Muscle Strength Reference Values and Correlation with Appendicular Muscle Mass in Mexican Children and Adolescents

A Causal Effect of Serum 25(OH)D Level on Appendicular Muscle Mass: Evidence From NHANES Data and Mendelian Randomization Analyses

BACKGROUND

Low serum vitamin D status was reported to be associated with reduced muscle mass; however, it is inconclusive whether this relationship is causal. This study used data from the National Health and Nutrition Examination Survey (NHANES) and two-sample Mendelian randomization (MR) analyses to ascertain the causal relationship between serum 25-hydroxyvitamin D [25(OH)D] and appendicular muscle mass (AMM).

METHODS

In the NHANES 2011-2018 dataset, 11 242 participants (5588 males and 5654 females) aged 18-59 years old were included, and multivariant linear regression was performed to assess the relationship between 25(OH)D and AMM measured by dual-energy X-ray absorptiometry. In two-sample MR analysis, 167 single nucleotide polymorphisms significantly associated with serum 25(OH)D at the genome-wide association level (p < 5 × 10-8) were applied as instrumental variables (IVs) to assess vitamin D effects on AMM in the UK Biobank (417 580 Europeans) using univariable and multivariable MR (MVMR) models.

RESULTS

In the NHANES dataset, serum 25(OH)D concentrations were positively associated with AMM (β = 0.013, SE = 0.001, p < 0.001) in all participants, after adjustment for age, race, season of blood collection, education, income, body mass index and physical activity. In stratification analysis by sex, males (β = 0.024, SE = 0.002, p < 0.001) showed more pronounced positive associations than females (β = 0.003, SE = 0.002, p = 0.024). In univariable MR, genetically higher serum 25(OH)D levels were positively associated with AMM in all participants (β = 0.049, SE = 0.024, p = 0.039) and males (β = 0.057, SE = 0.025, p = 0.021), but only marginally significant in females (β = 0.043, SE = 0.025, p = 0.090) based on IVW models was noticed. No significant pleiotropy effects were detected for the IVs in the two-sample MR investigations. In MVMR analysis, a positive causal effect of 25(OH)D on AMM was observed in the total population (β = 0.116, SE = 0.051, p = 0.022), males (β = 0.111, SE = 0.053, p = 0.036) and females (β = 0.124, SE = 0.054, p = 0.021).

CONCLUSIONS

Our results suggested a positive causal effect of serum 25(OH)D concentration on AMM; however, more researches are warranted to unveil the underlying biological mechanisms and evaluate the effects of vitamin D intervention on AMM.

Association between BMI z-score and body composition indexes with blood pressure and grip strength in school-age children: a cross-sectional study

Childhood obesity is linked to diverse health outcomes, including elevated blood pressure (EBP). Emerging evidence showed that excess fat mass (FM) may have a deleterious impact on blood pressure even in normal-weight children. The primary objective of this study was to assess the association between body weight status by BMI z-score and body composition parameters by conventional bioelectrical impedance analysis (BIA) and bioelectrical impedance vector analysis (BIVA). Also, we aimed to explore the performance of BMI z-score, %FM, and FM index (FMI) in discriminating EBP in a sample of school-age Mexican children. Children were classified as having normal weight, overweight or obesity according to WHO criteria for BMI z-score. FMI was considered high when above 75th percentile, and fat free mass index (FFMI) was considered low when below 25th percentile of the reference population. Body composition was also classified according to the BIVA method and EBP was determined when systolic and/or diastolic blood pressure ≥ 90th percentile. BMI z-score groups were compared by Student´s t-test or the Mann-Whitney U test, or by the chi-square test or Fisher exact test. Receiving operating characteristic (ROC) analysis was performed. 61 children were included (52.5% boys, median age 9.8 (25th, 75th percentiles: 8.5, 11.0)) years. High FMI was observed in 32.3% of children with normal weight. Low FFMI was present in 93.5% of children with normal weight and 53.3% of those with overweight/obesity. According to BIVA, 58.1% and 43.3% of children with normal weight and overweight/obesity were classified as having cachexia. All the three adiposity indicators showed significant areas under the ROC curve (AURC) greater than 0.775 for EBP, with the largest one displayed for FM% (0.794). Hight FMI and low FFMI are common in children with normal weight. Identifying deficiency of FFM might be limited by using solely BMI indicators. Cachexia by BIVA was present in a high proportion of children with either normal weight or overweight/obesity. Both BMI z-score and FM (% and FMI) performed well at discriminating EBP, with a numerically greater AURC observed for FM%. Body composition in pediatric population is relevant for identifying body composition abnormalities at early age.

Association between sugar-sweetened beverage consumption frequency and muscle strength: results from a sample of Chinese adolescents

BACKGROUND

Although sugar-sweetened beverage consumption has become an important and widespread concern, there are few studies on the association between sugar-sweetened beverage consumption frequency and muscle strength in Chinese adolescents. The objective of this study was to analyze the association between sugar-sweetened beverage consumption frequency and muscle strength in Chinese adolescents.

METHODS

A stratified whole-group sampling method was used to survey 25,893 adolescents aged 13-15 years old in China for sugar-sweetened beverage consumption frequency and muscle strength for grip strength and standing long jump. The subjects' basic information, body mass index (BMI), and covariates were investigated. The association between sugar-sweetened beverage consumption frequency and muscle strength was analyzed by multivariate logisitc regression analysis.

RESULTS

The proportions of Chinese adolescents who consumed sugar-sweetened beverage ≥ 3 times/week, 1-2 times/week, and < 1 time/week were 12.23%, 52.79%, and 34.98%, respectively. The differences in sugar-sweetened beverage consumption frequency were statistically significant when compared across gender, parental education, duration of physical activity, snacks, and mode of commuting to school (χ² values = 228.570, 51.422, 275.552, 3165.656, 10.988, P < 0.01). Logistic regression analysis showed that overall Chinese adolescents with sugary drinks 1-2 times/week (OR = 1.207, 95% CI:1.132-1.287) and sugary drinks ≥ 3 times/week (OR = 1.771, 95% CI:1.611-1.947) were associated with lower muscle strength compared to sugary drinks < 1 time/week showed a positive association (P < 0.01). The same trend was found for boys and girls.

CONCLUSION

Chinese adolescents' sugar-sweetened beverage consumption is common, and high-frequency sugar-sweetened beverage consumption is associated with lower muscle strength. In the future, we should control the use of sugar-sweetened beverages and increase muscular strength training in Chinese adolescents to promote healthy growth.