-rays of the left hand. RESULTS: Left hand 2D:4D digit ratio in world class elite female gymnasts (0.921±0.020) did not differ significantly from 2D:4D in age-matched sedentary girls (0.924±0.018), either with or without inclusion of potentially confounding covariates such as skeletal age, height, weight, somatotype components or androgyny index. Height (161.9±6.4 cm vs 155.4±6.6 cm p<0.01), weight (53.9±7.6 kg vs 46.2 6.3 kg p<0.01), BMI (20.51±2.41 kg/m(2) vs 19.05±1.56 kg/m(2)), skeletal age (15.2±1.1 y vs 14.5±1.2 y p>0.01), somatotype components (4.0/3.0/2.9 vs 1.7/3.7/3.2 for endomorphy (p<0.01), mesomorphy (p<0.01) and ectomorphy (p<0.05) respectively) all differed significantly between sedentary girls and elite gymnasts. As expressed by the androgyny index, gymnasts have, on average, broader shoulders relative to their hips, compared to the reference sample. Correlations between the 2D:4D ratio and chronological age, skeletal age, and the anthropometric characteristics are low and not significant. CONCLUSION: Although other anthropometric characteristics of sexual dimorphism were significantly different between the two samples, the present study cannot discriminate sedentary girls from world-class female gymnasts by means of the left hand 2D:4D ratio.

Prediction of adult height in girls: the Beunen-Malina-Freitas method.

The purpose of this study was to validate and cross-validate the Beunen-Malina-Freitas method for non-invasive prediction of adult height in girls. A sample of 420 girls aged 10-15 years from the Madeira Growth Study were measured at yearly intervals and then 8 years later. Anthropometric dimensions (lengths, breadths, circumferences, and skinfolds) were measured; skeletal age was assessed using the Tanner-Whitehouse 3 method and menarcheal status (present or absent) was recorded. Adult height was measured and predicted using stepwise, forward, and maximum R (2) regression techniques. Multiple correlations, mean differences, standard errors of prediction, and error boundaries were calculated. A sample of the Leuven Longitudinal Twin Study was used to cross-validate the regressions. Age-specific coefficients of determination (R (2)) between predicted and measured adult height varied between 0.57 and 0.96, while standard errors of prediction varied between 1.1 and 3.9 cm. The cross-validation confirmed the validity of the Beunen-Malina-Freitas method in girls aged 12-15 years, but at lower ages the cross-validation was less consistent. We conclude that the Beunen-Malina-Freitas method is valid for the prediction of adult height in girls aged 12-15 years. It is applicable to European populations or populations of European ancestry.

Changes in balance, functional performance and fall risk following whole body vibration training and vitamin D supplementation in institutionalized elderly women. A 6 month randomized controlled trial.

Falls in the elderly constitute a growing public health problem. This randomized controlled trial investigated the potential benefit of 6 months of whole body vibration (WBV) training and/or vitamin D supplementation on balance, functionality and estimated fall risk in institutionalized elderly women. A total of 113 women (mean age: 79.6) were randomly assigned to either a WBV or a no-training group, receiving either a conventional dose (880 IU/d) or a high dose (1600 IU/d) of vitamin D3. The WBV group performed exercises on a vibration platform 3×/week. Balance was evaluated by computerized posturography. Functionality was assessed by 10 m walk test, Timed up and Go (TUG) performance and endurance capacity (Shuttle Walk). Fall risk was determined with the Physiological Profile Assessment. Performance on the 10 m walk test and on TUG improved over time in all groups. For none of the parameters, high-dose vitamin D resulted in a better performance than conventional dosing. The improvements in the WBV group in endurance capacity, walking at preferred speed, and TUG were significantly larger than the changes with supplementation alone. No additional benefit of WBV training could be detected on fall risk and postural control, although sway velocity and maximal isometric knee extension strength improved only in the WBV group. This trial showed that a high-dose vitamin D supplementation is not more efficient than conventional dosing in improving functionality in institutionalized elderly. WBV training on top of vitamin D supplementation provided an added benefit with regard to walking, TUG performance, and endurance capacity.

Effect of different swim caps on the assessment of body volume and percentage body fat by air displacement plethysmography.

Isothermal air trapped in scalp hair generates an underestimation of body volume when it is measured by air displacement plethysmography. The aim of this study was to examine the effect of wearing different types of swim caps on the measurement of body volume and percentage body fat by air displacement plethysmography. It was hypothesized that wearing a silicone swim cap would more thoroughly compress scalp hair compared with a lycra swim cap, yielding higher estimates of body volume and percent body fat. Thirty female participants aged 25.7 ± 6.4 years were measured in random order when wearing no swim cap, a lycra swim cap or a silicone swim cap. For the no-cap versus lycra cap condition, the mean bias for body volume was -0.579 ± 0.380 litre (limits of agreement: -1.340 to 0.181 litre) and for percent fat -4.9 ± 3.1% fat (limits of agreement: -11.2 to 1.3% fat) (P < 0.05). For the silicone versus lycra condition, the mean bias for body volume was 0.137 ± 0.099 litre (limits of agreement: -0.062 to 0.335 litre) and for percent fat 1.2 ± 0.9% fat (limits of agreement: -0.5 to 2.9% fat) (P < 0.05). In conclusion, attention should be paid to optimal compression of isothermal air trapped in scalp hair when using air displacement plethysmography. The present results suggest that this compression may be more thorough when wearing a silicone swim cap.

The effects of whole-body vibration training and vitamin D supplementation on muscle strength, muscle mass, and bone density in institutionalized elderly women: a 6-month randomized, controlled trial.

Sarcopenia and osteoporosis represent a growing public health problem. We studied the potential benefit of whole-body vibration (WBV) training given a conventional or a high dose of daily vitamin D supplementation in improving strength, muscle mass, and bone density in postmenopausal women. In a 2 × 2 factorial-design trial, 113 institutionalized elderly females aged over 70 years (mean age 79.6 years) were randomly assigned either to a WBV or a no-training group, receiving either a conventional dose (880 IU/day) or a high dose (1600 IU/day) of vitamin D(3). The primary aim was to determine the effects of 6 months of WBV and/or vitamin D supplementation on isometric and dynamic strength, leg muscle mass, and hip bone mineral density (BMD). Additionally, the increase in 25-hydroxyvitamin D [25(OH)D] levels between conventional and high-dose supplementation was compared. After 6 months of treatment, dynamic muscle strength, hip BMD, and vitamin D serum levels improved significantly in all groups, whereas isometric strength and muscle mass did not change. When compared with no training, the WBV program did not result in additional improvements. When compared with 880 IU, a high dose of 1600 IU of vitamin D did result in higher serum vitamin D levels but did not result in additional improvements. In institutionalized women older than 70 years, the WBV training protocol tested is not more efficient in enhancing muscle mass, strength, and hip BMD compared with vitamin D supplementation. A higher dose of 1600 IU of vitamin D does not provide additional musculoskeletal benefit in this population compared with conventional doses.

Bias in self-reported height and weight in preadolescents.

OBJECTIVES: To examine the validity of self-reported height and weight and factors related to misreporting in preadolescents. The accuracy of screening for underweight (thinness), overweight, and obesity using self-reported data was also tested. STUDY DESIGN: Self-reported height and weight was administered and then measured in 798 fourth graders age 8 to 11 years. Body mass index (BMI) was calculated from self-reported and measured data and BMI categories were determined using international age- and sex-specific BMI criteria. RESULTS: Preadolescents overestimated their height by 0.54 ± 5.17 cm and underreported their weight by 0.80 ± 3.09 kg. BMI derived from self-reported data was underestimated by 0.47 ± 1.79 kg/m². Measured BMI category was an important independent predictor of bias in self-reported weight and BMI. Children who were overweight or obese underestimated their weight and BMI to a greater degree compared with normal weight/underweight children. The influence of sociodemographic factors on bias in self-reported values was relatively small. Approximately 15% of children were misclassified in BMI categories when self-reported data were used, especially in the underweight (thinness) and obese category. CONCLUSIONS: Children age 8 to 11 years were not able to accurately estimate their actual height and weight, leading to erroneous estimating rates of their weight status.

Cross-validation of the Beunen-Malina method to predict adult height.

The purpose of this study was to cross-validate the Beunen-Malina method for non-invasive prediction of adult height. Three hundred and eight boys aged 13, 14, 15 and 16 years from the Madeira Growth Study were observed at annual intervals in 1996, 1997 and 1998 and re-measured 7-8 years later. Height, sitting height and the triceps and subscapular skinfolds were measured; skeletal age was assessed using the Tanner-Whitehouse 2 method. Adult height was measured and predicted using the Beunen-Malina method. Maturity groups were classified using relative skeletal age (skeletal age minus chronological age). Pearson correlations, mean differences and standard errors of estimate (SEE) were calculated. Age-specific correlations between predicted and measured adult height vary between 0.70 and 0.85, while age-specific SEE varies between 3.3 and 4.7 cm. The correlations and SEE are similar to those obtained in the development of the original Beunen-Malina method. The Beunen-Malina method is a valid method to predict adult height in adolescent boys and can be used in European populations or populations from European ancestry. Percentage of predicted adult height is a non-invasive valid method to assess biological maturity.

Timing of adolescent somatic maturity and midlife muscle function: a 34-yr follow-up.

UNLABELLED: Midlife muscle function is associated with disability and premature mortality later in life. Biological maturity is associated with muscle function during growth; however, it is unknown whether biological maturity during adolescence is associated with muscle mass and function in middle-aged healthy men. PURPOSE: The purpose of this study is to evaluate if late maturation during adolescence is associated with better muscle function in middle-aged men. METHODS: One hundred and thirty-three middle-aged men 45 to 49 yr were included. During adolescence, height was measured at annual intervals, and age at peak height velocity was derived from the individual growth curves and was used to classify participants into early-, average-, and late-maturing groups. Outcome measurements and tests included lean body mass (dual-energy x-ray absorptiometry), muscle-bone areas, isometric strength, and muscle power. Stature, body mass, cardiorespiratory fitness (V O2peak), and physical activity level were included as confounding characteristics. RESULTS: Contrasting maturity groups did not differ in the confounding characteristics (size, mass, aerobic power, and physical activity). Furthermore, no differences were observed for lean mass and muscle-bone areas. Late-maturing adults had greater strength and power, and average differences were between 0.7 and 0.9 SD units (P < 0.05). CONCLUSIONS: Late maturation during adolescence is associated with better muscle function at middle age.

Effects of whole body vibration training on cardiorespiratory fitness and muscle strength in older individuals (a 1-year randomised controlled trial).

BACKGROUND: whole body vibration (WBV) training appears to be an efficient alternative for conventional resistance training in older individuals. So far, no data exist about the vibratory effect on cardiorespiratory fitness. OBJECTIVES: this randomised controlled trial assessed the effects of 1-year WBV training on cardiorespiratory fitness and muscle strength in community-dwelling adults over the age of 60. METHODS: a total of 220 adults (mean age 67.1 years) were randomly assigned to a WBV group, fitness group or control group. The WBV group exercised on a vibration platform, and the fitness group performed cardiovascular, resistance, balance and stretching exercises. The control group did not participate in any training. Heart rate was measured during a single WBV session. Peak oxygen uptake (VO(2peak)) and time-to-peak exercise (TPE) were measured during progressive bicycle ergometry. Muscle strength was assessed by a dynamometer. RESULTS: heart rate increased significantly during WBV training. After 1 year, VO(2peak), TPE and muscle strength increased significantly in the WBV and fitness groups. Both training groups improved similarly in VO(2peak) and muscle strength. The fitness group improved significantly more in TPE than the WBV group. CONCLUSION: WBV training in community-dwelling elderly appears to be efficient to improve cardiorespiratory fitness and muscle strength.

Genetic and environmental determination of tracking in subcutaneous fat distribution during adolescence.

BACKGROUND: The distribution of fat and adipose tissue is an important predictor of disease risk. Variation in fat distribution during adolescence is correlated with fat distribution in adulthood. OBJECTIVE: The objective was to gain insight into the relative contribution of genes and environment to the stability of subcutaneous fat distribution from early adolescence into young adulthood. DESIGN: Ratio of trunk to extremity skinfold thickness (TER) data from the Leuven Longitudinal Twin Study (n = 105 Belgian twin pairs followed from 10 to 18 y of age) was entered into a longitudinal path analysis. RESULTS: The best-fitting model included additive genetic sources of variance and nonshared environment. Heritabilities ranged between 84.3% (95% CI: 63.9-92.3%) and 88.6% (95% CI: 76.5-94.1%) in boys and between 78.4% (95% CI: 59.3-88.3%) and 88.3% (95% CI: 77.0-93.8%) in girls. The majority of the phenotypic tracking (boys: 0.40-0.78; girls: 0.38-0.72) could be attributed to the moderate-to-high genetic correlations (rG) (between 0.27-0.84 and 0.38-0.80 for the various age intervals in boys and girls, respectively). This rG could be attributed to both genetic sources of variance, which are the same throughout adolescence, as well as genetic sources of variance that are "switched-on" at a certain age, the effect of which is then transmitted to subsequent observations. Environmental correlations (rE) in boys ranged between 0.51 and 0.70 but contributed relatively little to phenotypic tracking because the amount of variance explained by the environment was low (11.4-15.7%). In girls rE was low to moderate at best (0.09-0.48). CONCLUSION: Phenotypic tracking in subcutaneous fat distribution during adolescence is predominantly explained by additive genetic sources of variance.

Impact of whole-body vibration training versus fitness training on muscle strength and muscle mass in older men: a 1-year randomized controlled trial.

BACKGROUND: This randomized controlled study investigated the effects of 1-year whole-body vibration (WBV) training on isometric and explosive muscle strength and muscle mass in community-dwelling men older than 60 years. METHODS: Muscle characteristics of the WBV group (n = 31, 67.3 +/- 0.7 years) were compared with those of a fitness (FIT) group (n = 30, 67.4 +/- 0.8 years) and a control (CON) group (n = 36, 68.6 +/- 0.9 years). Isometric strength of the knee extensors was measured using an isokinetic dynamometer, explosive muscle strength was assessed using a counter movement jump, and muscle mass of the upper leg was determined by computed tomography. RESULTS: Isometric muscle strength, explosive muscle strength, and muscle mass increased significantly in the WBV group (9.8%, 10.9%, and 3.4%, respectively) and in the FIT group (13.1%, 9.8%, and 3.8%, respectively) with the training effects not significantly different between the groups. No significant changes in any parameter were found in the CON group. CONCLUSION: WBV training is as efficient as a fitness program to increase isometric and explosive knee extension strength and muscle mass of the upper leg in community-dwelling older men. These findings suggest that WBV training has potential to prevent or reverse the age-related loss in skeletal muscle mass, referred to as sarcopenia.

Covariance of isometric and dynamic arm contractions: multivariate genetic analysis.

The purpose of the present study was to examine genetic and environmental contributions to individual differences in maximal isometric, concentric and eccentric muscle strength and muscle cross-sectional area (MCSA) of the elbow flexors. A generality versus specificity hypothesis was explored to test whether the 4 strength variables share a genetic component or common factors in the environment or whether the genetic/environmental factors are specific for each strength variable. The 4 variables under study were measured in 25 monozygotic and 16 dizygotic male Caucasian twin pairs (22.4 +/- 3.7 years). The multivariate genetic analyses showed that all 4 variables shared a genetic and environmental component, which accounted for 43% and 6% in MCSA (h2 = 81%), 47% and 20% in eccentric (h2 = 65%), 58% and 4% in isometric (h2 = 70%) and 32% and 1% in concentric strength (h2 = 32%) respectively. The remaining variation was accounted for by contraction type specific and muscle cross-sectional area specific genetic and environmental effects, which accounted for 38% and 14% in MCSA, 18% and 15% in eccentric, 12% and 26% in isometric and 0% and 67% in concentric strength respectively. This exploratory multivariate study suggests shared pleiotropic gene action for MCSA, eccentric, isometric and concentric strength, with a moderate to high genetic contribution to the variability of these characteristics.

Secular trends in anthropometric characteristics, physical fitness, physical activity, and biological maturation in Flemish adolescents between 1969 and 2005.

In this study, secular trends in anthropometric characteristics, physical fitness, physical activity, and biological maturity over the past 25-35 years in Flemish adolescents were investigated. Representative cross-sectional samples of 12-18-year-old secondary school children (11,899 assessments in boys in 1969-1974, 4,899 girls in 1979-1980, 1,429 boys and 1,772 girls in 2005) and parent-offspring pairs tested at approximately the same age during adolescence (55 father-son pairs, mean age fathers = 15.47 years, mean age sons = 15.38 years; 62 mother-daughter pairs, mean age mothers = 16.63 years, mean age daughters = 15.01 years) were used. The cross-sectional data were analyzed in 6 yearly age-categories using Wilcoxon rank sum tests. For the parent-offspring data paired t-tests, simple linear regressions to adjust for parent-offspring differences in chronological age and multiple linear regressions to adjust for parent-offspring differences in chronological and skeletal age were conducted. The cross-sectional study generally revealed an increase in weight, stature, BMI, skinfolds and trunk-extremity index, and a decrease in the performance on several physical fitness tests. In the parent-offspring study, only sons were maturationally advanced compared to fathers. Even after adjustment for parent-offspring differences in chronological age and in chronological and skeletal age, results for stature, trunk-extremity index and physical fitness were generally similar to the cross-sectional study. No secular trend was observed for sports participation. The fact that the positive secular trends in weight, BMI, and skinfolds of the cross-sectional study were not entirely confirmed in the parent-offspring study is probably due to higher similarity in genetic and familial background, higher socio-economic status, and more health-consciousness of the latter.

Effects of whole body vibration training on postural control in older individuals: a 1 year randomized controlled trial.

This randomized controlled trial investigated the effects of a 12 month whole body vibration training program on postural control in healthy older adults. Two hundred and twenty people were randomly assigned to a whole body vibration group (n=94), a fitness group (n=60) or a control group (n=66). The whole body vibration and fitness groups trained three times a week for 1 year. The vibration group performed exercises on a vibration platform and the fitness group performed cardiovascular, strength, balance and stretching exercises. Balance was measured using dynamic computerized posturography at baseline and after 6 and 12 months. Whole body vibration training was associated with reduced falls frequency on a moving platform when vision was disturbed and improvements in the response to toes down rotations at the ankle induced by the moving platform. The fitness group showed reduced falls frequency on the moving surface when vision was disturbed. Thus, whole body vibration training may improve some aspects of postural control in community dwelling older individuals.

Maturity offset in gymnasts: application of a prediction equation.

PURPOSE: To verify the applicability of the prediction equation for maturity offset in a sample of female gymnasts followed longitudinally through adolescence. METHODS: Fifteen gymnasts were followed longitudinally for 6-7 yr across adolescence. Weight, height, and sitting height were measured at annual intervals. The Preece-Baines Model I was fitted to longitudinal height data for individual gymnasts to derive age at peak height velocity (PHV). The curve-fitting protocol was successfully fit to the height records of 13 of the 15 gymnasts with standard errors of estimate between 0.02 and 0.28 cm. Maturity offset was calculated from measurements taken at each observation for the 13 gymnasts and also added to chronological age at each observation point to provide an estimated age at PHV. Age at PHV derived with the Preece-Baines model was used as the criterion. Differences between the criterion age at PHV and predicted age at PHV were calculated. RESULTS: Maturity offset overestimates age at PHV in gymnasts. Mean predicted ages at PHV deviate linearly from the criterion age at PHV, but the difference is significant only at 9 yr. Correlations between maturity offset predicted ages at PHV and criterion age at PHV range from -0.13 to +0.76. The Bland-Altman plot of criterion and predicted ages at PHV suggest a systematic bias in the predictions. CONCLUSION: Maturity offset appears to have limitations when applied to female gymnasts. Care is warranted in utilizing maturity offset per se and predicted age at PHV based on maturity offset as an indicator of maturity timing in female gymnasts and perhaps other short females.