Hand grip strength (HGS) is an important diagnostic tool for sarcopenia and a reliable predictor for age-related chronic diseases and mortality. Interventions in nutrition have been shown as a low-cost strategy to maintain muscular strength and mass. However, there are limited data on the effect of diet on HGS in Southeast Asian populations. This study aims to investigate the association of diet quality with HGS weakness and asymmetry in a multi-ethnic population in Singapore. This cross-sectional study used data from the Singapore Multi-Ethnic Cohort (n = 1547). Dietary data were collected using a validated semi-quantitative FFQ and summarised as the Dietary Quality Index – International (DQI-I). HGS was calculated as the maximum value of six measurements from both hands. HGS weakness and asymmetry were defined using well-recognised criteria. Multivariable linear regression and logistic regression were utilised for continuous and binary outcomes, respectively, adjusting for age, sex, ethnicity, physical activity and smoking status. It was found that the highest quartile of DQI-I was significantly associated with higher HGS (β = 1·11; 95 % CI 0·41, 1·82; Pfor trend < 0·001) and lower odds of HGS asymmetry (OR = 0·71; 95 % CI 0·53, 0·94; Pfor trend = 0·035) and both HGS weakness and asymmetry (OR = 0·50; 95 % CI 0·32, 0·76; Pfor trend = 0·004). Among the different components of DQI-I, only dietary adequacy was significantly associated with higher HGS (Pfor trend < 0·001) and lower odds for both HGS weakness and asymmetry (Pfor trend = 0·006). Our findings support that DQI-I, an indicator of overall diet quality, can be used to provide dietary guidelines for prevention and management of muscle wasting, sarcopenia and frailty.

Childhood is a critical period for muscle accumulation. Studies in elders have reported that antioxidant vitamins could improve muscle health. However, limited studies have assessed such associations in children. This study included 243 boys and 183 girls. A seventy-nine-item FFQ was used to investigate dietary nutrients intake. Plasma levels of retinol and α-tocopherol were measured using high-performance liquid chromatography with MS. Dual X-ray absorptiometry was used to assess appendicular skeletal muscle mass (ASM) and total body fat. The ASM index (ASMI) and ASMI Z-score were then calculated. Hand grip strength was measured using a Jamar® Plus+ Hand Dynamometer. Fully adjusted multiple linear regression models showed that for each unit increase in plasma retinol content, ASM, ASMI, left HGS and ASMI Z-score increased by 2·43 × 10−3 kg, 1·33 × 10−3 kg/m2, 3·72 × 10−3 kg and 2·45 × 10−3 in girls, respectively (P < 0·001–0·050). ANCOVA revealed a dose–response relationship between tertiles of plasma retinol level and muscle indicators (Ptrend: 0·001–0·007). The percentage differences between the top and bottom tertiles were 8·38 %, 6·26 %, 13·2 %, 12·1 % and 116 % for ASM, ASMI, left HGS, right HGS and ASMI Z-score in girls, respectively (Pdiff: 0·005–0·020). No such associations were observed in boys. Plasma α-tocopherol levels were not correlated with muscle indicators in either sex. In conclusion, high circulating retinol levels are positively associated with muscle mass and strength in school-age girls.

The longitudinal relationship between muscle strength, dietary intake and physical activity among adolescents is not well understood. We investigated the trend and longitudinal effects of dietary intakes and physical activity scores on muscle strength in adolescents. This prospective cohort study consisted of 436 adolescents (134 males; 302 females) aged 13 years at baseline (2012) who were followed up at the ages of 15 (2014) and 17 (2016) years, respectively. We measured muscle strength using a calibrated hand dynamometer, estimated dietary intake with a 7-d dietary history and physical activity scores with a validated physical activity questionnaire for older children. A generalised estimating equation was used to examine the effect of dietary intakes and physical activity on muscle strength changes. The analysis was performed separately by sex. The muscle strength for males and females had increased within the 5-year period. The dietary intakes (energy and macronutrients) also increased initially but plateaued after the age of 15 years for both sexes. Females recorded a significant declining trend in physical activity scores compared with males as they grew older. A significant positive longitudinal relationship was found between protein (β = 0·035; P = 0·016), carbohydrate intake (β = 0·002; P = 0·013) and muscle strength among males. However, no longitudinal relationship was found between dietary intake, physical activity and muscle strength among females. Higher protein and carbohydrate intake among males was associated with higher muscle strength but was not observed in females. Nutrition and physical activity focusing on strength building are required in early adolescence and need to be tailored to males and females accordingly.

Sarcopenia is a progressive and generalised skeletal muscle disorder associated with adverse outcomes. Ageing causes primary sarcopenia, while secondary causes include chronic kidney disease (CKD), long-term use of glucocorticoids and obesity. The aim of the present study was to evaluate the prevalence of sarcopenia using guidelines recommended by the European Working Group on Sarcopenia in Older People (EWGSOP, 2010; EWGSOP2, 2018) and the Foundation of the National Institutes of Health (FNIH) and analyse the relationship between sarcopenia and body adiposity in adult renal transplant recipients (RTR). This was a cross-sectional study of adult RTR (BMI ≥ 18·5 kg/m2). Body composition was evaluated by dual-energy X-ray absorptiometry (DXA) and anthropometry. Glomerular filtration rate was estimated (eGFR) by CKD-Epidemiology Collaboration equation. The prevalence of sarcopenia in adult RTR (n 185; 57 % men, 50 (se 0·82) years and eGFR 55·80 (se 1·52) ml/min) was 7 % (FNIH), 11 % (EWGSOP2) and 17 % (EWGSOP). Low muscle mass, muscle function and physical performance affected, respectively, up to 28, 46 and 10 % of the participants. According to EWGSOP and EWGSOP2, body adiposity evaluated by anthropometry and DXA (percentage trunk fat) was lower in participants with sarcopenia. Conversely, according to the FNIH criteria, RTR with sarcopenia presented higher waist:height ratio. The present study suggests that adult RTR sarcopenia prevalence varies according to the diagnostic criteria; low muscle mass, low muscle function and low physical performance are common conditions; the association of body adiposity and sarcopenia depends on the criteria used to define this syndrome; and the FNIH criteria detected higher adiposity in individuals with sarcopenia.