Body size and three estimates of skeletal age: Relationships with strength and motor performance among male soccer players 9-12 and 13-16 years.

OBJECTIVE: To estimate the associations between height, weight, and three estimates of skeletal age (SA) and the strength and motor performance of male soccer players in two chronological age (CA) groups, 9-12 (n = 60) and 13-16 (n = 52) years. METHODS: Height, weight, strength (grip), speed (5 m, 20 m sprints), acceleration (time at crossing 10 m in 20 m sprint), agility (figure-of-eight run), power (vertical jump), and endurance (intermittent shuttle run) were measured. SA was assessed with the TW2 RUS, TW3 RUS, and Fels methods; each SA was expressed as the standardized residual of the regression of SA on CA (SAsr). Hierarchical multiple regression was used. RESULTS: Body size accounted for ≥50% of the variance in grip strength in both CA groups; the body size × SAsr for each method and SAsr alone added little to the explained variance. Body size, body size × SAsr interactions, and SAsr per se with each method accounted for small percentages of variance in motor tasks among players 9-12 years, while body size explained a larger proportion of variance in motor tasks (except the endurance run) among players 13-16 years; body size × SAsr interactions for TW2 and TW3 more so than Fels added to the explained variances. For the endurance run, only SAsr per se with each method accounted for significant portions of the variance. CONCLUSION: Body size and the three estimates of SA significantly influenced strength and motor performance, but the explained variance varied between CA groups and among SA methods and performance tasks.

Interrelationships among skeletal age, growth status and motor performances in female athletes 10-15 years.

BACKGROUND: Motor performances of youth are related to growth and maturity status, among other factors. AIM: To estimate the contribution of skeletal maturity status per se to the motor performances of female athletes aged 10-15 years and the mediation effects of growth status on the relationships. SUBJECTS AND METHODS: Skeletal age (TW3 RUS SA), body size, proportions, estimated fat-free mass (FFM), motor performances, training history and participation motivation were assessed in 80 non-skeletally mature female participants in several sports. Hierarchical and regression-based statistical mediation analyses were used. RESULTS: SA per se explained a maximum of 1.8% and 5.8% of the variance in motor performances of athletes aged 10-12 and 13-15 years, respectively, over and above that explained by covariates. Body size, proportions, and hours per week of training and participation motivation explained, respectively, a maximum of 40.7%, 18.8%, and 22.6% of the variance in performances. Mediation analysis indicated specific indirect effects of SA through stature and body mass, alone or in conjunction with FFM on performances. CONCLUSION: SA per se accounted for small and non-significant amounts of variance in several motor performances of female youth athletes; rather, SA influenced performances indirectly through effects on stature, body mass and estimated FFM.

Genetic regulation of body size and morphology in children: a twin study of 22 anthropometric traits.

BACKGROUND: Anthropometric measures show high heritability, and genetic correlations have been found between obesity-related traits. However, we lack a comprehensive analysis of the genetic background of human body morphology using detailed anthropometric measures. METHODS: Height, weight, 7 skinfold thicknesses, 7 body circumferences and 4 body diameters (skeletal breaths) were measured in 214 pairs of twin children aged 3-18 years (87 monozygotic pairs) in the Autonomous Region of Madeira, Portugal. Factor analysis (Varimax rotation) was used to analyze the underlying structure of body physique. Genetic twin modeling was used to estimate genetic and environmental contributions to the variation and co-variation of the anthropometric traits. RESULTS: Together, two factors explained 80% of the variation of all 22 anthropometric traits in boys and 73% in girls. Obesity measures (body mass index, skinfold thickness measures, as well as waist and hip circumferences) and limb circumferences loaded most strongly on the first factor, whereas height and body diameters loaded especially on the second factor. These factors as well as all anthropometric measures showed high heritability (80% or more for most of the traits), whereas the rest of the variation was explained by environmental factors not shared by co-twins. Obesity measures showed high genetic correlations (0.75-0.98). Height showed the highest genetic correlations with body diameter measures (0.58-0.76). Correlations between environmental factors not shared by co-twins were weaker than the genetic correlations but still substantial. The correlation patterns were roughly similar in boys and girls. CONCLUSIONS: Our results show high genetic correlations underlying the human body physique, suggesting that there are sets of genes widely affecting anthropometric traits. Better knowledge of these genetic variants can help to understand the development of obesity and other features of the human physique.

Regional variation in growth status. The Peruvian health and optimist growth study.

OBJECTIVE: This study aims to (1) investigate differences in weight, body mass index (BMI), and waist circumference (WC) among Peruvian children and adolescents living in three areas located at different altitudes; (2) compare age- and sex-specific height, weight, and BMI within each site with US reference data. METHODS: We sampled 8753 subjects (4130 boys), aged 4 to 17 years from sea level, rainforest, and high-altitude. Height, weight, and WC were measured and BMI was calculated. Analysis of variance was used to compare variables across geographic regions, and the Hoff and Blackburn procedure was used to compare the Peruvian results with US reference data. RESULTS: Participants living at sea level were taller, heavier, had greater BMI and WC relative to those living at high-altitude and in the rainforest. Peruvian schoolchildren of both sexes from the three geographical areas were shorter and lighter than their American peers. Boys and girls living in the rainforest and at high-altitude had lower BMI, whereas WC values of American schoolchildren are higher than those of the Peruvian children by age and gender. CONCLUSIONS: Peruvians living at different altitudes differ in their growth indicators (height, weight, BMI, and WC), with significant differences between those living at sea level relative to their peers from other regions. Further, Peruvian schoolchildren of both sexes from the three geographical areas significantly differ from their US counterparts.

Physical fitness spurts in pre-adolescent boys and girls: Timing, intensity and sequencing.

We aim to (1) estimate age of attainment of the peak mid-growth spurt in stature (age-at-peak MGS) in pre-adolescent boys and girls; (2) identify the timing, intensity, and sequences of physical fitness (PF) spurts aligned by the age-at-peak MGS; and (3) identify any sex differences in PF spurts aligned by age-at-peak MGS. The sample included 180 Portuguese children (90 girls) aged 6 to 10 years at study entry who were followed annually for 4 years. Height, health-, and performance-related PF were assessed. Age-at-peak MGS and PF spurts were estimated using a non-smooth mathematical procedure. Boys' and girls' age-at-peak MGS occurred at 7.8 ± 0.47 years and 8.0 ± 0.72 years, respectively. PF spurts' timing aligned by age-at-peak MGS were as follows: (1) before age-at-peak MGS: boys - static strength, aerobic capacity, explosive leg strength, and flexibility; girls - speed, agility, aerobic capacity, and upper body strength; (2) coincident with age-at-peak MGS: girls - explosive leg strength and flexibility; (3) after age-at-peak MGS: boys - abdominal strength, upper body strength, agility, and speed; girls - abdominal strength and static strength. Boys and girls attained their MGS at relatively similar ages. However, the timing and sequences of PF spurts, aligned on age-at-MGS, were different between boys and girls.

Genetics of somatotype and physical fitness in children and adolescents.

OBJECTIVES: To analyze the influence of genetic and environmental factors on the variation in somatotype, physical fitness, and their mutual associations. METHODS: Twins from 214 pairs (87 monozygotic) of the Autonomous Region of Madeira, Portugal, from 3 to 18 years of age (51% girls) were assessed in anthropometry and physical fitness tests. We estimated endomorphy, mesomorphy, and ectomorphy based on anthropometric measures and physical fitness using the Eurofit test battery. Two age categories were analyzed: children (3-11 years) and adolescents (12-18 years). Genetic and environmental variations were estimated using quantitative genetic twin modeling. RESULTS: No genetic sex differences were found, thus boys and girls were pooled in all genetic analyses. Heritability estimates were high for somatotype (a2  = 0.80-0.93), physical fitness traits (a2  = 0.67-0.83), and largely similar in children and adolescents. Positive correlations were found for ectomorphy with motor ability and cardiorespiratory endurance as well as for endomorphy and mesomorphy with muscular strength (r = 0.25-0.37). In contrast, negative associations were found for ectomorphy with muscular strength, as well as for endomorphy and mesomorphy with motor ability and cardiorespiratory endurance (-0.46 to -0.26). Twin modeling indicated that these associations were explained mostly by genetic factors in common to the two associated traits (84% or more). CONCLUSIONS: Associations between somatotype and physical fitness tests are mainly explained by common genetic background in children and adolescents. Therefore, interventions in youth should consider that a child's performance in physical fitness tests partly reflects their inherited physique.

Physical fitness spurts in childhood: A study in boys.

This study aimed to (1) estimate age-at-mid-growth spurt (age-at-MGS) in Portuguese boys from two different regions-the Azores islands and Viana do Castelo, and (2) identify spurts in a variety of physical fitness (PF) components aligned by age-at-MGS in the two samples. A total of 176 (Azores, n = 91; Viana do Castelo, n = 85) boys aged 6 years old were followed annually to 10 years of age. Age-at-MGS and spurts in PF components (speed, explosive muscular strength, abdominal muscular strength, agility, and flexibility) were identified for each sample. The timing and intensities of the spurts were estimated using a non-smooth mathematical procedure. In Azorean boys, age-at-MGS occurred at 7.8 years (6.99 cm y-1 ), whereas in Viana do Castelo it occurred at 7.9 years (6.20 cm y-1 ). Spurt in speed was attained 12 months after the MGS in both samples (0.53 and 0.35 cm y-1 in Azores and Viana do Castelo, respectively), whereas spurts in explosive muscular strength and flexibility occurred 12 months before the MGS and at the MGS (Azores: 21.59 and 5.52 cm y-1 and Viana do Castelo: 14.12 and 2.5 cm y-1 , respectively). Agility and abdominal muscular strength peaked between 0 and 12 months after the MGS (Viana do Castelo: 0.37 m s-1  y-1 and 6.71 reps y-1 and Azores: 0.28 m s-1  y-1 and 19.36 reps y-1 , respectively). Results indicate that developmental spurts in explosive strength and flexibility occur before, or are coincident with, the mid-growth spurt in height, whereas spurts in speed, agility, and abdominal muscular strength occur after, or coincident with, the mid-growth spurt in height.

Patterns of physical performance spurts during adolescence: a cross-cultural study of Canadian, Brazilian and Portuguese boys.

BACKGROUND: Data relating physical performance to the timing of the adolescent growth spurt are limited. Aim: This study identifies: (i) age-at-peak height velocity (APHV), (ii) physical performance spurt patterns aligned to APHV; and (iii) cross-cultural and time patterns in Canadian, Brazilian and Portuguese boys. Subjects and methods: A total of 512 boys (131 Canadian, 250 Portuguese and 131 Brazilian), 8-17 years of age were followed serially using longitudinal data. APHV was identified and five physical performance measures velocities [trunk extension (TE), trunk flexion (TF), standing long jump (SLJ), curl-ups (CU) and handgrip strength (HG)] were aligned at 6-month intervals, 4 years around the attainment of PHV. Velocities were estimated using a non-smooth mathematical procedure. Results: APHV was 13.9 ± 1.0, 13.4 ± 1.6 and 13.0 ± 0.8 years for Canadian, Brazilian and Portuguese boys, respectively. Maximal velocity in SLJ was attained between 12 and 6 months prior to PHV. For HG, peaks were attained 12-24 months after PHV. Maximal velocity in TE occurred between 12 and 0 months prior to PHV, while CU peaked between PHV and 6 months after PHV. Conclusion: Patterns of spurts in physical performance have remained relatively the same and do not appear to be influenced by cross-cultural differences.

Muscle Mass and Muscle Strength Relationships to Balance: The Role of Age and Physical Activity.

OBJECTIVE: To investigate the relations of balance to muscle mass (MM) and muscle strength (MS), depending on age and physical activity, which is of particular importance to functional independence in older people. METHODS: This cross-sectional study included 802 volunteers (69.82 ± 5.60 years). The Fullerton Advanced Balance scale was used to assess balance and a composite score, including arm curl and chair stand tests for assessing MS. MM was estimated by dual-energy X-ray absorptiometry and physical activity by questionnaire. RESULTS: Greater MM (r = .26, p < .001) and MS (r = .53, p < .001) were positively correlated to balance. The old-old adults and less active individuals attained lower balance. Notably, moderation and subsequent simple slope analyses revealed that the relations of balance, MM, and MS were larger in less active and the old-old adults. CONCLUSIONS: The old-old and less active adults were more prone to muscle weakness and balance impairments. Tailored interventions should particularly consider these vulnerable groups.

Growth velocity curves and pubertal spurt parameters of Peruvian children and adolescents living at different altitudes. The Peruvian health and optimist growth study.

OBJETIVE: To estimate the growth parameters of Peruvian children and adolescents living at different altitudes. METHODS: The sample comprised 10 795 Peruvian children and adolescents (5781 girls, aged 6-7 years) from sea level, the Amazon region, and high altitude. Height was measured with standardized techniques. Mathematical and biological growth parameters were estimated using the Preece-Baines growth model I. RESULTS: Sea-level children and adolescents experienced peak height velocity (PHV) at an earlier age (girls, 8.56 ± 2.37 years; boys, 12.03 ± 0.58 years) were taller at the time of PHV (girls, 144.1 ± 1.9 cm; boys, 154.3 ± 1.4 cm), had higher PHV (girls, 6.23 ± 3.87 cm/year; boys, 7.52 ± 2.31 cm/year), and had a taller estimated final height (girls, 154.2 ± 0.3 cm; boys, 166.3 ± 1.0 cm) compared to those living at high altitude (girls, 152.7 ± 0.7 cm; boys, 162.8 ± 0.8 cm) or in the Amazon region (152.1 ± 0.4 cm; boys, 162.2 ± 0.6 cm). Across all geographical areas, PHV occurred approximately 2 years earlier in girls (9.68 ± 0.99 years) than in boys (12.61 ± 0.42 years), their estimated PHV was 5.88 ± 1.92 cm/year vs 6.45 ± 1.09 cm/year, their size at PHV was 142.2 ± 1.4 cm vs 152.8 ± 0.7 cm, and their final adult height was estimated to be 153.1 ± 0.3 cm vs 164.2 ± 0.7 cm. CONCLUSIONS: Peruvian children and adolescents' physical growth timing and tempo were influenced by their living altitudes. Those living at sea level experienced an earlier age at PHV were taller at time of PHV, had a higher PHV, and had a taller estimated final height compared to those living at higher altitudes. Girls and boys also differed significantly in their growth parameters.

Are there gross motor coordination spurts during mid-childhood?

OBJECTIVES: The aims of this study were (1) to identify the timing of the mid-growth spurt (MGS) in stature in children and (2) to identify gross motor coordination (GMC) spurts when aligned by the age of attainment of the MGS (aMGS). METHODS: Stature, weight, and GMC were measured in 245 Portuguese children followed annually from 6 to 10 years. GMC was assessed and to estimate children's MGS in stature as well as GMC spurts in each of the four tests aligned by aMGS, we used a nonsmoothed polynomial methodology. RESULTS: In boys, the aMGS was attained at 7.8 years, whereas in girls it was 8.0 years. In boys, the peak MGS was 6.2 cm∙yr-1 and in girls it was 6.4 cm∙yr-1 . In boys, the peak for walking backwards (WB) occurred 18 months before aMGS (14.9-points∙yr-1 ), jumping sideways (JS) was 12 months after aMGS (13.5-points∙yr-1 ), hopping on one leg (HO) was 18 months before aMGS (11.7-points∙yr-1 ), and shifting platform (SP) was 12 months before aMGS (6.8-points∙yr-1 ). In girls, WB spurts occurred 12 months after aMGS (13.3-points∙yr-1 ), JS was 12 months before aMGS (10.5-points∙yr-1 ), HO was coincident with aMGS (10.4-points∙yr-1 ), and SP was 18 as well as 12 months before aMGS (7.2-points∙yr-1 ). No differences were observed in the mean peak spurts between sexes in the GMC tests. CONCLUSIONS: Boys and girls reached their MGS in stature at about the same chronological age. Spurts in GMC did not express themselves in the same biological timing relative to aMGS in stature, and there are sex differences.

Motor performance, body fatness and environmental factors in preschool children.

The first aim of this study was to investigate the relationship between motor performance and body fatness among 3- to 5-year-old children. The second aim was to assess whether this relationship works similarly for boys and girls. We also investigated whether socioeconomic status (SES) and geographical area when children are aged 3 years old predicts the motor performance of 4 and 5-yr-old children. Motor performance was assessed through the Preschool Test Battery, while body fatness was estimated through body mass index (BMI). SES and geographical area were assessed via parent proxy-report questionnaires. BMI was negatively associated with standing long jump. The association of BMI and motor performance was not statistically different for boys and girls. Children from low SES performed better than high SES peers in tennis ball throw for distance. Rural children were better performers than urban peers in standing long jump. Rural area at baseline was also predictor of standing long jump and tennis ball throw for distance at time 1 and 2. In conclusion, BMI had a negative association with standing long jump and the relationship of BMI with all motor tests was similar for boys and girls. SES and rural area were predictors of motor performance.

Tracking of gross motor coordination in Portuguese children.

The purpose of this study was to investigate the tracking of gross motor coordination (GMC) and to profile children at 6 years of age who consistently showed higher stability patterns in different levels of GMC. The participants were 245 children (123 boys and 122 girls) who were assessed longitudinally from 6 to 9 years of age. GMC was assessed using the Korperkoordinationtest fur Kinder (KTK) test battery. Anthropometry, physical activity, and health- and performance-related physical fitness were also measured. Cohen's kappa (κ) was used to estimate tracking. Tracking was poor for all GMC tests (0.17 ≤ κ ≤ 0.38) and moderate for the GMC motor quotient (MQ) in both boys and girls (0.44 ≤ κ ≤ 0.45). Instability at the extremes was low in GMC tests and negligible for MQ. Children who consistently showed high GMC levels during the 4 years of follow-up were lighter, had lower body mass index and subcutaneous fat, and showed higher scores in physical fitness tests at 6 years of age than those who consistently had low GMC levels. In conclusion, GMC showed low-to-moderate tracking over time in childhood. However, children who consistently demonstrated high GMC levels over time had healthier profiles at 6 years of age.

Familial resemblance in gross motor coordination. The Peruvian Sibling Study on Growth and Health.

BACKGROUND: The development of gross motor coordination (GMC) is governed by biological and environmental factors whose effect sizes are still unclear. AIM: To investigate sibling resemblance in GMC, as well as biological and environmental correlates of GMC among Peruvian children. MATERIALS AND METHODS: The sample comprised 1256 biological siblings (6-15 years old), from three geographical areas of Peru. GMC was assessed using the Korperkoordinationtest für Kinder (KTK) test battery. Anthropometry, biological maturation and physical fitness (PF) were also measured. Multilevel modelling was performed using Stata 14 software. RESULTS: In general, sister-sister pairs (SS) showed the highest resemblance in GMC (ρ = 0.24) compared to brother-sister (BS) (ρ = 0.10) and brother-brother (BB) pairs (ρ = 0.07). On average, BB pairs had higher GMC than SS pairs and older siblings had higher GMC than younger siblings. Further, those with lower body mass index (BMI) and higher PF had higher GMC. There was also a significant interaction between age and PF with GMC. Siblings from the rainforest region demonstrated higher GMC than those from sea level and high-altitude siblings demonstrated lower GMC than their sea-level peers. CONCLUSION: These results demonstrate statistically significant sibling resemblance in GMC. Age, BMI, PF and geographical area were significant correlates of GMC.

High-Density Lipoprotein Cholesterol Level Relates to Working Memory, Immediate and Delayed Cued Recall in Brazilian Older Adults: The Role of Cognitive Reserve.

AIMS: The present study set out to investigate the relation of the high-density lipoprotein cholesterol (HDL-C) level to cognitive performance and its interplay with key markers of cognitive reserve in a large sample of older adults. METHODS: We assessed tests of working memory, immediate and delayed cued recall in 701 older adults from Amazonas, Brazil. The HDL-C level was derived from fasting blood samples. In addition, we interviewed individuals on their education, past occupation, and cognitive leisure activity. RESULTS: A critically low HDL-C level (<40 mg/dL) was significantly related to lower performance in working memory, immediate and delayed cued recall. Moderation analyses suggested that the relations of the HDL-C level to working memory and delayed cued recall were negligible in individuals with longer education, a higher cognitive level of the job, and greater engagement in cognitive leisure activity. CONCLUSION: Cognitive reserve accumulated during the life course may reduce the detrimental influences of a critically low HDL-C level on cognitive functioning in old age.

Correlates of health-related quality of life in young-old and old-old community-dwelling older adults.

PURPOSE: This study aimed (1) to examine the role of potential correlates of HRQoL in a large representative sample of older adults, and (2) to investigate whether the relationships between HRQoL and potential factors differ as a function of HRQoL component (physical vs. mental) and/or age cohort (young-old vs. old-old). METHODS: This cross-sectional study included 802 older adults aged 60-79 years old. HRQoL was assessed using the SF-36 questionnaire. Functional fitness was assessed using the Senior Fitness Test. Physical activity was measured via the Baecke questionnaire. Demographic information, mental and health features were obtained through questionnaires. RESULTS: A multiple regression analysis showed that BMI (ß = -0.15, p = 0.001), body strength (ß = 0.21, p < 0.001), aerobic endurance (ß = 0.29, p < 0.001), physical activity (ß = 0.11, p = 0.007), depressive symptoms (ß = -0.19, p < 0.001), falls (ß = -0.19, p < 0.001), and living alone (ß = -0.16, p < 0.001) were all significantly related to HRQoL-SF-36 total score. The positive relation with aerobic endurance was significantly higher for the physical component of HRQoL, while the negative relation with living alone was significantly higher for the mental component. The positive relation of HRQoL with physical activity was significantly higher in old-old compared to young-old adults. CONCLUSION: This data suggest that body composition, functional fitness, psycho-social factors, and falls are important correlates of HRQoL in old age. There are HRQoL-component and age-cohort differences regarding these correlates, underlying the need for specific strategies at the community level to promote HRQoL in older adults.

The relation of education, occupation, and cognitive activity to cognitive status in old age: the role of physical frailty.

BACKGROUND: It remains unclear so far whether the role of cognitive reserve may differ between physically frail compared to less frail individuals. Therefore, the present study set out to investigate the relation of key markers of cognitive reserve to cognitive status in old age and its interplay with physical frailty in a large sample of older adults. METHODS: We assessed Mini-Mental State Examination (MMSE) in 701 older adults. We measured grip strength as indicator of physical frailty and interviewed individuals on their education, past occupation, and cognitive leisure activity. RESULTS: Greater grip strength, longer education, higher cognitive level of job, and greater engaging in cognitive leisure activity were significantly related to higher MMSE scores. Moderation analyses showed that the relations of education, cognitive level of job, and cognitive leisure activity to MMSE scores were significantly larger in individuals with lower, compared to those with greater grip strength. CONCLUSIONS: Cognitive status in old age may more strongly depend on cognitive reserve accumulated during the life course in physically frail (compared to less frail) older adults. These findings may be explained by cross-domain compensation effects in vulnerable individuals.

Biological and environmental determinants of 12-minute run performance in youth.

BACKGROUND: The 12-minute run is a commonly used indicator of cardiorespiratory fitness in youth. Variation in growth and maturity status as potential correlates of test performance has not been systematically addressed. AIM: To evaluate biological and environmental determinants of 12-minute run performance in Portuguese youth aged 7-17 years. SUBJECTS AND METHODS: Mixed-longitudinal samples of 187 boys and 142 girls were surveyed in 1996, 1997 and 1998. The 12-minute run was the indicator of cardiorespiratory fitness. Height, body mass and five skinfolds were measured and skeletal maturity was assessed. Physical activity, socioeconomic status and area of residence were obtained with a questionnaire. Multi-level modelling was used for the analysis. RESULTS: Chronological age and sum of five skinfolds were significant predictors of 12-minute run performance. Older boys and girls ran longer distances than younger peers, while high levels of subcutaneous fat were associated with shorter running distances. Rural boys were more proficient in the 12-minute run than urban peers. Skeletal maturity, height, body mass index, physical activity and socioeconomic status were not significant predictors of 12-minute run performances. CONCLUSIONS: Age and sum of skinfolds in both sexes and rural residence in boys are significant predictors of 12-minute run performance in Portuguese youth.

Change, stability and prediction of gross motor co-ordination in Portuguese children.

BACKGROUND: The knowledge about intra- and inter-individual variation can stimulate attempts at description, interpretation and prediction of motor co-ordination (MC). AIM: To analyse change, stability and prediction of motor co-ordination (MC) in children. SUBJECTS AND METHODS: A total of 158 children, 83 boys and 75 girls, aged 6, 7 and 8 years, were evaluated in 2006 and re-evaluated in 2012 at 12, 13 and 14 years of age. MC was assessed through the Kiphard-Schilling's body co-ordination test and growth, skeletal maturity, physical fitness, fundamental motor skills (FMS), physical activity and socioeconomic status (SES) were measured and/or estimated. RESULTS: Repeated-measures MANOVA indicated that there was a significant effect of group, sex and time on a linear combination of the MC tests. Univariate tests revealed that group 3 (8-14 years) scored significantly better than group 1 (6-12 years) in all MC tests and boys performed better than girls in hopping for height and moving sideways. Scores in MC were also higher at follow-up than at baseline. Inter-age correlations for MC were between 0.15-0.74. Childhood predictors of MC were growth, physical fitness, FMS, physical activity and SES. Biological maturation did not contribute to prediction of MC. CONCLUSION: MC seemed moderately stable from childhood through adolescence and, additionally, inter-individual predictors at adolescence were growth, FMS, physical fitness, physical activity and SES.

Skeletal Muscle and Physical Activity in Portuguese Community-Dwelling Older Adults.

The aims of this study were to describe age- and sex-related differences in total body skeletal muscle (TB-SM) mass and to determine the variance explained by physical activity (PA). This cross-sectional study included 401 males and 402 females, aged 60-79 years. TB-SM was determined by dual-energy x-ray absorptiometry (DXA) and PA by Baecke questionnaire. Statistical analysis included t test, ANOVAs, Pearson correlations, and multiple regression analysis. TB-SM mass was higher in the youngest age group when compared with the oldest in males and females. Males had greater TB-SM values than females. PA made a significant and positive contribution to the variation in TB-SM, ß = 0.071; p = .016. Sex, height, fat mass, and PA explained 77% of the variance in TB-SM. The oldest cohorts and females had lower TB-SM than the younger cohorts and males. This study suggests that PA exerts a significant role in the explanation of TB-SM.