CLINICS 2011;66(9):1513-1518 and center-of-foot pressure signals were recorded using Balance Clinic Software (AMTI, USA). All participants performed the following eight trials: opened base, eyes open (OBEO); opened base, eyes closed (OBEC); closed base, eyes open (CBEO); closed base, eyes closed (CBEC); tandem right, eyes open; tandem left, eyes open; right unilateral stance, eyes open; left unilateral stance, eyes open. They were asked to maintain a standing posture while remaining as still as possible and to look straight ahead at a specific point on the wall at their eye level when their eyes were opened. Each trial lasted 60 seconds, and a rando- mized block design (four possible sequences of the described trials) was used to minimize fatigue and learning effects. The calculated stabilometric variables included the lateral standard deviation, anterior-posterior standard deviation, lateral range, anterior-posterior range, effective area, path length, and average velocity. During tandem and unilateral stances, the number of foot or hand contacts needed by the subject to avoid a fall was also recorded. Statistical Analysis Variable distributions were analyzed using Kolmogorov- Smirnov tests; if a meaningful number of variables did not have a normal distribution, nonparametric tests were selected. Variable values are presented as the median (first - third quartile). The sample was divided into two groups using the fat mass median. The Low Fat Mass Group was comprised of those elderly women with a fat mass #29.08 kg. The High Fat Mass Group was comprised of subjects with a fat mass .29.08 kg. Two different analyses were performed; the Low Fat Mass Group was compared with the High Fat Mass Group using the Mann-Whitney Test for numerical variables and the chi-square test for categorical variables. The correlation between body compo- sition variables and the number of foot and hand contacts required to avoid falls was evaluated using the Spearman Correlation Test.26 Statistical Package for Social Sciences (SPSS) 13.0 software for Windows was used for the statistical analysis, and significance was assigned when the p-value was less than 0.05. Ethics According to the recommendations of the Helsinki Declaration, the protocol was approved by the UNISUAM Ethics Committee (protocol number 003/10), and written informed consent was obtained from all participants before their participation in this study. RESULTS General and anthropometric characteristics and body composition variables derived from bioelectrical impedance measurements of the studied sample are presented in Table 1. As expected, the High and Low Fat Mass Groups were statistically different in terms of their weight, BMI, waist circumference, fat percentage, fat mass, and fat-free mass. Subject age, a possible confounding variable, was not statistically different between these groups. There was a considerable number of women with right leg dominance (88.89%) in the sample, and, when separated into Low and High Fat Mass Groups, this pattern was preserved (86.96% and 90.91%, respectively). Although not statistically sig- nificantly different, the number of subjects not using any 1515 Adiposity and Balance Control in the Elderly Mainenti MRM et al. support during right or left unilateral stances was higher in the Low Fat Mass Group (Table 1). The High Fat Mass Group showed significantly higher values for anterior-posterior standard deviation and range during OBEC and CBEC. The effective area was also greater for this group during OBEC (Table 2). A statistically significant difference in path length and average velocity was not observed between groups in any trial. Right and left tandem variables were analyzed only for those participants who used no foot or hand support to avoid falls. For this reason, the sample size for this investigation was smaller (19 vs. 15 and 19 vs. 16, respectively) (Table 2). When the whole sample was considered, fat percentage and fat mass showed significant and positive correlations with the number of contacts during right and left unilateral stances even when controlled for age and height. Weight, BMI, and waist circumference were also statistically correlated with contacts used during left unilateral stance and non-dominant unilateral stance (Table 3). Only eight individuals performed the right unilateral stance without foot or hand contacts, and eleven attained the left unilateral stance without foot or hand contacts. Because the sample size was small (eight and eleven), the stabilometric data were not analyzed for these trials. DISCUSSION This study showed that an association exists between body adiposity and postural balance control. Greve and co- workers8 analyzed the association between BMI and a general instability index in another type of sample (young male subjects), and their results showed a positive correla- tion that corroborates the data presented here. Barbosa and co-workers27 evaluated BMI in relation to selected physical performance tasks, and their results showed a significant association between balance and BMI for elderly women (60-79 years old). Although the studies cited above indicate that a relation- ship exists between fatness and balance, BMI has a poor diagnostic performance for identifying excess body fat, particularly in the elderly.28 The distinction between fat and lean mass has considerable importance because these factors are directly associated with the independence of elderly individuals.11 A study carried out in Canada showed that by 60 to 69 years of age, the percentage of subjects at high risk for health problems (classified using waist circumference values) was more than twice as high as that of individuals between 20 and 39 years (65% for females).15 The results reported here revealed a significant association between waist circumference and the number of foot or hand contacts needed by the subject to avoid a fall during left unilateral stance. Whether the association between waist circumference and instability is a result of an increased upper circumference area based on the inverted pendulum model29 or the increased total mass that must be controlled by the neuromuscular system is still unclear and should be investigated with prospective studies. Bioelectrical impedance analysis, a method previously used in elderly subjects,5,11,23 showed a high median fat percentage (44.28%), classifying the group as obese ($35% for women, independent of age),30 as observed in other studies evaluating elderly individuals.5,11 The fat-free mass results were similar to those of another study carried out in