Body composition by DEXA and its association with physical fitness in 140 conscripts
ABSTRACT The aim of the study was to determine the body composition of healthy young men and to investigate whether there exists an association between body composition and physical fitness.
A prospective cohort study of 140 healthy male conscripts (mean age 19.8yr, SD 1.0 yr) was conducted. We examined subject characteristics, aerobic performance, and muscle strength, and we assessed body composition using dual-energy x-ray absorptiometry (DEXA). The association between total body composition and lower-limb composition and physical performance was investigated by linear regression.
The mean body mass index (BMI) of the subjects was 24.6 kg.m (SD 4.7). Their mean bone mineral density (BMD) was 1.3 g.cm (SD 0.1), fat percentage (fat%) 22.6 (SD 9.7), lean mass 57.6 kg (SD 7.0), and bone mass 3.2 kg (SD 0.4) at the beginning of the military service. Fat percentage was significantly associated with 12-min running performance (P < 0.001), and a significant relationship was found between muscle strength and fat% (P< 0.001), and increasing BMD (P < 0.001), in multivariate analysis. Lean mass was not associated with physical performance.
DEXA measurement of the proportion of body fat is a useful tool to indirectly assess running performance and muscle strength in Finnish male conscripts. Increased fat mass and fat percentage were strong predictors of poorer physical fitness. Moreover, the relationship between muscle strength and BMD was confirmed. However, muscle mass did not predict muscle strength in our sample.
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- "Waist circumference was measured at the narrowest part of the waist (above the umbilicus and below the xiphoid process) (Ohrvall et al., 2000). Body composition was determined by dual energy xray absorptiometry (DEXA) using established methods (Mattila et al., 2007). "
ABSTRACT: Obesity contributes to stress induced impairments in endothelium-dependent vasodilation (EDV), a precursor to atherosclerosis. Since obesity is associated with inflammation and oxidative stress, we sought to determine if a single bout of strenuous weight lifting (SWL) reduces EDV among sedentary obese adults. Participants included 9 obese (OB) (BMI 30.0-40.0 kg/m(2)) and 8 lean (LN) (BMI 18.5-24.9 kg/m(2)) sedentary young women. All participants underwent a single bout of SWL using a progressive leg-press protocol. Brachial artery flow-mediated dilation (FMD) (an index of EDV) was determined using ultrasonography before and after SWL. Sublingual nitroglycerin (NTG) was used to determine brachial artery endothelium-independent vasodilation following SWL. Brachial artery FMD was significantly reduced in OB and LN women (LN: 6.4 ± 1.6%, p = 0.22) after SWL. There was no difference in the magnitude of change pre- and post-SWL between groups (OB: -2.4 ± 0.6% and LN: -2.2 ± 1.6%, p = 0.84). Dilation to NTG was lower in OB (21.6 ± 1.3%) compared to LN women (27.6 ± 2.1%, p = 0.02) and associated with body weight (r = -0.70, p = 0.01). These data suggest that EDV is reduced in woman after acute resistance exercise. Dilations to NTG were lower in obese compared to lean woman and associated with body weight suggesting that changes in sensitivity of blood vessels to NO occurs during obesity. These findings may be important for understanding vascular risk following acute exercise in obesity.Frontiers in Physiology 07/2014; 5:253. DOI:10.3389/fphys.2014.00253 · 3.50 Impact Factor
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- "Regular PA has been shown to reduce the risks for obesity and metabolic disease at all ages. Recent studies [4,18-20] support the finding that higher CRF is related to lower risks of obesity for both men and women. For example, Irwin et al.  reported higher levels CRF predicted less body weight and lower BF%. "
ABSTRACT: Background High levels of physical activity (PA) and cardiorespiratory fitness (CRF) are each associated with a favorable cardiovascular disease (CVD) risk profile. However, the relationship between CRF and obesity is still inconsistent across studies, and there has been no thorough exploration of the independent contribution of CRF to different CVD risk factors in Chinese women. This study investigated the relationship between CRF and CVD risk factors in 40–49 year old women in Beijing. Methods The study included 231 urban-dwelling asymptomatic 40–49 year old women. Body mass index (BMI), body fat percentage (BF%), blood glucose, blood lipids, blood pressure, and pulse wave velocity (PWV) were measured at rest. Cycle ergometer exercise tests were conducted to assess CRF as indicated by maximal oxygen uptake (VO2max). Participants were categorized into three CRF levels (low, moderate and high). Results High CRF level was associated with significantly less BF%, lower PWV, and higher weekly physical activity compared with low and moderate CRF (P < 0.05). Compared to high CRF, the odds ratios for having ≥3 main CVD risk factors (overweight, hypertension, and dyslipidemia) in low and moderate CRF were 2.09 (95% CI: 1.48-2.94) and 1.84 (95% CI: 1.29-2.62), respectively. The proportion of participants with clinical ST segment depression and prolonged QTC interval during cycle ergometer testing was significantly higher in women with low CRF. Conclusions Overall, Chinese middle-aged women demonstrated a moderate level of CRF. CRF was independently associated with CVD risk factors, including overweight, hypertension, dyslipidemia, arterial stiffness, and abnormal ECG during exercise, with the least fit women exhibiting the highest number of CVD risk factors.BMC Women's Health 05/2014; 14(1):62. DOI:10.1186/1472-6874-14-62 · 1.66 Impact Factor
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- "However, rarely do such studies account for body fatness and maturity when calculating these associations. It is well accepted that body fatness influences fitness levels in adults (Mattila et al., 2007). Similarly, increased body fat is likely to lead to a decrease in performance in children, particularly where body weight is lifted or carried over distance (i.e. "
ABSTRACT: Body fat and maturation both influence cardiorespiratory fitness, however few studies have taken these variables into account when using field tests to predict children’s fitness levels. The purpose of this study was to determine the relationship between two field tests of cardiorespiratory fitness (20 m Maximal Multistage Shuttle Run [20-MST], 550 m distance run [550-m]) and direct measurement of VO2max after adjustment for body fatness and maturity levels. Fifty-three participants (25 boys, 28 girls, age 10.6 ± 1.2 y, mean ± SD) had their body fat levels estimated using bioelectrical impedance (16.6% ± 6.0% and 20.0% ± 5.8% for boys and girls, respectively). Participants performed in random order, the 20-MST and 550-m run followed by a progressive treadmill test to exhaustion during which gas exchange measures were taken. Pearson correlation coefficient analysis revealed that the participants’ performance in the 20-MST and 550-m run were highly correlated to VO2max obtained during the treadmill test to exhaustion (r = 0.70 and 0.59 for 20-MST and 550-m run, respectively). Adjusting for body fatness and maturity levels in a multivariate regression analysis increased the associations between the field tests and VO2max (r = 0.73 for 20-MST and 0.65 for 550-m). We may conclude that both the 20-MST and the 550-m distance run are valid field tests of cardiorespiratory fitness in New Zealand 8-13 year old children and incorporating body fatness and maturity levels explains an additional 5-7% of the variance.Journal of Human Kinetics 04/2014; 40:83-92. DOI:10.2478/hukin-2014-0010 · 0.70 Impact Factor