Grip strength cutpoints for youth based on a clinically relevant bone health outcome

The Relationship of Handgrip Strength to Body Composition and Cardiopulmonary Fitness in Children and Young Adults

Objective

To investigate the relationship between handgrip strength (HGS) and sex, anthropometrics, body composition, and cardiovascular fitness has not been well studied in children, adolescents, and young adults.

Study design

A single-center retrospective review of patients <25 years old without known heart disease and referred for clinical cardiopulmonary exercise testing was performed. Each patient underwent HGS testing, bioelectrical impedance body composition analysis, and cardiopulmonary exercise testing. Relationships between variables were assessed using the Pearson correlation coefficient, linear regression, cubic spline, and multivariable analysis. Comparisons by sex were performed using the Student t test.

Results

The study included 316 patients without heart disease (age 15.1 ± 2.4 years old; 35% male). Male patients had greater peak dominant (34.4 ± 11.9 kg vs 27.8 ± 6.2 kg; P < .001) and nondominant (32.1 ± 11.1 kg vs 25.3 ± 6.0 kg; P < .001) HGS than female patients, with these differences more noticeable in the teenage years. Peak dominant HGS averaged 30.2 ± 9.3 kg and was correlated with age (r = 0.49, P < .001) and weight (r = 0.56, P < .0001); peak dominant HGS was even more strongly correlated with total body skeletal muscle mass (r = 0.80, P < .001), peak oxygen consumption (mL/min) (r = 0.69, P < .0001), and peak work rate (r = 0.70, P < .001).

Conclusions

HGS is strongly associated with total and segmental skeletal muscle mass, peak work rate, and peak oxygen consumption. Sex-based differences in handgrip strength values emerge in mid-teenage years in parallel to expected pubertal changes.

Growth and physical development of children at apparent risk of sarcopenia

BACKGROUND

The consequences of sarcopenia on growth have received little attention. We analysed the potential risk resulting from the low lean mass for age expressed through the appendicular lean body mass index (aLBMI) and the ratio aLBM/trunk fat mass (trFM).

METHODS

The sample consisted of 580 participants 10-13 yrs evaluated twice in a 12-month interval: height, trFM, total and aLBM, whole-body bone mineral density less head (WBLH BMD), tibia and radius SOS, maturity and handgrip strength were measured. All variables except maturity and BMI were standardised according to sex and age group (Z-score) using the sample as a reference. A high risk of sarcopenia was identified for Z-scores ≤ -1 on aLBMI (Group B) or aLBM/trFM (Group C), while Z-scores > -1 on both markers were considered at low risk for sarcopenia (Group A). The ANCOVA adjusted for maturity was used to compare the three groups.

RESULTS

Girls showed a more significant decrease in the total BMC/LBM ratio in Group B and a minor increase in WBLH BMD in Group C (p < 0.050); boys in Group B showed a tendency to gain less height (p = 0.053).

CONCLUSION

The high risk of sarcopenia expressed through aLBMI or aLBM/trFM Z-score ≤ -1 compromises bone mineralisation in girls.

IMPACT

The findings emphasise the necessity of implementing routine screening protocols for sarcopenia risk within clinical environments and educational institutions. Such screenings should extend beyond merely assessing body mass index to encompass broader body composition variables like lean body mass. By integrating these assessments into routine health evaluations, healthcare professionals and educators can proactively identify at-risk individuals and initiate timely interventions for suboptimal physical growth and development.

Upper Extremity Musculoskeletal Profiles in Tennis Players: A Systematic Review

CONTEXT

Tennis-specific musculoskeletal (MSK) screening can assess range of motion (ROM) and muscular imbalances. Identifying normative values before implementing a MSK screen is essential in contributing to athlete performance and injury risk profiles.

OBJECTIVE

To review upper extremity MSK data in healthy tennis players across age, sex, and level of play.

DATA SOURCE

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed for this review. A search was conducted in MEDLINE, SPORTDiscus, Embase, and CINAHL.

STUDY SELECTION

This review included shoulder, elbow, and wrist ROM, isometric strength, or isokinetic strength in a tennis population. Each article was critically appraised to help identify the internal and external validity of each study.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 3.

DATA EXTRACTION

A total of 41 studies met the search criteria. Each contributor organized the data elements of interest into data tables, with a second contributor assigned for review. Data elements of interest included player and study characteristics: ROM, isometric dynamometry, and isokinetic strength.

RESULTS

A total of 3174 players were included in the final studies. Most of the players included were competitive adolescents and young adults; 15 studies included ROM data. Male tennis players consistently had more external rotation (ER) gain (range, 1.8º to 8.8º) and internal rotation (IR) loss (range, -15.3º to -3.0º) when compared with their female counterparts (ER range, -2.5º to 5.8º; IR range, -10.4º to -3º). Shoulder IR and ER strength were measured in the majority of all the strength studies, with the external rotators generating at least two-thirds the strength of the internal rotators.

CONCLUSION

Overall MSK data of tennis players indicate that shoulder strength values are often larger than nontennis players, but equal to or slightly lower than comparable athletes in other overhead sports. Adaptive changes of the glenohumeral joint and subsequent rotational motion are similar to those of other overhead athletes.

High muscular fitness level may positively affect bone strength and body composition in children with overweight and obesity

Muscular fitness plays a major role in bone health and body composition in overweight and obese children. It is key that the development of this muscle fitness is affected by absolute isometric strength and dynamic strength.

PURPOSE

To compare bone health and body composition between overweight/obese children considering muscular fitness (MF) levels, and to investigate whether weight-bearing dynamic or absolute isometric strength, both involved in the development of this muscular fitness, are more related with bone health.

METHODS

MF of 59 overweight or obese children (10.1 ± 0.9 years, 27 females) was measured by a countermovement jump (CMJ), handgrip, and maximal isometric strength of knee extension. Participants were divided into four groups depending on their MF level performing a cluster analysis: 16 children with high MF (HMF) in all tests, 18 with high performance in isometric strength (HIS), 15 with high performance in CMJ (HCMJ) and 10 low isometric and low dynamic force values (LMF). Body composition values were measured by dual energy X-ray absorptiometry, and bone strength values were assessed by peripheral quantitative computed tomography. Motor skills were evaluated using TGMD-3. Multivariate analysis of covariance test was applied to analyse bone strength differences between children in the different MF groups, using maturity offset, height and weight as covariates, and correlations were investigated.

RESULTS

HMF excelled in bone health. HIS had higher cortical bone area, periosteal circumference, bone mass, polar strength strain index and fracture load than LMF, while HCMJ only showed better results in trabecular bone area than LMF. HMF had significantly better values of fracture load and periosteal and endosteal circumferences than HCMJ, but not than HIS.

CONCLUSIONS

High MF level shows positive effects on bone health in overweight/obese children. Those with highest isometric strength had better bone health compared to those with higher dynamic strength.

TRIAL REGISTRATION

The research project was registered in a public database Clinicaltrials.gov in June 2020 with the identification number NCT04418713.

Multivariable reference centiles for maximum grip strength in childhood to young adults

OBJECTIVES

Maximum grip strength (mGS) is a useful predictor of health-related outcomes in children and adults. The aim of the study was to generate sex- and age-adjusted reference centiles for mGS for children, adolescents and young adults, while adjusting for body height and body mass index (BMI).

METHODS

A retrospective analysis of longitudinal data from children and young adults participating in the DOrtmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study (single center, open cohort study) from 2004 to 2022 was conducted. To generate sex-, age-, height- and BMI-adjusted reference centiles, a new algorithm combining multiple linear regression and the LMS method was conducted.

RESULTS

Overall, 3325 measurements of mGS of 465 females and 511 males were eligible. The mean age at measurement of females was 12.6 ± 3.9 years, mean age of males was 12.4 ± 4.7 years. The median of number of repeated measurements per individual was 3 (range 1-8). The mGS was significantly (p < 0.001) correlated to body height and BMI (r = 0.303-0.432). Additional reference centiles for the change of z-scores of mGS were generated for children and young adults from 8 to 20 years.

CONCLUSIONS

We proposed to evaluate mGS in children, adolescents and young adults with the presented reference centiles adjusted to sex, age, height and BMI. The method presented may also be applicable to other biological variables that depend more than just on sex and age. For the first time, also reference centiles to assess the change of mGS in repeated measurements were presented.

Muscle strength deficits are associated with low bone mineral density in young pediatric cancer survivors: The iBoneFIT project

BACKGROUND

Pediatric cancer survivors are at increased risk of muscle weakness and low areal bone mineral density (aBMD). However, the prevalence of muscle strength deficits is not well documented, and the associations of muscle strength with aBMD are unknown in this population. Therefore, this study aimed to investigate the prevalence of upper- and lower-body muscle strength deficits and to examine the associations of upper- and lower-body muscle strength with age-, sex, and race-specific aBMD Z-scores at the total body, total hip, femoral neck, and lumbar spine.

METHODS

This cross-sectional study included 116 pediatric cancer survivors (12.1 ± 3.3 years old, mean ± SD; 42.2% female). Upper- and lower-body muscle strength were assessed by handgrip and standing long jump test, respectively. Dual‑energy X‑ray absorptiometry was used to measure aBMD (g/cm2). Associations between muscle strength and aBMD were evaluated in multivariable linear regression models. Logistic regression was used to evaluate the contribution of muscle strength (1-decile lower) to the odds of having low aBMD (Z-score ≤ 1.0). All analyses were adjusted for time from treatment completion, radiotherapy exposure, and body mass index.

RESULTS

More than one-half of survivors were within the 2 lowest deciles for upper- (56.9%) and lower- body muscle strength (60.0%) in comparison to age- and sex-specific reference values. Muscle strength deficits were associated with lower aBMD Z-scores at all sites (B = 0.133-0.258, p = 0.001-0.032). Each 1-decile lower in upper-body muscle strength was associated with 30%-95% higher odds of having low aBMD Z-scores at all sites. Each 1-decile lower in lower-body muscle strength was associated with 35%-70% higher odds of having low aBMD Z-scores at total body, total hip, and femoral neck.

CONCLUSION

Muscle strength deficits are prevalent in young pediatric cancer survivors, and such deficits are associated with lower aBMD Z-scores at all sites. These results suggest that interventions designed to improve muscle strength in this vulnerable population may have the added benefit of improving aBMD.

How to design and establish a national school-based physical fitness monitoring and surveillance system for children and adolescents: A 10-step approach recommended by the FitBack network

BACKGROUND

Providing individual- and population-level data on children's physical fitness (PF) is a crucial public health and education priority. However, few national fitness monitoring or surveillance systems are currently in practice internationally. We aim to summarize the current European PF monitoring and surveillance systems for school-aged children and to provide experience-based guidelines on how to design such systems.

METHODS

The FitBack network consists of experts from diverse backgrounds with the common interest to improve the accessibility of PF monitoring for young people globally. Through FitBack network, we identified and compared the national or regional PF monitoring and surveillance systems currently in operation across Europe. We formulated a 10-step approach for designing and establishing one's own system, based on analysis of experienced strengths, weaknesses, opportunities, and threats to monitoring childhood fitness.

RESULTS

We identified a total of eight PF monitoring systems in Finland, France, Galicia of Spain, Hungary, Lithuania, Portugal, Serbia, and Slovenia. The FitBack network recommends the following steps for designing and establishing one's own system: (1) set up mission statements and aims, (2) involve stakeholders, (3) utilize scientific background, (4) governance structure, (5) ensure sufficient funding, (6) data management planning, (7) provide meaningful feedback, (8) conduct pilot testing, (9) plan implementation process, and (10) invest in communication with stakeholders.

CONCLUSIONS

This study provides an updated overview of the best practices for school-aged children's fitness monitoring and surveillance in Europe. Additionally, it offers a 10-step approach to assist in the creation of similar systems in Europe or globally.

Physical fitness trends in a nationally representative sample of Portuguese youth: What has changed from 2008 to 2018?

This investigation aimed to describe the current physical fitness (PF) status of Portuguese youth, compare secular trends from 2008 and 2018, and establish updated age- and sex-specific percentile values for distinct PF tests. In 2008 and 2018, 22 048 and 8960 children and adolescents (10-18 years) were included in two national cross-sectional investigations. PF was evaluated using the FITESCOLA® battery tests and the handgrip strength test. Independent sample t-tests and chi-squared tests were used to model the results. Weight smoothed percentile values were calculated using Cole's Lambda-Mu-Sigma (LMS) method. All analyses were weighted according to age, sex, and geographic region. In 2018, boys surpassed girls in the 20-m shuttle run, curl-ups, push-ups, standing long, and vertical jump tests, while girls performed better in the sit-and-reach (p < 0.05). The percentage of boys and girls meeting the healthy zone in the 20-min shuttle run test did not differ between 2008 and 2018 (p ≥ 0.05). In boys, a higher percentage fell in the healthy zone for the curl-up and push-up tests in 2018 compared to 2008 (85.8% vs. 83.4%, and 57.8% vs. 53.8%; p < 0.05). Girls improved their flexibility component (sit-and-reach test), with a higher percentage meeting the healthy zone in 2018 (32.6% vs. 36.9%; p < 0.05); an opposite trend was seen for boys (65.5% vs. 50.1%; p < 0.05). The present investigation provides new and updated PF percentile curves for Portuguese youth, which can be used as a general overview of the current PF state among the Portuguese young population.

The Influence of Accelerometer Epoch Length on Associations of Physical Activity Intensity and Volume with Bone Outcomes

Two accelerometer metrics (intensity-gradient and average-acceleration) can be used to determine the relative contributions of physical activity (PA) volume and intensity for health, but it is unknown whether epoch length influences the associations detected. This is important when considering bone health, as bone is particularly responsive to high intensity PA, which may be underestimated by longer epochs. This study aimed to assess the associations between average-acceleration, a proxy measure of PA volume, and intensity-gradient, reflective of PA intensity distribution, from PA data from 1-s to 60-s epochs at age 17 to 23 years with bone outcomes at age 23 years. This is a secondary analysis of 220 participants (124 females) from the Iowa Bone Development Study, a longitudinal study of bone health from childhood to early adulthood. Accelerometer-assessed PA data, captured at age 17 to 23 years, were summarised over 1-s, 5-s, 15-s, 30-s, and 60-s epochs, to generate average-acceleration and intensity-gradient from each epoch length, averaged across ages. Regression analysed associations between mutually adjusted average-acceleration and intensity-gradient with dual-energy X-ray absorptiometry assessed total-body-less-head (TBLH) bone mineral content (BMC), spine areal bone mineral density (aBMD), hip aBMD, and femoral neck cross-sectional area and section modulus at age 23 years. Intensity-gradient was positively associated with TBLH BMC in females, with spine aBMD in males, and with hip aBMD and geometry in both sexes, when a 1 to 5-s epoch was used. Average-acceleration was positively associated with TBLH BMC, spine aBMD and hip aBMD in males, generally when the adjustment for intensity-gradient was from > 1-s epochs. Intensity and volume were important for bone outcomes in both sexes and males, respectively. A 1 to 5-s epoch length was most appropriate to assess the mutually adjusted associations of intensity-gradient and average-acceleration with bone outcomes in young adults.

Sprint and upper limbs power field tests for the screening of low bone mineral density in children

Background: The possibility of carrying out screening, with acceptable accuracy, of a child's bone mass status based on a physical fitness test can advance the concept of health-related physical fitness. In addition, the relevance of the applicability of this type of screening in educational environments is mainly due to the difficulty of direct assessments of bone health indicators. This study aimed to propose cut-off points for physical fitness tests based on children's bone health indicators. Methods: This is a two-phase cross-sectional study. Phase-1: 160 children (6-11 years-old) performed the 20-m sprint test (20-mST) and the 2 kg medicine ball throw test (2 kgMBTT). Areal bone mineral density (aBMD) and content was assessed by DXA. The area under the ROC curve greater than 70% was considered valid. Phase-2: It was carried out a secondary analysis in a sample with 8,750 Brazilians (6-11 years-old). The percentile values (identified in phase-1) were used to identify the values of the cut-off points in the unit of measurement of the tests. The validation of the cut-off points found was by odds ratio values and p ≤ 0.05. Results: Phase 1: The areas under the ROC curve were 0.710, 0.712 (boys and girls-20-mST), 0.703, and 0.806 (boys and girls-2 kgMBTT) with total spine and pelvis aBMD as the outcome. Phase 2: From percentile values, we find valid cut-off points in the Brazilian sample (OR > 3.00; p < 0.001) for boys and girls. Values ranged between 5.22 s-4.00 s to 20-mST and between 125.0 cm-160.0 cm to 2 kgMBTT. Conclusion. The 20-mST and the 2 kgMBTT presented sufficient accuracy for the screening of children aged between 6 and 11 years with greater chances of having low aBMD in the total spine and pelvis, with valid cut-off points.

Comparison of handgrip strength values in young children when using two different types of dynamometers

OBJECTIVE

A Smedley hand dynamometer is one of the standard devices for measuring handgrip strength (HGS) for children and adults. The aim was to compare the HGS values using two different types of dynamometers (Grip-A or Grip-D) in young children. To enable comparison between the two devices, we have redesigned the Grip-D (i.e., modified Grip-D).

METHODS

Twenty-five preschool children (10 girls and 15 boys) performed maximal voluntary HGS in the right hand using two different types of dynamometers. We ran a paired sample t-test on the difference in HGS between the two devices.

RESULTS

The measured values of HGS were 9.95 kg for Grip-A and 8.56 kg for modified Grip-D, and the difference between the two devices [1.39 (SD 0.65) kg] was greater than we expected (95% limits of agreement: 0.11, 2.6 kg). Thus, we then calibrated both dynamometers ourselves using known weights. The measured values were corrected if there was an error between the known weight and each dynamometer. Following adjustment, there was still a statistical difference (p < 0.001) in HGS between Grip-A [10.65 (SD 1.52) kg] and modified Grip-D [9.98 (SD 1.85) kg]. However, the difference between the two devices was 0.67 (SD 0.69) kg with the 95% limits of agreement between -0.68 and 2.0 kg.

CONCLUSION

It is concluded that the HGS values of children measured with the company-calibrated new Grip-A and modified Grip-D could provide reasonably close estimates.

Handgrip strength and associated factors among Brazilian adolescents: A cross-sectional study

BACKGROUND

The handgrip strength (HGS) is an indicator of muscle strength associated with several health outcomes in adolescents and adults. This cross-sectional study aimed to identify HGS levels and associated modifiable and non-modifiable risk factors in adolescents.

METHODS

The study included 971 adolescents (496 boys) aged 15-18 years. The HGS was measured by a dynamometer, and the maximum value of right and left hands were summed for a total score. Age, economic status, balanced diet, physical activity, and sedentary behavior were assessed by questionnaires, while body mass index was determined by measuring body weight and height. Multiple linear regression was carried out to examine the association.

RESULTS

65.4% of the adolescents presented low levels of HGS (boys: 73.8%; girls: 56.6%). Low levels of HGS were associated with weight status and height in both sexes. In boys, low levels of HGS were associated with age, balanced diet, physical activity, and sedentary behavior.

CONCLUSION

About six out of ten adolescentes presented low levels of HGS. The main predictors of low levels of HGS in boys were age, physical activity, sedentary behavior, and balanced diet, and weight status and height in both sexes.

Health-Related Motor Testing of Children in Primary School: A Systematic Review of Criterion-Referenced Standards

Being physically fit in younger years prevents several diseases in the presence as well as in the life course. Therefore, monitoring physical fitness and motor competence through motor testing is essential for determining developmental status and identifying health-related risks. The main objectives of this systematic review were (1) to identify currently available health-related criterion-referenced standards and cut-off points for physical fitness and motor competence test items, (2) to frame the methodological background on setting health-related criterion-referenced standards and (3) to give implications for a health-related evaluation system for physical fitness and motor competence tests. The electronic data base search (PubMed, Web of Science and SURF) yielded 2062 records in total and identified six empirical studies reporting cut-off points of motor test items for children (7-10 years), as well as 30 methodological papers discussing determination approaches to health-related criterion-referenced standards. Data collection, selection and analyses followed the PRISMA guidelines. Health-related motor test standards need to be gender- and age-specific but should refer to an absolute cut-off point rather than to relative performance in the reference group. Due to the lack of data on health-related criterion referenced standards, receiver-operating-characteristic (ROC) curves provide a tool for the determination of cut-off points and criterion referenced standards for physical fitness and motor competence tests. A standardized approach forms the fundamental base for a globally applicable evaluation of health-related fitness tests.

Handgrip strength as a surrogate marker of lean mass and risk of malnutrition in paediatric patients

BACKGROUND & AIMS

The use of handgrip strength (HGS) as a proxy of nutritional status in sick children has not been studied. This study created HGS centile charts in healthy children and explored the utility of HGS z-scores as markers of body composition and screening of malnutrition risk in sick children.

METHODS

Data from 535 healthy children aged 5-16 years were used for the development of HGS centiles adjusted either for age or height. In 595 sick children, relationships between HGS z-scores with body composition, malnutrition risk (Paediatric Yorkhill Malnutrition Score-PYMS), length of hospital stay (LOS) and biomarkers of disease severity were explored. The use of HGS z-score to identify sick children in need of further dietetic assessment was investigated.

RESULTS

Children scoring at high malnutrition risk with PYMS had lower HGS z-scores for age (by 0.51 SD, p < 0.001) and height (by 0.46 SD, p = 0.001) than those who scored low. A HGS z-score at cut-offs of -0.81 SD and -1.2 SD for age and height, respectively, was predictive of need for dietetic intervention in sick children with sensitivity of 79% and 70% and specificity of 56% and 69%, respectively. HGS z-scores were predictive of fat free mass (FFM) in sick and healthy (all p < 0.001) children, while fat mass was not. HGS z-scores were inversely related with plasma CRP (rho, age: -0.21; height: -0.23, both p = 0.001). HGS was not predictive of LOS.

CONCLUSION

HGS is predictive of FFM, could compliment assessment of malnutrition risk, and may help identify children for further dietetic intervention on admission to hospital.

Temporal Trends in the Standing Broad Jump Performance of 10,940,801 Children and Adolescents Between 1960 and 2017

BACKGROUND

The standing broad jump (SBJ) is an excellent functional measure of explosive lower-body strength that is significantly related to health among children and adolescents.

OBJECTIVES

The aim of this study was to estimate national (country-level) and international (pooled global data) temporal trends in SBJ performance for children and adolescents, and to examine the relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

METHODS

Data were obtained from a systematic search of studies reporting temporal trends in SBJ performance for 9- to 17-year-olds, and by examining national fitness datasets. Sample-weighted regression models estimated trends at the study/dataset-country-sex-age level, with national and international trends estimated by a post-stratified population-weighting procedure. Pearson's correlations quantified relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

RESULTS

Data from 34 studies/datasets were extracted to estimate trends for 10,940,801 children and adolescents from 24 high-, 4 upper-middle-, and 1 low-income countries between 1960 and 2017. Collectively, there was a negligible (per decade) improvement in SBJ performance of 1.73 cm (95% CI 1.71-1.75), 0.99% (95% CI 0.97-1.01) or a standardized effect size of 0.07 (0.07-0.07) over the entire period, with the rate of improvement steady from the 1960s to the 1980s, slowing in the 1990s, before declining. Sex- and age-related temporal differences were negligible. Trends differed between countries, with most countries experiencing declines. National trends in SBJ performance were not significantly related to national trends in health-related and socioeconomic/demographic indicators.

CONCLUSIONS

SBJ performance of children and adolescents has declined since 2000 (at least among most of the countries in this analysis) and is suggestive of a modern decline in functional explosive lower-body strength. Growing recognition of the importance of muscular fitness as a marker of population health highlights the need for continued tracking of temporal trends in SBJ, especially among low- and lower-middle-income countries for which temporal data are lacking.

PROSPERO REGISTRATION NUMBER

CRD42013003657.

Testing the Functional Model of Bone Development: Direct and Mediating Role of Muscle Strength on Bone Properties in Growing Youth

This study examines the functional model of bone development in peri-pubertal boys and girls. Specifically, we implemented a mixed-longitudinal design and hierarchical structural models to provide experimental evidence in support of the conceptual functional model of bone development, postulating that the primary mechanical stimulus of bone strength development is muscle force. To this end, we measured radial and tibial bone properties (speed of sound, SOS), isometric grip and knee extensors strength, bone resorption (urinary NTX concentration), body mass index (BMI), somatic maturity (years from peak height velocity) and skeletal maturity (bone age) in 180 children aged 8–16 years. Measurements were repeated 2–4 times over a period of 3 years. The multilevel structural equation modeling of 406 participant-session observations revealed similar results for radial and tibial SOS. Muscle strength (i.e., grip strength for the radial and knee extension for tibial model) and NTX have a significant direct effect on bone SOS (β = 0.29 and −0.18, respectively). Somatic maturity had a direct impact on muscle strength (β = 0.24) and both a direct and indirect effect on bone SOS (total effect, β = 0.30). Physical activity and BMI also had a significant direct impact on bone properties, (β = 0.06 and −0.18, respectively), and an additional significant indirect effect through muscle strength (β = 0.01 and 0.05, respectively) with small differences per bone site and sex. Muscle strength fully mediated the impact of bone age (β = 0.14) while there was no significant effect of energy intake on either muscle strength or bone SOS. In conclusion, our results support the functional model of bone development in that muscle strength and bone metabolism directly affect bone development while the contribution of maturity, physical activity, and other modulators such as BMI, on bone development is additionally modulated through their effect on muscle strength.

Bone characteristics and physical fitness in children and adolescents with visual impairment

BACKGROUND

Lower habitual physical activity in adolescents with visual impairment (VI) have detrimental effect on their general health such as bone quality and physical fitness. The aim of this study was to demonstrate the bone quality in children with VI and to analyze the correlations of their bone characteristics with anthropometric and physical fitness tests.

METHODS

The participants (N=38) were adolescents (14.85±2.79yrs) with low vision (n=18) or blindness (n=20). Dual-energy-X-ray absorptiometry (DEXA) was used to measure bone mineral density (BMD), bone mineral content (BMC) of the total body and L1-L4 of the lumbar spinal region. After anthropometry physical fitness was examined by laboratory test (VO2peak) and field tests (strength and running).

RESULTS

Height, weight, body mass index (BMI), VO2peak were similar in the two groups. Blind boys showed significant higher handgrip strength. Estimated VO2peak (from 20-m shuttle running test) was significantly lower in blind children (43.84±4.42ml/kg/min) than in children with low vision (35.08±5.23ml/kg/min;p<0.001). BMD and BMC did not differ in subgroups, Z-score of total body BMD was significantly lower in blind children. Means of Z-score in L1-L4 lumbal spinal region were negative values and similar in blind and low vision adolescents' subgroups. A linear regression model in the collective group revealed significant associations of BMD (r2=0.538;p=0.0001) and BMC (r2=0.698;p=0.048) with BMI and handgrip strength test.

CONCLUSIONS

Adolescents with VI have generally decreased bone health and physical fitness level. BMI and handgrip strength are predictors of total body BMD and BMC. Suggesting that these measures may be adequate to estimate bone health.

Vitamin D status is associated with muscular strength in a nationally representative sample of US youth

AIM

To evaluate the association between serum 25-hydroxyvitamin D (25OHD) and muscular strength in a nationally representative sample of US youth.

METHODS

Participants (n = 3350) were 6- to 18-y-olds from 2011 to 2014 National Health and Nutrition Examination Survey. Relative handgrip strength was quantified using age- and sex-specific z-scores. Poor strength was defined as those <25th percentile. Multivariate general linear and logistic models were used to compare strength and poor strength status by clinically relevant groupings of 25OHD.

RESULTS

Approximately 20.2% of youth had 25OHD <50 nmol/L. Mean relative strength was highest for those at ≥75 nmol/L of 25OHD. The percentage of boys/girls with poor strength in the <50 nmol/L, 50-74.9 nmol/L and ≥75 nmol/L groups was 34.9%/32.3%, 25.8%/28.2% and 14.0%/15.8%, respectively. The odds of boys and girls with <50 nmol/L 25OHD having poor strength were 2.8 (95% CI: 1.4, 5.5) and 3.4 (1.7, 6.8) times higher compared to those with ≥75 nmol/L, respectively.

CONCLUSION

Higher levels of circulating vitamin D were associated with higher relative strength, and poor strength was more prevalent when 25OHD was <75 nmol/L. These findings highlight the value of vitamin D for the muscle-bone unit and potential extraskeletal ramifications.

Influence of Health Related Fitness on the Morphofunctional Condition of Second Mature Aged Women

To analyze the influence of health-related fitness on the condition of second mature aged women. Participants: 65 women divided into two groups. Group 1-40 women, (43.33 ± 0.93) years old and group 2-25 women (44.40 ± 0.93) years old. The participants trained for 8 months, three times a week for 1 h. Group 1 trained dance aerobics (Monday), strength fitness (Wednesday) and stretching (Friday). Group 2 trained only stretching. The body length and mass, handgrip strength test, vital capacity, blood pressure, heart rate, Stange and Genchi tests, and motion amplitude in joints were evaluated before and after the program. The significance of the differences between the groups was evaluated by Student's criterion (t) and Rosenbaum (Q). The different intensity of the health-related effect was confirmed at the end of the program. Physiometric indicators significantly increased in group 1. The complex physical activity led to a decrease in heart rate. The results of the Stange and Genchi tests significantly increased. Goniometric indicators of group 2 increased. The comparative analysis of the participants indicators confirms the generalized and higher health-related effect of the complex fitness program. The effect of such a program showed an increase of the adaptive potential, a significant increase in the functional capabilities of women, and the optimization of the studied indicators. With the same time expenditure for health-related fitness, the complex program has a more multifaceted effect in comparison with stretching.

Association of Body Shape Index (ABSI) with Hand Grip Strength

Hand grip is a leading measure of muscle strength and general health, yet its association with body shape is not well characterized. Here, we examine correlations between grip strength, a body shape index (ABSI), and body mass index (BMI) in the 2011-2014 United States National Health and Nutrition Examination Survey cohorts. Grip strength was found to correlate negatively with ABSI (though positively with BMI), suggesting that those with a more central body profile tend to be weaker than others with the same weight. Individuals with low grip strength, as well as those with high ABSI, were more likely to die during follow up, whereas there was no association of BMI with mortality hazard. Transforming the grip strength, ABSI, and BMI by taking their logarithm prior to standardization did not meaningfully change the associations seen. These findings suggest that combining anthropometrics (ABSI, BMI) with grip strength may better identify individual mortality hazard in research studies and clinical practice.

A Systematic Analysis of Temporal Trends in the Handgrip Strength of 2,216,320 Children and Adolescents Between 1967 and 2017

OBJECTIVE

To estimate national and international temporal trends in handgrip strength for children and adolescents, and to examine relationships between trends in handgrip strength and trends in health-related and sociodemographic indicators.

METHODS

Data were obtained through a systematic search of studies reporting temporal trends in the handgrip strength for apparently healthy 9-17-year-olds, and by examining large national fitness datasets. Temporal trends at the country-sex-age level were estimated by sample-weighted regression models relating the year of testing to mean handgrip strength. International and national trends were estimated by a post-stratified population-weighting procedure. Pearson's correlations quantified relationships between national trends in handgrip strength and national trends in health-related/sociodemographic indicators.

RESULTS

2,216,320 children and adolescents from 13 high-, 5 upper-middle-, and 1 low-income countries/special administrative regions between 1967 and 2017 collectively showed a moderate improvement of 19.4% (95% CI 18.4-20.4) or 3.8% per decade (95% CI 3.6-4.0). The international rate of improvement progressively increased over time, with more recent values (post-2000) close to two times larger than those from the 1960s/1970s. Improvements were larger for children (9-12 years) compared to adolescents (13-17 years), and similar for boys and girls. Trends differed between countries, with relationships between national trends in handgrip strength and national trends in health-related/sociodemographic indicators negligible-to-weak and not statistically significant.

CONCLUSIONS

There has been a substantial improvement in absolute handgrip strength for children and adolescents since 1967. There is a need for improved international surveillance of handgrip strength, especially in low- and middle-income countries, to more confidently determine true international trends.

PROSPERO REGISTRATION NUMBER

CRD42013003657.

Low muscle mass and strength in pediatrics patients: Why should we care?

Skeletal muscle plays major roles in metabolism and overall health across the lifecycle. Emerging evidence indicates that prenatal (maternal diet during pregnancy and genetic defects) and postnatal factors (physical activity, hormones, dietary protein, and obesity) influence muscle mass acquisition and strength early in life. As a consequence, low muscle mass and strength contributes to several adverse health outcomes during childhood. Specifically, studies demonstrated inverse associations of muscle mass and strength to single and clustered metabolic risk factors. The literature also consistently reports that low muscle mass and strength are associated with reduced bone parameters during growth, increasing the risk of osteoporosis in old age. Furthermore, muscle mass gains are associated with improved neurodevelopment in the first years of life. Given these negative implications of low muscle mass and strength on health, it is crucial to track muscle mass and strength development from childhood to adolescence. Several body composition techniques are currently available for estimation of muscle mass, all with unique advantages and disadvantages. The value of ultrasound as a technique to measure muscle mass is emerging in pediatric research with potential for translating the research findings to clinical settings. For the assessment of muscle strength, the handgrip strength test has been widely employed but without a standardized protocol. Although further research is needed to define normative data and cut points for the low muscle mass and strength phenotype, the use of such non-invasive medical monitoring is a promising strategy to identify early abnormalities and prevent low muscle mass in adulthood.

Supplementation with Beef Extract Improves Exercise Performance and Reduces Post-Exercise Fatigue Independent of Gut Microbiota

Beef extract (BE) is a nutritional supplement obtained by cooking beef meat. Compared with traditional chicken essence or clam extract, BE is cheaper to produce and may be used for wound healing, as a chemotherapy supplement, or to prevent fatigue. In this study, we evaluated the potential beneficial effects of BE on exercise performance and the related role of the gut microbiota. Pathogen-free male BALB/c mice were divided into three groups to receive vehicle or BE (0, 12.3, or 24.6 mL/kg) by oral gavage for 28 days. Exercise performance was evaluated using forelimb grip strength, swimming time to exhaustion, and physiological levels of fatigue-related biomarkers (serum lactate, blood urea nitrogen, and glucose levels) after physical challenges. BE supplementation elevated endurance and grip strength in a dose-dependent manner; significantly decreased lactate and blood urea nitrogen levels after physical challenge; and significantly increased muscle glycogen content. The germ-free mice supplemented with BE or an equal-calorie portion of albumin did not show significant differences from the other groups in exercise performance and levels of related biomarkers. Therefore, BE supplementation improved endurance and reduced fatigue, which might be related to BE composition, but had no correlation with the gut microbiota.