Risk of obesity in relation to physical activity tracking from youth to adulthood

PURPOSE: Maintaining a high level of physical activity throughout one's lifetime may decrease the risk of obesity. We evaluated how physical activity patterns from youths (9-18 yr) to adulthood are associated with body mass index (BMI) and waist circumference (WC) in a population of young adults. METHODS: As part of the longitudinal Cardiovascular Risk in Young Finns Study, we assessed physical activity over a 21-yr follow-up in a cohort of 1319 subjects. Physical activity was measured using a questionnaire completed in conjunction with a medical examination. RESULTS: During the follow-up, 33.1% of men and 32.0% of women were classified as persistently active, and 11.5% of men and 7.4% of women as persistently inactive. Both decreasingly active and persistently inactive subjects were more likely to be obese as adults compared with persistently active subjects. In women, being decreasingly active from youth to adulthood compared with being persistently active was independently associated with the risk of being overweight (BMI = 25.0-29.9 kg.m(-2), odds ratio (OR) = 2.35, confidence interval (CI) = 1.16-4.78), obese (BMI > or = 30.0 kg.m(-2), OR = 2.72, CI = 1.04-7.09), mildly abdominally obese (WC = 800-879 mm, OR = 2.21, CI = 1.01-4.84), and severely abdominally obese (WC > or = 880 mm, OR = 2.19, CI = 1.03-4.67), after adjustment for several variables including childhood fatness. In men, decreasing physical activity during their lifetime was associated with mild (WC = 940-1019 mm, odds ratio (OR) = 1.78, CI = 1.00-3.19) and severe (WC > or = 1020 mm, OR = 2.47, CI = 1.27-4.78) abdominal obesity in unadjusted analyses, but these two associations disappeared after adjustment for confounding variables (OR = 1.51, CI = 0.72-3.17 and OR = 1.62, CI 0.66-4.02, respectively). In men, changes in physical activity were not associated with obesity or overweight as defined by cut-points of BMI. CONCLUSIONS: Maintaining a high level of physical activity from youth to adulthood is independently associated with lower risk of abdominal obesity in among women, but not men. These findings suggest that changes in physical activity patterns during the lifetime may contribute to the development of abdominal obesity in women.     

Evaluation of body fat estimated from body mass index and impedance in Belgian male military candidates: comparing two methods for estimating body composition

OBJECTIVE: The study objective was to evaluate whether a classification based on body mass index (BMI) agrees with a classification based on body fat mass, estimated by bioelectrical impedance. METHODS: A random sample of 448 male candidates between 18 and 20 years was selected during their medical visit in a military recruitment center. BMI was determined as weight/height2 and was considered normal between 20.0 and 25.0 kg/m2 (cfr. WHO classification). Percentage of body fat was estimated with bioelectrical impedance, using the Omron Body Fat Analyzer HBF-306. Subjects with a body fat percentage measured by bipolar bioelectrical impedance analysis (BF%(IMP)) < or = 20.9% were considered normal weight, while subjects with a BF%(IMP) > or = 21.0% were considered overweight. We used the following classification: true positives were normal scores for BMI and impedance; false positives were normal scores for BMI but not for impedance; true negatives were overweight scores for BMI and for impedance; and false negatives were overweight scores for BMI but not for impedance. Data were analyzed using the SPSS statistical program. RESULTS: BMI ranged from 17.0 to 29.4 kg/m2; percentage of fat mass varied between 5.3 and 31.4% of body weight. Of the total sample, 328 (73.2%) candidates were classified as true positive, 29 (6.5%) as false negative, 47 (10.5%) as false positive, and finally 44 (9.8%) as true negative. The difference in classification in normal weight versus overweight between the BMI method and the bipolar bioelectrical impedance method was statistically significant (chi2 with one df = 86.04; p < 0.001). CONCLUSIONS: To limit false-negative classifications, additional impedance measurements in the BMI category between 25.0 and 27.0 kg/m2 is mandatory to determine whether there is really an excess fat mass.     

Relationship of obesity with physical activity, aerobic fitness and muscle strength in Flemish adults

AIM: The aim of this study was to analyse differences in physical activity, cardiorespiratory fitness (CRF) and muscle strength between normal weight, overweight and obese adults and to investigate the role of physical activity variables in the analyses of differences in CRF and muscle strength between these groups. METHODS: A total of 807 men and 633 women (age: 18-75 years) were included in this cross-sectional study. Weight, height, waist circumference (WC) and bioelectrical impedance were measured. Different dimensions of physical activity were assessed using a validated questionnaire. CRF (VO(2peak)) was evaluated by a maximal test on a cycle ergometer. Knee strength was measured with a calibrated Biodex System Pro 3 dynamometer. Three methods were used for classification in obesity groups: body mass index (BMI), WC and combined BMI-WC classification. RESULTS: Health-related sports and physical activity level are negatively associated with obesity in men, but not in women. Television viewing is positively associated with obesity, while VO(2peak)/fat free mass (FFM) and knee strength/FFM show a negative association with obesity in both genders. Overall, subjects with normal WC seem to be more physically active and to have somewhat better values for CRF compared to those with high WC within the same BMI category. Lower values for relative CRF and knee strength in obese subjects compared to their lean counterparts remain after adjustment for physical activity. CONCLUSION: This study confirms the lower level of physical activity and the impaired CRF and knee strength in obese adults compared to their lean counterparts. This study also sustains the importance of measuring WC and CRF during clinical examinations.     

高原地区肥胖对糖代谢的影响

目的 :探讨高原地区肥胖对糖代谢的影响。方法 :在海拔 370 0m以上的青海果洛地区随机对 14 95例当地居住者 (其中藏族 10 4 9人 ,汉族 4 46人 )采用日本京都血糖仪 (GT - 16 40 )测空腹毛细血管血糖 ,对空腹毛细血管血糖≥ 5 .5mmol/L者行OGTT (口服 75 g葡萄糖 )试验 ,按WHO标准筛查出高血糖 (包括糖尿病、糖调节障碍 )。同时测血压、体重指数 (BMI)及腰围 (WC)。结果 :调查者中肥胖 (BMI≥ 2 5 )的患病率为 2 6 .5 % ;肥胖者高血糖的患病率 (6 .6 % )显著高于非肥胖者 (4 .0 % ) ;男性腹型肥胖 (WC >85cm )的患病率 (11.3)显著高于腰围正常者 (4 .5 % )。结论 :肥胖特别是男性腹型肥胖是高原地区发生高血糖的危险因素     

Prevalence, challenges, and solutions for (18)F-FDG PET studies of obese patients: a technologist's perspective

Obesity has reached epidemic proportions in the United States; hence, it is frequently encountered in patients undergoing (18)F-FDG PET studies. The purpose of the current study was to present a technologist's perspective on the prevalence of obesity and the challenges and solutions in imaging obese patients in our PET facility. METHODS: From October 2002 to October 2003, whole-body (18)F-FDG PET was performed on 1,164 patients with a known or suspected malignancy. Images were acquired 45-60 min after (18)F-FDG injection (7.4 MBq [0.2 mCi]/kg, with a maximum of 925 MBq [25 mCi]) on a PET scanner using a 4-min emission and 3-min transmission time per bed position. A database was maintained of patient height and weight, and body mass index (BMI) was calculated. Patient obesity was classified as overweight (BMI > or = 25 kg/m(2)), obese (BMI > or = 30 kg/m(2)), or malignantly obese (BMI > or = 40 kg/m(2)). In addition, PET technologists recorded any problems and attempted solutions related to the patient weight. RESULTS: BMI calculations showed that 528 patients (45.4%) were overweight or obese (322 men and 206 women; mean age, 55 y). Of those, 201 (38%) were overweight, 270 (51%) were obese, and 57 (11%) were malignantly obese. Problems encountered in these patients included difficult intravenous access (15%), difficult patient positioning (10%), patient motion (7%), an incomplete study (emission only) (1%), and potentially higher radiation exposure to the technologist because of extra time spent near the patient. Attempted solutions included adjusting the schedule to allow more time per patient, adjusting the dose based on body weight, using varied positioning techniques, dividing the study to allow a respite between different image combinations, and dividing time spent with obese patients among the technologists involved. CONCLUSION: Excessive body weight and related problems have commonly been encountered in our PET facility. (18)F-FDG PET studies of obese patients represent an ongoing challenge, which requires patient-tailored solutions to avoid compromising image quality and risking higher radiation exposure to the technologists.     

Physical activity, obesity status, and glycemic control: The ATTICA study

PURPOSE: We aimed to evaluate the relationship of physical activity and obesity with glycemic control and insulin resistance. METHODS: A randomized, population-based, cross-sectional health and nutrition survey was conducted in the province of Athens, Greece. Subjects included 1514 men and 1528 women without evidence of cardiovascular or other chronic disease. Participants were classified as inactive, minimally active, or health-enhancing physical activity (HEPA) active based on the International Physical Activity Questionnaire. Insulin sensitivity was assessed by the homeostatic model (HOMA), and overweight or obesity was assessed according to BMI (BMI >or= 25). Related social, biological, and lifestyle factors were also recorded and used as potential confounders. RESULTS: Five hundred sixty-five (37.3%) men and 493 (32.3%) women were classified as physically active. From the 1058 (34.8%) subjects who were classified as active, 306 (10.1%) met the criteria for HEPA active, and the rest were minimally active. HEPA active and minimally active subjects smoked less and had lower BMI, waist, and waist-to-hip ratio. Lean and overweight or obese subjects with sedentary lifestyle had greater levels of glucose, insulin, and insulin resistance [corrected] However, overweight or obese volunteers with physical activity levels classified as HEPA had similar levels of glucose and insulin sensitivity, with lower insulin than lean inactive individuals. Linear regression analysis between HOMA and physical activity, taking into consideration several social and biological factors, showed that physical activity (MET x min x wk(-1)), age, BMI, and total energy intake are important predictors of HOMA, whereas other factors such as waist circumference did not reach statistical significance. CONCLUSION: Our data show that physical activity is a significant factor on insulin sensitivity, whereas increased physical activity may ameliorate the well-known effects of obesity on insulin sensitivity.     

Croatian rugby project-Part I. Anthropometric characteristics, body composition and constitution.

BACKGROUND: There are no data in important literature about the anthropometric characteristics of rugby players in countries where rugby is not a popular sport. The goals of this study were to analyze morphological anthropometric characteristics, body composition and constitution of players in the first Croatian-Slovenian rugby league (CSRL) with regard to player's position in the team, team position in the division, and to compare results with the results of rugby players from the more popular rugby leagues. METHODS: The study was carried out in a sample of voluntarily included 111 male rugby players from six clubs members of the CSRL, in the season 1996/97. Eleven anthropometric measures required for the calculations of body mass index (BMI), body fat percentage (BF%), and somatotype components were obtained in the clubs according to the recommendations by Jackson and Pollock and Heath and Carter. RESULTS: Forwards in the CSRL are on the average 93.5 kg heavy, 182.4 cm tall, with BMI 28.3 kg/m2, BF% 20.8% and somatotype 6.7-5.9-1.4. Backs are on average 82.2 kg heavy, 178.3 cm tall, with BMI 26.1 kg/m2, BF% 16.9% and somatotype 5.3-5.3-1.5. Backs from upper half of the division are on the average heavier than those from lower half, BF% in forwards from upper half of the division is higher than in forwards from lower half. Both differences were found to be statistically significant (p<0.05). CONCLUSIONS: Compared with the rugby players from more developed rugby leagues, forwards from the CSRL are lighter, backs are heavier and both have higher body fat percentage. Backs and forwards are more endomorphic and forwards are less mesomorphic compared with the rugby players from more developed rugby leagues.     

4周低氧运动结合饮食控制对肥胖青年体重、血脂及胰岛素抵抗的影响

目的:观察4周低氧运动干预结合饮食控制对肥胖青年的减肥效果和血脂、胰岛素抵抗等指标的变化。方法:18名肥胖成年人,分为低氧组11人,常氧组7人,进行为期4周的减肥训练,每周训练6天。低氧组每周进行3次低氧训练,隔天1次,其它为常氧训练,与常氧组相同。低氧训练环境为模拟海拔高度2500~2800米。按极轻体力劳动者的能量需求和营养均衡为原则制定食谱。采用人体三维扫描系统和人体成分分析仪分别于实验前后测试腰围、体重、体脂,采用生化法检测血糖、胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C),采用免疫抑制比浊法检测血清糖化血红蛋白(HbA1c),采用放免法检测血清胰岛素,计算胰岛素抵抗指数(HOMA-IR)。结果:4周训练后低氧组体重、腰围、BMI、体脂及体脂百分比与实验前相比均呈显著下降,分别减少了7.27%、6.80%、7.62%、18.84%和13.5%;TC、TG、LDL-C、HbA1c、HOMA-IR与实验前相比也均显著下降,分别降低了9.86%、33.57%、17.2%、6.60%和55.05%;HDL-C与实验前相比升高约5.71%。常氧组体重、腰围、BMI、体脂及体脂百分比与实验前相比均呈显著性下降,分别减少了4.18%、7.77%、4.26%、10.86%和6.79%;TC、TG、LDL-C、HbA1c、HOMA-IR与实验前相比也均显著下降,分别降低了17.8%、50.45%、22.54%、18.50%和59.04%;HDL-C与实验前相比升高约3.33%。将两组各指标训练前后的变化量(△值)进行独立样本t检验发现,低氧组体重和BMI的下降量显著性大于常氧组(P<0.01)。结论:与常氧运动相比,4周低氧运动明显降低了肥胖青年体重和BMI。4周低氧运动和常氧运动均能降低肥胖青年糖化血红蛋白和胰岛素抵抗等II型糖尿病危险因素,降低患病风险。     

The effect of cardiorespiratory fitness and obesity on cancer mortality in women and men

PURPOSE: The purpose of this study was to determine the independent and combined effects of cardiorespiratory fitness and obesity on all-cause cancer mortality for women and men. METHODS: Using the Lipids Research Clinics Prevalence Study, we examined the relationship of fitness and obesity on cancer mortality among 2585 women and 2890 men followed from 1972-1976 to 1998. Cardiorespiratory fitness was measured using a treadmill test and obesity was assessed using body mass index (BMI) calculated from measured height and weight. Gender-specific hazard ratios (HR) were calculated from proportional hazard models, which included covariates for age, education, smoking, alcohol intake, Keys score, and menopause (women only). RESULTS: Adjusted cancer mortality was significantly lower in the most fit quintile relative to the other four quintiles for men (HR = 0.47; 95% CI, 0.27-0.81) but not for women (HR = 0.84; 95% CI, 0.52-1.36). Adjusted cancer mortality was significantly higher in the highest BMI quintile relative to the other four BMI quintiles for women (HR = 1.49; 95% CI, 1.06-2.09) but not for men (HR = 1.05; 95% CI, 0.77-1.43). Further adjustment for BMI on fitness and adjustment for fitness on BMI did not meaningfully change the HR. There were no significant interactions between fitness and obesity in predicting cancer mortality for either women or men. CONCLUSION: In this study, high fitness was a stronger predictor of cancer mortality in men, whereas high BMI was a stronger predictor of cancer mortality in women.     

Significant increases in body mass indexes (BMI) in an adult autopsy population from 1986 to 2006--implications for modern forensic practice

A study was undertaken of two coronial autopsy populations aged >or= 17 years in Adelaide, South Australia in 1986 and in 2006 to determine whether there had been any increase in body mass index over the intervening 21 years. In 1986 there were 689 cases; M:F=2.8:1. The average BMI was 25.1, with a range from 12.5 to 55.5. 47% of cases had a normal BMI (18.5-24.9), 14.8% were obese (BMI >or= 30), with a subset of 1.3% of cases classified as morbidly obese (BMI >or= 40). In 2006 there were 1176 cases; M:F=1.9:1. The average BMI was 27.1 with a range from 10.5 to 80.6. 32.1% of cases had a normal BMI, 27.2% were obese, with a subset of 4.8% of cases classified as morbidly obese. This study has confirmed that there has been a marked relative and absolute increase in numbers of obese individuals undergoing coronial post-mortem examinations in South Australia, with 218 more autopsies in 2006 involving obese bodies, including 47 more cases where morbid obesity was documented. This trend is undoubtedly occurring in other countries. Significant problems exist in trying to handle obese and particularly morbidly obese individuals in mortuaries designed for bodies with normal BMIs. Lifting, transport, transfer, storage and autopsy dissection are all difficult. Obesity enhances putrefaction that further complicates handling. Unless mortuaries are modified to deal with the increasing numbers of morbidly obese individuals, with reinforced and robust equipment including lifting hoists, the autopsy examination of such cases may be compromised, and staff will be confronted with ongoing and increasing risk of injury.     

Influence of previous body mass index and sex on regional fat changes in a weight loss intervention

Objectives: Men and women may lose weight in a different fashion. This study compares the changes in different anatomical regions after a well-controlled weight loss program by sex and initial BMI.

Methods: A total of 180 subjects (48 overweight women, 36 overweight men, and 48 obese women and 48 obese men) were recruited to participate in a 22-week weight loss programme (diet + exercise).

Results: Regarding percentage body weight change from baseline, there was no triple interaction (BMI, sex and anatomical region), but there was interaction between BMI and anatomical region (F2,840 = 34.5; p < 0.001), and between sex and anatomical region (F2,840 = 98.8; p < 0.001). Usually, the arms and legs are the regions that lose more weight in obese participants, but men lose the highest percentage of mass from the trunk. There were differences between men and women for the areas of left trunk mass (750g), right trunk mass (700g), total mass of the trunk (1400g), android mass (350g), and finally in the total mass in overweight participants (1300g), with higher values for men than for women. The region that loses more weight and fat is the trunk, followed by the legs, and then the arms, when the loss is observed in function of the total weight or fat lost.

Conclusion: Both BMI and sex exert a definite influence fat loss, especially in some anatomical regions.     

Physical activity in an Old Order Amish community

One method to assess the impact of modern technology on physical activity is to examine a group whose lifestyle has not changed markedly in the last 150 yr. The Old Order Amish refrain from driving automobiles, using electrical appliances, and employing other modern conveniences. Labor-intensive farming is still the preferred occupation. PURPOSE: The purposes of this study were to characterize the physical activity (PA) levels in an Old Order Amish farming community and to examine measures of adiposity in this group. METHODS: Ninety-eight Amish adults (18-75 yr of age) in southern Ontario were studied. Anthropometric variables included height, weight, body mass index (BMI), and percent body fat (% BF). Participants were asked to wear an electronic pedometer for 7 d and to fill out a log sheet on which they recorded steps per day and physical activities. After 1 wk, they returned the pedometers and log sheets and filled out the International Physical Activity Questionnaire. RESULTS: The average number of steps per day was 18,425 for men versus 14,196 for women (P < 0.05). Men reported 10.0 h.wk-1 of vigorous PA, 42.8 h.wk-1 of moderate PA, and 12.0 h.wk-1 of walking. Women reported 3.4 h.wk-1 of vigorous PA, 39.2 h.wk-1 of moderate PA, and 5.7 h.wk-1 of walking. Men had higher levels of energy expenditure than women (P < 0.001). A total of 25% of the men and 27% of the women were overweight (BMI > or = 25), and 0% of the men and 9% of the women were obese (BMI > or = 30). CONCLUSIONS: The Amish we studied had very high levels of physical activity, which may contribute to their low prevalence of obesity. This group probably represents an upper extreme for "lifestyle PA" in North America today.     

Fitness, performance and anthropometric characteristics of 19,185 Canadian Forces personnel classified according to body mass index

The Canadian Forces (CF), concerned with the possible adverse effects of obesity on military performance and image, recently adopted the body mass index (BMI) to monitor excess weight among its personnel. Subsequently, the records of 17,098 CF men (32.0 +/- 8 years) and 2,087 CF women (26.2 +/- 5 years) were examined. Approximately 50% of the men and 25% of the women had a BMI greater than 25 kg/m2, while 26% of the men and 12% of the women had a BMI greater than 27 kg/m2. Except for grip strength, both men and women in higher BMI zones typically demonstrated significantly lower fitness and performance scores than those in lower BMI zones. For men and women, increasing BMI was associated with progressive and significant increases in body weight, chest girth, waist girth, gluteal girth, thigh girth, waist-to-hip ratio, and waist-to-height ratio, and decreases in difference between chest-minus-waist girths. Waist girth increased proportionately more than other circumferences with increasing BMI, thus indicating a greater relative deposition of body fat in the abdominal region. In view of the relationship between high BMI and compromised fitness, appearance, and health observed in this population, the CF would benefit from continued educational and clinical efforts to reduce the prevalence of obesity. The BMI would serve as a useful epidemiologic standard to help monitor progress in these areas.     

Physical activity in leisure-time is not associated with 10-year changes in waist circumference

To examine whether physical activity (PA) is associated with changes in waist circumference (WC), and changes in WC given changes in body mass index (BMI). Longitudinal population-based study including 2026 men and 2782 women aged 21-81 years. Subjects were examined in 1991-1993 (baseline) and 2001-2003 (follow up), where height, weight and WC were measured. Information about overall PA in leisure-time (LTPA), walking, biking and sports activity was collected with self-administrated questionnaires at baseline. Outcomes were changes in WC and changes in WC given changes in BMI between baseline and follow up. The median increase in WC was 3.0 cm in men and 3.5 cm in women during follow-up, and with a considerable inter-individual variation. LTPA, walking and biking were not significantly associated with the outcomes. Inverse associations between sports activity and the outcomes were observed in both sexes, and these were significant in some analyses. Associations were not altered by adjustment for confounders or by exclusions of subjects with diseases and/or treatment by obesity-inducing medication. This study suggests that LTPA, walking and biking have no appreciable effects on changes in WC or changes in WC given changes in BMI, whereas sports activity may have small preventive effects.     

Cardiovascular risk,obesity, and myocardial blood flow in postmenopausal women

Background. This study was designed to determine whether overweight or obese status is independently associated with myocardial flow reserve (MFR), an established predictor of cardiovascular mortality, in a group of postmenopausal women with no previous cardiovascular disease. Postmenopausal women are the largest group of overweight and physically inactive individuals in the United States. Increased body mass index (BMI) is consistently associated with increased cardiovascular mortality in this population. Whether this is because of obesity itself or the accompanying increase in cardiovascular risk factors (CRFs) remains controversial. Methods. We examined the relationship of myocardial blood flow (MBF), coronary vascular resistance, and MFR to BMI in 60 postmenopausal women with no coronary heart disease. Subjects underwent dynamic N-13 ammonia positron emission tomography for the measurement of MBF and MFR. Baseline demographics, CRF, and hemodynamic parameters were recorded for each subject. Datasets were divided into 3 groups according to BMI: normal (18 to 24), overweight (25 to 29), and obese (≥30). Results. The overweight and obese groups showed significantly higher resting MBF and lower MFR than the normal-weight group (both P<.001), even after adjusting for CRF. A further analysis of subjects without any CRF (n=35) showed that the MFR remained significantly lower in the obese compared with normal-weight subjects (P=.05). Levels of known markers of vascular inflammation (high-sensitivity C-reactive protein and homocysteine) and high-density lipoprotein cholesterol levels correlated with declining MFR. Conclusions. These findings provide a mechanistic link between obesity and coronary heart disease in this population. This study was funded by a Veterans Health Administration MERIT Review Award. C.S.D. is on the Speaker’s Bureau at Pfizer, Inc., and has received grant support from Pfizer, Inc., Eli Lilly & Co., and the Veterans Health Administration.     

Whole body vibration added to endurance training in obese women - a pilot study

Whole body vibration (WBV) training is an increasingly popular training method that is strongly promoted for weight loss, but scientific data on its effectiveness, particularly in obese subjects, are sparse. 14 obese women (BMI: 37.4±1.3 kg/m2) randomized to 2 different groups (each n=7) participated in a 6-week endurance training program that was either combined or not combined with additional WBV training. Anthropometric measures, phase angle and body composition (assessed by bioelectrical impedance analysis; BIA), and resting energy expenditure (REE) were obtained before and after the training program. Body weight did not change during the training period (P=0.87), but waist circumference decreased in both groups (P=0.007; WBV: -3.4±1.4 cm; no-WBV: -1.7±0.7 cm) independent of WBV training (P=0.29 for group×time interaction). BIA revealed an enhancing effect of WBV training in comparison to no-WBV training on the phase angle (+0.20±0.12° vs. -0.19±0.12°; P=0.04) and calculated body cell mass (+0.8±0.2 vs. -0.3±0.4 kg; P=0.02), while calculated percentage fat mass decreased in both conditions (P=0.05) to similar extent (P=0.59; WBV: -0.8±0.2%; no-WBV: -0.4±0.5%). REE increased across the training (P=0.01; WBV: +77±33 kcal/24 h; no-WBV: +68±34 kcal/24 h), with this increase again not depending on WBV condition (P=0.85). Results of our pilot study in obese women provide preliminary evidence for a beneficial effect of WBV, when added to endurance training, on the bioelectrical phase angle, an increasingly recognized marker of individual's health status.     

Pedometer-determined physical activity and body composition in New Zealand children

PURPOSE: The objectives of this study were to examine current levels of pedometer-determined physical activity in a multiethnic sample of New Zealand children and to investigate associations among weekday and weekend step counts, body mass index (BMI), waist circumference (WC), and percentage body fat (%BF). METHODS: A total of 1115 children (536 boys, 579 girls) aged 5-12 yr wore sealed multiday memory pedometers for three weekdays and two weekend days. The ethnic composition of the sample was 49.2% European, 30.0% Polynesian, and 16.5% Asian, with 4.3% from other ethnicities. BMI was determined from height and weight, and %BF was measured using hand-to-foot bioelectrical impedance analysis. Participants were classified as normal weight, overweight, or obese using international BMI cutoff points (4), and into normal or central fat distribution groups using national WC standards (28). The 90th percentile of %BF for each age and sex subgroup was used to identify normal and high body fatness. RESULTS: Mean step counts for this sample were 16,133 +/- 3,864 (boys) and 14,124 +/- 3,286 (girls) on weekdays, and 12,702 +/- 5,048 (boys) and 11,158 +/- 4,309 (girls) on weekends. Significant differences in step counts were observed between weekdays and weekends, boys and girls, and among age, ethnic, and socioeconomic groups. Analysis of variance revealed stronger associations between step counts and %BF category than between step counts and BMI or WC groups. CONCLUSION: This study provides evidence of a link between daily step counts and body fatness in children. Our results also suggest that the promotion of physical activity during the weekend is a key priority for young New Zealanders.     

Effects of body mass index on the accuracy of an electronic pedometer

Electronic pedometers are accurate for assessing steps taken while walking in normal weight adults but the accuracy of these devices has not been tested in overweight and obese men and women. The primary purpose of this study was to assess the accuracy of an electronic pedometer for measuring steps taken at various walking speeds in groups of adults with variations in body mass index (BMI). The secondary purpose was to determine if the manufacturer recommended position is the best placement position for overweight and obese adults. Participants were categorized into one of three BMI categories identified by the World Health Organization: normal (N = 25; < 25 kg x m(-2)), overweight (N = 24; 25 - 29.9 kg x m(-2)), or obese (N = 17; > or = 30 kg x m(-2)). Participants walked on a treadmill for 3 min at 54, 67, 80, 94, and 107 m x min(-1) for a total of 15 min. During the treadmill walking, three electronic pedometers tallied steps taken. The pedometers were placed at the waist level, one on the anterior mid-line of the thigh (front; manufacturer recommended placement), one on the mid-axillary line (side), and one on the posterior mid-line of the thigh (back). Concurrently, a researcher counted steps using a hand-tally counter. Category of BMI did not affect the accuracy of the pedometer at any walking speed (54 m x min(-1), p = 0.991; 67 m x min(-1), p = 0.556; 80 m x min(-1), p = 0.591; 94 m x min(-1), p = 0.426; 107 m x min(-1), p = 0.869). At 54 m x min(-1), the front, side, and back pedometers significantly underestimated hand-tally counted steps by 20 % (p < 0.001), 33 % (p < 0.001), and 26 % (p < 0.001), respectively. At 67 m x min(-1) the front, side, and back pedometers significantly underestimated hand-tally counted steps by 7 % (p = 0.027), 13 % (p < 0.001), 11 % (p = 0.002), respectively. The steps recorded by the electronic pedometers placed at the front, side and back of the waist were not significantly different than steps counted by the hand-tally counter at speeds of 80 m x min(-1) and higher for all subjects combined. An electronic pedometer accurately quantified steps walked at speeds of 80 m x min(-1) or faster in persons with a normal BMI and those classified as overweight or obese. The placement of the pedometer on the front, side or back of the waistband did not affect accuracy of the pedometer for counting steps.     

Relationship between body composition, body mass index and bone mineral density in a large population of normal, osteopenic and osteoporotic women

Purpose

The knowledge of factors modulating the behaviour of bone mass is crucial for preventing and treating osteoporotic disease; among these factors, body weight (BW) has been shown to be of primary importance in postmenopausal women. Nevertheless, the relative effects of body composition indices are still being debated. Our aim was to analyze the relationship between body mass index (BMI), fat and lean mass and bone mineral density (BMD) in a large population of women. Moreover, this study represents a first important report on reference standard values for body composition in Italian women.

Materials and methods

Between 2005 and 2008, weight and height of 6,249 Italian women (aged 30?C80 years) were measured and BMI was calculated; furthermore BMD, bone mineral content, fat and lean mass were measured by dual-energy X-ray absorptiometry. Individuals were divided into five groups by decades (group 1, 30.0?C39.9; group 2, 40.0?C49.9; group 3, 50.0?C59.9; group 4, 60.0?C69.9; group 5, 70.0?C79.9). Differences among decades for all variables were calculated using a one-way analysis of variance (ANOVA) and Bonferroni test by the SPSS programme.

Results

Mean BW was 66.8±12.1 kg, mean height 159.1±6.3 cm and mean BMI 26.4±4.7 kg/m². According to BW and BMI, there was an increase of obesity with age, especially in women older than 50 years (p<0.001). Lean mass increased until 50 years of age but significantly decreased after this age (p<0.001). The percentage of osteopenia and osteoporosis in the examined population was 43.0% and 16.7%, respectively.

Conclusions

Our data show that obesity significantly decreased the risk for osteoporosis but did not decrease the risk for osteopenia. It is strongly recommended that a strong policy regarding prevention of osteopenia and osteoporosis be commenced. An overall examination of our results suggests that both fat and lean body mass can influence bone mass and that their relative effect on bone could be modulated by their absolute amount and ratio to total BW.     

Changes in physical activity behavior and the development of body mass index during the last 30 years in Norway

Body mass index (BMI; kg/m(2)) has increased markedly in the last decades. We hypothesized that highly physically active persons both at work and at leisure would be resistant to weight gain. The hypothesis was tested by analyzing Norwegian cross-sectional data collected in the period 1972-2002. Participants were 214,449 men and 206,136 women (aged 20-70 years). During the last 30 years in men and the last 15 years in women, a systematic larger BMI increase per year was observed in the sedentary [regression coefficients (SE) in men 0.060 (0.004) kg/m(2) and women 0.137 (0.012) kg/m(2)] compared with highly physically active groups [regression coefficients (SE) in men 0.036 (0.00 4) kg/m(2), and in women -0.001 (0.039) kg/m(2)]. Analyses were robust to adjustments for age, smoking and education. There was a larger absolute net increase in the prevalence of obesity among the sedentary compared with persons performing light, moderate or heavy physical activity (PA) at leisure. PA level in women both at work and in leisure was not associated with weight gain during the last decades. This association was less evident among men. Men and women who were lightly, moderately or highly active at leisure were less likely to be obese compared with those who were sedentary.