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The Tol-Pal system spans the cell envelope of Gram-negative bacteria, transducing the potential energy of the proton motive force (PMF) into dissociation of the TolB-Pal complex at the outer membrane (OM), freeing the lipoprotein Pal to bind the cell wall. The primary physiological role of Tol-Pal is to maintain OM integrity during cell division through accumulation of Pal molecules at division septa. How the protein complex couples the PMF at the inner membrane into work at the OM is unknown. The effectiveness of this trans-envelope energy transduction system is underscored by the fact that bacteriocins and bacteriophages co-opt Tol-Pal as part of their import/infection mechanisms. Mechanistic understanding of this process has been hindered by a lack of structural data for the inner membrane TolQ-TolR stator, of its complexes with peptidoglycan (PG) and TolA, and of how these elements combined power events at the OM. Recent studies on the homologous stators of Ton and Mot provide a starting point for understanding how Tol-Pal works. Here, we combine ab initio protein modeling with previous structural data on sub-complexes of Tol-Pal as well as mutagenesis, crosslinking, co-conservation analysis and functional data. Through this composite pooling of in silico, in vitro, and in vivo data, we propose a mechanism for force generation in which PMF-driven rotary motion within the stator drives conformational transitions within a long TolA helical hairpin domain, enabling it to reach the TolB-Pal complex at the OM.

Context:Static stretching is commonly used during the treatment and rehabilitation of orthopedic injuries to increase joint range of motion (ROM) and muscle flexibility. Understanding the physiological adaptations that occur in the neuromuscular system as a result of long-term stretching may provide insight into the mechanisms responsible for changes in flexibility.Objective:To examine possible neurological origins and adaptations in the Ia-reflex pathway that allow for increases in flexibility in ankle ROM, by evaluating the reduction in the synaptic transmission of Ia afferents to the motoneuron pool.Design:Repeated-measures, case-controlled study.Setting:Sports medicine research laboratory.Participants:40 healthy volunteers with no history of cognitive impairment, neurological impairment, or lower extremity surgery or injury within the previous 12 mo.Intervention:Presynaptic and postsynaptic mechanisms were evaluated with a chronic stretching protocol. Twenty subjects stretched 5 times a wk for 6 wk. All subjects were measured at baseline, 3 wk, and 6 wk.Main Outcome Measures:Ankle-dorsiflexion ROM, Hmax:Mmax, presynaptic inhibition, and disynaptic reciprocal inhibition.Results:Only ROM had a significant interaction between group and time, whereas the other dependent variables did not show significant differences. The experimental group had significantly improved ROM from baseline to 3 wk (mean 6.2 ± 0.9, P < .001), 3 wk to 6 wk (mean 5.0 ± 0.8, P < .001), and baseline to 6 wk (mean 11.2 ±0.9, P < .001).Conclusions:Ankle dorsiflexion increased by 42.25% after 6 wk of static stretching, but no significant neurological changes resulted at any point of the study, contrasting current literature. Significant neuromuscular origins of adaptation do not exist in the Ia-reflex-pathway components after a long-term stretching program as currently understood. Thus, any increases in flexibility are the result of other factors, potentially mechanical changes or stretch tolerance.

Background: The dramatic increase in pediatric obesity has renewed interest in accurate methods and screening indexes for identifying at-risk children and youth. Whether age-specific standards are needed is a factor that remains uncertain. Purpose: This study was designed to describe the age-specific fatness-risk factor relationship in boys and girls across a wide age range. Methods: Data were from 12,279 white, black, and Mexican-American children and adolescents from the National Health and Nutritional Examination Surveys (NHANES) III (1998 -1994) and IV (1999 -2004). Children were grouped based on percent fat, estimated from subscapular and triceps skinfolds, and the age-specific relationships between percent fat and chronic disease risk factors (e.g., blood pressure, lipids and lipoprotein levels, glucose, insulin, and circulating C-reactive protein levels) were described in boys and girls, aged 6 -18 years. Results: Percent fat was significantly related to risk factor levels. At higher levels of percent fat, the prevalence of adverse cardiovascular disease risk factors was higher, particularly above 20% fat in boys and above 30% fat in girls. In boys and girls, the interaction term age by percent fat was a significant predictor of risk factors, whereas the percent fat by race interaction term was nonsignificant. Conclusions: The results demonstrate a strong relationship between chronic disease risk factors and percent fat in children and youth that varies by age in boys and girls. (Am J Prev Med 2011;41(4S2):S77-S86) © 2011 American Journal of Preventive Medicine

This study examined whether differences in waist circumference (WC) and pedometer placement (anterior vs. midaxillary vs. posterior) affect the agreement between pedometer and observed steps during treadmill and self-paced walking. Participants included 19 pairs of youth (9- 15-years-old) who were matched for sex, race, and height and stratified by WC (high WC: HWC; low WC: LWC). Participants performed 3-min treadmill-walking trials at speeds of 59, 72, and 86 m x min(-1) and a 400-m self-paced walking trial on level ground. Bland-Altman plots were used to assess the agreement between pedometer and observed steps of spring-levered pedometers by WC, pedometer placement, and walking speed. In the HWC group, the posterior pedometer placement consistently agreed most closely with observed steps at all treadmill speeds and during self-paced walking. In the LWC group, no single pedometer placement consistently agreed most closely with observed steps at all treadmill speeds and during self-paced walking. We conclude that a posterior pedometer placement improves step-count accuracy in most youth with an HWC at a range of walking speeds on level ground.

The purpose of the study is to determine whether cardiovascular disease risk factor differences exist between Active Special Olympians, Inactive Non-Special Olympians, and Active Non-Special Olympians. Resting blood pressure, total and abdominal body fat, fasting cholesterol profiles, and fasting insulin were measured in 145 (72 women, 73 men) adults with mild mental retardation. Active Special Olympians (n = 45) possessed lower diastolic blood pressures, body fat percentages, abdominal fat, triglycerides, and insulin than Inactive Non-Special Olympians (n = 38) and possessed lower body fat percentages than Active Non-Special Olympians (n = 62). Active Non-Special Olympians possessed lower triglycerides and insulin than Inactive Non-Special Olympians. Future prospective trials are needed to determine whether Special Olympics participation may be one effective component of community-based physical activity programs aimed at reducing cardiovascular disease risk.

The objective was to determine whether higher physical activity is associated with lower serum C-reactive protein (CRP), independent of oral hormone replacement therapy (HRT) status and body fatness, in 133 postmenopausal women using a cross-sectional exploratory design at a university research laboratory. The subjects were 133 postmenopausal women, age 50-73 years, with no evidence of coronary artery disease or diabetes. The main outcome measures were: serum CRP, physical activity as measured by Stanford 7-day activity recall, body fat (both total and regional) as measured by dual energy X-ray absorptiometry (DXA), and anthropometry (waist and hip circumference). Secondary outcome measures included fasting plasma glucose and insulin as well as fasting serum triglycerides, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Higher physical activity energy expenditures were significantly associated with lower serum CRP levels (r = -0.18, P = 0.041), independent of oral HRT use, age, smoking behavior, alcohol consumption, aspirin use, and statin use. However, in the complete multivariate model, which included body fat, older ages (P = 0.047), greater trunk fat masses (P < 0.001), any oral HRT use (P < 0.001), and unopposed oral estrogen use (P = 0.012) were the sole independent predictors of higher serum CRP levels. The complete multivariate model accounted for 58% of the variance in serum CRP. We conclude that the association between higher physical activity and lower serum CRP levels is dependent on the lower body fat of the more active women, yet independent of oral HRT use. Future intervention trials should determine whether diet- and exercise-related reductions in body fat may be effective ways to diminish the proinflammatory effects of oral HRT in postmenopausal women.

Little information has been reported on the leisure time physical activity (LTPA) habits of adults with mental retardation. Prevalence of physical inactivity and recommended LTPA of adults with mild to moderate mental retardation who live in community settings was described. Adults with mental retardation (76 men, 74 women) reported their physical activity habits. Overall, men and women who resided in community settings were similarly inactive, with 47% to 51% of individuals participating in little to no LTPA. Forty-two to 47% of them reported participation in moderate to vigorous LTPA five or more times per week. Limitations to quantifying physical activity through questionnaire process is discussed and development and implementation of programs designed to increase physical activity levels recommended.

This paper reviews age related changes in body fat, fat-free body mass, and the subcomponents of FFM including protein, mineral, and body water. It gives an overview of common methods and their limitations in the elderly and reviews the effects of physical activity on body composition in middle-aged and older individuals. Surprisingly little information is available on this important topic in men and women >80 years of age. Although research to date has described a number of qualitative trends with aging and shown the correlations between changes in fat and FFM with disease risk, quantification of rate of change has proven difficult. This is partly because changes in the aging body affect the indicators of body composition, leading to estimation errors, and because few long-term longitudinal studies have been completed. The increasing awareness of the important relationships among health, nutrition, and body composition, and the profound change in population demographics projected for the next 25 to 50 years, has focused attention on this problem and will undoubtedly stimulate additional research in this area.

Background:One of the goals of Healthy People 2020 is to increase physical activity (PA) and reduce health disparities among different racial and ethnic segments of the U.S. population. Few studies have been conducted to examine PA differences by birthplace and sex in youth of Mexican heritage.Methods:Participants were 101 youth (43 boys, 58 girls, 59% U.S.-born, 41% Mexico-born) who wore a sealed New Lifestyles NL-1000 pedometer for 7 consecutive days.Results:Mexico-born youth took more steps, on average, than their U.S.-born counterparts (P = .038). However, moderate-to-vigorous intensity (MVI) time did not differ between Mexico- and U.S.-born youth (P = .146). By contrast to birthplace, sex-related differences were more consistent, as boys took more steps (P = .005) and accumulated more MVI time (P = .043) than girls. Only 4% of our sample met either one or both of the PA recommendations.Conclusions:We conclude that PA may differ by birthplace and by sex in youth of Mexican heritage, as U.S.-born girls were the least active segment of our sample. Culturally sensitive interventions to increase daily PA must become a higher public health priority for youth of Mexican heritage, in particular, for U.S.-born girls of Mexican heritage.

Previous studies have shown that children have a higher aqueous fraction of the fat-free body mass (FFM) than young adults. In older adults, methodological differences among studies limit evaluation of potential age-related differences in the water content of the FFM (W/FFM). Therefore, we determined W/FFM in 28 healthy white prepubescent children (age = 5–10 yr), 31 young adults (age = 22–39 yr), and 62 older adults (age = 65–84 yr), using 2H2O dilution to estimate total body water and a multicomponent approach based on body density, total body water, and regional bone mineral density to estimate FFM. To quantify the extent to which variation in W/FFM affects percent fat estimation error, differences in percent fat between our multicomponent approach and the Siri two-component model were related to W/FFM. Prepubescent children (72.7 +/- 1.6%) and older adults (72.5 +/- 1.4%) were found to have significantly higher (P < 0.01) mean W/FFM than young adults (70.8 +/- 1.2%). Differences in percent fat between the multicomponent and two-component models ranged from -10 to 6% fat and were significantly associated with W/FFM (r = -0.62, P < 0.0001). We conclude that prepubescent children and older adults, on average, have a higher W/FFM than young adults, and that, in adults, individual differences in W/FFM account for a substantial portion of the percent fat estimation errors associated with the use of two-component body composition models.

Dehydroepiandrosterone (DHEA) has an antiobesity effect in rodents, and elevated endogenous levels of its sulfate ester (DHEAS) are associated with reductions in risk for cardiovascular disease (CVD) in men. To examine the association of body fat and fat distribution, established correlates of CVD and CVD risk factors, with circulating DHEAS levels in women, we measured trunk and limb skinfold thicknesses and circumferences, total and regional body fat from dual energy x-ray absorptiometry (DXA), and serum levels of DHEAS in 96 healthy Caucasian females aged 28-39 yr. Body mass index, percentage fat from DXA and the waist-to-hip ratio were not significantly correlated (ror = 0.15, Por = 0.156) with serum DHEAS levels, regardless of statistical control for age, smoking behavior, and fasting status. However, the ratio of trunk/total skinfold thicknesses (r = 0.23, P = 0.030) and the percentage of total fat located on the trunk from DXA (r = 0.32, P = 0.002) were positively correlated with DHEAS, whereas the ratio of leg/total skinfold thicknesses (r = -0.25, P = 0.015) and the percentage of total fat located on the legs from DXA (r = -0.25, P = 0.015) were inversely correlated with DHEAS after adjusting for age, smoking, and fasting status. With the exception of the trunk/total skinfold thickness ratio, the correlations of DXA- and skinfold-derived estimates of fat distribution remained significant (Por = 0.033) even after further adjustment for percentage fat or body mass index. It is concluded that increased amounts of total fat located on the trunk and decreased amounts of total fat located on the legs are associated with increased serum DHEAS concentrations in normally menstruating females.

BACKGROUND. Recent studies have shown considerable variation in body fatness among children and adolescents defined as obese by a percentile rank for skinfold thickness. METHODS. We examined the relationship between percent body fat and risk for elevated blood pressure, serum total cholesterol, and serum lipoprotein ratios in a biracial sample of 3320 children and adolescents aged 5 to 18 years. Equations developed specifically for children using the sum of subscapular (S) and triceps (T) skinfolds were used to estimate percent fat. The S/T ratio provided an index of trunkal fat patterning. RESULTS. Significant overrepresentation (greater than 20%) of the uppermost quintile (UQ) for cardiovascular disease (CVD) risk factors was evident at or above 25% fat in males (32.2% to 37.3% in UQ) and at or above 30% fat in females (26.6% to 45.4% in UQ), even after adjusting for age, race, fasting status, and trunkal fat patterning. CONCLUSIONS. These data support the concept of body fatness standards in White and Black children and adolescents as significant predictors of CVD risk factors. Potential applications of these obesity standards include epidemiologic surveys, pediatric health screenings, and youth fitness tests.

(2006). Agreement in Body Fat Estimates Between a Hand-Held Bioelectrical Impedance Analyzer and Skinfold Thicknesses in African American and Caucasian Adolescents. Research Quarterly for Exercise and Sport: Vol. 77, No. 4, pp. 519-526.

Purpose: To develop an historical bone loading questionnaire that assesses loads applied to the skeleton using bone loading units and to determine its reproducibility. Additional purposes were to correlate bone loading units with areal bone mineral density (aBMD) and to determine whether low levels of bone loading increase the odds for low aBMD in healthy premenopausal women. Methods: Premenopausal women (N = 80; age: 31 +/- 7.7 yr) completed the newly developed bone loading history questionnaire (BLHQ) twice within 4-6 wk to establish reproducibility. aBMD (g[middle dot]cm-2) of the whole body, lumbar spine (L2-4), and right hip (proximal femur) were assessed with dual energy x-ray absorptiometry (DXA) in the women. Results: The questionnaire demonstrated good test-retest reliability in premenopausal women using intraclass correlation coefficients (spine r = 0.89, P < 0.001; hip r = 0.92, P < 0.001). Total spine bone loading exposure (r = 0.338; P = 0.002) and hip bone loading exposure (r = 0.317; P = 0.004) were significantly and independently correlated with femoral neck aBMD, after adjusting for BMI. Logistic regression analyses revealed increased odds for low femoral neck aBMD among those in the lowest tertile for recent hip bone loading exposure after adjusting for older ages, oral contraceptive use, low calcium intake, and an overweight BMI (OR = 3.62; CI = 1.09-11.94; P = 0.035). Conclusion: Historical bone loading activity can be reliably assessed and is moderately associated with femoral neck aBMD. This questionnaire could help to identify women with low femoral neck aBMD prior to menopause.

To determine the relations among peak aerobic capacity, physical activity, functional ability, components of the metabolic syndrome (high-density lipoprotein cholesterol [HDL-C], triglycerides [TG], glucose, insulin, abdominal obesity, high blood pressure), and inflammatory factors (interleukin-6 [IL-6], C-reactive protein [CRP]) in men with paraplegia.Cross-sectional exploratory design.University research laboratory.Twenty-two men (age, 39+/-9y; duration of injury, 17+/-9y; level of injury, T2-L2) with functionally complete paraplegia volunteered to participate.Not applicable.Peak aerobic capacity was measured using a graded peak exercise test with an arm ergometer, and physical activity was assessed by the Physical Activity and Disability Scale. Functional ability was assessed by the Self-Report Functional Measure. Circulating glucose, insulin, HDL-C, TG, total cholesterol, IL-6, and CRP levels were determined by specific enzyme or immunologic assays. Body fat was determined by dual-energy x-ray absorptiometry, and central obesity was estimated from abdominal sagittal diameters.Lower peak aerobic capacities were associated with lower HDL-C and lower physical activity levels ( P.014). Lower physical activity levels were associated with higher fasting glucose, lower HDL-C level, and larger abdominal sagittal diameters ( P.036). Larger abdominal sagittal diameters were associated with higher fasting glucose, higher fasting and postload insulin, lower HDL-C, higher TG, and higher CRP levels ( P.05).Diet and exercise trials are needed to determine the efficacy and effectiveness of lifestyle interventions aimed at slowing the progression of the metabolic syndrome in people with spinal cord injury.

We tested the hypothesis that exercise training (Ex) attenuates the effects of hyperlipidemia on endothelial function by enhancing NO-mediated vasorelaxation in porcine brachial (Br) arteries. Adult female pigs were fed a normal-fat (NF) or high-fat (HF) diet for 20 wk. Four weeks after initiation of the diet, pigs underwent Ex or remained sedentary (Sed) for 16 wk. Relaxation to ACh was impaired by HF ( P = 0.03). The combination of HF and Sed impaired ACh-induced relaxation more than HF or Sed alone ( P = 0.0002). Relaxation to high doses of bradykinin (BK) was impaired by HF ( P = 0.0002). Ex significantly improved ACh-induced relaxation ( P = 0.01) and tended to improve relaxation to BK ( P = 0.38). To determine the mechanism(s) by which HF and Ex affected relaxation to ACh and BK, relaxation was assessed in the presence of N G-nitro-l-arginine methyl ester (l-NAME; to inhibit NO synthase), indomethacin (Indo; to inhibit cyclooxygenase), or l-NAME + Indo. In the presence of l-NAME, Indo, or l-NAME + Indo, ACh-induced relaxation was no longer different between HF and NF arteries; however, relaxation remained greater in Ex than in Sed arteries. In the presence of l-NAME or Indo, BK-induced relaxation was no longer altered by HF but was enhanced by Ex. In the presence of l-NAME + Indo, BK-induced relaxation was enhanced by HF and Ex. These data indicate that hyperlipidemia impairs ACh- and BK-induced relaxation by impairing NO- and PGI2-mediated relaxation. Ex attenuates the effects of HF by enhancing a vasodilator mechanism independent of NO and PGI2.

Little information has been reported on the leisure time physical activity (LTPA) habits of adults with mental retardation. Prevalence of physical inactivity and recommended LTPA of adults with mild to moderate mental retardation who live in community settings was described. Adults with mental retardation (76 men, 74 women) reported their physical activity habits. Overall, men and women who resided in community settings were similarly inactive, with 47% to 51% of individuals participating in little to no LTPA. Forty-two to 47% of them reported participation in moderate to vigorous LTPA five or more times per week. Limitations to quantifying physical activity through questionnaire process is discussed and development and implementation of programs designed to increase physical activity levels recommended.

The association between physical activity, dietary behaviors, and elevated cardiovascular disease risk factor components of the insulin resistance syndrome in adults with mental retardation was identified. Established clinical cutoff points were used to identify 145 participants with mild mental retardation and hyperinsulinemia, borderline high triglycerides, low high-density lipoprotein cholesterol, hypertension, and abdominal obesity. Odds ratios were calculated from logistic regression analysis. Those who participated in more frequent bouts of physical activity or who consumed lower dietary fat intakes were approximately one third as likely to have hyperinsulinemia and abdominal obesity compared to those who participated in less frequent physical activity or who consumed higher fat intakes, suggesting that these behaviors are protective against elevated components of the insulin resistance syndrome.

A reduced expression of the insulin resistance syndrome, a common neuroendocrine disorder underlying atherosclerosis, may play a role in reduced atherosclerosis in adults with Down syndrome. We compared selected components of the insulin resistance syndrome between 75 adults with Down syndrome and 70 with mental retardation due to other causes. After adjusting for age differences, residence, cigarette smoking, and medication use, women with Down syndrome had lower fasting plasma glucose and lower systolic blood pressure than comparison women. Men with Down syndrome had lower systolic and diastolic blood pressure than comparison men. Results suggest that women with Down syndrome may be less likely to express the insulin resistance syndrome, and men and women with Down syndrome may possess fewer atherosclerotic risk factors than the comparison groups.

Background and Objectives The pain following total knee arthroplasty can be associated with significant morbidity, especially in the elderly. Regional anesthetic techniques attenuate or eliminate postoperative pain, which may reduce this morbidity. Methods A 74-year-old patient with history of an epidural abscess underwent elective bilateral total knee arthroplasty for degenerative joint disease. Bilateral lumbar plexus catheters were placed via the fascia iliaca compartments. Lidocaine was infused postoperative through both catheters, and serum lidocaine levels were followed. Results The patient received significant postoperative pain relief based on physical and subjective examination. There were no complications or untoward effects related to the technique. Conclusion Lumbar plexus blockade with continuous local anesthetic infusion via the fascia iliaca compartment is an effective means of providing postoperative analgesia after total knee arthroplasty when epidural analgesia is contraindicated.

Due to age-related decreases in bone minera11,2 and total body protein3 coupled with a possible increase in the hydration of the fat-free mass (1,1-M)4, it is likely that, on average, the density of the FFM is lower in older relative to younger adults. Other investigators have speculated that the density of the FFM may become more variable with advancing age5,6. In either case, erroneous estimates of body fat percentage (%Fat) will result when traditional two-component (2C: fat and fat-free) models7 are used in older adults. More complex four component (4C: fat, water, mineral and fat-free residual) models3,5,8 may provide more valid substitutes for the 2C model7 in older adults.

The relationship of skinfold thicknesses and body density to body fatness was assessed, and skinfold prediction equations were developed for the estimation of body fatness determined from measures of body density, total body water, and bone mineral in a sample of 91 males and 116 females aged 34-84 years. For a given skinfold thickness, adjustment for individual deviations in the water and bone mineral fractions of the fat-free body assumed constant by traditional body composition models resulted in absolute reductions in overstimates of body fatness from 4.5 to 1.9% in females and from 2.8 to 1.7% in males for every 15 year increase in age. Percentage fat from density, water, and bone was estimated from skinfold thicknesses with SEEs of 2.9% in males and 3.8% in females. When compared to percentage fat from our multicomponent-derived criterion, percentage fat from body density and a two-component model resulted in individual errors ranging from underestimates of 5.6% fat to overestimates of 14.0% fat. The multicomponent prediction equations presented herein should produce more valid estimates of body composition in middle-aged and older men and women than equations based on two-component models. © 1992 Wiley-Liss, Inc.

The dietary intake of adults with mental retardation among three different community residential settings was described and compared. Two dietary screeners were administered to 325 adults. The women's Fruit and Vegetable Screener scores from group homes were significantly higher than scores from those with family members and in semi-independent settings. No significant differences were found in dietary intake across residences for men. Overall, 0% to 6% of the participants consumed the recommended 5 or more fruits and vegetables per day, and 15% to 30% consumed the recommendedor=30% or less of calories from fat. Results suggest that regardless of residential setting, men and women do not consume enough fruits and vegetables and consume too much dietary fat.

The association between physical activity, dietary behaviors, and elevated cardiovascular disease risk factor components of the insulin resistance syndrome in adults with mental retardation was identified. Established clinical cutoff points were used to identify 145 participants with mild mental retardation and hyperinsulinemia, borderline high triglycerides, low high-density lipoprotein cholesterol, hypertension, and abdominal obesity. Odds ratios were calculated from logistic regression analysis. Those who participated in more frequent bouts of physical activity or who consumed lower dietary fat intakes were approximately one third as likely to have hyperinsulinemia and abdominal obesity compared to those who participated in less frequent physical activity or who consumed higher fat intakes, suggesting that these behaviors are protective against elevated components of the insulin resistance syndrome.

A reduced expression of the insulin resistance syndrome, a common neuroendocrine disorder underlying atherosclerosis, may play a role in reduced atherosclerosis in adults with Down syndrome. We compared selected components of the insulin resistance syndrome between 75 adults with Down syndrome and 70 with mental retardation due to other causes. After adjusting for age differences, residence, cigarette smoking, and medication use, women with Down syndrome had lower fasting plasma glucose and lower systolic blood pressure than comparison women. Men with Down syndrome had lower systolic and diastolic blood pressure than comparison men. Results suggest that women with Down syndrome may be less likely to express the insulin resistance syndrome, and men and women with Down syndrome may possess fewer atherosclerotic risk factors than the comparison groups.

The purpose of this study was to compare the relationships of anthropometric, bioelectrical impedance analysis (BIA), and near infrared interactance (NIR) measurements with a multiple-component (MC) criterion estimate of body composition derived from body density (D), body water (W), and bone mineral (B) in 48 white adults aged 49-80 yr. Relative errors of predicting the MC criterion from the practical measurements were determined by simple regressions within gender and calculated as the SEE divided by the criterion mean and expressed as a percentage. Relative errors were lowest for the BIA variable, height2/resistance (4.8-5.0%), higher for body mass index and the sum of 10 skinfold thicknesses (7.0-14.5%), and highest for NIR-derived optical density readings at the biceps and the sum of 10 sites (10.8-15.8%). Due to the low relative prediction error for height2/resistance, sex-specific BIA formulas for estimating fat-free mass from D, W, and B (FFM-DWB) were developed. The SEEs for predicting FFM-DWB from BIA, weight, and age were both 1.5 kg in women and men. Because BIA is not limited to ambulatory subjects, it is concluded that BIA may be a particularly useful, practical technique for estimating body composition in older adults.