Jeffer Eidi Sasaki

Validation and comparison of ActiGraph activity monitors

OBJECTIVE To compare activity counts from the ActiGraph GT3X to those from the ActiGraph GT1M during treadmill walking/running. A secondary aim was to develop tri-axial vector magnitude (VM3) cut-points to classify physical activity (PA) intensity. METHODS Fifty participants wore the GT3X and the GT1M on the non-dominant hip and exercised at 4 treadmill speeds (4.8, 6.4, 9.7, and 12 km h(-1)). Vertical (VT) and antero-posterior (AP) activity counts (counts min(-1)) as well as the vector magnitudes of the two axes (VM2) from both monitors were tested for significant differences using two-way ANOVAs. Bland-Altman plots were used to assess agreement between activity counts from the GT3X and GT1M. Linear regression analysis between VM3 countsmin(-1) and oxygen consumption data was conducted to develop VM3 cut-points for moderate, hard and very hard PA. RESULTS There were no significant inter-monitor differences in VT activity counts at any speed. AP and VM2 activity counts from the GT1M were significantly higher (p<0.01) than those from the GT3X at 4.8, 9.7 and 12 km h(-1). High inter-monitor agreement was found for VT activity counts but not for AP and VM2 activity counts. VM3 cut-points for moderate, hard, and very hard PA intensities were 2690-6166, 6167-9642, >9642 counts min(-1). CONCLUSION Due to the lack of congruence between the AP and VM2 activity counts from the GT1M and the GT3X, comparisons of data obtained with these two monitors should be avoided when using more than just the VT axis. VM3 cut-points may be used to classify PA in future studies.

Validation of the Fitbit wireless activity tracker for prediction of energy expenditure.

OBJECTIVE The purpose of this study was to examine the accuracy of the Fitbit wireless activity tracker in assessing energy expenditure (EE) for different activities. METHODS Twenty participants (10 males, 10 females) wore the Fitbit Classic wireless activity tracker on the hip and the Oxycon Mobile portable metabolic system (criterion). Participants performed walking and running trials on a treadmill and a simulated free-living activity routine. Paired t tests were used to test for differences between estimated (Fitbit) and criterion (Oxycon) kcals for each of the activities. RESULTS Mean bias for estimated energy expenditure for all activities was -4.5 ± 1.0 kcals/6 min (95% limits of agreement: -25.2 to 15.8 kcals/6 min). The Fitbit significantly underestimated EE for cycling, laundry, raking, treadmill (TM) 3 mph at 5% grade, ascent/descent stairs, and TM 4 mph at 5% grade, and significantly overestimated EE for carrying groceries. Energy expenditure estimated by the Fitbit was not significantly different than EE calculated from the Oxycon Mobile for 9 activities. CONCLUSION The Fitbit worn on the hip significantly underestimates EE of activities. The variability in underestimation of EE for the different activities may be problematic for weight loss management applications since accurate EE estimates are important for tracking/monitoring energy deficit.

Physical activity, cardiorespiratory fitness, and metabolic syndrome in adolescents: A cross-sectional study

BackgroundIn adults, there is a substantial body of evidence that physical inactivity or low cardiorespiratory fitness levels are strongly associated with the development of metabolic syndrome. Although this association has been studied extensively in adults, little is known regarding this association in adolescents. The aim of this study was to analyze the association between physical activity and cardiorespiratory fitness levels with metabolic syndrome in Brazilian adolescents.MethodsA random sample of 223 girls (mean age, 14.4 ± 1.6 years) and 233 boys (mean age, 14.6 ± 1.6 years) was selected for the study. The level of physical activity was determined by the Bouchard three-day physical activity record. Cardiorespiratory fitness was estimated by the Leger 20-meter shuttle run test. The metabolic syndrome components assessed included waist circumference, blood pressure, HDL-cholesterol, triglycerides, and fasting plasma glucose levels. Independent Student t-tests were used to assess gender differences. The associations between physical activity and cardiorespiratory fitness with the presence of metabolic syndrome were calculated using logistic regression models adjusted for age and gender.ResultsA high prevalence of metabolic syndrome was observed in inactive adolescents (males, 11.4%; females, 7.2%) and adolescents with low cardiorespiratory fitness levels (males, 13.9%; females, 8.6%). A significant relationship existed between metabolic syndrome and low cardiorespiratory fitness (OR, 3.0 [1.13-7.94]).ConclusionThe prevalence of metabolic syndrome is high among adolescents who are inactive and those with low cardiorespiratory fitness. Prevention strategies for metabolic syndrome should concentrate on enhancing fitness levels early in life.

Classification Accuracy of the Wrist-Worn Gravity Estimator of Normal Everyday Activity Accelerometer

PURPOSE The purpose of this study was to determine whether the published left-wrist cut points for the triaxial Gravity Estimator of Normal Everyday Activity (GENEA) accelerometer are accurate for predicting intensity categories during structured activity bouts. METHODS A convenience sample of 130 adults wore a GENEA accelerometer on their left wrist while performing 14 different lifestyle activities. During each activity, oxygen consumption was continuously measured using the Oxycon mobile. Statistical analysis used Spearmans rank correlations to determine the relationship between measured and estimated intensity classifications. Cross tabulations were constructed to show the under- or overestimation of misclassified intensities. One-way χ2 tests were used to determine whether the intensity classification accuracy for each activity differed from 80%. RESULTS For all activities, the GENEA accelerometer-based physical activity monitor explained 41.1% of the variance in energy expenditure. The intensity classification accuracy was 69.8% for sedentary activities, 44.9% for light activities, 46.2% for moderate activities, and 77.7% for vigorous activities. The GENEA correctly classified intensity for 52.9% of observations when all activities were examined; this increased to 61.5% with stationary cycling removed. CONCLUSIONS A wrist-worn triaxial accelerometer has modest-intensity classification accuracy across a broad range of activities when using the cut points of Esliger et al. Although the sensitivity and the specificity are less than those reported by Esliger et al., they are generally in the same range as those reported for waist-worn, uniaxial accelerometer cut points.

Comparison of Raw Acceleration from the GENEA and ActiGraph™ GT3X+ Activity Monitors

Purpose: To compare raw acceleration output of the ActiGraph™ GT3X+ and GENEA activity monitors. Methods: A GT3X+ and GENEA were oscillated in an orbital shaker at frequencies ranging from 0.7 to 4.0 Hz (ten 2-min trials/frequency) on a fixed radius of 5.08 cm. Additionally, 10 participants (age = 23.8 ± 5.4 years) wore the GT3X+ and GENEA on the dominant wrist and performed treadmill walking (2.0 and 3.5 mph) and running (5.5 and 7.5 mph) and simulated free-living activities (computer work, cleaning a room, vacuuming and throwing a ball) for 2-min each. A linear mixed model was used to compare the mean triaxial vector magnitude (VM) from the GT3X+ and GENEA at each oscillation frequency. For the human testing protocol, random forest machine-learning technique was used to develop two models using frequency domain (FD) and time domain (TD) features for each monitor. We compared activity type recognition accuracy between the GT3X+ and GENEA when the prediction model was fit using one monitor and then applied to the other. Z-statistics were used to compare the proportion of accurate predictions from the GT3X+ and GENEA for each model. Results: GENEA produced significantly higher (p < 0.05, 3.5 to 6.2%) mean VM than GT3X+ at all frequencies during shaker testing. Training the model using TD input features on the GENEA and applied to GT3X+ data yielded significantly lower (p < 0.05) prediction accuracy. Prediction accuracy was not compromised when interchangeably using FD models between monitors. Conclusions: It may be inappropriate to apply a model developed on the GENEA to predict activity type using GT3X+ data when input features are TD attributes of raw acceleration.

Performance of Activity Classification Algorithms in Free-Living Older Adults.

PURPOSE The objective of this study is to compare activity type classification rates of machine learning algorithms trained on laboratory versus free-living accelerometer data in older adults. METHODS Thirty-five older adults (21 females and 14 males, 70.8 ± 4.9 yr) performed selected activities in the laboratory while wearing three ActiGraph GT3X+ activity monitors (in the dominant hip, wrist, and ankle; ActiGraph, LLC, Pensacola, FL). Monitors were initialized to collect raw acceleration data at a sampling rate of 80 Hz. Fifteen of the participants also wore GT3X+ in free-living settings and were directly observed for 2-3 h. Time- and frequency-domain features from acceleration signals of each monitor were used to train random forest (RF) and support vector machine (SVM) models to classify five activity types: sedentary, standing, household, locomotion, and recreational activities. All algorithms were trained on laboratory data (RFLab and SVMLab) and free-living data (RFFL and SVMFL) using 20-s signal sampling windows. Classification accuracy rates of both types of algorithms were tested on free-living data using a leave-one-out technique. RESULTS Overall classification accuracy rates for the algorithms developed from laboratory data were between 49% (wrist) and 55% (ankle) for the SVMLab algorithms and 49% (wrist) to 54% (ankle) for the RFLab algorithms. The classification accuracy rates for SVMFL and RFFL algorithms ranged from 58% (wrist) to 69% (ankle) and from 61% (wrist) to 67% (ankle), respectively. CONCLUSIONS Our algorithms developed on free-living accelerometer data were more accurate in classifying the activity type in free-living older adults than those on our algorithms developed on laboratory accelerometer data. Future studies should consider using free-living accelerometer data to train machine learning algorithms in older adults.

Atividade física, consumo de lipídios e fatores de risco para aterosclerose em adolescentes

FUNDAMENTO: A aterosclerose e a doenca coronariana que acomete com maior frequencia a populacao adulta brasileira. Embora seja uma doenca predominantemente adulta, os fatores de risco associados podem surgir em individuos jovens. OBJETIVO: Verificar a associacao do nivel de atividade fisica (NAF) e o consumo de lipidios com os fatores de risco para aterosclerose em adolescentes. METODOS: Foram avaliados 260 meninos e 237 meninas com idades entre 10-18 anos. O nivel de atividade fisica foi estimado atraves do recordatorio proposto por Bouchard e cols.. O consumo de lipidios foi avaliado atraves do inquerito alimentar desenvolvido por Sichieri e Everhart. A pressao arterial foi mensurada utilizando um esfigmomanometro de coluna de mercurio. O colesterol total, o HDL-C e os triglicerides foram determinados atraves do metodo enzimatico-colorimetrico. O LDL-C foi calculado pela formula de Friedewald. Na analise estatistica, foi empregada a regressao logistica, com nivel de significância estipulado em p < 0,05. RESULTADOS: Quanto ao NAF, 17,3% dos meninos e 22,6% das meninas foram classificados como sedentarios. Para os habitos alimentares, 54% e 48,6% dos meninos e meninas, respectivamente, apresentaram consumo de lipidios acima das recomendacoes. Meninos com niveis elevados de colesterol total e de LDL-C tiveram maior razao de chances de serem sedentarios do que seus pares mais ativos. Apresentar niveis elevados de LDL-C esteve associado ao consumo excessivo de gordura saturada em ambos os sexos. CONCLUSAO: Os resultados avigoram as evidencias previas de que jovens devem ser encorajados desde cedo a adocao de um estilo de vida fisicamente mais ativo associado a uma ingestao alimentar apropriada.BACKGROUND Atherosclerosis is the coronary disease that most often affects the adult Brazilian population. Although it is a predominantly adult disease, the risk factors can appear in young individuals. OBJECTIVE To verify the association between the physical activity level (PAL) and the consumption of lipids with the risk factors for atherosclerosis in adolescents. METHODS A total of 260 boys and 237 girls aged 10-18 years were assessed. The PAL was estimated based on the activity record proposed by Bouchard et al. The consumption of lipids was assessed through the food frequency questionnaire developed by Sichieri and Everhart. Blood pressure was measured using a mercury-column sphygmomanometer. Total cholesterol (TC), HDL-c and triglycerides (TG) were measured by the enzymatic-colorimetric method. LDL-c was calculated by Friedewalds formula. The statistical analysis was carried out through logistic regression, with a level of significance set at p < 0.05. RESULTS Regarding the PAL, 17.3% of the boys and 22.6% of the girls were classified as sedentary. As for the diet, 54% and 48.6% of the boys and girls, respectively, presented a consumption of lipids above the recommended level. Boys with high TC and LDL-c levels had a higher OR to be sedentary than their more active peers. High levels of LDL-c were associated with the excessive consumption of saturated fats in both sexes. CONCLUSION The results reinforce the previous evidence that young people must be encouraged since an early age to adopt a more physically active lifestyle, associated to more adequate dietary habits.

Socio-demographic, clinical and health behavior correlates of sitting time in older adults

BackgroundIdentifying correlates of sedentary behavior in older adults is of major importance to healthcare. To our knowledge, there are no population studies in Latin America examining which factors are associated to high sitting time in older adults. Thus, the purpose of this study is to identify socio-demographic, clinical, and health behavior correlates of sitting time in a representative sample of older adults living in Southeastern Brazil.MethodsA cross-sectional study was conducted in twenty-four municipalities of the Triangulo Mineiro region in the State of Minas Gerais, Southeastern Brazil. A structured questionnaire was applied to obtain information on socio-demographic, clinical, and health behavior factors. Overall sitting time was assessed using a self-report instrument. A Multiple Correspondence Analysis was used to verify the association of sitting time with socio-demographic, clinical, and health behavior factors.Results3,296 older adults (61.5% women and 38.5% men) were included in the analysis. The overall median was 240.0 minutes of sitting time/day. The Multiple Correspondence Analysis showed that the group with the highest sitting time presented the following characteristics: women, age greater than 70 years, unschooled status, arterial hypertension, diabetes mellitus, use of medication, poor self-rated health, dependence in basic activities of daily living, and absence of regular physical activity.ConclusionThis study reveals that socio-demographic, clinical, and health behavior factors are associated with high sitting time in older adults from Southeastern Brazil. The results may help to identify older adults that should be targeted in interventions aiming at reducing sitting time.

Sitting Time and Quality of Life in Older Adults: A Population-Based Study

BACKGROUND Quality of life is influenced by several factors and one aspect that has been negatively associated with health is sedentary behavior. Thus, the purpose of this study was to investigate the association between sitting time and quality of life in older adults. METHODS This was a cross-sectional study conducted with individuals ≥ 60 years old residing in 24 Brazilian municipalities. Total sitting time was evaluated according to self-report of sitting time on a regular weekday and usual weekend day. The quality of life was evaluated by the WHOQOL-BREF and WHOQOL-OLD instruments. RESULTS 3206 older adults were analyzed. In the univariate logistic regression analysis, all domain and facets of quality of life were associated to the longest sitting time; however, in the multivariate analysis, only the physical domain and the social participation facet remained significant in the model. After adjustment for sex, age group, education and regular practice of physical activity, longest sitting time remained associated with the lowest score for the physical domain (OR = 1.80; 95% CI: 1.39-2.34) and social participation facet (OR = 1.42; 95% CI: 1.10-1.84). CONCLUSION In this study, older adults who sat the most presented the worst scores in the physical domain and social participation facet of quality of life.

Physical activity, lipid consumption and risk factors for atherosclerosis in adolescents

FUNDAMENTO: A aterosclerose e a doenca coronariana que acomete com maior frequencia a populacao adulta brasileira. Embora seja uma doenca predominantemente adulta, os fatores de risco associados podem surgir em individuos jovens. OBJETIVO: Verificar a associacao do nivel de atividade fisica (NAF) e o consumo de lipidios com os fatores de risco para aterosclerose em adolescentes. METODOS: Foram avaliados 260 meninos e 237 meninas com idades entre 10-18 anos. O nivel de atividade fisica foi estimado atraves do recordatorio proposto por Bouchard e cols.. O consumo de lipidios foi avaliado atraves do inquerito alimentar desenvolvido por Sichieri e Everhart. A pressao arterial foi mensurada utilizando um esfigmomanometro de coluna de mercurio. O colesterol total, o HDL-C e os triglicerides foram determinados atraves do metodo enzimatico-colorimetrico. O LDL-C foi calculado pela formula de Friedewald. Na analise estatistica, foi empregada a regressao logistica, com nivel de significância estipulado em p < 0,05. RESULTADOS: Quanto ao NAF, 17,3% dos meninos e 22,6% das meninas foram classificados como sedentarios. Para os habitos alimentares, 54% e 48,6% dos meninos e meninas, respectivamente, apresentaram consumo de lipidios acima das recomendacoes. Meninos com niveis elevados de colesterol total e de LDL-C tiveram maior razao de chances de serem sedentarios do que seus pares mais ativos. Apresentar niveis elevados de LDL-C esteve associado ao consumo excessivo de gordura saturada em ambos os sexos. CONCLUSAO: Os resultados avigoram as evidencias previas de que jovens devem ser encorajados desde cedo a adocao de um estilo de vida fisicamente mais ativo associado a uma ingestao alimentar apropriada.BACKGROUND Atherosclerosis is the coronary disease that most often affects the adult Brazilian population. Although it is a predominantly adult disease, the risk factors can appear in young individuals. OBJECTIVE To verify the association between the physical activity level (PAL) and the consumption of lipids with the risk factors for atherosclerosis in adolescents. METHODS A total of 260 boys and 237 girls aged 10-18 years were assessed. The PAL was estimated based on the activity record proposed by Bouchard et al. The consumption of lipids was assessed through the food frequency questionnaire developed by Sichieri and Everhart. Blood pressure was measured using a mercury-column sphygmomanometer. Total cholesterol (TC), HDL-c and triglycerides (TG) were measured by the enzymatic-colorimetric method. LDL-c was calculated by Friedewalds formula. The statistical analysis was carried out through logistic regression, with a level of significance set at p < 0.05. RESULTS Regarding the PAL, 17.3% of the boys and 22.6% of the girls were classified as sedentary. As for the diet, 54% and 48.6% of the boys and girls, respectively, presented a consumption of lipids above the recommended level. Boys with high TC and LDL-c levels had a higher OR to be sedentary than their more active peers. High levels of LDL-c were associated with the excessive consumption of saturated fats in both sexes. CONCLUSION The results reinforce the previous evidence that young people must be encouraged since an early age to adopt a more physically active lifestyle, associated to more adequate dietary habits.