BMI as a mediator of the relationship between muscular fitness and cardiometabolic risk in children: a mediation analysis

Cardiorespiratory fitness and socioeconomic influences in Chilean schoolchildren: a cross-sectional study

OBJECTIVE

To compare the cardiovascular risk and physical fitness, according to type of school in a national sample of Chilean school students.

METHODS

A total of 7,218 students participated, who completed all the national tests of the National System for Measuring the Quality of Education, which included physical fitness and anthropometric tests. The results were compared according to the type of educational establishment and anthropometric indicators were considered. Physical fitness was measured by lower extremity strength, abdominal strength, upper extremity strength, trunk flexibility, exertional heart rate, and cardiorespiratory fitness. Body mass index, heart rate, and waist-to-height ratio were analyzed as predictors of cardiovascular risk.

RESULTS

There were differences according to the type of establishment in the predictors of cardiovascular risk (p < 0.05). Differences were also found in the physical fitness tests evaluated (p < 0.01). Students in private schools (PSC) and subsidized schools (SC) had lower levels of cardiovascular risk and higher levels of physical fitness than public schools (PS) and schools with delegated administration (DA).

CONCLUSIONS

In conclusion, students in educational establishments with a higher socioeconomic level have lower levels of cardiovascular risk and better physical fitness than students in public establishments. The authors suggest considering specific school interventions to mitigate cardiovascular risk and improve physical fitness among this vulnerable population. To this end, future studies should analyze the characteristics of physical activity and nutritional habits in schools to determine the factors that affect the results.

The impact of reduced muscular fitness on cardiometabolic risk factors in children aged 9-11 years

AIM

To analyse the relationships between muscular fitness (MF), fat mass (FM), fat-free mass (FFM) and its combined ratio with cardiometabolic risk (CMR) and whether the relationship between MF and CMR is mediated by body composition in schoolchildren.

METHODS

A cross-sectional study was conducted on schoolchildren from Cuenca, Spain, between September and November 2017. FM and FFM were estimated using bioimpedance analysis. The CMR index was calculated from triglycerides-HDL-c ratio, arterial pressure and fasting insulin. The MF index was assessed using handgrip and standing long jump tests. Analysis of covariance models assessed CMR index differences across the MF index and the FM/FFM ratio categories. Mediation analysis examined whether the MF index and the CMR index association were mediated by FM, FFM or FM/FFM ratio.

RESULTS

The analyses involved 485 schoolchildren aged 9-11 years (55.4% girls). Children with a higher MF index had a lower CMR index (p < 0.05). This association did not persist after controlling for FM/FFM. FM, FFM and FM/FFM ratio mediated the relationship between the MF index and the CMR index.

CONCLUSION

Better levels of MF are associated with better cardiometabolic profile, but a healthy body composition is determinant to improve future health.

Accelerometer-Measured Physical Activity, Fitness and Indicators of Cardiometabolic Risk among Rural Adolescents: A Cross-Sectional Study at 15-Year Follow-up of the MINIMat Cohort

BACKGROUND

Little is known about the relationship of physical activity (PA) and fitness with cardiometabolic risk among rural adolescents in low- and middle-income countries. Thus, we examined the associations of PA and fitness with selected cardiometabolic indicators along with potential gender-based differences in a birth cohort of rural adolescents from southeast Bangladesh.

METHODS

We utilized data from the 15-year follow-up of Maternal and Infant Nutrition Interventions in Matlab (MINIMat) cohort (n = 2253). Wrist-worn ActiGraph wGT3x-BT accelerometers were used to estimate sedentary time (ST) and PA. Fitness was assessed using: handgrip strength, standing long jump, and Chester Step Test. Anthropometric parameters, systolic blood pressure (SBP), and fasting lipid, insulin and glucose levels were measured. We calculated insulin resistance using the Homeostasis Model Assessment equation (HOMA-IR). Linear regression and isotemporal substitution models were fitted.

RESULTS

The adolescents spent 64 min/day (inter-quartile range: 50-81) in moderate-to-vigorous physical activity (MVPA). A 10-minute-per-day higher vigorous PA (VPA) was associated with: 4.9% (95% confidence interval (CI): 2.9-6.8%) lower waist circumference (WC), 3.2 mmHg (95% CI: 1.5-4.8) lower SBP, 10.4% (95% CI: 2.9-17.3%) lower TG, and 24.4% (95% CI: 11.3-34.9%) lower HOMA-IR. MVPA showed similar associations of notably smaller magnitude. Except for WC, the associations were more pronounced among the boys. Substituting ST with VPA of equal duration was associated with lower WC, SBP, triglyceride and HOMA-IR. Grip strength was favorably associated with all indicators, displaying considerably large effect sizes.

CONCLUSION

Our findings indicated beneficial roles of PA- particularly VPA- and muscular fitness in shaping cardiometabolic profile in mid-adolescence. VPA and grip strength may represent potential targets for preventive strategies tailored to adolescents in resource-limited settings.

Role of muscle mass in the association between handgrip strength and blood pressure in children and adolescents

Studies have reported conflicting results on the association between handgrip strength (HGS) and blood pressure during childhood and adolescence. High multicollinearity involving somatic components that influence both HGS and blood pressure might be an important source of bias. This study sought to investigate the independent effects of HGS and muscle mass on blood pressure levels in children and adolescents. Muscle mass and fat mass (Multifrequency Electrical Bioimpedance) and systolic (SBP) and diastolic (DBP) blood pressure (Automatic oscillometric device) were assessed in 833 volunteers aged 6-18 years, of both sexes. Handgrip strength-for-age quartiles were calculated and participants were assigned to groups by HGS quartiles. Analysis of covariance was conducted to address the linear association between HGS and SBP adjusted for height, muscle mass, and fat mass. To test for linear trend, contrast analysis was conducted. Partial eta-squared was used to confirm or rule out a small significant effect of the independent variables on SBP. The effect size of HGS on SBP was not significant in both sexes. In girls, 1.7% of the between-groups variance in SBP was accounted for by muscle mass (P = 0.016). In boys, 2.3% and 1.8% of the between-groups variance in SBP was accounted for by muscle mass (P = 0.001) and height (P = 0.005), respectively. In conclusion, children with a more advanced physical maturity for their age, that is, who are taller, stronger, and have greater fat-free mass, may be nearly reaching the physiological parameters of adulthood, and consequently have higher systolic blood pressure.

The Effects of a Physical Activity Intervention on Adiposity, Physical Fitness and Motor Competence: A School-Based, Non-Randomized Controlled Trial

Evidence suggests that early physical activity interventions are a means of preventing childhood obesity and are more effective when delivered in a school setting and based on the ecological model. Therefore, the present study aims to determine the effect of a multicomponent intervention based on the ecological model on adiposity, physical fitness and motor competence in children aged 4 to 5 years.

METHODS

This study is a non-randomized controlled trial involving 173 children from Chile. The intervention was based on an ecological model and consisted of a physical activity program with three simultaneous parts, affecting intra- and interpersonal dimensions. The adiposity index, body mass index and waist circumference were measured. For physical fitness, muscle strength in the lower part, speed/agility and cardiorespiratory fitness were measured. Motor competence was assessed using catching, aiming and dynamic and static balance tests.

RESULTS

After the intervention, there was no reduction in adiposity indices; in the intervention group, body mass index increased significantly with a high effect size. The intervention group showed significant differences in physical fitness in the components of muscle strength in the lower part (p = 0.000) and speed/agility (p = 0.002). For motor competence, the intervention group showed significant improvements in most components.

CONCLUSIONS

The multicomponent intervention did not reduce adiposity indices; however, it caused significant improvements in the physical fitness and motor competence components, so it seems prudent to continue implementing it, given the benefits that adequate levels of motor competence and physical fitness bring to children's health, both in the short and long term.

Reduced muscle strength in patients with long-COVID-19 syndrome is mediated by limb muscle mass

Understanding the impact of COVID-19 on muscle strength may help to elucidate the organ systems that contribute to acute and chronic COVID-19 sequelae. We questioned whether patients with postdischarge symptoms after COVID-19 had compromised muscle strength compared with a control group, and if this potential relationship was mediated by the lower appendicular lean mass index (ALMI). A total of 99 patients with long-COVID-19 and 97 control participants were screened. Maximal grip strength was assessed with a TKK 5101 digital dynamometer, and leg extension 1RM was measured using EGYM Smart Strength machines. Body composition (fat mass percentage, lean mass, visceral fat, and appendicular lean mass index) was determined using a whole body dual-energy X-ray densitometer. Results showed that grip strength and leg extension strength were significantly higher in controls than in COVID-19 survivors (mean [SD], 32.82 [10.01] vs. 26.94 [10.33] kg; difference, 5.87 kg; P < 0.001) and (mean [SD], 93.98 [33.73] vs. 71.59 [33.70] kg; difference, 22.38 kg; P < 0.001), respectively). The relationship between long-COVID syndrome and grip/leg strength levels was partly mediated by ALMI, which explained 52% of the association for grip strength and 39% for leg extension. Our findings provide novel insights into the mechanisms underlying the relationship between long-COVID syndrome and grip/leg strength levels, supporting the negative effects of long-COVID syndrome on muscle function.NEW & NOTEWORTHY The causes of post-COVID-19 syndrome are uncertain. Limb muscle wasting common to patients with COVID-19 limits daily activities and exercise. In this cross-sectional study, we found that patients with long-COVID-19 syndrome had significantly lower absolute and relative muscle strength measurements than control participants. Interestingly, we identified that these relationships were mostly mediated by limb muscle mass. Our data thus suggest that the evident reduced upper and lower muscle mass is a putative cause of-or contributor to-the functional limitation of patients with long-COVID-19 syndrome.

Cross-sectional association between physical fitness and cardiometabolic risk in Chilean schoolchildren: the fat but fit paradox

BACKGROUND

Previous studies have examined the "fat but fit" paradox, revealing that greater levels of physical fitness may diminish the harmful consequences of excess weight on cardiometabolic risk. Despite the above, specific information about the "fat but fit" paradox in prepuberal population is scarce. The aim of this study was to determine the relationship between cardiometabolic risk across (individual and combined) physical fitness and excess weight status and whether the "fat but fit" paradox is met in the sample of schoolchildren analyzed.

METHODS

A cross-sectional study was conducted including 452 children (59.1% girls), aged 7-9 years from Santiago (Chile). Physical fitness was assessed as cardiorespiratory fitness and muscular fitness. Cardiorespiratory fitness was determined by the 6-minute-walk-test and muscle strength was assessed by the handgrip and standing long jump tests. Excess weight (overweight and obesity) was computed through body mass index (z-score). Cardiometabolic risk was established by summing the z-score of the serum glucose, triglycerides, high-density lipoprotein, insulin and waist-to-height ratio.

RESULTS

Schoolchildren with high physical fitness (individual or combined) showed the lowest cardiometabolic risk mean scores (P for trend <0.001 for all physical fitness groups). Conversely, schoolchildren with low physical fitness (individual or combined) showed the highest cardiometabolic risk mean scores (P for trend <0.001 for all categories). Additionally, schoolchildren without excess weight and with high individual or combined physical fitness status exhibits lower cardiometabolic risk mean scores compared to schoolchildren with excess weight and low physical fitness status (individual or combined) (P for trend <0.001 for all physical fitness groups). A lower odd of having high cardiometabolic risk was found in schoolchildren without excess weight and with both high physical fitness (both cardiorespiratory fitness and muscular fitness) [odds ratio (OR) =0.08; 95% confidence interval (CI): 0.04 to 0.16] in comparison to those with excess weight and low physical fitness.

CONCLUSIONS

Our results suggest that improvements in both fatness and aerobic fitness could be associated with lower cardiometabolic risk.

Muscular Fitness and Cardiometabolic Variables in Children and Adolescents: A Systematic Review

BACKGROUND

The importance of muscular fitness (MF) in the performance of activities of daily living is unequivocal. Additionally, emerging evidence has shown MF can reduce cardiometabolic risk in children and adolescents.

OBJECTIVES

The purpose of this study was to examine and summarize the evidence regarding the relationship between MF phenotypes (i.e., maximum muscular strength/power, muscular endurance, and maximum muscular strength/power/endurance) and cardiometabolic variables (obesity, blood pressure, lipids, glucose homeostasis, inflammatory markers, and clustered cardiometabolic variables) in children and adolescents.

DESIGN

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number CRD42020179273.

DATA SOURCES

A systematic review was performed on five databases (PubMed, EMBASE, SciELO, Scopus, and Web of Knowledge) from database inception to May 2020, with complementary searches in reference lists.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Eligibility criteria included (1) a study sample of youth aged ≤ 19 years, (2) an assessment of MF with individual or clustered cardiometabolic variables derived from adjusted models (regardless of test/measurement adopted or direction of reported association), and (3) a report of the association between both, using observational studies. Only original articles published in peer-reviewed journals in English, Portuguese, and Spanish languages were considered. The quality of the included studies was assessed by using the National Heart, Lung, and Blood Institute checklist. The percentage of results reporting a statistically significant inverse association between each MF phenotype and cardiometabolic variables was calculated.

RESULTS

Of the 23,686 articles initially identified, 96 were included (77 cross-sectional and 19 longitudinal), with data from children and adolescents from 35 countries. The score for the quality of evidence ranged from 0.33 to 0.92 (1.00 maximum). MF assessed by maximum muscular strength/power was inversely associated with lower obesity (64/113 total results (56.6%)) and reduction in clustered cardiometabolic risk (28/48 total results (58.3%)). When assessed by muscular endurance, an inverse association with obesity (30/44 total results (68.1%)) and cardiometabolic risk (5/8 total results (62.5%)) was identified. Most of the results for the relationship between MF phenotypes with blood pressure, lipids, glucose homeostasis, and inflammatory markers indicated a paucity of evidence for these interrelationships (percentage of results below 50.0%).

CONCLUSION

MF assessed by maximum muscular strength/power or muscular endurance is potentially associated with lower obesity and lower risk related to clustered cardiometabolic variables in children and adolescents. There is limited support for an inverse association between MF with blood pressure, lipids, glucose homeostasis biomarkers, and inflammatory markers in children and adolescents.

Muscle strength and its association with cardiometabolic variables in adolescents: does the expression of muscle strength values matter?

BACKGROUND

We investigate the association between different muscle strength (MS) indices with cardiometabolic variables in adolescents.

METHODS

Cross-sectional study comprising 351 adolescents (male 44.4%, age 16.6 ± 1.0 years) from Brazil. MS was assessed by handgrip strength and analyzed in five different ways: absolute MS and MS normalized for body weight, body mass index (BMI), height, and fat mass, respectively. Cardiometabolic variables investigated as outcomes were systolic and diastolic blood pressure (DBP), waist circumference (WC), high-sensitive C-reactive protein (hs-CRP), lipid and glucose metabolism markers. Multiple linear regression models adjusted for confounding factors were used.

RESULTS

Absolute MS and/or MS normalized for height was directly associated with WC [up to 32.8 cm, standard error (SE) = 4.7] and DBP (up to 8.8 mmHg, SE = 0.8), and inversely associated with high-density lipoprotein cholesterol (up to -8.0 mg/dL, SE = 14.1). MS normalized for body weight, BMI or fat mass was inversely associated with WC (up to -17.5 cm, SE = 2.2). According to sex, MS normalized for fat mass was inversely associated with triglycerides (male: 0.02 times lower, SE = 0.01; female: 0.05 times lower, SE = 0.01) and homeostatic model assessment for insulin resistance (male: 0.02 times lower, SE = 0.01; female: 0.06 times lower, SE = 0.01), and inversely associated with hs-CRP only among male (0.03 times lower, SE = 0.01).

CONCLUSION

When normalized for body weight, BMI or fat mass, MS was superior to absolute MS or MS normalized for height in representing adequately cardiometabolic variables among adolescents.

Association between relative handgrip strength and hypertension in Chinese adults: An analysis of four successive national surveys with 712,442 individuals (2000-2014)

OBJECTIVES

This study aimed to identify the 15-year trends of handgrip strength-to-weight (relative HS) and assess the association between relative HS and hypertension among Chinese adults aged 20-69.

METHODS

Using a complex, stratified, multistage probability cluster sampling, we analyzed data collected from 712,442 adults aged 20-69 years in four successive national surveys (2000-2014). We used a handheld dynamometer to measure strength and divided by body weight to calculate the relative HS. Blood pressure was recorded with a sphygmomanometer and hypertension was defined as resting systolic blood pressure at least 140 mmHg or diastolic at least 90 mmHg. The Mann-Kendall trend test examined trends in relative HS over time. We also computed odd ratios (OR) and 95% confidence intervals (95% CI) by tertile of relative HS and examined the association between relative HS and hypertension.

RESULTS

The relative HS level decreased with the increase of age in both male and females (p trend <0.001). In each of four surveys, one interquartile decrease in relative HS was associated with an increased risk of hypertension by 44% (OR = 1.44, 95%CI: 1.40-1.47), 58% (OR = 1.58, 95%CI: 1.54-1.62), 48% (OR = 1.48, 95%CI: 1.45-1.52), 43% (OR = 1.43, 95%CI: 1.40-1.47), respectively.

CONCLUSION

In the Chinese adult population, the relative HS level decreased from 2000 to 2014 across all ages in both males and females. A lower relative HS was associated with a higher risk of hypertension. The findings provided evidence for the association between muscle strength and hypertension in large-scaled population.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

Physical activity among children and adolescents is associated with lower adiposity, improved cardio-metabolic health, and improved fitness. Worldwide, fewer than 30% of children and adolescents meet global physical activity recommendations of at least 60 minutes of moderate to vigorous physical activity per day. Schools may be ideal sites for interventions given that children and adolescents in most parts of the world spend a substantial amount of time in transit to and from school or attending school.

OBJECTIVES

The purpose of this review update is to summarise the evidence on effectiveness of school-based interventions in increasing moderate to vigorous physical activity and improving fitness among children and adolescents 6 to 18 years of age. Specific objectives are: • to evaluate the effects of school-based interventions on increasing physical activity and improving fitness among children and adolescents; • to evaluate the effects of school-based interventions on improving body composition; and • to determine whether certain combinations or components (or both) of school-based interventions are more effective than others in promoting physical activity and fitness in this target population.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, BIOSIS, SPORTDiscus, and Sociological Abstracts to 1 June 2020, without language restrictions. We screened reference lists of included articles and relevant systematic reviews. We contacted primary authors of studies to ask for additional information.

SELECTION CRITERIA

Eligible interventions were relevant to public health practice (i.e. were not delivered by a clinician), were implemented in the school setting, and aimed to increase physical activity among all school-attending children and adolescents (aged 6 to 18) for at least 12 weeks. The review was limited to randomised controlled trials. For this update, we have added two new criteria: the primary aim of the study was to increase physical activity or fitness, and the study used an objective measure of physical activity or fitness. Primary outcomes included proportion of participants meeting physical activity guidelines and duration of moderate to vigorous physical activity and sedentary time (new to this update). Secondary outcomes included measured body mass index (BMI), physical fitness, health-related quality of life (new to this update), and adverse events (new to this update). Television viewing time, blood cholesterol, and blood pressure have been removed from this update.  DATA COLLECTION AND ANALYSIS: Two independent review authors used standardised forms to assess each study for relevance, to extract data, and to assess risk of bias. When discrepancies existed, discussion occurred until consensus was reached. Certainty of evidence was assessed according to GRADE. A random-effects meta-analysis based on the inverse variance method was conducted with participants stratified by age (children versus adolescents) when sufficient data were reported. Subgroup analyses explored effects by intervention type.

MAIN RESULTS

Based on the three new inclusion criteria, we excluded 16 of the 44 studies included in the previous version of this review. We screened an additional 9968 titles (search October 2011 to June 2020), of which 978 unique studies were potentially relevant and 61 met all criteria for this update. We included a total of 89 studies representing complete data for 66,752 study participants. Most studies included children only (n = 56), followed by adolescents only (n = 22), and both (n = 10); one study did not report student age. Multi-component interventions were most common (n = 40), followed by schooltime physical activity (n = 19), enhanced physical education (n = 15), and before and after school programmes (n = 14); one study explored both enhanced physical education and an after school programme. Lack of blinding of participants, personnel, and outcome assessors and loss to follow-up were the most common sources of bias.  Results show that school-based physical activity interventions probably result in little to no increase in time engaged in moderate to vigorous physical activity (mean difference (MD) 0.73 minutes/d, 95% confidence interval (CI) 0.16 to 1.30; 33 studies; moderate-certainty evidence) and may lead to little to no decrease in sedentary time (MD -3.78 minutes/d, 95% CI -7.80 to 0.24; 16 studies; low-certainty evidence). School-based physical activity interventions may improve physical fitness reported as maximal oxygen uptake (VO₂max) (MD 1.19 mL/kg/min, 95% CI 0.57 to 1.82; 13 studies; low-certainty evidence). School-based physical activity interventions may result in a very small decrease in BMI z-scores (MD -0.06, 95% CI -0.09 to -0.02; 21 studies; low-certainty evidence) and may not impact BMI expressed as kg/m² (MD -0.07, 95% CI -0.15 to 0.01; 50 studies; low-certainty evidence). We are very uncertain whether school-based physical activity interventions impact health-related quality of life or adverse events.

AUTHORS' CONCLUSIONS

Given the variability of results and the overall small effects, school staff and public health professionals must give the matter considerable thought before implementing school-based physical activity interventions. Given the heterogeneity of effects, the risk of bias, and findings that the magnitude of effect is generally small, results should be interpreted cautiously.

Associations between relative grip strength and type 2 diabetes mellitus: The Yangpyeong cohort of the Korean genome and epidemiology study

Objective

To investigate the association between relative grip strength and the prevalence of type 2 diabetes mellitus (T2DM) independently and in combination with body mass index (BMI) in Korean adults.

Methods

The cross-sectional study includes 2,811 men and women (age 40 to 92 years old) with no history of heart disease, stroke, or cancer. Relative grip strength was measured by a handheld dynamometer and calculated by dividing absolute grip strength by body weight. Logistic regression analysis was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of T2DM by sex-specific quintiles of relative grip strength. In a joint analysis, participants were classified into 4 groups: “weak (lowest 20% quintile one) and normal weight (BMI <25.0 kg/m²)”, “weak and overweight/obese (BMI ≥25.0 kg/m²)”, “strong (upper 80% four quintiles) and normal weight” or “strong and overweight/obese”.

Results

Among the 2,811 participants, 371 were identified as having T2DM. Compared with the lowest quintile of relative grip strength (weakest), the ORs (95% CIs) of T2DM were 0.73 (0.53–1.02), 0.68 (0.48–0.97), 0.72 (0.50–1.03), and 0.48 (0.32–0.74) in upper quintiles two, three, four, and five, respectively, after adjusting for BMI and other potential confounders. In the joint analysis, compared with the “weak and overweight/obese” reference group, the odds of T2DM [ORs (95% CIs)] was lower in the “strong and overweight/obese” group [0.65 (0.46–0.92)] and the “strong and normal weight” group [0.49 (0.35–0.67)], after adjusting for potential confounders.

Conclusion

In this cross-sectional study, greater relative grip strength was associated with a lower prevalence of T2DM independent of BMI in Korean adults. Additional prospective studies are needed to determine whether a causal association exists between relative grip strength and T2DM prevalence considering BMI.

Mediation and Moderation of Adiposity Indicators for the Association Between Grip Strength and Cardiovascular Disease Risk Scores

Background: This cross-sectional study evaluated mediation or moderation of adiposity indicators on the association between handgrip strength (HGS) and the 10-year cardiovascular disease risk scores (CVDR). Methods: In data of 15,206 Korean adults (6961 men and 8245 women) aged ≥30 years using the Korea National Health and Nutrition Examination Survey, HGS, body mass index (BMI), height, waist circumference, the components of Framingham CVDR, and covariates (sociodemographic factors, health behaviors, perceived stress, health, functional status, and nutritional status) were used. BMI, waist circumference, and waist-to-height ratio were used as adiposity indicators. Gender-specific general linear model and PROCESS Macro were applied. Results: HGS had an inverse association with the CVDR after adjusting for the covariates and BMI (or waist circumference), while adiposity indicators had positive associations with the CVDR after adjusting for the covariates and HGS. Mediation analysis shows indirect effects of adiposity indicators (0.010-0.019, P < 0.05) and direct effect of HGS on the CVDR (-0.08 to -0.09, P < 0.05) after adjusting for the covariates. Moderation analysis reveals positive interactions between HGS and adiposity indicators in the relationship with the CVDR after adjusting for the covariates (P < 0.05). The inverse association between the HGS and the CVDR tended to be stronger with decrease in adiposity levels. Conclusions: Adiposity indicators mediated and moderated the association between HGS and the CVDR in Koreans. The moderating effects indicate that the lower the levels of the adiposity indicators, the stronger the CVDR improvement effect of HGS.

Mediation role of cardiorespiratory fitness on the association between fatness and cardiometabolic risk in European adolescents: The HELENA study

PURPOSE

This study was aimed to analyze the mediation role of cardiorespiratory fitness (CRF) on the association between fatness and cardiometabolic risk scores (CMRs) in European adolescents.

METHODS

A cross-sectional study was conducted in adolescents (n = 525; 46% boys; 14.1 ± 1.1 years old, mean ± SD) from 10 European cities involved in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. CRF was measured by means of the shuttle run test, while fatness measures included body mass index (BMI), waist to height ratio, and fat mass index estimated from skinfold thicknesses. A clustered CMRs was computed by summing the standardized values of homeostasis model assessment, systolic blood pressure, triglycerides, total cholesterol/high-density lipoprotein cholesterol ratio, and leptin.

RESULTS

Linear regression models indicated that CRF acted as an important and partial mediator in the association between fatness and CMRs in 12-17-year-old adolescents (for BMI: coefficients of the indirect role β = 0.058 (95% confidence interval (95%CI): 0.023-0.101), Sobel test z = 3.11 (10.0% mediation); for waist to height ratio: β = 4.279 (95%CI: 2.242-7.059), z =3.86 (11.5% mediation); and for fat mass index: β = 0.060 (95%CI: 0.020-0.106), z = 2.85 (9.4% mediation); all p < 0.01).

CONCLUSION

In adolescents, the association between fatness and CMRs could be partially decreased with improvements to fitness levels; therefore, CRF contribution both in the clinical field and public health could be important to consider and promote in adolescents independently of their fatness levels.

Low Muscular Strength, Weight Status, and Metabolic Syndrome in Adolescents: National Health and Nutrition Examination Survey 2011-2014

PURPOSE

To investigate the association between muscular strength and metabolic syndrome (MetS), with a specific focus on the role of weight status, using a nationally representative sample of US youth.

METHODS

The analysis included 409 boys and 415 girls from the 2011 to 2014 National Health and Nutrition Examination Survey between 12 and 18 years of age. The prevalence of MetS was defined using age- and sex-specific criteria for abdominal obesity, elevated triglycerides, blood pressure, fasting glucose, and low high-density lipoprotein (HDL) cholesterol. Strength was assessed via handgrip dynamometer and expressed as age- and sex-specific z scores of relative strength. Low strength was defined as a relative strength below the 25th percentile. Analyses controlled for age, sex, race/ethnicity, physical activity, and weight status.

RESULTS

The sample prevalence of MetS was approximately 5.3%. However, MetS prevalence was 18.5% in overweight/obese youth with low strength. The adjusted odds of MetS were 3.1 (95% confidence interval, 1.5-6.3, P < .001) times higher for overweight/obese youth with low strength versus sufficient strength.

CONCLUSION

Muscular strength is predictive of adolescent MetS, specifically in those with unhealthy weight status. Approximately one in 5 overweight/obese youth with low strength had MetS. These findings highlight the relevance of muscular strength in youth cardiometabolic morbidities.

Plasma Interleukin-10 and Cholesterol Levels May Inform about Interdependences between Fitness and Fatness in Healthy Individuals

Relationships between demographic, anthropometric, inflammatory, lipid and glucose tolerance markers in connection with the fat but fit paradigm were investigated by supervised and unsupervised learning. Data from 81 apparently healthy participants (87% females) were used to generate four classes of fatness and fitness. Principal Component Analysis (PCA) revealed that the principal component was preponderantly composed of glucose tolerance parameters. IL-10 and high-density lipoprotein, low-density lipoprotein (LDL), and total cholesterol, along with body mass index (BMI), were the most important features according to Random Forest based recursive feature elimination. Decision Tree classification showed that these play a key role into assigning each individual in one of the four classes, with 70% accuracy, and acceptable classification agreement, κ = 0.54. However, the best classifier with 88% accuracy and κ = 0.79 was the Naïve Bayes. LDL and BMI partially mediated the relationship between fitness and fatness. Although unsupervised learning showed that the glucose tolerance cluster explains the highest quote of the variance, supervised learning revealed that the importance of IL-10, cholesterol levels and BMI was greater than the glucose tolerance PCA cluster. These results suggest that fitness and fatness may be interconnected by anti-inflammatory responses and cholesterol levels. Randomized controlled trials are needed to confirm these preliminary outcomes.

Gut microbiome mediates host genomic effects on phenotypes: a case study with fat deposition in pigs

A large number of studies have highlighted the importance of gut microbiome composition in shaping fat deposition in mammals. Several studies have also highlighted how host genome controls the abundance of certain species that make up the gut microbiota. We propose a systematic approach to infer how the host genome can control the gut microbiome, which in turn contributes to the host phenotype determination. We implemented a mediation test that can be applied to measured and latent dependent variables to describe fat deposition in swine (Sus scrofa). In this study, we identify several host genomic features having a microbiome-mediated effects on fat deposition. This demonstrates how the host genome can affect the phenotypic trait by inducing a change in gut microbiome composition that leads to a change in the phenotype. Host genomic variants identified through our analysis are different than the ones detected in a traditional genome-wide association study. In addition, the use of latent dependent variables allows for the discovery of additional host genomic features that do not show a significant effect on the measured variables. Microbiome-mediated host genomic effects can help understand the genetic determination of fat deposition. Since their contribution to the overall genetic variance is usually not included in association studies, they can contribute to filling the missing heritability gap and provide further insights into the host genome – gut microbiome interplay. Further studies should focus on the portability of these effects to other populations as well as their preservation when pro-/pre-/anti-biotics are used (i.e. remediation).

The Genetic Architecture of the Clustering of Cardiometabolic Risk Factors: A Study of 8- to 17-Year-Old Chinese Twins

We explored the genetic architecture of metabolic risk factors of cardiovascular diseases (CVDs) and their clustering in Chinese boys and girls. Seven metabolic traits (body mass index [BMI], waist circumference [WC], systolic blood pressure [SBP], diastolic blood pressure [DBP], total cholesterol [TC], triglyceride [TG], and uric acid [UA]) were measured in a sample of 1016 twins between 8 and 17 years of age, recruited from the Qingdao Twin Registry. Cholesky, independent pathway, and common pathway models were used to identify the latent genetic structure behind the clustering of these metabolic traits. Genetic architecture of these metabolic traits was largely similar in boys and girls. The highest heritability was found for BMI (a2 = 0.63) in boys and TC (a2 = .69) in girls. Three heritable factors, adiposity (BMI and WC), blood pressure (SBP and DBP), and metabolite factors (TC, TG, and UA), which formed one higher-order latent phenotype, were identified. Latent genetic, common environmental, and unique environmental factors indirectly impacted the three factors through one single latent factor. Our results suggest that there is one latent factor influencing several metabolic traits, which are known risk factors of CVDs in young Chinese twins. Latent genetic, common environmental, and unique environmental factors indirectly imposed on them. These results inform strategies for gene pleiotropic discovery and intervening of CVD risk factors during childhood and adolescence.

Prevalence of Risk of Eating Disorders and its Association with Obesity and Fitness

The university stage is a critical developmental period for young adults, where lifestyles can determine future health. A cross-sectional study including 481 college students was conducted, with the following objectives: 1) to examine the prevalence of risk of developing eating disorders in college students, 2) to assess differences in obesity and physical fitness in those with and without risk of eating disorders, and 3) to determine whether cardiorespiratory fitness, muscular fitness or fat mass were associated with the risk of eating disorders. We measured fat mass percentage (by densitometry), risk of feeding or eating disorders (by SCOFF questionnaire), cardiorespiratory fitness levels and a muscular fitness index. The prevalence of risk of eating disorders in women (32.4%) was higher than in men (17.4%) (p<0.001). In both sexes, higher obesity indicator mean values were observed among those who were at risk of eating disorders. Men participants without risk had higher cardiorespiratory fitness means than their at-risk peers [39.4 (8.3) vs. 32.4 (5.5), p<0.001)], and women showed differences only in the dynamometry/weight variable. In college students, it is necessary to promote healthy habits, including good levels of physical fitness, and to prevent excess body fat to effectively prevent eating disorders.

The association between screen time and cardiometabolic risk in young children

OBJECTIVES

While studies exist on the association between screen time and cardiometabolic risk among adolescents, research examining the effect of screen time on cardiometabolic risk in young children is lacking. The primary objective of this study was to examine the association between daily screen time and cardiometabolic risk (CMR) [sum of age- and sex-standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein (HDL) cholesterol divided by the square root of five] in young children. Secondary objectives included examining individual CMR risk factors, including waist-to-height ratio and non high-density lipoprotein (non-HDL) cholesterol, as well as the individual cut-offs of these risk factors. Additional analyses include examining the association between screen time and CMR by handheld/non-handheld devices.

METHODS

A study was conducted among young children 3 to 6 years from the TARGet Kids! practice-based research network in Toronto and Montreal, Canada. Children with one or more measures of screen time and CMR were included in this study. Generalized estimating equation (GEE) multivariable linear regressions and multivariable logistic regressions, using published cut-offs, were conducted to evaluate these associations.

RESULTS

Data from 1317 children [mean age 52 months (SD = 13.36), 44.34% female] were included for analyses. There was no evidence of associations between screen time and total CMR score or individual risk factors (p > 0.05) after adjusting for confounders. A statistically significant, but small association between daily screen time and non-HDL cholesterol was found (B = 0.046; CI = [0.017 to 0.075]; p = 0.002.

CONCLUSIONS

Though no relationship was reported between daily screen time and the majority of CMR factors in early childhood, there was an association between daily screen time and non-HDL cholesterol. As the relationship between daily screen time and CMR factors may not be apparent in early childhood, studies to evaluate longer-term cardiometabolic effects of screen time are needed. Although there is an evidence-based rationale to reduce screen time in early childhood, prevention of cardiometabolic risk may not be the primary driver.

Association of handgrip strength with the prevalence of hypertension in a Chinese Han population

Objective

Handgrip strength (HGS) exercise has been reported to reduce blood pressure in both hypertensive and normotensive patients. In this study, we evaluated the association of HGS with hypertension in a Chinese Han Population.

Methods

A total of 11,151 subjects mainly consisting of a rural population were recruited with a multi-stage sampling method in Jurong city, Jiangsu Province, China. Besides hypertension and diabetes, major chronic diseases were excluded. HGS was categorized into tertiles by age and gender. Logistic regression was used to estimate the association of HGS and hypertension with the odds ratio (OR) and 95% confidence interval (CI).

Results

From low to high tertiles of HGS, diastolic blood pressure (DBP) was significantly increased (74.52 ± 7.39, 74.70 ± 7.03, and 75.54 ± 7.01 mmHg, respectively; P_trend = 0.001), as well as in females (P_trend=0.003). The differences in DBP among the tertiles of HGS were still significant in females even after adjusting for covariates (P_trend=0.048). No significant differences in systolic blood pressure (SBP) were observed among the tertiles of HGS (P>0.05). Compared to low HGS, high HGS was significantly associated with hypertension after adjustment for age and gender (adjusted OR, 1.19; 95% CI, 1.06–1.34; P =0.004). A stratified analysis showed that the significant association of high HGS and hypertension was also observed with the following factors even after adjusting for age and gender: female gender (adjusted OR, 1.25; 95% CI, 1.08–1.46; P=0.004), ages of 60–69 years (adjusted OR, 1.29; 95% CI, 1.06–1.57; P=0.011), and married (adjusted OR, 1.20; 95% CI, 1.06–1.37; P=0.005). However, no significant associations were found after adjusting for age, gender, smoking status, drinking status, body mass index, physical activity level, glucose, high- and low-density lipoprotein cholesterol, total cholesterol, and triglyceride (P>0.05).

Conclusion

The findings of the current study suggest that HGS was positively correlated with DBP in a rural population, and high HGS was associated with hypertension in females; however, the association may be modified by smoking status, drinking status, body mass index, physical activity, cholesterol level, and glucose level. Further utilization of HGS exercises to intervene in the development and prognosis of hypertension should be verified in the future.

Muscle Fitness Cut Points for Early Assessment of Cardiovascular Risk in Children and Adolescents

OBJECTIVES

To study the cross-sectional and longitudinal (2-year follow-up) association between muscle fitness and cardiovascular disease (CVD) risk factors in youth; whether there are muscle fitness cut points associated with CVD risk (cross-sectional); and whether the health-related muscle fitness cut points identified at baseline are associated with CVD risk 2 years later.

STUDY DESIGN

In total, 237 children (110 girls) aged 6-10 years and 274 adolescents (131 girls) aged 12-16 years with complete data were included in the study (10.3% drop out). The handgrip strength and the standing long jump tests were used to assess muscle fitness. CVD risk score was computed with sum of 2 skinfolds, systolic blood pressure, insulin, glucose, triglycerides, and total cholesterol/high density lipoprotein cholesterol.

RESULTS

Muscle fitness at baseline was associated inversely with single CVD risk factors and CVD risk score at baseline and 2-year follow-up (all P < .05). Receiver operating characteristics curve analyses showed a significant discriminating accuracy of handgrip strength in identifying CVD risk in children and adolescents (boys: ≥ 0.367 and ≥0.473; girls: ≥ 0.306 and ≥0.423 kg/kg body mass, respectively, all P < .001). Similarly, the standing long jump cut points for children and adolescents were ≥104.5 and ≥140.5 in boys, and ≥81.5 and ≥120.5 cm in girls, respectively (all P < .05). These cut points were associated with CVD risk 2 years later (all P < .01).

CONCLUSIONS

Muscle fitness is associated with present and future cardiovascular health in youth, and is independent of cardiorespiratory fitness. It should be monitored to identify youth at risk who could benefit from intervention programs.

Effectiveness of a school-based physical activity intervention on adiposity, fitness and blood pressure: MOVI-KIDS study

OBJECTIVE

To test a physical activity intervention (MOVI-KIDS) on obesity indicators, physical fitness and blood pressure (BP) in children.

METHODS

A crossover randomised cluster trial was conducted, which comprised 1434 children (4-7 years old) from 21 schools in the provinces of Cuenca and Ciudad Real in the Castilla-La Mancha region of Spain. The intervention consisted of three 60 min sessions/week on weekdays between October 2013 and May 2014. Changes in anthropometric variables, physical fitness and BP parameters were measured. The analyses used were mixed regression models to adjust for baseline covariates under cluster randomisation.

RESULTS

There was no significant improvement in overweight/obesity with the intervention compared with the control group in both sexes. Further, the intervention did not alter other adiposity indicators or BP parameters. Improvements in cardiorespiratory fitness were seen in girls (1.19; 95% CI 0.31 to 2.08; p=0.008), but not in boys. Finally, there was an improvement in velocity/agility in both girls (-2.51 s; 95% CI -3.98 to -1.05; p=0.001) and boys (-2.35 s; 95% CI -3.71 to -0.98; p=0.001), and in muscular strength in both girls (0.66; 95% CI 0.03 to 1.28; p=0.038) and boys (1.26; 95% CI 0.03 to 1.28; p<0.001).

CONCLUSION

MOVI-KIDS was not successful in reducing the adiposity and maintained BP levels at previous healthy values in children. The intervention, however, showed significant improvements in cardiorespiratory fitness in girls, and muscular strength and velocity/agility in boys and girls.

TRIAL REGISTRATION NUMBER

NCT01971840; Post-results.

Normal weight obesity and physical fitness in Chinese university students: an overlooked association

BACKGROUND

The primary aim of this study was to examine the associations of normal weight obesity (NWO) with physical fitness in Chinese university students. As a secondary aim, we assessed whether possible differences in physical fitness between students classified as NWO and normal weight non-obese (NWNO) were mediated by skeletal muscles mass.

METHODS

A total of 383 students (205 males and 178 females, aged 18-24 years) from two universities volunteered to participate in this study. Body height and weight were measured by standard procedures and body composition was assessed by bio-impedance analysis (InBody 720). NWO was defined by a BMI of 18.5-23.9 kg/m2 and a body fat percentage of > 20% or > 30% in male and female students, respectively. Physical fitness was measured using a 10-min intermittent endurance running test (Andersen test), countermovement jumps (CMJ) and a 5 × 5 m shuttle run test (5mSR). The level of leisure time physical activity (PA) was assessed by a questionnaire.

RESULTS

13.7% of male and 27.5% of female students were classified as NWO. Compared to NWNO, students classified as NWO showed a significantly poorer performance in the Andersen test (males: 1146 ± 70 m vs. 1046 ± 95 m, females: 968 ± 61 m vs. 907 ± 67 m, p < 0.001), CMJ (males: 55.0 ± 7.6 cm vs. 44.9 ± 7.5 cm, females: 39.8 ± 8.0 cm vs. 33.7 ± 5.9 cm, p < 0.001) and 5mSR (males: 18.7 ± 1.0 s vs. 20.0 ± 0.9 s, females: 21.1 ± 1.1 s vs. 22.4 ± 1.3 s, p < 0.001), respectively. The lower levels of physical fitness in NWO were partially explained by lower skeletal muscle mass (p < 0.001) both in male and female students.

CONCLUSIONS

NWO was associated with poorer physical fitness and the relationship was partially mediated by lower skeletal muscle mass. The study indicated that attention should be paid for the potential hidden health risk in university students with normal body mass index but excessive fat mass.

Association of muscle strength with cardiovascular risk in Korean adults: Findings from the Korea National Health and Nutrition Examination Survey (KNHANES) VI to VII (2014-2016)

There are few existing studies that examine the association between muscle strength and cardiovascular disease (CVD) risk stratified by sex. Evaluation of the handgrip strength is a simple, quick, and inexpensive method to measure muscle strength. This study assessed the association of handgrip strength with the risk of CVD in the Korean general population.Data were derived from a subset of an ongoing nationally representative survey: the Korea National Health and Nutrition Examination Survey (KNHANES), 2014 to 2016, which included 8576 participants aged 40 to 79 years (men: 3807; women: 4769). Individual CVD risk was evaluated by calculating the atherosclerotic cardiovascular disease (ASCVD) risk score and the Framingham risk score (FRS) in subjects aged 40 to 79 years without prior CVD.Multivariate linear regression analysis revealed a significant inverse association (in both men and women) between relative handgrip strength and cardiovascular risk factors, including blood pressure, levels of fasting glucose and triglycerides, waist circumstance, FRS, high sensitivity C-reactive protein levels, and ASCVD risk. A significant positive association between relative handgrip and a low level of high density cholesterol levels in both men and women was identified. In both men and women, subjects in the lowest quartile of handgrip strength had an increased risk of CVD compared with those within the highest quartile (odds ratio range 2.05-3.03).The results of this study suggest that increased handgrip is associated with a lower degree of cardiovascular risk in both men and women. Longitudinal studies are needed to examine the association between muscle strength and cardiovascular risk.

Muscular Fitness and Cardiovascular Risk Factors in Children and Adolescents: A Systematic Review

Rodrigues de Lima, T, Custódio Martins, P, Henrique Guerra, P, and Augusto Santos Silva, D. Muscular fitness and cardiovascular risk factors in children and adolescents: A systematic review. J Strength Cond Res 34(8): 2394-2406, 2020-The purpose of this study was to identify and summarize the relationships between muscular fitness (MF) and individual components of metabolic syndrome (high waist circumference [WC], high blood pressure [BP], high systolic BP [SBP], high diastolic BP [DBP], high triglycerides [TG], fasting blood glucose [FG], and low HDL cholesterol levels [HDL-C]) in children and adolescents. A systematic review was conducted in 5 electronic databases, with complementary searches in reference lists, and the inclusion criteria were children and adolescents (age group up to 19 years of age) with no special clinical conditions. In all articles, risk of bias was analyzed by a standardized instrument. Of the 5,973 articles initially identified, 21 were included, with data on 22,261 children and adolescents. Higher MF values were associated with lower TG (n = 07) and WC values (n = 15). Different results in relation to the relationship between MF and SBP (n = 10) and MF and DBP (n = 07) were verified. In addition, there was no relationship between MF and FG (n = 06). In addition, inconclusive results were verified in the relationship between MF and HDL-C (n = 07). Concluded higher MF values were related to lower WC values and lower TG concentrations.

The Role of Adiposity in the Association between Muscular Fitness and Cardiovascular Disease

OBJECTIVES

To test the associations of muscular fitness and body mass index (BMI), individually and combined, with clustered cardiovascular disease risk factors in children and adolescents and to analyze the mediator role of BMI in the association between muscular fitness and clustered cardiovascular disease risk factors.

STUDY DESIGN

In total, 239 children (113 girls) and 270 adolescents (128 girls) participated in this cross-sectional study. Height and weight were assessed, and BMI was calculated. A cardiovascular disease risk factors index (CVDRF-I) was created from the combination of the following variables: waist circumference, systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, and glucose. Handgrip strength/weight and standing long jump tests were used to assess muscular fitness. A muscular fitness index was computed from the combination of both tests.

RESULTS

Muscular fitness index was associated with CVDRF-I in children of both sexes and adolescent boys; however, these associations disappeared after accounting for BMI. BMI was associated with CVDRF-I in both children and adolescents, even after adjusting for muscular fitness (all P < .001). In male and female children and in adolescent boys, the association between muscular fitness and CVDRF-I was mediated by BMI (all P < .001). Because there was no association between muscular fitness and CVDRF-I in adolescent girls, the mediation hypothesis was discarded.

CONCLUSIONS

BMI is an independent predictor of CVDRF-I in children and adolescents of both sexes. Conversely, the effect of muscular fitness on CVDRF-I seems to be fully mediated by BMI levels in male and female children and in adolescent boys.

Handgrip Strength and Blood Pressure in Children and Adolescents: Evidence From NHANES 2011 to 2014

BACKGROUND

Previous studies have reported that handgrip strength, a measure of muscular fitness, is associated with cardiovascular risk factors. However, the association of handgrip strength with blood pressure (BP) in children has been inconsistent. We tested the association of handgrip strength with systolic and diastolic BP in children and adolescents from the National Health and Nutrition Examination Survey (NHANES) 2011-2014.

METHODS

The study included 3,929 participants aged 8-19 years who underwent a handgrip test. The sum of the maximum handgrip strength from both hands was used. General linear models were used to examine the associations between handgrip strength and the outcome variables.

RESULTS

After adjustment for age, race, sex, body mass index, and physical activities, handgrip strength was significantly and positively associated with systolic (P < 0.0001) and diastolic (P = 0.01) BP. There was an increasing trend in systolic BP as handgrip strength increased from the bottom quartile to the top quartile, with 2.1 mm Hg difference between the top and the bottom quartiles (P for trend <0.0001). Similar results were observed for diastolic BP.

CONCLUSIONS

Muscular fitness is positively associated with BP in children and adolescents. The implications and underlying mechanisms for these results need further examinations.

Handgrip strength is associated with insulin resistance and glucose metabolism in adolescents: Evidence from National Health and Nutrition Examination Survey 2011 to 2014

BACKGROUND

Previous studies have reported that handgrip strength, a measure of muscular fitness, is associated with insulin resistance in children and adolescents, with conflicting results. Further, no studies have examined the association between handgrip strength with 2-hour glucose levels.

OBJECTIVE

We tested the association of handgrip strength with measures of insulin resistance (fasting insulin and homeostasis model assessment of insulin resistance [HOMA-IR]) and glucose metabolism (fasting and 2-hour glucose levels) in adolescents from the National Health and Nutrition Examination Survey (NHANES) 2011 to 2014.

METHODS

The study included 959 participants aged 12 to 19 years who underwent a handgrip test and a glucose tolerance test. General linear models were used to examine the associations between handgrip strength and the outcome variables.

RESULTS

After adjustment for age, race, sex, body mass index, and physical activities, handgrip strength was inversely associated with fasting insulin levels (P = .017) and HOMA-IR (P = .025). Although there was no association between handgrip strength and fasting glucose levels (P = .77), handgrip strength was inversely associated with 2-hour glucose levels (P < .0001). Insulin and 2-hour glucose levels decreased linearly as handgrip strength increased from the bottom quartile to the top quartile (P for trend: .045 for fasting insulin levels and .004 for 2-hour glucose levels).

CONCLUSIONS

Muscular fitness, measured by handgrip strength, is associated with insulin resistance and glucose metabolism in adolescents, which indicates that increasing muscular fitness may have beneficial effects for early prevention of insulin resistance and type 2 diabetes.

Handgrip strength is positively related to blood pressure and hypertension risk: results from the National Health and nutrition examination survey

Background

Isometric handgrip resistance exercise, a nonpharmacological lifestyle modification, has been recommended as a first-line treatment for hypertension. This study aimed to examine the relationship of handgrip strength to blood pressure and the risk of hypertension.

Methods

The responses and examination of 4597 participants in the National Health and Nutrition Examination Survey (NHANES) were analyzed in this study. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were transformed to age- and sex-specific z-scores. Handgrip strength was adjusted by weight (kg) and converted to an age- and sex-specific z-score. The relationships of SBP and DBP to handgrip strength were analyzed by Pearson correlation test and multivariable linear regression. Binary logistic regression was used to analyze the association between handgrip strength and prevalence of hypertension.

Results

Handgrip strength was positively related to higher DBP in men and women. In men, logistic regression models revealed that increased handgrip strength was associated with higher risk of hypertension after adjusting for age, BMI, smoking and drinking status; OR was 1.24 (95%CI: 1.04–1.48). After stratifying on BMI, handgrip strength was significantly associated with higher risk of hypertensions after adjusting for age, BMI, smoking and drinking status in overweight and obese men; OR was 1.31 (95%CI: 1.05–1.63). No significant associations were observed in women.

Conclusions

Increased handgrip strength is associated with higher DBP in men and women. In men, especially overweight and obese men, strong handgrip strength may be associated with higher risk of hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0734-4) contains supplementary material, which is available to authorized users.

Fatness mediates the influence of muscular fitness on metabolic syndrome in Colombian collegiate students

The purpose of this study was two-fold: to analyze the association between muscular fitness (MF) and clustering of metabolic syndrome (MetS) components, and to determine if fatness parameters mediate the association between MF and MetS clustering in Colombian collegiate students. This cross-sectional study included a total of 886 (51.9% women) healthy collegiate students (21.4 ± 3.3 years old). Standing broad jump and isometric handgrip dynamometry were used as indicators of lower and upper body MF, respectively. Also, a MF score was computed by summing the standardized values of both tests, and used to classify adults as fit or unfit. We also assessed fat mass, body mass index, waist-to-height ratio, and abdominal visceral fat, and categorized individuals as low and high fat using international cut-offs. A MetS cluster score was derived by calculating the sum of the sample-specific z-scores from the triglycerides, HDL cholesterol, fasting glucose, waist circumference, and arterial blood pressure. Linear regression models were used to examine whether the association between MF and MetS cluster was mediated by the fatness parameters. Data were collected from 2013 to 2016 and the analysis was done in 2016. Findings revealed that the best profiles (fit + low fat) were associated with lower levels of the MetS clustering (p <0.001 in the four fatness parameters), compared with unfit and fat (unfit + high fat) counterparts. Linear regression models indicated a partial mediating effect for fatness parameters in the association of MF with MetS clustering. Our findings indicate that efforts to improve MF in young adults may decrease MetS risk partially through an indirect effect on improvements to adiposity levels. Thus, weight reduction should be taken into account as a complementary goal to improvements in MF within exercise programs.

Anthropometric indicators as predictors of total body fat and cardiometabolic risk factors in Chilean children at 4, 7 and 10 years of age

BACKGROUND/OBJECTIVE

To compare the association between anthropometric indicators of global and central obesity as predictors of total body fat (TBF) and cardiometabolic risk factors in children.

SUBJECTS/METHODS

A total of 1044 children were evaluated at 4 years (n=320), 7 years (n=1044) and 10 years (n=483). The following anthropometric indices were determined: body mass index (BMI) for age (BAZ, WHO), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). To estimate TBF we used validated predictive equations. We measured blood sample concentrations of glucose, insulin, triglycerides, total cholesterol, Low-density lipoprotein (LDL) and High-density lipoprotein (HDL), adiponectin, C-reactive protein (CRP) and Insulin-like growth factor-1 (IGF-1).

RESULTS

Adiposity and cardiometabolic markers, particularly those related to glucose metabolism increased from 4 years to 10 years. BAZ and WC were highly correlated to body fat at all ages (all r>0.8) but at 10 years WC was more strongly correlated than BAZ (r=0.94 WC vs r=0.88 BAZ, P<0.05); conversely, WHtR was significantly associated with body fat from 7 years (r=0.85) and 10 years (r=0.88). WHR was unrelated all over the period studied at all ages. Anthropometrical adiposity indicators became associated to cardiometabolic markers only from 7 years on with associations being slightly higher at 10 years, particularly for adiponectin and lipid markers. At all ages, BAZ, WC and WHtR performed similarly as cardiometabolic markers (P<0.05) while WHR was a slightly weaker marker.

CONCLUSIONS

Relationship between anthropometrical indicators of adiposity and cardiometabolic markers becomes stronger from 7 years onwards; BAZ, WC and WHtR perform similarly as markers of cardiometabolic risk at least until 10 years of age.

The association between blood pressure and grip strength in adolescents: does body mass index matter?

Increased body mass index (BMI) has been related to both low grip strength and high blood pressure (BP) in adolescents. Previous reports of high BP associated with decreased grip strength could be due to the inherent increase in BP in youths with high BMI. This cross-sectional study aimed to examine the association between grip strength and BP in adolescents independent of BMI. A total of 88 865 Chinese adolescents aged 13-17 years were included in this study. Sex-, age- and height-specific references were applied to calculate the BP z-score and define elevated BP. Grip strength was evaluated as handgrip (kg)/weight (kg) and converted into a sex- and age-specific z-score for analysis. Using fractional polynomial regression, we found that increased BMI was associated with enhanced BP and decreased grip strength; however, after stratification by or adjustment for BMI, strong grip strength was related to an increased BP. Logistic regression models revealed that a one s.d. increase in boys' grip strength z-score was associated with an 18% (95% confidence interval: 12, 25) to 37% (19, 59) higher risk of elevated BP when adjusted for BMI. These associations remained significant after further adjustment for cardiorespiratory fitness. A similar pattern was also observed in girls. These results indicated that strong grip strength was associated with increased adolescent BP after adjustment for BMI. Our findings raise questions about using muscle-strengthening training as an approach to improve the BP profile in adolescents.

On the relevance of surrogate parameter deduction in biomedical research: mediated regression analysis for variance explanation of cervical range of motion

PURPOSE

Research on cervical range of motion (ROM) often includes age and body mass index (BMI) as potential variables to explain inter-individual variances. The BMI may not be a predictor of ROM but an age-affected surrogate parameter: the described effect of BMI on ROM is, thus, suspected being partially or completely mediated by age.

METHODS

Healthy and adult volunteers (n = 139, 65 female, age 19-75 years, BMI 24.2 ± 3.8 kg m^-2) performed five repetitive maximal cervical movements in the sagittal plane to assess maximal ROM (primary outcome). After the examination of underlying assumptions, data were analysed by mediation regression analyses using a SPSS-macro provided by Hayes. ROM represented the outcome variable, independent variable was BMI and mediator variable was age. Total as well as direct and indirect effects were calculated: (1) for all subjects included and (2) for subject with a BMI <35 kg m^-2.

RESULTS

Analysis including all subjects revealed both a direct (-1.1, s _e .46, p < .05, 95 %CI -2; -1.7) and an existing indirect effect (mediated by age, -2.4, s _e .33, p < .05, 95 %CI -3.1; -1.8) of BMI on ROM. Analysis without obese 2 subjects showed no direct effect of BMI (effect -1, s _e .54, p > .05, 95 %CI -2.1; +.1) but a systematic indirect effect, mediated by age, on ROM (effect -2.4, s _e .33, p < .001, 95 %CI -3.1; -1.8).

CONCLUSIONS

After the withdrawal of the surrogate parameter BMI, age explains 53 % of maximal ROM. No impact of BMI on ROM was detected after excluding highly obese participants. Our results illustrate the relevance of including each supposable predictor in causal mediation models development.