Determinants of muscle power and force as assessed by Jumping Mechanography in rural Indian children

OBJECTIVES: To: 1. Assess muscle function (MF) of rural Indian children (6-11y, n=232), using Jumping Mechanography (JM) and hand dynamometer, 2. Investigate gender differences, 3. Identify determinants of MF. METHODS: Data on anthropometry, muscle mass%, diet, physical activity, sunlight exposure, MF (maximum relative power Pmax/mass, maximum relative force Fmax/BW by JM; relative grip strength (RGS) by hand dynamometer) were collected. Pearson’s correlation and hierarchical linear regression was performed. RESULTS: Pmax/mass, Fmax/BW and RGS of the group were 31.7±5.0W/kg, 3.0±0.3 and 0.4±0.1 (mean±SD), respectively. The Pmax/mass Z-score was –1.1±0.9 and Fmax/BW Z-score was –0.9±1 (mean±SD) which was significantly lower than the machine reference data (p<0.05). Positive association of muscle mass% and protein intake was observed with all MF parameters and moderate+vigorous physical activity with Fmax/BW (p<0.05). Determinants of MF identified through regression for Pmax/mass were age (β=1.83,95% CI=0.973 – 2.686), muscle mass% (β=0.244,95% CI=0.131–0.358) and protein intake (β=3.211,95% CI=1.597–4.825) and for Fmax/BW was protein intake (β=0.130,95% CI=0.023–0.237) (p<0.05). Male gender was a positive predictor of having higher Pmax/mass (β=1.707,95% CI=0.040–3.373) (p<0.05). CONCLUSION: MF was lower than in western counterparts. To optimize MF of rural Indian children, focus should be on improving muscle mass, ensuring adequate dietary protein, and increasing physical activity, especially in girls.