Physical Energy Expenditure Research Articles

Validation of Pattern-Recognition Monitors in Children Using Doubly Labeled Water

Accurate assessments of physical activity and energy expenditure (EE) are needed to advance research on childhood obesity prevention. The objective of this study is to evaluate the validity of two SenseWear Armband monitors (the Pro3 (SWA) and the recently released Mini) (BodyMedia Inc., Pittsburgh, PA) under free-living conditions in a youth population. Twenty-eight healthy children age 10-16 yr wore both monitors for 14 consecutive days, including sleeping time. Estimates of total EE from the monitors were computed using two different algorithms (version 2.2, available in the SenseWear software 6.1 and 7.0, and the newly developed 5.0 algorithms). The EE estimates were compared with estimates derived from doubly labeled water (DLW) methodology using a three-way mixed model ANOVA (sex × monitor × algorithm), correlation analyses, and Bland-Altman plots. The mixed-model ANOVA revealed nonsignificant gender and monitor main effects but a significant main effect for algorithm (P < 0.001). The mean absolute percentage error values were considerably lower with the 5.0 (SWA: 10.9%; Mini: 11.7%) than for the 2.2 algorithm (SWA: 20.7%; Mini: 18.3%). Correlations were high for all comparisons (>0.90), but the Bland-Altman plots revealed consistent bias (greater overestimation at higher EE values). The variance in the differences between methods that was attributable to the mean level of EE ranged from R(2) = 0.17 to R(2) = 0.44. The magnitude of random error (estimated as the SD of the residuals) ranged from 227 to 299 kcal, but values tended to be lower with the 2.2 algorithm and with the Mini monitor. The newly developed SenseWear Armband 5.0 algorithms outperformed the version 2.2 algorithms for group comparisons, but additional work is needed to understand factors contributing to large individual variability.

WS14.6 Physical activity, energy expenditure and quality of life in CF adults receiving intravenous antibiotics at home and in hospital

WS14.6 Physical activity, energy expenditure and quality of life in CF adults receiving intravenous antibiotics at home and in hospital

Greater Short-Term Weight Loss in Women 20–45 versus 55–65 Years of Age Following Bariatric Surgery

Whether and how sex and age affect bariatric-surgery outcome is poorly understood. Estrogens regulate body composition in women and animals, and increase weight loss in a rodent model of gastric bypass, suggesting that premenopausal women may lose more weight following bariatric surgery. One thousand three hundred fifty-six female gastric-bypass or gastric-banding patients were retrospectively grouped as 20-45years old (presumptively premenopausal; n = 1,199) and 55-65years old (presumptively postmenopausal; n = 157). Mixed-model ANCOVA followed by Bonferroni-corrected t tests were used to categorically test the effect of age on percent excess body weight loss (%EBWL) at 1 and 2years post-surgery, controlling for preoperative EBW and surgery type. Age effects were also tested dimensionally in all women and in 289 male patients. Twenty- to forty-five-year-old women showed greater %EBWL 1 and 2years post-surgery than 55-65-year-old women (p's < 0.0005). No age effect was detected in 20-25- vs. 30-35-, 30-35- vs. 40-45-, or 20-25- vs. 40-45-year-old women (p's > 0.2) This age effect was detected only after gastric banding, with 20-45-year-old women losing ∼7kg more than 55-65-year-old women after 2years. Dimensional analysis confirmed a significant inverse effect of age on bariatric surgery outcome in women, but did not detect any effect in men. Results indicate that 55-65-year-old women lose less weight than 20-45-year-old women in the initial 2years after bariatric surgery, especially gastric banding; this may be mediated by age- or menopause-associated changes in physical activity, energy expenditure, or energy intake.

D-21 Free Communication/Poster - Assessment of Physical Activity and Energy Expenditure

D-21 Free Communication/Poster - Assessment of Physical Activity and Energy Expenditure

Temporal profiles of physical activity and energy expenditure in cancer in-patients

Fifty-three cancer in-patients (37 males and 16 females) were randomly selected from the Regional Cancer Center, Pt. J.N.M. College, Dr. B.R. Ambedkar Hospital, Raipur, India. Rhythms in physical activity (PA) and energy expenditure (EE) were studied non-invasively using Actical (Mini Mitter Co. Inc., USA) and compared with 24 apparently healthy subjects (11 males and 13 females). Data were gathered at 1-min epoch length for at least three to four consecutive days and were analyzed using several statistical techniques, such as Cosinor rhythmometry, ANOVA, Duncan's multiple-range test, and t-test. Most of the cancer in-patients and all control subjects exhibited a statistically significant circadian rhythm in PA and EE. However, the rhythm detection ratio was low among cancer in-patients. Patients had significantly lower 24-h average, lower amplitude, and an earlier acrophase in PA and EE rhythms. Further, significant effect of factor disease was discerned on total activity count (TAC) and total energy expenditure (TEE). TAC and TEE were significantly lower in cancer in-patients as compared to control subjects, irrespective of gender. In addition, a gradual decrement in PA intensity levels from sedentary to vigorous was validated in patients. From the present findings, it can be concluded that the factor disease might alter the temporal profiles of the PA and EE. However, further intensive studies involving more patients are required to reinforce the above conclusion.

Substituting dietary monounsaturated fat for saturated fat is associated with increased daily physical activity and resting energy expenditure and with changes in mood

The Western diet increases risk of metabolic disease. We determined whether lowering the ratio of saturated fatty acids to monounsaturated fatty acids in the Western diet would affect physical activity and energy expenditure. With the use of a balanced design, 2 cohorts of 18 and 14 young adults were enrolled in separate randomized, double-masked, crossover trials that compared a 3-wk high-palmitic acid diet (HPA; similar to the Western diet fat composition) to a low-palmitic acid and high-oleic acid diet (HOA; similar to the Mediterranean diet fat composition). All foods were provided by the investigators, and the palmitic acid (PA):oleic acid (OA) ratio was manipulated by adding different oil blends to the same foods. In both cohorts, we assessed physical activity (monitored continuously by using accelerometry) and resting energy expenditure (REE). To gain insight into a possible mood disturbance that might explain changes in physical activity, the Profile of Mood States (POMS) was administered in cohort 2. Physical activity was higher during the HOA than during the HPA in 15 of 17 subjects in cohort 1 (P = 0.008) (mean: 12% higher; P = 0.003) and in 12 of 12 subjects in the second, confirmatory cohort (P = 0.005) (mean: 15% higher; P = 0.003). When the HOA was compared with the HPA, REE measured during the fed state was 3% higher for cohort 1 (P < 0.01), and REE was 4.5% higher in the fasted state for cohort 2 (P = 0.04). POMS testing showed that the anger-hostility score was significantly higher during the HPA (P = 0.007). The replacement of dietary PA with OA was associated with increased physical activity and REE and less anger. Besides presumed effects on mitochondrial function (increased REE), the dietary PA:OA ratio appears to affect behavior. The second cohort was derived from a study that was registered at clinicaltrials.gov as R01DK082803.

Depression, physical activity, energy consumption, and quality of life in OSA patients before and after CPAP treatment

A variety of studies have demonstrated improvement in quality of life and depressive symptoms in obstructive sleep apnea (OSA) patients after continuous positive airway pressure (CPAP) treatment. However, very little is known about the effect of OSA treatment on physical activity and energy consumption. The aim of this study was to evaluate the changes in depression, physical activity, energy expenditure, and quality of life (QoL) in OSA patients before and after CPAP therapy. Forty-one patients with OSA as revealed by polysomnography, were included to the study. They responded to the generic World Health Organization Quality of Life (WHOQoL) questionnaire, to the specific-disease Quebec Sleep Questionnaire, and to Center for Epidemiologic Studies Depression Scale (CES-D) in order to evaluate QoL and the incidence of depression. In addition, all patients wore an accelerometer which measured physical activity and energy expenditure during a week. At least 6months after initiation of CPAP treatment (mean time, 9months) we re-examined 24 patients who met the compliance with the treatment criteria. Patients after CPAP therapy had significantly higher scores in all domains of the Quebec Sleep Questionnaire and in the domains of physical health/level of independence and psychological health/spirituality of the WHOQoL. Depression scores were also better in CES-D after treatment. However, despite the improvement in QoL and psychological status, CPAP therapy had no impact on physical activity and energy expenditure. CPAP therapy improves QoL and lessens depressive symptoms in our group of well-treated OSA patients. However, physical activity and energy expenditure did not present statistically significant improvement in the same group of OSA patients.

Energy expenditure and sex differences of golf playing

The purpose of the study was to assess the average physical intensity and energy expenditure during a single round of golf on hilly and flat courses in a heterogeneous group of healthy men and women of varying age and golf handicap. Forty-two males and 24 females completed an incremental cycle-ergometer exercise test to determine exercise performance markers. The heart rate (HR), duration, distance, walking speed, ascent and descent were measured via a global positioning system (GPS)/HR monitor during the game and energy expenditure was calculated. Playing 9 or 18-holes of golf, independent of the golf course design, the average HR was not significantly different between sexes or the subgroups. The intensities were light with respect to the percentage of maximal HR and metabolic equivalents of task (METs). Total energy expenditure of all participants was not significantly different for hilly (834 ± 344 kcal) vs. flat courses (833 ± 295 kcal) whereas male players expended significantly greater energy than female players (926 ± 292 vs. 556 ± 180 kcal), but did not have significantly greater relative energy expenditure (2.8 ± 0.8 vs. 2.2 ± 0.7 METs). As a high volume physical activity, playing golf is suggested to yield health benefits. Since the intensity was well below recommended limits, golf may have health related benefits unrelated to the intensity level of the activity.

Screening obesity by direct and derived anthropometric indices with evaluation of physical efficiency among female college students of kolkata.

Background:The available information regarding the obesity pattern of the undergraduate female students of Kolkata is inadequate, though there are several reports which indicate the complications and/or awful consequences of obesity on female health particularly, during the reproductive years.Aim:The present investigation has thus been carried out to report their present physiological status along with the prevalence of obesity, based on their body mass index (BMI), some direct and derived anthropometric indices, and physical fitness.Subjects and Methods:This small-scale cross-sectional study conducted in randomly selected 100 female students of different colleges of Kolkata with the age of 18-22 [mean age 20.4 (2.3)] years. Measurements of body composition included total 24 variables, with thirteen direct and eleven derived anthropometric variables; while physical efficiency parameters were physical fitness index, VO2max, energy expenditure and anaerobic power. The data of the experimental group were compared with those of the control group by t-test, using SPSS v.15.0 and MS-Excel v.2013.Results:Analysis of collected data showed majority of the students have normal range of BMI (67.95%), but, 21.95% of students found to be overweight and 3.84% are obese. They also showed higher fat mass [14.40 (4.11)], but, lower waist-to-hip ratio and conicity index. They were found to have poor to moderate physical fitness [57.60 (3.90)] and higher energy expenditure [5.61 (0.72)].Conclusion:The findings of the present obesity screening reports almost one of four female students (24 out of 100 participants) are overweight/obese, indicated higher body fat distribution and increased propensity of being obese with age. Thus, the overall data along with their low physical fitness points out to health risks among female undergraduates of Kolkata.

The ActivityStat Hypothesis

The ActivityStat hypothesis suggests that when physical activity is increased or decreased in one domain, there will be a compensatory change in another domain, in order to maintain an overall stable level of physical activity or energy expenditure over time. The ActivityStat debate is gaining momentum in the literature and most of the research to date is based on observational studies. The objective of this paper is to conceptually clarify the ActivityStat hypothesis and to examine the experimental research aiming to demonstrate or refute compensation using a systematic review process. A systematic review was conducted using electronic database searches with the aim of detecting studies experimentally investigating the ActivityStat hypothesis or compensation in physical activity or energy expenditure. Included studies were critically appraised using a specifically designed tool to address the conceptual considerations of the ActivityStat hypothesis. Searches identified 28 studies that met the inclusion criteria. Publications spanned 26years and had multiple methodological approaches, including randomized and non-randomized controlled trials, crossover designs, cluster randomized controlled trials and pre-post trials. Populations of the included studies ranged from children, to adults and the elderly, across a range of weight statuses and used both aerobic, resistance and mixed-exercise interventions. The timeframe of interventions ranged from 1day to 4years and outcomes were measured using doubly labelled water, accelerometry, heart rate monitoring, resting metabolic rate, indirect calorimetry, pedometry, subjective recall questionnaire and the activity-related time index. Fifteen of 28 included studies provided evidence of compensation, while 13 did not. Subgroup analyses by population, type and duration of intervention, weight status and study quality also showed mixed findings. There is a substantial body of experimental literature investigating compensation that has largely been overlooked in the ActivityStat debate. However, this evidence is currently inconclusive and lacks a cohesive approach to the question of an ActivityStat. Recommendations for the design of future experimental research investigating the ActivityStat hypothesis are presented.

The research of physical condition, physical activity and nutrition of teacher education students

The goal of the research is to identify and assess parameters of physical development, actual nutrition, energy expenditure and energy requirement of the young adult males. The research was conducted in 2008–2010 and students (n=84) of biology, physical education and psychology specialties at Vilnius Pedagogical University participated in it. Height and weight measurements were taken by electronic medical scales with the height measuring equipment. We analysed an average energy value of a daily food ration; the intake of carbohydrates, protein, and fat; physical activity and energy requirement by using 7-day nutrition and physical activity diaries filled out by the students participating in the research (20.35±0.99 years old). The body weight of the majority of the young adult males was normal (69.05 per cent), 26.19 per cent of them had the body weight above the normal range, and the body weight of 4.76 per cent of the students was insufficient. Physical activity ratio of the future teachers is 1.79±0.382. An average energy value of nutrition ration corresponds to energy expenditure (p=0.684) but is lower than energy requirement (p<0.001). The ratio of the main nutrients (protein, fat, and carbohydrates) in the nutrition of the young adult males is unbalanced; 27.38 per cent of them consume too much protein, and 1.19 per cent exceeds the recommended daily intake of protein more than twice. According to our data, only 7.14 per cent of the students get enough fat, 36.91 per cent of them consume too much fat, and 55.95 percent of the respondents get too little fat although close to the norm. Our research demonstrated that there is a deficiency of carbohydrate in a daily ration food of 95.24 per cent of the young adult males, and the carbohydrate content in the nutrition of 34.52 per cent of the young men is more than twice lower than the norm. In comparison with the individual norms of these nutrients (considering the respondent’s body weight, age, and physical activity), protein intake of the young adult males is too high (p<0.001), the received fat content corresponds to the recommended intake (p=0.663), and there is carbohydrate deficiency in a daily food ration (p<0.001).

Physiologic Responses and Energy Expenditure of Kinect Active Video Game Play in Schoolchildren

To evaluate the physiologic responses and energy expenditure of active video gaming using Kinect for the Xbox 360. Comparison study. Kirkby Sports College Centre for Learning, Liverpool, England. Eighteen schoolchildren (10 boys and 8 girls) aged 11 to 15 years. A comparison of a traditional sedentary video game and 2 Kinect activity-promoting video games, Dance Central and Kinect Sports Boxing, each played for 15 minutes. Physiologic responses and energy expenditure were measured using a metabolic analyzer. Heart rate, oxygen uptake, and energy expenditure. Heart rate, oxygen uptake, and energy expenditure were considerably higher (P < .05) during activity-promoting video game play compared with rest and sedentary video game play. The mean (SD) corresponding oxygen uptake values for the sedentary, dance, and boxing video games were 6.1 (1.3), 12.8 (3.3), and 17.7 (5.1) mL · min-1 · kg-1, respectively. Energy expenditures were 1.5 (0.3), 3.0 (1.0), and 4.4 (1.6) kcal · min-1, respectively. Dance Central and Kinect Sports Boxing increased energy expenditure by 150% and 263%, respectively, above resting values and were 103% and 194% higher than traditional video gaming. This equates to an increased energy expenditure of up to 172 kcal · h-1 compared with traditional sedentary video game play. Played regularly, active gaming using Kinect for the Xbox 360 could prove to be an effective means for increasing physical activity and energy expenditure in children.

Abstract IA12: Technology to assess physical activity and sedentary behavior.

Abstract Physical inactivity is an urgent public health concern, being strongly implicated as a risk factor for many chronic diseases including certain types of cancer. It is not possible to understand or alter physical activity and inactivity levels without first being able to accurately measure these behaviors. Objective assessment of physical activity and inactivity using wearable accelerometer-based monitors has overcome the problems and limitations associated with more commonly used self-report tools. These wearable sensors are ideal for collecting information about physical activity (PA) and sedentary behavior (SB). They can be worn for extended periods of time, impose minimal inconvenience to the participant and researcher, are relatively inexpensive and can produce detailed accounts of PA and SB that are relevant to health (e.g. estimates of energy expenditure, time in moderate-to-vigorous physical activity, sedentary time) These PA and SB metrics can then be used to comprehensively characterize dose-response relationships. This presentation will highlight recent advances in objective monitoring of physical activity and sedentary behavior. The talk will describe recent work that uses machine learning tools for processing activity monitor data to classify physical activity intensity and estimate energy expenditure. Additionally, the assessment of sedentary behavior, which has been shown to be an independent risk factor for disease, will be discussed. The approach we use to assess physical activity and sedentary behavior with wearable sensors first involves the calibration of sensors. In the lab, we directly measure energy expenditure or directly observe behavior while participants perform a variety of locomotion, household, sport activities and sedentary behaviors (e.g. sitting performing computer work, filing). Simultaneously, signals from the wearable accelerometers are collected continuously. We then use features from the accelerometer signal to generate machine learning algorithms (e.g. neural networks) to predict energy expenditure, intensity of physical activity or to identify activity type. As a final step we validate these algorithms on independent samples to test the precision and accuracy of these algorithms. To examine the performance of these algorithms in the field, we have subjects carry out their normal activities in a natural setting while wearing the monitors (subjects are observed and the direct observation data are recorded continuously). This presentation will describe data from these laboratory and field studies to demonstrate performance of algorithms for predicting activity levels and sedentary behavior in free-living settings. Evidence supporting the sensitivity of these algorithms in estimating change in activity level will also be presented. Citation Format: Patty S. Freedson. Technology to assess physical activity and sedentary behavior. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr IA12.

Risk Factors for Musculoskeletal Injuries for Soldiers Deployed to Afghanistan

This study determined injury incidence and examined the association between musculoskeletal injuries and potential intrinsic and extrinsic risk factors. This retrospective cohort study involved a survey of 593 volunteers from two battalions of a Stryker Brigade Combat Team upon completion of a 12-mo deployment to Afghanistan. The survey included questions on physical characteristics, work duties, equipment worn, fitness training, and injuries experienced during the deployment. Of the surveyed soldiers, 45% sustained an injury during the deployment. Total injuries resulted in 5049 d of limited duty, an average of 8.5 d per injury. The body regions with the largest numbers of injuries were the low back (17.4%), knee (12.7%), and shoulder (10.0%). The majority (65%) of injuries occurred while working. The most frequent activities soldiers reported as the cause of injury were lifting and carrying (9.8%), dismounted patrolling (9.6%), and physical training (8.0%). Older age, higher enlisted rank, female sex, months deployed, more time spent standing, longer strength training sessions, heaviest load worn, and heavier or more frequent lifting tasks were all associated with injury. Tasks requiring physical energy expenditure such as load carriage, lifting, or standing resulted in an increased risk of musculoskeletal injury in this study. Lifting/carrying, dismounted patrols, and physical training were associated with 26% of musculoskeletal injuries. The weight of loads carried and lifting may be exceeding the work capacity of the soldiers, resulting in injury. These injuries in turn limit available work days for military units, reducing combat power.

Are persons with rheumatoid arthritis deconditioned? A review of physical activity and aerobic capacity

BackgroundAlthough the general assumption is that patients with rheumatoid arthritis (RA) have decreased levels of physical activity, no review has addressed whether this assumption is correct.MethodsOur objective was to systematically review the literature for physical activity levels and aerobic capacity (VO2max). in patients with (RA), compared to healthy controls and a reference population. Studies investigating physical activity, energy expenditure or aerobic capacity in patients with RA were included. Twelve studies met our inclusion criteria.ResultsIn one study that used doubly labeled water, the gold standard measure, physical activity energy expenditure of patients with RA was significantly decreased. Five studies examined aerobic capacity. Contradictory evidence was found that patients with RA have lower VO2max than controls, but when compared to normative values, patients scored below the 10th percentile. In general, it appears that patients with RA spend more time in light and moderate activities and less in vigorous activities than controls.ConclusionPatients with RA appear to have significantly decreased energy expenditure, very low aerobic capacity compared to normative values and spend less time in vigorous activities than controls.

Assessment of Physical Activity and Energy Expenditure by GPS Combined With Accelerometry in Real-Life Conditions

Physical activity (PA) and related energy expenditure (EE) is often assessed by means of a single technique. Because of inherent limitations, single techniques may not allow for an accurate assessment both PA and related EE. The aim of this study was to develop a model to accurately assess common PA types and durations and thus EE in free-living conditions, combining data from global positioning system (GPS) and 2 accelerometers. Forty-one volunteers participated in the study. First, a model was developed and adjusted to measured EE with a first group of subjects (Protocol I, n = 12) who performed 6 structured and supervised PA. Then, the model was validated over 2 experimental phases with 2 groups (n = 12 and n = 17) performing scheduled (Protocol I) and spontaneous common activities in real-life condition (Protocol II). Predicted EE was compared with actual EE as measured by portable indirect calorimetry. In protocol I, performed PA types could be recognized with little error. The duration of each PA type could be predicted with an accuracy below 1 minute. Measured and predicted EE were strongly associated (r = .97, P < .001). Combining GPS and 2 accelerometers allows for an accurate assessment of PA and EE in free-living situations.

Testing the activitystat hypothesis: a randomised controlled trial protocol.

BackgroundThe activitystat hypothesis proposes that when physical activity or energy expenditure is increased or decreased in one domain, there will be a compensatory change in another domain to maintain an overall, stable level of physical activity or energy expenditure. To date, there has been no experimental study primarily designed to test the activitystat hypothesis in adults. The aim of this trial is to determine the effect of two different imposed exercise loads on total daily energy expenditure and physical activity levels.MethodsThis study will be a randomised, multi-arm, parallel controlled trial. Insufficiently active adults (as determined by the Active Australia survey) aged 18–60 years old will be recruited for this study (n=146). Participants must also satisfy the Sports Medicine Australia Pre-Exercise Screening System and must weigh less than 150 kg. Participants will be randomly assigned to one of three groups using a computer-generated allocation sequence. Participants in the Moderate exercise group will receive an additional 150 minutes of moderate to vigorous physical activity per week for six weeks, and those in the Extensive exercise group will receive an additional 300 minutes of moderate to vigorous physical activity per week for six weeks. Exercise targets will be accumulated through both group and individual exercise sessions monitored by heart rate telemetry. Control participants will not be given any instructions regarding lifestyle. The primary outcome measures are activity energy expenditure (doubly labeled water) and physical activity (accelerometry). Secondary measures will include resting metabolic rate via indirect calorimetry, use of time, maximal oxygen consumption and several anthropometric and physiological measures. Outcome measures will be conducted at baseline (zero weeks), mid- and end-intervention (three and six weeks) with three (12 weeks) and six month (24 week) follow-up. All assessors will be blinded to group allocation.DiscussionThis protocol has been specifically designed to test the activitystat hypothesis while taking into account the key conceptual and methodological considerations of testing a biologically regulated homeostatic feedback loop. Results of this study will be an important addition to the growing literature and debate concerning the possible existence of an activitystat.Trial registrationAustralian New Zealand Clinical Trials Registry ACTRN12610000248066

Measuring sleep–wake patterns with physical activity and energy expenditure monitors

This study assessed the validity of using an energy expenditure actimeter for sleep–wake monitoring. Twelve participants underwent five to nine days of continuous actigraphy, simultaneously wearing an actimeter measuring energy expenditure (Actical) and an actimeter commonly used for sleep–wake assessment (Actiwatch-L) on their non-dominant wrist. Sleep timing variables measured with the two actimeters correlated above 0.90 and the correlation for sleep consolidation variables was above 0.75. Significant positive correlations between the two monitors were also found for an actigraphy based index assessing circadian rhythms. These results support the use of energy expenditure based actimeters to monitor sleep–wake patterns.

Validity of hip-mounted uniaxial accelerometry with heart-rate monitoring vs. triaxial accelerometry in the assessment of free-living energy expenditure in young children: the IDEFICS Validation Study

One of the aims of Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants (IDEFICS) validation study is to validate field measures of physical activity (PA) and energy expenditure (EE) in young children. This study compared the validity of uniaxial accelerometry with heart-rate (HR) monitoring vs. triaxial accelerometry against doubly labeled water (DLW) criterion method for assessment of free-living EE in young children. Forty-nine European children (25 female, 24 male) aged 4-10 yr (mean age: 6.9 ± 1.5 yr) were assessed by uniaxial ActiTrainer with HR, uniaxial 3DNX, and triaxial 3DNX accelerometry. Total energy expenditure (TEE) was estimated using DLW over a 1-wk period. The longitudinal axis of both devices and triaxial 3DNX counts per minute (CPM) were significantly (P < 0.05) associated with physical activity level (PAL; r = 0.51 ActiTrainer, r = 0.49 uniaxial-3DNX, and r = 0.42 triaxial Σ3DNX). Eight-six percent of the variance in TEE could be predicted by a model combining body mass (partial r(2) = 71%; P < 0.05), CPM-ActiTrainer (partial r(2) = 11%; P < 0.05), and difference between HR at moderate and sedentary activities (ModHR - SedHR) (partial r(2) = 4%; P < 0.05). The SE of TEE estimate for ActiTrainer and 3DNX models ranged from 0.44 to 0.74 MJ/days or ∼7-11% of the average TEE. The SE of activity-induced energy expenditure (AEE) model estimates ranged from 0.38 to 0.57 MJ/day or 24-26% of the average AEE. It is concluded that the comparative validity of hip-mounted uniaxial and triaxial accelerometers for assessing PA and EE is similar.

Changes in daily physical activity before and after total hip arthroplasty. A pilot study using accelerometry

The present single-centre prospective follow-up study assessed the objective changes in physical activity undertaken before and after total hip arthroplasty (THA) using accelerometry. We enrolled 12 female patients who underwent home-based accelerometry assessment one month before and six months after the THA procedure. We assessed the daily amount of physical activity and energy expenditure related to physical activities. We also recorded the intensity of the physical activity, and pre- and post-operative clinical evaluation with the Harris Hip Score (HHS). At 6 months after surgery, we found a statistically significant increase of the total energy cost of physical activity (DA) (P=0.02), without significant increase of activity time (P>0.05). The energy cost of moderate/vigorous activity was statistically significant increased after surgery (P=0.008). Finally, HHS improved form 53.9±15.3 pre-operatively to 78.1±12.2 post-operatively (P=0.03). In our patients, the improvement was significant only for the total energy cost of daily activity. Thus, although patients did not exhibit a more active lifestyle, as shown by the slight increase of the activity time, they significantly increased the amount of moderate or vigorous activities performed after surgery.