Energy Expenditure Data Research Articles

Active play: An important physical activity strategy in the fight against childhood obesity

To quantify and compare the number of calories that school-aged Canadian children expend to meet established benchmarks for active play and organized physical activities (i.e., organized sport, physical education, active transportation). This study was informed by the benchmarks (i.e., amount of activity a child needs to be sufficiently active) and grades (i.e., how Canada as a country is doing) for the physical activity domains included in the Active Healthy Kids Canada Report Card on Physical Activity for Children and Youth. Established physical activity energy expenditure data were used to calculate the number of calories that the average 6-11 year old child would expend to meet the Report Card physical activity benchmarks. The increase in energy expenditure at the population-level that would occur if each Report Card grade was to improve by one letter grade was estimated based on the aforementioned estimates and the proportion of the population impacted should the grade improve. When averaged across all 365 days of the year, the average 6-11 year old Canadian would expend an added 186 kcal/day to meet the active play benchmark, 23 kcal/day to meet the organized sport benchmark, 6 kcal/day to meet the physical education benchmark, and 16 kcal/day to meet the active transportation to school benchmark. Increasing the Report Card grades for these four domains would address 37%, 1%, 1%, and 3% of the energy gap, respectively. Initiatives aimed at increasing physical activity in an attempt to address childhood obesity should include an active play component.

Pre‐ and postoperative nutritional assessment and health‐related quality of life in recipients of living donor liver transplantation

The nutritional state of living donor liver transplantation (LDLT) recipients is one of the most important factors affecting postoperative outcome. Although the assessment of health-related quality of life (HRQOL) is of increasing importance, few studies have examined this in conjunction with LDLT recipient nutritional state. Ten LDLT recipients with end-stage liver disease were recruited for this study. Measurements of energy expenditure, anthropometrics and laboratory data were performed before and 1, 6 and 12-24 months after LDLT. HRQOL was measured by using the 36-item Short-Form (SF-36) before and 1, 3, 6 and 12-24 months after LDLT. The preoperative value of non-protein respiratory quotient (npRQ) was 0.796 ± 0.026 and it increased significantly after the operation. Serum non-esterified fatty acid (NEFA) levels were high in the preoperative state, but had significantly decreased 1 month after the operation. A negative correlation between npRQ and NEFA was observed throughout the study period. Cholinesterase and albumin levels improved to normal levels within 6 and 12-24 months, respectively. The recovery of the physical component summary of the SF-36 was observed after the improvement of all domains of laboratory data and energy metabolism based on the nutritional state. This study demonstrated that the recovery of metabolic function, laboratory data and HRQOL in LDLT recipients are variable, and it took more than 6 months to normalize the liver protein synthetic capacity and physical HRQOL score periods. Therefore, long-term nutritional support is required in LDLT recipients.

Favorable survival and metabolic outcome for children with diencephalic syndrome using a radiation-sparing approach

Diencephalic syndrome (DS) is a clinical disorder of metabolism associated with poor outcome in children with low-grade gliomas (LGGs). Since survival has been primarily reported with aggressive therapy, we report outcome data for these patients using a current, contrasting chemotherapy-driven approach. We performed a population-based review of DS patients treated with chemotherapy from 1997-2012. Metabolic rate was assessed in selected cases using open-circuit calorimetry to generate resting energy expenditure (REE) data. Tumor tissue was analyzed for BRAF alterations. Survival was compared with an age-related, radiotherapy naïve cohort of non-DS children with location-matched LGGs. Nine children (1.7% of 520 LGG diagnoses) fulfilled DS criteria. The median diagnostic age was 1.49 years (0.55-2.69 years), although neurofibromatosis Type-I patients were older (p = 0.005). All tumors analyzed exhibited either NF1 mutation or BRAF fusion. Seven tumors were histologically confirmed as low grade astrocytomas, one demonstrated neurocytic features, and one NF1 case was diagnosed using imaging and clinical criteria. All patients received chemotherapy, with seven cases also receiving initial nutritional supplementation. All nine gained weight after only 6 months of treatment. Two DS patients had serial REE measurements, revealing a hypermetabolic state (over 200% of predicted REE) at diagnosis which reduced to normal range with therapy. First-line chemotherapy treatment resulted in one minor response, stable disease in four cases, with progression in the remaining four patients. Although DS patients demonstrated inferior initial progression-free survival when compared to non-DS counterparts (5 years: 22 versus 60%, p = 0.015), all DS children remain alive at a median follow up of 5.3 years (1.2-14.9 years) with none requiring radiotherapy. Long-term sequelae included pituitary and visual dysfunction, learning difficulties and paradoxical, inappropriate weight gain. DS can be managed with non-aggressive chemotherapeutic, radiation-sparing strategies supplemented by temporary nutritional support. Multiple lines of therapy may be required to overcome disease progression but excellent survival and metabolic outcomes can be achieved. Continued surveillance is mandatory to prevent significant weight gain and support affected children with clinical sequelae.

Energy Expenditure Compared to Physical Activity Measured by Accelerometry and Self-Report in Adolescents: A Validation Study

BackgroundPhysical inactivity is responsible for 5.3 million deaths annually worldwide. To measure physical activity energy expenditure, the doubly labeled water (DLW) method is the gold standard. However, questionnaires and accelerometry are more widely used. We compared physical activity measured by accelerometer and questionnaire against total (TEE) and physical activity energy expenditure (PAEE) estimated by DLW.MethodsTEE, PAEE (TEE minus resting energy expenditure) and body composition were measured using the DLW technique in 25 adolescents (16 girls) aged 13 years living in Pelotas, Brazil. Physical activity was assessed using the Actigraph accelerometer and by self-report. Physical activity data from accelerometry and self-report were tested against energy expenditure data derived from the DLW method. Further, tests were done to assess the ability of moderate-to-vigorous intensity physical activity (MVPA) to predict variability in TEE and to what extent adjustment for fat and fat-free mass predicted the variability in TEE.ResultsTEE varied from 1,265 to 4,143 kcal/day. It was positively correlated with physical activity (counts) estimated by accelerometry (rho = 0.57; p = 0.003) and with minutes per week of physical activity by questionnaire (rho = 0.41; p = 0.04). An increase of 10 minutes per day in moderate-to-vigorous intensity physical activity (MVPA) relates to an increase in TEE of 141 kcal/day. PAEE was positively correlated with accelerometry (rho = 0.64; p = 0.007), but not with minutes per week of physical activity estimated by questionnaire (rho = 0.30; p = 0.15). Physical activity by accelerometry explained 31% of the vssariability in TEE. By incorporating fat and fat-free mass in the model, we were able to explain 58% of the variability in TEE.ConclusionObjectively measured physical activity significantly contributes to the explained variance in both TEE and PAEE in Brazilian youth. Independently, body composition also explains variance in TEE, and should ideally be taken into account when using accelerometry to predict energy expenditure values.

Energy Expenditure Evaluation in Humans and Non-Human Primates by SenseWear Armband. Validation of Energy Expenditure Evaluation by SenseWear Armband by Direct Comparison with Indirect Calorimetry

IntroductionThe purpose of this study was to compare and validate the use of SenseWear Armband (SWA) placed on the arm (SWA ARM) and on the back (SWA BACK) in healthy humans during resting and a cycle-ergometer exercise and to evaluate the SWA to estimate Resting Energy Expenditure (REE) and Total Energy Expenditure (TEE) in healthy baboons.MethodsWe studied 26 (15F/11M) human subjects wearing SWA in two different anatomical sites (arm and back) during resting and a cycle-ergometer test and directly compared these results with indirect calorimetry evaluation (IC), performed at the same time. We then inserted the SWA in a metabolic jacket for baboons and evaluated the TEE and REE in free living condition for 6 days in 21 (8F/13M) non-human primates.ResultsIn humans we found a good correlation between SWA place on the ARM and on the BACK with IC during the resting experiment (1.1±0.3 SWAs, 1±0.2 IC kcal/min) and a slight underestimation in the SWAs data compared with IC during the cycle-ergometer exercise (5±1.9 SWA ARM, 4.5±1.5 SWA BACK and 5.4±2.1 IC kcal/min). In the non-human primate (baboons) experiment SWA estimated a TEE of 0.54±0.009 kcal/min during free living and a REE of 0.82±0.06 kcal/min.ConclusionSWA, an extremely simple and inexpensive apparatus, provides quite accurate measurements of energy expenditure in humans and in baboons. Energy expenditure data obtained with SWA are highly correlated with the data obtained with “gold standard”, IC, in humans.

Energy Expenditure in Rock/Pop Drumming

Despite the vigorous nature of rock/pop drumming, there are no precise data on the energy expenditure of this activity. The aim of this study was to quantify the energy cost of rock/pop drumming. Fourteen male drummers (mean±SD; age 27±8 yrs.) completed an incremental drumming test to establish the relationship between energy expenditure and heart rate for this activity and a ramped cycle ergometer test to exhaustion as a criterion measure for peak values (oxygen uptake and heart rate). During live concert performance heart rate was continuously measured and used to estimate energy expenditure (from the energy expenditure vs. heart rate data derived from the drumming test). During concert performance, estimated energy expenditure (mean±SD) was 623±168 kcal.h⁻¹ (8.1±2.2 METs) during performances of 38.6±15.6 min, and drummers achieved a peak heart rate of 186±16 b.min⁻¹. During the drumming test participants attained 78.7±8.3% of the cycle ergometer peak oxygen uptake. Rock/pop drumming represents a relatively high-intensity form of physical activity and as such involves significant energy expenditure. Rock/pop drumming should be considered as a viable alternative to more traditional forms of physical activity.

Effects of growth hormone treatment in adults with Prader–Willi syndrome

ObjectiveSince limited data exist on adults with Prader–Willi syndrome (PWS) and growth hormone (GH) treatment, we report our experience on the effects of treatment for one year on body composition, physical activity, strength and energy expenditure, diet, general chemistry and endocrine data with quality of life measures. DesignWe studied 11 adults with PWS (6F:5M; average age=32yrs) over a 2year period with GH treatment during the first year only. Electrolytes, IGF-I, glucose, thyroid, insulin, lipids, body composition, physical activity and strength, diet, energy expenditure and quality of life data were collected and analyzed statistically using linear modeling at baseline, at 12months following GH therapy and at 24months after treatment cessation for 12months. ResultsTotal lean muscle mass was significantly increased (p<0.05) during GH treatment along with moderate-vigorous physical activity and plasma IGF-I and HDL levels, but returned to near baseline after treatment. Percent body fat decreased during the 12months of GH treatment but increased after treatment. ConclusionsPreviously reported beneficial effects of GH treatment in children with PWS were found in our adults regarding body composition, physical activity and plasma HDL and IGF-I levels. Several beneficial effects diminished to near baseline after cessation of GH treatment for 12months supporting the continuation of treatment in PWS into adulthood and possibly adults not previously treated during childhood.

Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

Abstract: Past theories on total lifetime energy expenditures and entropy generation in biological systems (BS) dealt with whole systems, but the recent literature suggests that the total metabolic rate of a BS,q̇body (W) is a sum of product of specific metabolic rate q̇k,m (W/kg of organ k) of each vital life organ, k {k = brain, heart, kidney and liver, or abbreviated as BHKL, and rest of the organ mass (R)} and mass of each organ k (mk). Using this hypothesis, Kleiber’s law on metabolic rate of BS (q̇body) for animals of different sizes was validated. In this work, a similar procedure is adopted in estimating total entropy generation rate of whole human body (σ̇body, W/K) as a sum of product of specific entropy generation rate for each organ, σ̇k,m (W/{K kg of organ k·}) and the organ mass at any given age (t). Further integrating over life span for each organ (tlife), the lifetime specific entropy generated by organ k, σk,m,life (J of organ k/ {K kg organ k}) is calculated. Then lifetime entropy generation of unit body mass, σbody,M,life (J/{K kg body mass·}) is calculated as a sum of the corresponding values contributed by all vital organs to unit body mass and verified with previously published literature. The higher the σk,m,life , the higher the entropy stress level (which is a measure of energy released by unit organ mass of k as heat) and the irreversibility within the organ, resulting in faster degradation of organ and the consequent health problems for the whole BS. In order to estimate σ̇k (W/K of organ k), data on energy release rate (q̇) is needed over lifetime for each organ. While the Adequate Macronutrients Distribution Range (AMDR)/Adequate Intake (AI) publication can be used in estimating the energy intake of whole body vs. age for the human body, the energy expenditure data is not available at organ level. Hence the σk,m,life was computed using existing allometric laws developed for the metabolism of the organs, the relation between the mk of organ and body mass mB, and the body mass growth data mB(t) over the lifetime. Based on the values of σk, m, life, the organs were ranked from highest to lowest entropy generation and the heart is found to be the most entropy-stressed organ. The entropy stress levels of the other organs are then normalized to the entropy stress level (NESH) of the heart. The NESH values for organs are as follows: Heart: 1.0, Kidney: 0.92, Brain: 0.46, Liver: 0.41, Rest of BS: 0.027. If normalized to rest of body (R), NESR, heart: 37, Kidney: 34, Brain: 17, Liver: 15, Rest of BS: 1.0; so heart will fail first followed by kidney and other organs in order. Supporting data is provided.

A guide to analysis of mouse energy metabolism

We present a consolidated view of the complexity and challenges of designing studies for measurement of energy metabolism in mouse models, including a practical guide to the assessment of energy expenditure, energy intake and body composition and statistical analysis thereof. We hope this guide will facilitate comparisons across studies and minimize spurious interpretations of data. We recommend that division of energy expenditure data by either body weight or lean body weight and that presentation of group effects as histograms should be replaced by plotting individual data and analyzing both group and body-composition effects using analysis of covariance (ANCOVA).

!Kung nutritional status and the original "affluent society" - a new analysis

The theme of the 2011 meetings of the German Anthropological Society, "Biological and Cultural Markers of Environmental Pressure", provides the entree to revisit one of Anthropology's most enduring canons - hunters and gathers are well-nourished and healthy. The Dobe !Kung foragers of the Kalahari Desert often serve as a model of hunter-gatherer adaptation for both extant and Paleolithic humans. A re-analysis of food intake, energy expenditure, and demographic data collected in the 1960s for the Dobe !Kung finds that their biocultural indicators of nutritional status and health were, at best, precarious and, at worst, indicative of a society in danger of extinction. Hunting and gathering is the lifestyle to which the human species was most persistently adapted, in terms of the biological, cultural, and emotional meanings of the word 'adapted.' However, the few remaining foraging groups studied in the 20th Century are unlikely to serve as the ideal models of that ancient way of life.

Response to Comment on: Kaiyala et al. (2010) Identification of Body Fat Mass as a Major Determinant of Metabolic Rate in Mice. Diabetes;59:1657–1666

We thank MacLean (1) for his insightful comments regarding both the need to present unadjusted energy expenditure (EE) data and the issue of model selection for EE normalization. We agree with the recommendation to present unadjusted EE data as part of the analysis—indeed, this standard should be widely adopted in metabolic research. The question of whether to adjust EE for only the best estimate of “metabolic mass,” e.g., lean body mass (LBM), is complex and raises issues of both theoretical and practical importance. From a theoretical perspective, MacLean notes that when a genetic or other intervention influences EE by altering …

Knee arthroplasty: a cross-sectional study assessing energy expenditure and activity

What has been missing from current assessment tools post knee arthroplasty is a means by which a patient's mobility and activity levels can be objectively measured over time in a real world setting. The Intelligent Device for Energy Expenditure and Activity (Minisun, Fresno, USA) (IDEEA) is one such device that meets these criteria. It quantifies activity by measuring energy expenditure and records the type of activity performed. The purposes of this study were to (i) determine if there were differences in energy expenditure in different groups of patients at various time points pre- and post-surgery and (ii) determine the correlations between energy expenditure and each of the subjective International Knee Documentation Committee (IKDC), Oxford and Tegner scoring systems. Sixty-five total knee arthroplasty (TKA) patients were recruited into a cross-sectional study to collect energy expenditure and activity data using the IDEEA. Data were collected preoperatively and post-operatively at 6-week, 3-month, 6-month and 12-month time intervals. Energy expenditure and type of activity did not significantly change over the five recording periods. The patients spent <5% of the recording time walking, stepping or in transitions between movements. Energy expenditure showed a low to moderate correlation with the subjective IKDC, Oxford and Tegner questionnaires. Current evaluation questionnaires may not accurately record activity levels and TKA patients spend less time walking than the normal population. We believe the IDEEA is an effective tool for objectively measuring activity and energy expenditure following knee arthroplasty.

A Recurring Problem With the Analysis of Energy Expenditure in Genetic Models Expressing Lean and Obese Phenotypes

Defining the molecular mechanisms linking obesity with insulin resistance is important for developing new therapies against the rising incidence of type 2 diabetes in industrialized nations. Maintaining a balance between calorie intake and energy expenditure is critical for preventing insulin resistance, the precursor for type 2 diabetes (1). Mouse genetics has made enormous contributions to theoretical models explaining how organisms balance energy intake and energy expenditure. A seminal event was the positional cloning of the obese gene (now called the Leptin gene) by Friedman and colleagues in the early 1990s (2). Leptin deficiency causes severe obesity in mice and humans (3), and leptin was proposed to regulate energy homeostasis by suppressing appetite and increasing energy expenditure (4). However, it has clearly been forgotten that the interpretation of energy expenditure data from mice homozygous for the Lepob mutation was challenged shortly after the initial publication (5). Increasingly sophisticated technologies for manipulating the mouse genome are now used routinely to analyze new genes linked to energy homeostasis, resulting in many new mouse models with obese or lean phenotypes. Altered energy expenditure is frequently cited as the primary mechanism underlying the obese or lean phenotype. However, in many cases the same issues with interpretation of energy expenditure data are evident. Here, we discuss what has developed into a recurring problem in the literature with the analysis of energy balance. Specifically, we shall discuss the practice of using body weight as a denominator in analyzing energy balance to overestimate the role of energy expenditure. The growing number of individuals with chronic metabolic diseases like type 2 diabetes provides a powerful incentive for investigating mechanisms linking obesity with insulin resistance. That a balance between food intake and energy expenditure (thermogenesis) is maintained through homeostatic mechanisms is a central tenet of obesity research. A major …

Challenge of predicting resting energy expenditure in children undergoing surgery for congenital heart disease

To determine pre- and postoperative predictors of energy expenditure in children with congenital heart disease requiring open heart surgery; and to compare measured resting energy expenditure with current predictive equations. Prospective resting energy expenditure data were collected, using indirect calorimetry, for ventilated children admitted consecutively to the pediatric intensive care unit after surgery for congenital heart disease. A 30-min steady-state measurement was performed in suitable patients. Resting energy expenditure was compared to pre- and postoperative clinical variables, and to predicted energy expenditure, using currently used predictive equations. Pediatric intensive care unit at the Royal Brompton Hospital, London. Children ventilated in the pediatric intensive care unit post surgery for congenital heart disease. Measurement of energy expenditure by indirect calorimetry. Twenty-one mechanically ventilated children (n = 17 boys, 4 girls) were enrolled in the study. Mean +/- sd measured resting energy expenditure was 67.8 +/- 15.4 kcal/kg/day. Most children had inadequate delivery of nutrients compared with actual requirements. Cardiopulmonary bypass had a significant influence on energy expenditure after surgery; in patients who underwent cardiopulmonary bypass during surgery, mean resting energy expenditure was 73.6 +/- 14.45 kcal/kg/day vs. 58.3 +/- 10.29 kcal/kg/day in patients undergoing nonbypass surgery. Children who were malnourished preoperatively had greater resting energy expenditure postoperatively. There was also a significant difference between measured energy expenditure and the Schofield (p = .006), World Health Organization (p = .002), and pediatric intensive care unit-specific formula (p < .0001). However, energy expenditure or a relative energy deficit in the early postoperative period was not associated with severity or duration of organ dysfunction. Poor nutritional status preoperatively and cardiopulmonary bypass were associated with a greater energy expenditure post cardiac surgery. None of the current predictive equations predicted energy requirements within acceptable clinical accuracy.

DATE: Depressed adolescents treated with exercise: Study rationale and design for a pilot study

There is an important need for non-medication interventions for depressed youth. The aim of this study is to evaluate the feasibility of using a standardized aerobic exercise regime to treat non-medicated clinically depressed adolescents based on adherence and completion rates, including 1) establishing effect sizes for the primary outcomes including the Chidren's Depression Rating Scale – Revised (CDRS-R) and Actical (energy expenditure data) as well as selected secondary outcomes; (e.g., Clinical Global Improvement, depression rating scales, exercise logs, attitudes), and 2) determining whether moderate to strenuous exercise (12 kcal/kg/week [KKW]) versus a control stretching activity (<4 KKW) for 12 weeks leads to a clinically meaningful reduction in depressive symptoms and/or improved psychosocial functioning. The challenge is to develop an exercise intervention that can motivate a typically sedentary depressed adolescent to exercise on a regular basis. The goal is to demonstrate that exercise alone can provide an important and effective non-medication intervention for adolescent depression. This paper reports on the rationale and design of a pilot study which aims to inform the design of a larger trial to evaluate the efficacy of aerobic exercise to treat adolescent depression. After describing the case for exercise within the broader context of the prevalence of adolescent depression and other treatments, the paper describes the intervention and procedures for data collection.

Influence of resistance exercise volume on recovery energy expenditure in women

The acute effects of resistance exercise on energy expenditure in the post-exercise period have not been well studied in women, even though they are at high risk for weight gain and so would benefit greatly from exercise-related increases in energy expenditure. The purpose of this study was to identify factors that influence recovery energy expenditure in women after an acute bout of resistance exercise. Seventeen healthy women aged 40–55 years completed an acute bout of resistance exercise followed by measurement of energy expenditure for 120 min of recovery. Body composition was measured via air displacement plethysmography. The resistance exercise bout consisted of three sets of 8–12 repetitions of eight exercises at 50% of one-repetition maximum (1-RM) for the first set and 80% 1-RM for the second and third sets. Oxygen consumption (VO2) was measured before and for 120 min after resistance exercise. Post-exercise energy expenditure data were analysed as 4-min means at 0, 20, 40, 60, 90, and 120 min of recovery. Mean (± s x ) training volume was 7604.1±450.64 kg and overall mean recovery energy expenditure was 133±6 kcal. Pearson's correlation analysis found no significant relationship between post-exercise energy expenditure and age, body mass index, exercise time or delay between cessation of exercise and commencement of metabolic measurement. Absolute (kg) lean mass was also not significantly related to energy expenditure at any time post-exercise, although relative (%) lean mass was during the late recovery period only (40 min of recovery: r = 0.49, P = 0.05; 60 min: r = 0.51, P = 0.04; 90 min: r = 0.63, P < 0.01). The factor most consistently related to post-exercise energy expenditure was total exercise volume, which had a moderately strong relationship through 90 min of the recovery period (0 min of recovery: r=0.49. P = 0.05; 20 min: r = 0.52, P = 0.03; 40 min: r = 0.53, P = 0.03; 60 min: r = 0.50, P = 0.04; 90 min: r=0.48, P = 0.05). In the present sample of women, acute post-exercise energy expenditure was influenced primarily by total training volume, although lean mass had a limited effect. Based on these findings, it is recommended that women be encouraged to lift at higher intensities (70–80% 1-RM) to maximize post-exercise energy expenditure and potentially promote fat loss.

Energy expenditure in office workers with identified health risks

Objective. To measure the daily energy expenditure in employees previously identified as having ≥2 risk factors for chronic disease, and to identify potential risk-reducing interventions for implementation within or outside the workplace. Design. A total of 122 employees with ≥2 risk factors for chronic disease identified in an in-house screening programme were invited to participate in a 6-month health management programme. Physical assessments included anthropometric measurements, blood pressure, blood glucose and cholesterol estimations, and bicycle ergometry. Participants were invited to wear a ‘metabolic armband' (Body Media SenseWear Pro Armband®) for 6 days. Metabolic measures included active and total energy expenditure (AEE, TEE), and daily MET levels (metabolic equivalents expressed as kcal/kg/hour). Differences were explored between genders, and relationships sought between energy expenditure, lifestyle and anthropometric data. Setting. A corporate working environment. All measures and assessments were carried out in the in-house fitness facility. Interventions. The health management programme involved physical assessments and personalised weight and activity management plans. Main outcome measures. TEE per day, duration and quantification of physical activity, METS, AEE, number of steps per day and body position recording. Relationships were explored between the latter and anthropometric measures such as body mass index (BMI) and percentage body fat. Result. Altogether 53 (43%) of the eligible subjects volunteered for the 6-month programme and 49 enrolled for the metabolic armband study. The males were more active than the females, but both had BMI and body fat estimates that categorised them as overweight to obese. METS and AEE were positively correlated with duration of exercise rather than intensity, and negatively correlated with BMI. In a stepwise regression analysis for the total group 77% of the variance in MET levels was accounted for by per cent body fat and steps per day. Multivariate analysis by gender (with per cent body fat as the dependent variable) suggested that males would have to increase the duration of vigorous exercise in order to reduce body fat, while females would benefit from sitting less, sleeping more, and increasing the duration of moderate exercise. Conclusion and clinical relevance. In a self-selected sample involving motivated individuals, the SenseWear® armband provided information that would be useful in directing further research in women, focusing on sleeping pattern and moderately increasing activity levels. South African Journal of Sports Medicine Vol. 20 (2) 2008: pp. 40-43

3축 가속도계와 신체정보를 이용한 보행 및 주행시 에너지 소비량의 예측

본 연구의 목적은 신체활동 시에 간단하고 실용적인 방법으로 에너지 소비를 예측하는데 있다. 신체활동은 허리에 부착된 3축 가속도계 센서를 사용하여 가속도의 함으로써 정량화하였다. 에너지 소비량과 가속도계 데이터의 관계를 찾기 위하여 11명(남성 6명, 여성 5명)의 피험자를 상대로 1.5, 3.0, 4.5, 6.0, 6.5, 7.0, 8.5km/hr의 속도로 트레드밀에서 걷거나 달리는 동작을 시행하였다. 각 피험자는 트레드밀 속도가 6.0km/hr 일 경우에는 걷는 동작을 6.5km/hr 이상일 경우께는 달리는 동작을 수행하였다. 실제 에너지 소비량은 가스분석기를 통하여 측정되었다. 예측 식은 피험자의 성, BMI(Body Mass Index), 가속도 데이터로 이루어졌으며 걷기, 달리기로 총 2개의 다중회귀식으로 구현되었다. 실제 측정된 에너지 소비량과 예측된 에너지 소비량 간의 상관계수와 결정계수는 걷기와 달리기에서 각각 R=0.956, R2=0.876와 R=0.881, R2=0.776를 나타내었다. 추후의 연구에서는 보다 많은 피험자의 데이터를 이용하여 보다 신뢰성 있는 에너지 소비량 예측의 회귀식을 구현하고자 한다. The purpose of this study was to estimate the energy expenditure simply and practically during physical activities. The physical activity is quantified by the integration of the accelerometer signals obtained from the triaxial accelerometer attached at the waist level of the human body. To find a relationship between energy expenditure and accelerometer data, 6 male and 5 female subjects walked and ran on the treadmill with speeds of 1.5, 3.0, 4.5, 6.0, 6.5, 7.0, and 8.5 km/hr. Each subject performed walking at the speed lower than 6.0 km/hr and running at the speed higher than 6.5 km/hr. Actual energy expenditure was determined by a continuous direct gas analyzer. Two predictive equations of walking and running mode for energy expenditure which includes gender, body mass index(BMI) and data from accelerometer were developed using multiple regression analysis. The correlation coefficients and coefficients of determination between the estimated and measured energy expenditure were R=0.936, R2=0.876 and R=0.881, R2=0.776 in walking and running mode, respectively. For further study, experiments on a larger scale of test subjects are essential for acquiring more reliable results.

Predicting Physical Activity Intention and Behavior in School-Age Children

Two studies were conducted to predict physical activity in school-aged children. Study 1 tested the utility of an integrated model in predicting physical activity (PA) intention and behavior-the theory of planned behavior (TPB) and self-efficacy theory. Six hundred and forty-five New Zealand children (aged 11-13 years) completed measures corresponding to the integrated model and a self-reported measure of PA one week later. Perceived behavioral control (PBC) and subjective norm were the two strongest predictors of intentions. Task efficacy and barrier efficacy were the two strongest predictors of PA. A second study (Study 2) was conducted to determine whether the self-efficacy measures could discriminate objectively measured PA levels. Sixty-seven Canadian children (aged 11-13 years) completed task and barrier self-efficacy measures. The following week, children classified as 'high' (n = 11) and 'lower' (n = 7) for both task and barrier efficacy wore an Actical® monitor for seven consecutive days to provide activity-related energy expenditure (AEE) data. Results showed that children with high efficacy expended significantly greater AEE than their lower efficacious counterparts. Findings from these two studies provide support for the use of self-efficacy interventions as a potentially useful means of increasing PA levels among school-aged children.

The Metabolic Stress Experienced by Agricultural Workers During a Typical Day of Labor

Musculoskeletal disorders including low back pain are the most frequent symptoms reported by farm workers. Strong epidemiologic evidence exists linking low back disorders/pain to overexertion during lifting tasks. NIOSH has developed a lifting equation (NIOSH Lifting Equation) that estimates the amount of weight that can be safely lifted (Recommended Weight Limit -RWL). The equation was developed based upon assumptions relative to biomechanical, psychophysical, and metabolic demands of the work environment. These assumptions have yet to be validated in the farm work environment. PURPOSE: The purpose of this study is to validate the metabolic assumptions used in the NIOSH lifting equation by measuring the metabolic demands experienced by farm workers during a typical day of work. METHODS: Adult male farm workers participated in the investigation (n=5, age=39.0±15.0yrs, ht=163.6±4.2cm, mass=66.1±9.6kg, BMI=24.7±3.2). Each worker wore an armband energy dosimeter that continuously monitored energy expenditure (kcal/min) during the harvest of heirloom tomatoes. Energy expenditure data collected were compared with the metabolic assumptions utilized by the NIOSH lifting equation. RESULTS: Approximately 90 hours of data were collected from work shifts spanning 1.5 weeks. Energy expenditure averaged 6.5±0.3kcal/min across the shifts, exceeding the NIOSH metabolic assumptions by as much as 107%. CONCLUSIONS: Within the parameters of this study, it appears the metabolic assumptions used in the NIOSH Lifting Equation to calculate the RWL are well below the metabolic demands incurred in the farm work environment.