活动记录辅助加速度仪测量总能量消耗的初步研究

目的 用活动记录辅助加速度仪测量人体日常活动的能量消耗,为监测个体总能量消耗(TEE)提供简便易行的方法.方法 采用气体代谢法标定加速仪不同活动强度记录所对应的能量消耗;41名受试者连续佩戴加速度仪7 d,同时记录每日活动,间接估算每日总能量消耗.结果 加速仪测量TEE,男性(9761±866)kJ/d[(2332±207)kcal/d,休力活动水平(PAL)1.46±0.11],女性(7526±879)kJ/d[(1798±210)kcal/d,PAL 1.43±0.09];加速仪结合活动记录的测量结果为,男性(10573±804)kJ/d[(2526±192)kcal/d,PAL 1.58±0.10],女性(8191±737)kJ/d[(1957±176)kcal/d,PAL 1.56±0.08].结论 加速度仪配合活动记录所得TEE值在既往报道的范围之内,可以作为监测个体TEE和体力活动水平变化的简便方法.     

天津市部分大学生体力活动水平与身体成分的相关性

探讨天津市大学生体力活动水平与身体成分的相关性,为提高大学生健康水平提供理论参考.方法 招募天津大学、天津商业大学、天津理工大学363名在校大学生为测试对象.采用InBody 520人体成分分析仪测量身体成分,采用ActiGraph-GT3X加速度计记录7d体力活动数据.运用SPSS 23.0软件分析数据.结果 男生肌肉量、去脂体重、骨骼肌、躯干肌肉量均高于女生,体脂百分比低于女生(t值分别为6.20,6.16,6.18,6.47,-3.09,P值均<0.05).男、女生每天静坐时间均为10 h,女生每天中高等体力活动时间低于男生.男、女生每天静坐时间与体脂百分比、体脂肪均呈正相关,与肌肉量、去脂体重、骨骼肌、躯干肌肉量均呈负相关(P值均<0.01);每天轻体力活动时间、每天中高等体力活动时间、日均能量消耗、每周运动次数、每周运动时间与体脂百分比、体脂肪均呈负相关,与肌肉量、去脂体重、骨骼肌、躯干肌肉量均呈正相关(P值均<0.05).结论 静坐时间过长是天津市大学生超重肥胖的危险因素,增加中等以上体力活动时间可以降低肥胖风险.     

人体总能量消耗测量方法研究进展

人体总能量消耗(total energy expenditure,TEE)是指在个体或群体水平上一段时间内平均每天的能量消耗量[1],成人的TEE主要包括基础代谢、身体活动和食物热效应.测量人体TEE对于制定适宜的能量需要量,进而维持最佳的健康状况和身体机能至关重要.     

成年早期日常中高强度体力活动与身体成分最优模型研究

构建大学生日常中高及高强度体力活动及其主要身体成分的最优模型,寻求改善大学生身体成分的有效体力活动量.方法 采用ActiGraph-GT3X 加速度计对天津市3 所大学的363 名大学生进行7 d日常体力活动监测,采用Inbody 520 获得受试者的身体成分.采用曲线拟合构建大学生中高及高强度体力活动与去脂体重、体脂百分比之间的模型,根据校正拟合优度最大值同时信息论标准(information theoretical criterion,AIC) 值最小的原则获得最佳模型.结果 男生日常中高及高强度体力活动时间分别为25.7,10.2 min,女生分别为20.2,6.6 min; 男生超重、肥胖率分别为22.9%, 22.3%,女生分别为17.9%,7.6%.体脂百分比与中高强度、高强度体力活动时间之间存在负相关,去脂体重与中高强度、高强度体力活动时间之间存在正相关.男、女生5 种拟合曲线中仅直线、二次及三次曲线的AIC 值和R2 值有统计学意义,且男女生分别是三次、二次方程同时满足AIC 值最小和校正拟合优度R2 值最大.结论 成年早期男性中高及高强度体力活动时间与其去脂体重、体脂百分比之间的最优模型均为三次方程,女性则均为二次方程.增加中高及高强度体力活动时间有利于降低肥胖风险.     

基于步数的中国成人身体活动水平预测公式的建立和验证

目的 根据平均每日步数,建立适用于中国成人的身体活动水平(physical activity level, PAL)预测公式,并验证其预测效果。方法 招募800名身体活动不受限制的成年人作为调查对象,排除连续佩戴Actigragh WGT3X-BT型加速度计不满3天者,最终纳入743名研究对象(男性324人,女性419人,平均年龄31.4岁)。获得加速度计所测量的每日步数(steps)、低强度身体活动(light physical activity, LPA)、中等强度身体活动(moderate physical activity, MPA)、高强度身体活动(vigorous physical activity, VPA)的时间和身体活动能量消耗(physical activity energy expenditure, PAEE)。采用简单线性回归模型拟合步数与低中强度的PAL预测公式。采用外部验证的方法,以间接测热法测定的基础代谢率和双标水方法测定的总能量消耗计算得到的PAL作为金标准,利用Bland-Altman分析验证预测公式与标准的一致性,采用正确率验证预测公式准确性。结果 ...     

国际体力活动问卷中文版的信度和效度研究

目的 评价国际体力活动问卷(IPAQ)中文版的信度和效度,提供体力活动水平测量工具。方法 系统抽样94名大学生,间隔3天重复调查检验信度;在39名自愿受试者中,用体力活动(PA)记录和Caltrac加速度计为参照标准检验效度。结果 长短卷各项体力活动组内相关系数均在0.7以上。长卷的体力活动能量消耗与PA记录接近。短卷一日总能量消耗低于PA记录和Cltrac监测值。两个问卷与PA记录的目标体力活动量达标一致率均在70％以上。长卷、短卷和PA记录的每天静坐时间差异无显著性。结论 IPAQ中文版在大学生中的重测信度和效度高于或等于同类问卷。长短卷检测体力活动量达标率与PA记录接近,短卷低估体力活动能量消耗。     

中国北方农村健康成人不同体力活动能量消耗研究

目的对30名农村健康成人进行能量代谢及关键技术的测定,并同时对其进行双标水标定实验,获得中国北方农村成年男女不同体力活动水平的能量消耗量数据。方法选择符合纳入标准的30名北方农村健康成人为研究对象,男女各15名,严格控制实验条件,采用K4b2便携式心肺功能测定仪测量其基础代谢和7项体力活动(慢走、快走、慢跑、骑自行车、上下楼梯和看电视)的耗氧量(VO2)和二氧化碳生成量(VCO2),用微量凯式定氮法测量24小时尿氮,结合试验期间对象的体重变化,得到我国北方健康成人不同体力活动能量消耗的数据。结果各项体力活动平均能量消耗量(kJ.h-1.kg-1)为:慢走平均耗能12.60±5.54,其中男性11.46±2.19,女性15.47±6.97;快走平均耗能20.79±10.46,其中男性15.95±3.59,女性25.33±12.70;慢跑平均耗能34.78±16.00,其中男性30.45±5.07,女性38.84±21.58;骑自行车平均耗能16.47±3.95,其中男性14.77±2.57,女性18.74±4.85;上楼梯平均耗能23.55±5.05,其中男性23.61±3.43,女性23.49±6.41;下楼梯平均耗能12.46±6.30,其中男性10.43±1.27,女性14.49±8.48;看电视平均耗能3.85±1.97,其中男性3.56±0.86,女性4.16±2.79。除上楼梯消耗能量大致相等外,按公斤体重计算,男性各项体力活动能量消耗量均低于女性P<0.05。结论对于农村健康成人来说,各种体力活动能量消耗差异较大,慢走、看电视、下楼梯属于低强度体力活动快走、骑自行车、上楼梯属于中强度体力活动,慢跑属于高强度体力活动。     

中国南方中青年体力活动能量消耗研究

目的研究中国南方中青年常见体力活动的能量消耗。方法通过问卷调查和体格检查筛选出轻体力活动健康中青年64名,采用k4b2便携式心肺功能测定仪测量其基础代谢和七项体力活动(慢走、快走、慢跑、骑自行车、上下楼梯和看电视)的耗氧量(VO2)和二氧化碳生成量(VCO2),用微量凯式定氮法测量24小时尿氮,利用Weir公式计算其能量消耗量。结果各项体力活动平均能量消耗量(kJ·h-1·kg-1)分别为:慢走14.77±2.47,快走22.18±3.68,慢跑41.34±7.32,骑自行车18.41±3.89,上楼梯26.11±4.18,下楼梯13.68±2.89,看电视5.06±1.09;男性各项体力活动能量消耗量均高于女性(P<0.05)。结论体力活动能量消耗差异较大,看电视为低强度体力活动,骑自行车、上下楼、慢走及快走为中强度体力活动,慢跑为高强度体力活动。     

某高校大一学生骨密度增长及影响因素分析

了解大学生骨密度变化情况及其影响因素,为制定促进大学生骨健康的有效干预措施提供科学依据.方法 对118名沈阳医学院大一学生进行左足跟骨超声密度测定、体格测量、体成分测量、7d膳食调查(食物频率法)和体力活动情况调查.结果 超声骨强度指数年增长率,男生为3.83%,女生为5.14%,差异无统计学意义(t=1.006,P=0.318).多元逐步回归分析对大学生超声骨强度指数年增长率有正性影响作用的因素由大到小依次是瘦体重年变化率(β=0.24)、步行能量消耗年变化率(β=0.199)和每天食用奶类及其制品(β=0.177)(P值均<0.05).结论 低年级大学生尚处于骨量增长期,增加奶类及其制品摄入量和步行运动,提高机体瘦体重能够促进骨量增加.     

与作息安排相结合的青少年3日体力活动记录工具效度研究

采用体力活动客观测量工具加速度计作为效标,研制适合中国青少年的三日体力活动记录工具,并进行信效度研究,为有效调查中国青少年体力活动提供参考.方法 抽取北京市某校初高中148名12~17岁青少年(男生70名,女生78名).记录工具与ActiGraph GT3X+加速度计一同发放,1周后统一回收加速度计和记录工具.再次发放记录工具填写进行信度检验.通过分析记录工具和加速度计体力活动水平的Spearman相关系数和Bland-Altman图来评价效度,通过组内相关系数评价信度.结果 记录工具结果同加速度计测量值之间的Spearman系数处于0.246~0.557之间(P<0.05).Bland-Altman的一致性分析显示中强度、高强度、中高强度体力活动结果的一致性分别为94.59%,95.27%,93.24%,具有较高的效度.2次测量的平均每天代谢当量总分的组内相关系数系数均大于0.7,表明该记录工具的信度较好.结论 3d体力活动记录工具具有较好的可靠性和有效性,可用于青少年的日常体力活动大样本调查.     

Is the ArteACC index a valid indicator of free-living physical activity in adolescents?

OBJECTIVE: The principal aim of this study was to validate a proposed new index of physical activity, the activity-related time equivalent based on accelerometry (ArteACC), in adolescents. A secondary aim was to develop regression equations for prediction of total energy expenditure (TEE) and activity energy expenditure [AEE = 0.9 x TEE - resting metabolic rate (RMR)]. RESEARCH METHODS AND PROCEDURES: RMR and energy expenditure (EE) under standardized exercises were measured by indirect calorimetry in 36 adolescents (14 to 19 years old). TEE was measured by the doubly labeled water method, and physical activity was assessed simultaneously with an accelerometer for 14 days. AEE, AEE in relation to body weight (AEE per kilogram), and activity-related time equivalent based on energy expenditure (ArteEE = AEE/[EE reference activity - RMR]) were calculated from laboratory and free-living EE data. ArteACC was calculated as total activity counts/activity counts of reference activity. RESULTS: ArteACC was significantly related to AEE per kilogram (r = 0.57; p < 0.0001) and ArteEE (r = 0.68; p < 0.001). The absolute amount of time (minutes per day) spent in physical activity was significantly lower when calculated from ArteACC than from ArteEE (p < 0.001). TEE was significantly influenced by RMR, sex, and ArteACC (r(2) = 0.89). AEE was significantly influenced by sex and ArteACC (r(2) = 0.59). DISCUSSION: Despite an absolute difference between the two indexes, ArteEE and ArteACC, ArteACC seems to be a valid indicator of free-living physical activity. It contributed significantly, by 3.3% and 12.5%, to the explained variations in TEE and AEE, respectively.     

Body movement and physical activity energy expenditure in children and adolescents: how to adjust for differences in body size and age

BACKGROUND: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure. OBJECTIVE: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age. DESIGN: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE). RESULTS: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01). CONCLUSIONS: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.     

Relation between physical activity and energy expenditure in a representative sample of young children

BACKGROUND: Strategies for the prevention and treatment of childhood obesity require a better understanding of the relation between the pattern of free-living physical activity and total energy expenditure (TEE). OBJECTIVE: We assessed the relations between TEE and physical activity level (PAL) during engagement in different intensities of physical activity. DESIGN: We used a cross-sectional study of 104 children (median age: 5.4 y) in Scotland. TEE was measured with use of doubly labeled water (DLW), and resting energy expenditure was predicted to determine PAL. Time spent sedentary and in light-intensity activity and in moderate- and vigorous-intensity physical activity (MVPA) was assessed by accelerometry concurrent with DLW measurements. Correlation and regression were used to assess the relations between measures of sedentary behavior, intensities of activity, and PAL as the dependent variable. RESULTS: Time spent sedentary was negatively correlated with PAL (r = -0.33, P < 0.01), and time spent in light-intensity activity was positively correlated with PAL (r = 0.31, P < 0.01). In multiple regression analyses, both time spent sedentary and in light-intensity activities were significantly associated with PAL. Time spent in MVPA was not associated with PAL; engagement in MVPA was limited in this sample (median: 3% of waking hours; range: 0-14%). PAL was significantly higher in boys than in girls. CONCLUSION: In this sample and setting, PAL was not influenced by engagement in MVPA but was influenced by time spent sedentary and in light-intensity activities. This study suggests that in young children, MVPA could make only a minor contribution to free-living TEE and PAL.     

Energy requirements of urban Chinese adults with manual or sedentary occupations,determined using the doubly labeled water method

OBJECTIVE: To examine total energy expenditure (TEE) in relation to occupation and reported leisure time activities in free-living Chinese adults, and to determine whether measured TEE values differ from current international dietary energy recommendations. SETTING AND SUBJECTS: Seventy three weight-maintaining adults aged 35-49 y, leading unrestricted lives in urban Beijing, with a wide variety of occupations. DESIGN AND METHODS: A cross-sectional study in which TEE was determined by doubly labeled water, body composition by deuterium oxide ((2)H(2)O) dilution, resting energy expenditure (pREE) by prediction equations, and occupational and leisure time activities by questionnaire. RESULTS: For men and women respectively, TEE averaged 12.10+/-0.32 and 9.53+/-0.23 MJ/day (P<0.001), and physical activity level (PAL=TEE/pREE) was 1.77+/-0.04 and 1.66+/-0.02 (P<0.05). Fat-free mass (FFM) was the single best predictor of TEE (adjusted r(2)=0.71, P<0.001). Occupational category (light, moderate and heavy) further predicted TEE, independent of FFM (adjusted multiple r(2)=0.82, P<0.001). Both TEE adjusted for weight and PAL increased with occupational category. Measured TEE was slightly but significantly higher than the 1985 FAO/WHO/UNU estimates for women with light occupations, but did not differ from estimates for men with light occupations, or for adults with moderate or heavy occupations. CONCLUSION: Level of occupational activity, but not duration or type of leisure activity, significantly predicted TEE in free-living urban Chinese adults. Current energy requirement recommendations slightly underestimated the energy needs of women with light occupations but were accurate for men and women with moderate and heavy occupations. SPONSORSHIP: NIH grants DK53404 and F32-DK09747.     

Total energy expenditure in the Yakut (Sakha) of Siberia as measured by the doubly labeled water method

BACKGROUND: Populations in transition to a Western lifestyle display increased incidences of obesity, type 2 diabetes, and other chronic diseases; the mechanisms responsible for these changes, however, remain incompletely understood. Although reduced physical activity has been implicated, few studies have accurately quantified energy expenditure in subsistence populations. OBJECTIVE: The aim of the study was to examine the relation of total energy expenditure (TEE) and activity [physical activity level (PAL), activity energy expenditure (AEE), and weight-adjusted AEE (AEE/kg)] with body composition and lifestyle in the Yakut (Sakha), an indigenous high-latitude Siberian group. DESIGN: We measured TEE using doubly labeled water and resting metabolic rate using indirect calorimetry in 28 young adults (14 women and 14 men) from Berdygestiakh, Russia. RESULTS: The men had higher TEE (12,983 compared with 9620 kJ/d; P < 0.01), AEE (5248 compared with 3203 kJ/d; P < 0.05), AEE/kg (72.7 compared with 48.8 kJ . kg(-1) . d(-1); P < 0.05), and PAL (1.7 compared with 1.5; P = 0.09) than did the women, although this may reflect, in part, body size and composition differences. Overweight men and women had modestly higher TEEs than did lean participants; when adjusted for body size, activity levels were not significantly different between the groups. Persons with more traditional lifestyles had higher TEEs and PALs than did persons with more modernized lifestyles; this difference correlated with differences in participation in subsistence activities. CONCLUSIONS: Activity levels in the Yakut were lower than those in other subsistence groups, especially the women, and were not significantly different from those in persons in industrialized nations. Persons who participated in more subsistence activities and consumed fewer market foods had significantly higher activity levels.     

Energy requirements in the eighth decade of life

BACKGROUND: Knowledge of energy requirements among relatively healthy elderly is limited. OBJECTIVES: The objectives of the study were to measure total energy expenditure (TEE)-derived energy requirements in a biracial population of older adults without limitations to daily life and to test these empirical measures against national and international recommendations. DESIGN: TEE (measured by the doubly labeled water method), resting metabolic rate (RMR), activity-related energy expenditure (AEE), and body composition were measured in 288 persons aged 70-79 y selected from the Health, Aging, and Body Composition Study. RESULTS: TEE was lower in women (approximately 530 kcal/d; P < 0.0001) than in men because of the women's lower RMR and AEE. Fat-free mass explained the sex difference in RMR, but body weight failed to account for the women's lower AEE (approximately 1 kcal x kg(-1) x d(-1); P = 0.007). Blacks had lower TEE than did whites (approximately 100 kcal/d, P = 0.03), and that was explained by blacks' lower RMR. Physical activity level (TEE/RMR) did not differ significantly between sexes and races (1.70 +/- 0.23). The World Health Organization (WHO) recommendations overestimated TEE by 10 +/- 15% (P < 0.0001) in women but not in men, and the dietary reference intakes (DRIs) were accurate to 0 +/- 14% (P = 0.1). Both WHO and DRI recommendations are based on an underestimated physical activity level, and WHO recommendations are based on overestimated RMR. CONCLUSIONS: This study of well-functioning older adults confirms the racial difference in energy metabolism and supports the use of the 2002 DRIs. Because the DRIs and WHO recommendations underestimated PAL, new predictive equations of energy requirements are proposed.     

Longitudinal changes in energy expenditure in girls from late childhood through midadolescence

BACKGROUND: Longitudinal data on energy expenditure in children and adolescents are scarce. OBJECTIVE: The purpose of this study was to examine changes in energy expenditure and physical activity in girls from late childhood through midadolescence. DESIGN: We measured total energy expenditure (TEE) by doubly labeled water, resting metabolic rate (RMR) by indirect calorimetry, body composition by 18O dilution, and time spent in activity by an activity diary in 28 initially nonobese girls at approximately 10, approximately 12, and approximately 15 y of age. Changes with age in TEE, RMR, and activity energy expenditure (AEE), both in absolute terms and in adjusted analyses, and in physical activity level (PAL) and time spent sleeping, being sedentary, and in moderate and vigorous activity were evaluated by mixed-model repeated-measures analyses. RESULTS: Absolute TEE and AEE increased significantly from age 10 to age 15 y (P < 0.0001 for both). Absolute RMR at ages 12 and 15 y did not differ significantly, despite significant increases in fat-free mass and fat mass between the visits. PAL was significantly higher (P < 0.0001) at age 15 y than at age 10 or 12 y, whereas time spent being sedentary increased significantly from age 10 to age 15 y (P < 0.001), and AEE adjusted for fat-free mass appeared to decrease over the same interval. CONCLUSION: Conclusions drawn regarding changes with age in physical activity depend on the measure of physical activity assessed.     

Total energy expenditure, resting metabolic rate and physical activity level in free-living rural elderly men and women from Cuba, Chile and México

OBJECTIVE: The objective of this study was to assess total energy expenditure (TEE), resting metabolic rate (RMR) and physical activity level (PAL), and to estimate energy requirements (ERs) in free-living elderly subjects from Cuba, Chile and Mexico. DESIGN: Cross-sectional study designed to estimate ERs. SETTING: Rural regions of Cuba, Chile and Mexico. SUBJECTS: Forty subjects >60 years old were selected to participate in this study. INTERVENTIONS: A dose of doubly labeled water (DLW) was administered and urine samples were collected in the following 12-14 days. From the isotopic analysis, TEE was derived. RMR was measured by indirect calorimetry. RESULTS: TEE in Chilean (8.8+/-1.6 MJ/day) and Cuban (8.3+/-1.3 MJ/day) elderly was not different, and was higher for the Mexican group (9.5+/-1.5 MJ/day) (P < 0.0001). RMR was not different between countries. PAL and activity energy expenditure (AEE) were only different between Chile and Mexico (P < 0.002). For the three regions, overall PALs were 1.70+/-0.16 for male and 1.62+/-0.13 for female subjects (P < 0.02), and AEE was 3.05+/-0.66 and 2.27+/-0.66 MJ/day for male and female subjects, respectively (P < 0.001). Predictive equations (MJ/day) were RMR = 1.6447 + 0.05714 x weight (kg) + 0.449 sex (male = 1; female = 0) (R2 = 0.75; SEE = 0.479) and TEE = 3.414 + 0.0795 x weight (kg) + 1.227 x sex (male = 1; female = 0) (R2 = 0.75; SEE = 0.668). CONCLUSIONS: There were differences in TEE and PAL owing to sex and region. The average PAL in men was higher than the PAL reported either with factorial approach or with the DLW method in elderly. Predictive ER equations based on RMR and TEE gave very similar results to calculations from the 2004 FAO/WHO/UNU report.     

Measuring free-living energy expenditure and physical activity with triaxial accelerometry

OBJECTIVE: To investigate the ability of a newly developed triaxial accelerometer to predict total energy expenditure (EE) (TEE) and activity-related EE (AEE) in free-living conditions. RESEARCH METHODS AND PROCEDURES: Subjects were 29 healthy subjects between the ages of 18 and 40. The Triaxial Accelerometer for Movement Registration (Tracmor) was worn for 15 consecutive days. Tracmor output was defined as activity counts per day (ACD) for the sum of all three axes or each axis separately (ACD-X, ACD-Y, ACD-Z). TEE was measured with the doubly labeled water technique. Sleeping metabolic rate (SMR) was measured during an overnight stay in a respiration chamber. The physical activity level was calculated as TEE x SMR(-1), and AEE was calculated as [(0.9 x TEE) - SMR]. Body composition was calculated from body weight, body volume, and total body water using Siri's three-compartment model. RESULTS: Age, height, body mass, and ACD explained 83% of the variation in TEE [standard error of estimate (SEE) = 1.00 MJ/d] and 81% of the variation in AEE (SEE = 0.70 MJ/d). The partial correlations for ACD were 0.73 (p < 0.001) and 0.79 (p < 0.001) with TEE and AEE, respectively. When data on SMR or body composition were used with ACD, the explained variation in TEE was 90% (SEE = 0.74 and 0.77 MJ/d, respectively). The increase in the explained variation using three axes instead of one axis (vertical) was 5% (p < 0.05). DISCUSSION: The correlations between Tracmor output and EE measures are the highest reported so far. To measure daily life activities, the use of triaxial accelerometry seems beneficial to uniaxial.     

Effects of familial predisposition to obesity on energy expenditure in multiethnic prepubertal girls

BACKGROUND: The prevalence of childhood obesity is increasing and the causes of this are unknown. OBJECTIVE: The objective of this study was to determine whether energy expenditure (EE), measured by 24-h calorimetry and doubly labeled water, differed in normal-weight-for-height, multiethnic prepubertal girls with or without a familial predisposition to obesity. DESIGN: Normal-weight, prepubertal white (n = 52), African American (n = 30), and Hispanic (n = 19) girls with a mean (+/-SD) age of 8.5 +/- 0.4 y were studied according to parental leanness and overweight or obesity. The girls were grouped according to whether they had 2 lean parents (n = 30), 2 obese parents (n = 27), or 1 lean and 1 obese parent (n = 44). Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24-h EE, respiratory quotient, heart rate, and activity were measured by 24-h room calorimetry; free-living total EE (TEE), activity-related EE (AEE), and physical activity level were measured by doubly labeled water. EE was standardized by fat-free mass (FFM). RESULTS: There were no significant differences among familial groups in weight, height, fat mass, FFM, or percentage body fat. African American girls had a higher FFM than did white or Hispanic girls (P < 0.05). BMR, SMR, 24-h EE, respiratory quotient, heart rate, and activity levels were not significantly different among familial groups. Additionally, there were no significant familial group differences in TEE, AEE, or physical activity level. However, BMR, SMR, and TEE were lower in African American girls than in white girls (P < 0.05). CONCLUSION: There was no significant difference in EE between normal-weight, multiethnic prepubertal girls predisposed to obesity and those not predisposed to obesity.