Relationship between grip strength and bone mineral density in healthy Hong Kong adolescents.

UNLABELLED: This study evaluated the magnitude of the correlations among grip strength, bone mineral density (BMD) and bone mineral content (BMC), after controlling for weight, height, pubertal development, weight-bearing activities and calcium intake. The results lead to the conclusion that grip strength is an independent predictor of bone mass in both sexes. The relationship between muscle strength and bone mass is systemic. INTRODUCTION: Previous studies had shown a site-specific relationship between muscle strength and bone in pubertal children. This study evaluated the magnitude of the correlations among grip strength, bone mineral density (BMD) and bone mineral content (BMC) at distant bone. METHODS: Cross-sectional data of 169 11- to 12-year-old boys and 173 10- to 11-year-old girls came from the baseline result of a cohort study. Grip strength, BMD, BMC, weight, height, pubertal development, weight-bearing activities and calcium intake were measured. Pearson correlations and multiple regressions were used to calculate univariate and adjusted associations among grip strength and bone mass at distant bone. RESULTS: Significant correlations were shown between grip strength and bone mass at hip, spine and whole body (boys: BMC:0.72-0.74, BMD:0.38-0.60; girls: BMC:0.71-0.72, BMD:0.44-0.63; p<0.0001). Multiple regressions with all covariates showed that about 70% and 50%, respectively, of the variations in BMC and BMD could be explained but not for whole body BMD. Grip strength was an independent predictor of bone mass, except hip BMD in boys and whole body BMD in girls. Stepwise regression showed that grip strength was a robust predictor in both sexes. Prediction models by grip strength and weight explained about 60% and 40% of the variations in BMC of different sites and in BMD of hip and spine, respectively. CONCLUSIONS: We found that grip strength is an independent predictor of bone mass in both sexes. The relationship between muscle strength and bone mass is systemic.

Persistent osteopenia in adolescent idiopathic scoliosis--longitudinal monitoring of bone mineral density until skeletal maturity.

The aim of this study was to monitor BMD changes occurring during periods of rapid growth and to investigate whether osteopenia was a persistent phenomenon in skeletally matured AIS girls. 196 AIS Chinese girls and 122 healthy controls, aged 11-16, were follow-up for 3.5 years. Bilateral femoral neck bone mineral density (BMD) and volumetric BMD (vBMD) of the distal tibia were obtained by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Osteopenia was defined if the age-adjusted BMD was below or equal to -1 standard deviation (SD). The average age at the final follow-up was 16.8 years old. The median initial Cobb angle for this group of patients was 26 degrees. The prevalence of osteopenia at the baseline measurement was 35.9%. Longitudinal BMD results demonstrated that 86.0% of osteopenic AIS girls had persistently low BMD at the time of skeletal maturity (age of 16). vBMD of distal tibia of AIS was significantly lower than that of the controls throughout the age of 13 to 17 during the period of rapid growth. In addition, there were also significant differences in vBMD among AIS (moderate and severe group) and the controls by one-way ANOVA (p<0.05). The present study for the first time revealed that over 86% of osteopenic AIS patients had persistently low BMD, at both distal tibia and femoral neck regions, at the time of skeletal maturity. Early detection and treatment of AIS-related osteopenia might help in maximizing peak bone mass during peripubertal growth that thereby minimizing risks of developing osteoporotic fractures later in life.

A community-based study of the prevalence of constipation in young children and the role of dietary fibre.

OBJECTIVES: To study the prevalence of constipation in young children, and to explore its association with dietary fibre intake. DESIGN: Cross-sectional community-based study. SETTING: Three kindergartens randomly selected from the eastern district of Hong Kong. PARTICIPANTS: Between October 2003 and January 2004, parents of children aged 3 to 5 years completed a specially designed questionnaire and a 3-day dietary record form, which were used to collect information on bowel function and dietary intake. Children with constipation were identified based on Rome criteria. Children with normal bowel habits served as a comparison group. MAIN OUTCOME MEASURES: Dietary intake of energy, protein, and dietary fibre. RESULTS: Of 778 children recruited, 561 complete sets of data were successfully obtained from the participating kindergartens. One hundred and sixty-six (29.6%) children were found to be constipated. The incidence of a family history of constipation was significantly higher in the constipated group (14%) than in the non-constipated group (7%) [P=0.013]. Mean dietary fibre consumption was 4.1 g/d (standard deviation, 2.3 g/d) in all children corresponding to 45.5% (standard deviation, 24.9%) of the daily recommendation. Constipated children (mean, 40.7%; standard deviation, 20.5%) had a significantly lower dietary fibre intake of the daily recommendation than the non-constipated group (mean, 47.5%; standard deviation, 26.2%) [P=0.017]. CONCLUSION: Up to 30% of preschool children in the eastern district had constipation. A family history of constipation was related to its occurrence in the studied children. Dietary fibre intake was insufficient in all children and even lower in those who were constipated.