Differences in motor performance between children and adolescents in Mozambique and Portugal: impact of allometric scaling

Influence of an increased number of physical education lessons on the motor performance of adolescents-A non-interventional cohort study

Increasing the amount of regular physical education lessons in school is currently discussed in many countries in order to increase physical activity in youth. The purpose of this study was to compare the motor performance of pupils from an observation group participating in a school trial of two additional physical education lessons (5 lessons of each 50 min/week) without a specific intervention program to a control group with a regular amount of three physical education lessons (3 lessons of each 50 min/week) as indicated by the standard Austrian school curriculum. In this cohort study motor performance of 140 adolescents (12.7±0.5 years) was assessed by means of the German Motor Performance Test 6–18 over a period of 1.5 years with measurement time points before (T1), after eight months (T2) and at the end of the observation period (T3). Two- and three-way mixed analysis of variance were used to detect time, group and interaction effects. Although the observation group demonstrated a higher total motor performance score at all time points (P = 0.005), the improvement over time in total motor performance (P < 0.001) was more pronounced in the control group. Girls and boys developed differently over time (time*gender interaction: P = 0.001), whereby group allocation did not affect this interaction (time*gender*group: P = 0.167). Anyway, girls of control group tend to benefit most of additional physical education lessons. Sports club members scored significantly higher in motor performance across the observation period (P = 0.018) irrespective of group allocation. These findings indicate that there could be a ceiling effect in what the pupils could achieve in terms of motor performance as the pupils of the observation group might have reached this point earlier than their counterparts in the control group. Nevertheless, sports club membership seems to reveal some benefits. Whether improving quality and specificity of the single physical lessons might be superior to merely adding additional ones needs to be confirmed in future studies.

Normative data for handgrip strength in Iranian healthy children and adolescents aged 7-18 years: comparison with international norms

BACKGROUND

Grip strength is an essential component of physical fitness. The objective of this study was to develop normative handgrip strength data for Iranian healthy boys and girls comparing their handgrip strength with international reference values.

METHODS

Handgrip strength was measured in 2637 healthy children/adolescents (1391 boys and 1246 girls), aged 7-18 years, using a standard adjustable Jamar hand dynamometer (Model 5030 J1, Sammons Preston Rolyan, Bolingbrook, IL, USA). Body mass (kg) and stature (cm) were measured and body mass index was computed in kg/m2. The sample was stratified by gender, age, and hand preference.

RESULTS

Handgrip strength increased with age and was considerably higher in boys than in girls for all age groups (p < 0.001). Grip strength had a parallel and linear growth for both genders until the age of about 11 years and showed a steeper upward slope in boys than in girls thereafter. The findings of the current investigation were significantly different from those of the previously published normative data, especially for boys over the age of 12 years and girls in the age range of 7-18 years (p < 0.001). This difference was mainly in such a way that the Iranians had lower handgrip strength.

CONCLUSIONS

The differences between present results and those of similar available in the literature in this field emphasize the significant role of using normative data specific to a particular population in research or clinical settings.

Speed agility trends in children according to growth

BACKGROUND

Speed agility is considered as the whole assessment of speed of movement, agility and coordination. The 10x4m test has been broadly used to evaluate physical fitness and overall health in children of developmental ages. A myriad of studies have investigated the ecology of speed agility (SA). However, body dimensions are rarely appraised, and this is a weakness because body shapes are affected by growth.

AIM

This study aimed to model SA-specific allometric equations, and develop an approach objectively predictive for performance while controlling for maturity through age at peak height velocity (agePHV).

SUBJECTS AND METHODS

A total of 7317 (3627 girls) children aged 8-11 years were SA-tested. Multiplicative models with allometric body-size components, agePHV, and categorical differences, were implemented to evaluate SA performance.

RESULTS

Model 1 accounted for body-size and shape only, whereas Model 2 included agePHV and Model 3 considered standing broad jump (SBJ) as a surrogate marker for explosive strength. An ectomorphic dominance was revealed across all the models.

CONCLUSION

The explosive strength resulted in influencing SA per height-to-weight ratio. Further, positive exponent of agePHV suggested that the late maturers were likely to show better SA performances. Predictive equations modelled on developmental factors are fundamental to scrutinise performances as valuable health and fitness outcomes in childhood.

Relationship between cardiorespiratory fitness and latitude in children and adolescents: Results from a cross-sectional survey in China

Background

This study assessed the correlation between latitude and the cardiorespiratory fitness (CRF) of children and adolescents.

Methods

In 16 provinces and autonomous regions in China, 25,941 children and adolescents aged 10–18 were included. CRF was measured using the 20 m shuttle run test (20 m SRT) and estimated peak oxygen uptake (VO_2peak). One-way ANOVA and multiple regression analysis were used to explore the correlation between CRF and latitude in children and adolescents.

Results

The VO_2peak values of the low (south), middle, and high (north) latitude groups for boys were 43.1, 43.1, and 40.7 mL/kg/min, respectively, and 40.0, 40.0, and 38.5 mL/kg/min for girls, respectively. After adjusting for confounding factors, the regression coefficients (β) between VO_2peak-Z and both latitude-Z and (latitude-Z)² for boys were −0.151 and −0.043, respectively. For girls, they were −0.142 and −0.020, respectively. The Partial correlation coefficient (r) for latitude-Z and (latitude-Z)² were −0.14 and −0.04 for boys, and −0.13 and −0.02 for girls, respectively.

Conclusion

The CRF among children and adolescents in high latitude regions is significantly lower than that in middle and low latitude region, and it generally shows a “parabolic” trend between Latitude-Z and VO_2peak-Z.

Changes in Physical Fitness Among Preschool Children From Kraków (Poland) From 2008 to 2018

BACKGROUND

The aim of this study was to analyze the secular changes of the physical fitness of preschool children from Kraków, Poland between 2008 and 2018.

METHODS

The study group consisted of 2143 children (3- to 7-y-olds; 2008 cohort included 1037 children and the 2018 cohort included 1106 children). The following physical fitness tests were carried out: overhead medicine ball throw, standing broad jump, sit-and-reach test, and handgrip strength. Statistical differences between the cohorts were obtained using 2-way analysis of variance and Tukey tests.

RESULTS

Negative changes were noted for the standing broad jump and its relative results among boys. A negative trend was also observed for flexibility and ball throw. Positive changes were noted for the standing broad jump among girls, as well as the absolute and normalized results of handgrip strength in both sexes. Besides the flexibility, observed discrepancies were practically significant between the age groups. Differences between the cohorts reached practical significance in the case of absolute and normalized handgrip strength.

CONCLUSIONS

There was at least partial progress in the children's fitness. Physical fitness, in turn, is one of the most important health markers. Moreover, its low level is a predictor of diseases, including metabolic and cardiovascular ones, lower academic performance, and psychosocial problems.

Cross-cultural comparisons of aerobic and muscular fitness in Tanzanian and English youth: An allometric approach

Comparisons of physical fitness measures between children or within group measures over time are potentially confounded by differences in body size. We compared measures of strength (handgrip) and aerobic fitness (running-speed [20m shuttle-run]) of 10.0–15.9 year-olds from Dar es Salaam, Tanzania (n = 977) with schoolchildren from England (n = 1014) matched for age and sex. Differences in fitness were analyzed using general linear models, with allometric scaling for body size (mass and stature) and further adjustments for physical activity. Mean handgrip of Tanzanians was lower than English youth (F = 165.0, P<0.001, η_p² = .079). The difference became trivial when run-speed was scaled for body size (η_p² = .008). Running-speed of the English children was higher than in Tanzanians (F = 16.0, P<0.001, η_p² = .014). Allometric scaling for accentuated this between-county difference in running-speed (η_p² = .019) but when adjusted for physical activity between-country differences in running-speed were trivial (η_p² = .008). These data contradict those studies showing poor muscular fitness in African youth and highlight the need for appropriate scaling techniques to avoid confounding by differences in body size. In contrast to those from rural areas, our sample of contemporary urban Tanzanians were less aerobically fit than European youth. Differences were independent of body size. Lower aerobic fitness of urban Tanzanian youth may be due to reported physical activity levels lower than those of English youth and lower still than previously reported in rural Tanzania.

Temporal trends in muscular fitness of English 10-year-olds 1998-2014: An allometric approach

OBJECTIVES

To identify temporal trends in muscular fitness of English children using allometric scaling for height and weight to adjust for the influence of body size.

DESIGN

Repeated cross-sectional study.

METHODS

We measured; height, weight, standing broad-jump, handgrip, sit-ups and bent-arm hang in 10-year-old boys and girls from Chelmsford, England in: 2014 (n=306), 2008 (n=304) and 1998 (n=310). Physical activity was (PAQ-C) was assessed in 2008 and 2014. Muscular fitness was allometrically scaled for height and weight. We assessed temporal trends using General Linear Models (fixed factors: wave and sex) and reported effect sizes using partial eta squared (η_P²). We compared percentage change per year 1998-2008 with 2008-2014.

RESULTS

Ten-year-olds in 2014 were taller and heavier than in 2008 and 1998 but there were no differences in BMI. Compared with 2008, physical activity was lower in boys (η_P²=0.012) and girls (η_P²=0.27) assessed in 2014. There were significant main effects of wave for handgrip (η_P²=0.060), sit-ups (η_P²=0.120) and bent-arm hang (η_P²=0.204). Pairwise comparisons showed muscular fitness of both sexes was significantly lower in 2014 than in 1998. From 2008 to 2014 percent change per year in handgrip (1.6%) and sit-ups (3.9%) were greater than for the preceding decade (handgrip 0.6%, sit-ups 2.6%).

CONCLUSIONS

Downward temporal trends in muscular fitness appear independent of secular changes in body size. We found a decrease in self-reported physical activity concurrent with the accelerated declines in fitness from 2008 to 2014. These findings suggest the declines in children are not engaging in physical activities which support development of muscular fitness.

Socio-demographic differences in Colombian children's muscular fitness: Does scaling for differences in body size present a challenge to conventional thinking?

OBJECTIVES

In low- to middle-income countries, children from less-deprived areas (from families of higher socio-economic status [SES]) have superior muscular fitness than those from low-SES groups. They are also taller and heavier, factors associated with muscular fitness. The purpose of this study was to identify any socio-demographic differences in Colombian children's muscular fitness and examine how these conclusions can be modified by scaling for differences in body size.

METHODS

A total of 38,098 youths (46% girls), ninth grade students (aged 14-15 years), participated in a study of cross-sectional design. We recorded SES and family incomes, stature, and mass. Standing broad jump and handgrip strength were used to assess muscular fitness. A multiplicative allometric model was adopted to adjust for body-size differences.

RESULTS

Children from the mid- to high-SES groups jumped significantly higher than children from the lowest SES group, although no SES group difference in grip strength was observed. After adjusting for body size, children from higher SES and with higher family incomes had significantly lower handgrip strength, and their superior jump height performances remained but were greatly reduced. Only children from the highest SES now jumped significantly higher that the lowest SES group.

CONCLUSIONS

The superior jump performance and no difference in handgrip strength of Colombian children from higher SES may simply reflect their superior physiques. When body size is accounted for, these differences are reduced or even reversed, suggesting that children from higher SES groups should not be complacent regarding their apparent superior muscular fitness.