Study of growth in rural school children from Buenos Aires, Argentina using upper arm muscle area by height and other anthropometric dimensions of body composition.

The primary objective was to compare growth and body composition in an infantile rural population by means of the upper arm muscle area by height and other antropometric measurements. Research was carried out by way of a cross sectional study, including 80% (321 6-13 year olds) of the schoolchildren living in General Lavalle, a rural community of about 3000 inhabitants. The methods and procedures included the evaluation of mother's educational levels and anthropometric measurements. Height (H), weight, mid upper arm circumference, and triceps skinfold (TS) were measured. The body mass index (BMI), the upper arm muscle area (UAMA), the upper arm fat area (UAFA) and the upper arm muscle area by height (UAMAH) were calculated. Variables were grouped by gender and age and transformed into z-scores, using the US anthropometric standards as reference. The results showed that: (1) the mother educational status was, in relation to z-scores, as in an urban population, and (2) the z-scores for BMI, UAFA and TS were above the reference, while the ones for H, UAMA and UAMAH were below the reference. The differences between z-scores in relation to mother's educational levels were statistically significant (p < 0.05). UAMA was correlated strongly with H (r = 0.67). The children of General Lavalle tend to be fatty and overweight, while their muscle mass and H are proportionally low, but with values within the reference. Thus, low muscle mass and H are, in general terms, indicative of low protein reserves, the systematically low-anthropometry found for UAMAH suggests that this index should be used in conjunction with other indexes (e.g. BMI, UAFA) to obtain a more complete assessment of body composition and nutritional status.