RT3 Accelerometer Research Articles

Effect of BMI on Prediction of Accelerometry-Based Energy Expenditure in Youth

The objective of this study is to determine the effect of body mass index (BMI) on level of agreement between six previously established prediction equations for three commonly used accelerometers to predict summary measures of energy expenditure (EE) in youth. One hundred and thirty-one youth between the ages of 10-17 yr and BMI from 15 to 44 kg·m were outfitted with hip-worn ActiGraph GT1M (Pensacola, FL), Actical (MiniMiter/Respironics, Bend, OR), and RT3 (StayHealthy, Monrovia, CA) accelerometers and spent approximately 24 h in a whole-room indirect calorimeter while performing structured and self-selected activities. Five commonly used regression and one propriety equations for each device were used to predict the minute-to-minute EE (normalized to METs), daily physical activity level (PAL), and time spent in sedentary, light, moderate, and vigorous physical activity intensity categories. The calculated values were compared with criterion measurements obtained from the room calorimeter. All predictive equations, except RT3, significantly over- or underpredicted daily PAL (P < 0.001), with large discrepancies observed in the estimate of sedentary and light activity. Discrepancies between actual and estimated PAL ranged from 0.05 to 0.68. In addition, BMI represented a modifier for two ActiGraph predictive equations (AG1 and AG2), affecting the accuracy of physical activity-related EE predictions. ActiGraph (AG3) and the RT3 closely predicted overall PAL (within 4.2% and 6.8%, respectively) as a group. When adjusting for age, sex, and ethnicity, Actical (AC1 and AC2) and ActiGraph (AG3) were not influenced by BMI. However, a gap between some hip-worn accelerometer predictive and regression equations was demonstrated compared with both criterion measurement and each other, which poses a potential difficulty for interstudy (e.g., different accelerometers) and intrastudy (e.g., BMI and adiposity) comparisons.

Calibration of ActiGraph GT3X, Actical and RT3 accelerometers in adolescents

The objective of this study was to develop count cut-points for three different accelerometer models: ActiGraph GT3X, RT3 and Actical to accurately classify physical activity intensity levels in adolescents. Seventy-nine adolescents (10–15 years) participated in this study. Accelerometers and oxygen consumption () data were collected at rest and during 11 physical activities of different intensities. Accelerometers were worn on the waist and was measured by a portable metabolic system: Cosmed K4b2. Receiver operating characteristic (ROC) curves were used to determine cut-points. Cut-points for sedentary (SED), moderate-to-vigorous (MVPA) and vigorous-intensity physical activity (VPA) were 46, 607 and 818 counts·15s−1 to the vertical axis of ActiGraph; 180, 757 and 1112 counts·15s−1 to the vector magnitude of ActiGraph; 17, 441 and 873 counts·15s−1 for Actical; and 5.6, 20.4 and 32.2 counts·s−1 for RT3, respectively. For all three accelerometer models, there was an almost perfect discrimination of SED and MVPA (ROC >0.97) and an excellent discrimination of VPA (ROC>0.90) observed. Areas under the ROC curves indicated better discrimination of MVPA by ActiGraph (AUC=0.994) and Actical (AUC=0.993) when compared to RT3 (AUC=0.983). The cut-points developed in this study for the ActiGraph (vector magnitude), RT3 and Actical accelerometer models can be used to monitor physical activity level of adolescents.

Validity of combining heart rate and uniaxial acceleration to measure free-living physical activity energy expenditure in young men

Combining accelerometry (ACC) with heart rate (HR) monitoring is thought to improve activity energy expenditure (AEE) estimations compared with ACC alone to evaluate the validity of ACC and HR used alone or combined. The purpose of this study was to estimate AEE in free-living conditions compared with doubly labeled water (DLW). Ten-day free-living AEE was measured by a DLW protocol in 35 18- to 55-yr-old men (11 lean active; 12 lean sedentary; 12 overweight sedentary) wearing an Actiheart (combining ACC and HR) and a RT3 accelerometer. AEE was estimated using group or individual calibration of the HR/AEE relationship, based on an exercise-tolerance test. In a subset (n = 21), AEE changes (ΔAEE) were measured after 1 mo of detraining (active subjects) or an 8-wk training (sedentary subjects). Actiheart-combined ACC/HR estimates were more accurate than estimates from HR or ACC alone. Accuracy of the Actiheart group-calibrated ACC/HR estimates was modest [intraclass correlation coefficient (ICC) = 0.62], with no bias but high root mean square error (RMSE) and limits of agreement (LOA). The mean bias of the estimates was reduced by one-third, like RMSE and LOA, by individual calibration (ICC = 0.81). Contrasting with group-calibrated estimates, the Actiheart individual-calibrated ACC/HR estimates explained 40% of the variance of the DLW-ΔAEE (ICC = 0.63). This study supports a good level of agreement between the Actiheart ACC/HR estimates and DLW-measured AEE in lean and overweight men with varying fitness levels. Individual calibration of the HR/AEE relationship is necessary for AEE estimations at an individual level rather than at group scale and for ΔAEE evaluation.

Reliability and validity of the 7-day Physical Activity Recall interview in a Spanish population

The aim of this study was to assess the reliability and convergent validity of the 7-day Physical Activity Recall (7-day PAR) interview in a sample of the Spanish population. Valid 7-day PAR interviews were conducted and RT3 accelerometer measurements taken for 160 subjects from the primary care population aged 24–83, 75 men and 85 women. Two 7-day PAR interviews were conducted, with a one-week interval, with 147 of these participants. Test–retest reliability was assessed using intraclass correlation coefficients. Convergent validity between the 7-day PAR and the accelerometer data were examined using Spearman's correlation coefficients, and the kappa index of agreement was calculated. The 7-day PAR reliability coefficients were 0.68 (95%CI: 0.58–0.76) for total energy expenditure, 0.65 (95%CI: 0.54–0.73) for the activity dose, and 0.61 (95%CI: 0.50–0.70) and 0.75 (95%CI: 0.67–0.81) for time spent on moderate and vigorous-intensity activity, respectively. These coefficients ranged from 0.91 to 0.96 in participants who reported a typical week in both interviews. Convergent validity ranged from 0.25 for time spent on vigorous activity to 0.52 for the activity dose, and the kappa index was 0.43 (95%CI: 0.30–0.56). Reliability and convergent validity coefficients in the Spanish population were generally moderate and similar to those found in other studies.

African American Preschool Children's Physical Activity Levels in Head Start

The purpose of this study was to describe the physical activity levels of urban inner city preschoolers while attending Head Start, the federally funded preschool program for children from low-income families. Participants were 158 African American children. Their physical activity during Head Start days was measured using programmed RT-3 accelerometers. Results revealed that the children spent the most time in sedentary and light physical activity, while their participation in moderate-to-vigorous physical activities was low. Given the sedentary class format and limited physical space for the Head Start programs observed, we suggest adding a structured physical activity component to Head Start schools to fight the overweight and obesity crisis.

African American Preschool Children's Physical Activity Levels in Head Start

The purpose of this study was to describe the physical activity levels of urban inner city preschoolers while attending Head Start, the federally funded preschool program for children from low-income families. Participants were 158 African American children. Their physical activity during Head Start days was measured using programmed RT-3 accelerometers. Results revealed that the children spent the most time in sedentary and light physical activity, while their participation in moderate-to-vigorous physical activities was low. Given the sedentary class format and limited physical space for the Head Start programs observed, we suggest adding a structured physical activity component to Head Start schools to fight the overweight and obesity crisis.

Comparative Interinstrument Reliability of Uniaxial and Triaxial Accelerometers in Free-Living Conditions

The aim of this study was to measure the inter-instrument reliability of the ActiGraph and RT3 accelerometers in free-living conditions. 15 healthy adults wore eight ActiGraph accelerometers and five RT3 accelerometers fastened to their back with an elastic belt and adjustable buckle in free-living conditions. For both accelerometers, the inter-instrument coefficient of variation (CV) decreased with increasing physical activity intensity. The inter-instrument CV of the ActiGraph (3% to 10.5%) was significantly lower than that of the RT3 (12.6% to 35.5%; p < 0.05). This finding demonstrates that the ActiGraph has higher inter-instrument reliability than the RT3. For both accelerometers, the inter-instrument reliability was higher for moderate and vigorous physical activity, the two intensities recommended for public health purposes. Studies using these devices can be compared with a low risk of misclassification of participants who meet the recommendation to perform moderate to vigorous physical activity.

Psychological factors unrelated to activity level in patients with chronic musculoskeletal pain

Enhancement of physical activities is an important goal in rehabilitation programmes for patients with chronic musculoskeletal pain (CMP). A relationship between activity level and psychological factors is suggested but studied scarcely. To explore the relationship between the activity level and psychological factors in patients with CMP. Study design is cross-sectional, explorative. Participants are patients with CMP, included for outpatient multidisciplinary pain rehabilitation. Activity level was measured by the RT3 accelerometer during 1 week; pain intensity was measured with a 100-mm visual analogue scale; depression, somatization and distress were measured with Symptom Checklist-90-Revised (SCL-90-R), coping strategy with the Utrecht Coping List (UCL, scales active coping, passive coping, avoiding), fear of movement measured with Tampa Scale of Kinesiophobia (TSK), scale activity avoidance. Depending on data distribution, correlations between the mean number of activity counts and psychological factors were tested with Pearson or Spearman correlation coefficients. Fifty three patients were included: age mean 39.9 years [standard deviation (SD) 11.3]; activity counts per day mean 198,243 (SD 78,000); pain intensity mean 58 (SD 27.7); SCL-90-R mean 149.4 (SD 42.5); UCL active coping mean 17.9 (SD 3.7); UCL passive coping mean 12.3 (SD 3.7); UCL avoiding mean 15.3 (SD 3.0); TSK total mean 35.4 (SD 7.4); TSK activity avoidance mean 16.9 SD (4.7). Correlations between psychological factors and the mean number of activity counts per day ranged from r = -0.27 to r = 0.01 and were all non-significant (p ≥ 0.05). Psychological factors and activity level were unrelated in patients with CMP.

The Relationship between Physical Activity Variety and Objectively Measured Moderate-to-Vigorous Physical Activity Levels in Weight Loss Maintainers and Normal-Weight Individuals

Given the importance of physical activity (PA) for weight control, identifying strategies to achieve higher PA levels is imperative. We hypothesized that performing a greater variety of self-reported moderate-to-vigorous activities (MVPAs) would relate to higher objectively measured MVPA minutes in two groups who were successfully maintaining their body weight: weight loss maintainers (WLM/n = 226) and normal-weight individuals (NW/n = 169). The Paffenbarger Questionnaire and RT3 accelerometer were used to determine variety/number of different MVPAs performed and MVPA minutes, respectively. The variety/number of different activities performed by WLM and NW was similar (1.8 ± 1.2 versus 1.7 ± 1.2, P = 0.52). Regression analyses showed that greater variety (P < 0.01) and WLM status (P < 0.05) were each positively related to greater MVPA minutes/day and meeting the ≥250 MVPA minutes/week guideline for long-term weight maintenance. The association between greater variety and higher MVPA was similar in NW and WLM. Future studies should test whether variety can facilitate engagement in higher MVPA levels for more effective weight control.

Comportamiento de la actividad física cotidiana en pacientes con hipertensión arterial pulmonar en tratamiento con antagonistas de los receptores de la endotelina

IntroductionThe assessment of daily physical activity is important to prevent and treat many diseases more effectively. Objectivesto evaluate daily physical activity using Tri-axial accelerometers in patients with pulmonary arterial hypertension and treated with endothelin receptor antagonists. Material and methodsSix patients with pulmonary arterial hypertension diagnosed by right heart catheterization were included. World Health Organization functional class, 6-minute walking test, daily physical activity evaluated with the London Chest Activity of Daily Living Scale and with RT3 accelerometers devices were assessed in two opportunities, before and after three months of treatment with nonselective endothelin receptor antagonist drugs. ResultsMean scores of the London Chest Activity of Daily Living Scale scale before and after three months treatment were 35.0 (26.8–43.5) [median and interquartilic range] and 22.0 (16.5–28.3), respectively (p=0.068). Daily physical activity measured by accelerometer was associated with the minimum oxygen saturation during the 6-minute walking test (r=0.825, p=0.043). The total period of low intensity physical activity registered was associated with pulmonary vascular resistances (r=0.989; p=0.001) and the total period of heavy intensity physical activity registered with the systemic vascular resistances (r=0.0890; p=0.043). ConclusionDaily physical activity of patients with pulmonary arterial hypertension could be evaluated with accelerometers. In this way, physical activity is associated with the exercise tolerance and with hemodynamic measures.

Validation of Uniaxial and Triaxial Accelerometers for the Assessment of Physical Activity in Preschool Children

Given the unique physical activity (PA) patterns of preschoolers, wearable electronic devices for quantitative assessment of physical activity require validation in this population. Study objective was to validate uniaxial and triaxial accelerometers in preschoolers. Room calorimetry was performed over 3 hours in 64 preschoolers, wearing Actical, Actiheart, and RT3 accelerometers during play, slow, moderate, and fast translocation. Based on activity energy expenditure (AEE) and accelerometer counts, optimal thresholds for PA levels were determined by piecewise linear regression and discrimination boundary analysis. Established HR cutoffs in preschoolers for sedentary/light, light/moderate and moderate/vigorous levels were used to define AEE (0.015, 0.054, 0.076 kcal·kg-1·min-1) and PA ratio (PAR; 1.6, 2.9, 3.6) thresholds, and accelerometer thresholds. True positive predictive rates were 77%, 75%, and 76% for sedentary; 63%, 61%, and 65% for light; 34%, 52%, and 49% for moderate; 46%, 46%, and 49% for vigorous levels. Due to low positive predictive rates, we combined moderate and vigorous PA. Classification accuracy was improved overall and for the combined moderate-to-vigorous PA level (69%, 82%, 79%) for Actical, Actiheart, and RT3, respectively. Uniaxial and triaxial accelerometers are acceptable devices with similar classification accuracy for sedentary, light, and moderate-to-vigorous levels of PA in preschoolers.

Reliability and criterion validity of the Self-Administered Physical Activity Checklist in Greek children

The purpose of this study was to assess the test–retest reliability and criterion validity the Self-Administered Physical Activity Checklist (SAPAC) translated into the Greek language. To evaluate reliability, 72 students (35 girls and 37 boys) of the fifth and sixth grade completed SAPAC on two separate occasions, two weeks apart. Internal consistency was determined with Cronbach alpha coefficient and test–retest reliability with the intraclass correlation coefficient (ICC). To evaluate criterion validity, the RT3 Research Tracker accelerometer was used as standard measure, in 90 randomly selected Greek children (51 girls and 39 boys), aged between 10 and 13. Each subject participated for two consecutive days. On day one, an accelerometer was fitted when school started. On day two, the accelerometers were returned and each subject completed the questionnaire. The internal consistency and the test–retest reliability of SAPAC on total metabolic equivalent (MET) score, MET score of low physical activities (LPA) and MET score of moderate to vigorous physical activities (MVPA) were very satisfactory (all Cronbach's alpha > 0.87, and all ICC > 0.85, P <0.001). The Kendall's tau-b test revealed that the degree of agreement between SAPAC and RT3 accelerometer on total MET score and MET score of MVPA were 0.31 and 0.37, respectively (P <0.01). It was concluded that the Greek translated version of SAPAC is a reliable questionnaire that provides valid estimates of total, as well as moderate to vigorous activities MET scores.

Effects of an 8-Month Exercise Training Program on Off-Exercise Physical Activity

An active lifestyle is widely recognized as having a beneficial effect on cardiovascular health. However, no clear consensus exists as to whether exercise training increases overall physical activity energy expenditure (PAEE) or whether individuals participating in regular exercise compensate by reducing their off-exercise physical activity. The purpose of this study was to evaluate changes in PAEE in response to aerobic training (AT), resistance training (RT), or combined aerobic and resistance training (AT/RT). Data are from 82 participants in the Studies of Targeted Risk Reduction Interventions through Defined Exercise-Aerobic Training versus Resistance Training study, a randomized trial of overweight (body mass index = 25-35 kg·m(-2)) adults, in which participants were randomized to receive 8 months of AT, RT, or AT/RT. All subjects completed a 4-month control period before randomization. PAEE was measured using triaxial RT3 accelerometers, which subjects wore for a 5- to 7-d period before and after the exercise intervention. Data reduction was performed with a previously published computer-based algorithm. There was no significant change in off-exercise PAEE in any of the exercise training groups. We observed a significant increase in total PAEE that included the exercise training, in both AT and AT/RT but not in RT. Eight months of exercise training was not associated with a compensatory reduction in off-exercise physical activity, regardless of exercise modality. The absence of compensation is particularly notable for AT/RT subjects, who performed a larger volume of exercise than did AT or RT subjects. We believe that the extended duration of our exercise training program was the key factor in allowing subjects to reach a new steady-state level of physical activity within their daily lives.

Activity Counts From Accelerometers Do Not Add Value to Energy Expenditure Predictions in Sedentary Overweight Individuals During Weight Loss Interventions

Knowing the total energy expenditure (TEE) of overweight adults is important for prescribing weight loss interventions. However, objective measurements of TEE may not always be readily available and can be expensive. This study aimed to investigate the validity of RT3 accelerometers in predicting the TEE of sedentary overweight adults, and to identify any sensitivity to anthropometric changes. The analysis used data from a 12-week weight loss study. At baseline and 12-week, TEE was predicted using RT3 accelerometers during whole room calorimeter stays. Bias between 2 methods was compared at and between the baseline and 12-week measurement points. Multiple regression analyses of TEE data were conducted. Predicted and measured values for TEE were not different at baseline (P = .677) but were significantly different after weight loss (P = .007). However, the mean bias between methods was small (<100 kcal/d) and was not significantly different between 2 time-points. RT3 activity counts explained an additional 2% of the variation in TEE at 12-week but not at baseline. RT3 accelerometers are not sensitive to body composition changes and do not explain variation in TEE of overweight and obese individuals in a sedentary environment.

Validation of the GENEA Accelerometer

The study aims were: 1) to assess the technical reliability and validity of the GENEA using a mechanical shaker; 2) to perform a GENEA value calibration to develop thresholds for sedentary and light-, moderate-, and vigorous-intensity physical activity; and 3) to compare the intensity classification of the GENEA with two widely used accelerometers. A total of 47 GENEA accelerometers were attached to a shaker and vertically accelerated, generating 15 conditions of varying acceleration and/or frequency. Reliability was calculated using SD and intrainstrument and interinstrument coefficients of variation, whereas validity was assessed using Pearson correlation with the shaker acceleration as the criterion. Next, 60 adults wore a GENEA on each wrist and on the waist (alongside an ActiGraph and RT3 accelerometer) while completing 10-12 activity tasks. A portable metabolic gas analyzer provided the criterion measure of physical activity. Analyses involved the use of Pearson correlations to establish criterion and concurrent validity and receiver operating characteristic curves to establish intensity cut points. The GENEA demonstrated excellent technical reliability (CVintra = 1.4%, CVinter = 2.1%) and validity (r = 0.98, P < 0.001) using the mechanical shaker. The GENEA demonstrated excellent criterion validity using VO2 as the criterion (left wrist, r = 0.86; right wrist, r = 0.83; waist, r = 0.87), on par with the waist-worn ActiGraph and RT3. The GENEA demonstrated excellent concurrent validity compared with the ActiGraph (r = 0.92) and the RT3 (r = 0.97). The waist-worn GENEA had the greatest classification accuracy (area under the receiver operating characteristic curve (AUC) = 0.95), followed by the left (AUC = 0.93) and then the right wrist (AUC = 0.90). The accuracy of the waist-worn GENEA was virtually identical with that of the ActiGraph (AUC = 0.94) and RT3 (AUC = 0.95). The GENEA is a reliable and valid measurement tool capable of classifying the intensity of physical activity in adults.

Gender differences in recovery outcomes after an early recovery symptom management intervention

Background Despite known gender differences in recovery, few studies have examined symptom management (SM) interventions or responses by gender after coronary artery bypass surgery (CABS). Objective The purpose of this subanalysis was to describe and evaluate differences in response by gender to an SM intervention on the presence and burden of symptoms, physical activity, and physical functioning in elderly CABS patients during the early discharge period (3 and 6 weeks after CABS, and 3 and 6 months after CABS). Methods The parent study whose data were analyzed to examine gender differences involved a two-group, randomized clinical trial design. The 6-week early recovery SM telehealth intervention was delivered by the Health Buddy. Measures included the Cardiac Symptom Survey, a Modified 7-Day Activity Interview, an RT3 accelerometer, an Activity Diary, and the Medical Outcomes Study Short Form 36. This study was not powered for a gender × group analysis, and we used descriptive statistics, χ 2 tests, t tests, and analysis of variance for statistical analyses. Results Subjects (n = 232) included 192 men and 40 women, with a mean age of 71.2 SD, 7 years. The intervention group consisted of 86 men and 23 women, and the usual care (UC) group consisted of 106 men and 17 women. Data trends suggest that the SM intervention exerted greater impact on women than on men for symptoms such as fatigue, depression, sleep problems, and pain. Again, men exhibited higher levels of physical activity than did women. However, women in the SM group generally had higher scores than did women in the UC group. Conclusion Although the parent study found no effect of an early recovery SM intervention, this exploratory secondary analysis indicated that women in the intervention group demonstrated more improvement in measures of physical activity than did those in the UC group. Further study, using a larger sample, is necessary to test these preliminary results.

Pre‐ to Postoperative Physical Activity Changes in Bariatric Surgery Patients: Self Report vs. Objective Measures

Bariatric surgery patients report significant pre- to postoperative increases in physical activity (PA). However, it is unclear whether objective measures would corroborate these changes. The present study compared self-reported and accelerometer-based estimates of changes in moderate-to-vigorous intensity PA (MVPA) from pre- (pre-op) to 6 months postsurgery (post-op). Twenty bariatric surgery (65% laparoscopic-adjustable gastric banding, 35% gastric bypass) patients (46.2 ± 9.8 years, 88% female, pre-op BMI = 50.8 ± 9.7 kg/m(2)) wore RT3 accelerometers as an objective measure of MVPA and completed the Paffenbarger Physical Activity Questionnaire (PPAQ) as a subjective measure before and 6 months after bariatric surgery. Time (min/week) spent in MVPA was calculated for the PPAQ and RT3 (≥ 1-min and ≥ 10-min bouts) at pre-op and post-op. Self-reported MVPA increased fivefold from pre-op to post-op (44.6 ± 80.8 to 212.3 ± 212.4 min/week; P < 0.005). By contrast, the RT3 showed nonsignificant decreases in MVPA for both ≥ 1-min (186.0 ± 169.0 to 151.2 ± 118.3 min/week) and ≥ 10-min (41.3 ± 109.3 to 39.8 ± 71.3 min/week) bouts. At pre-op, the percentage of participants who accumulated ≥ 150-min/week of MVPA in bouts ≥ 10-min according to the PPAQ and RT3 was identical (10%). However, at post-op, 55% of participants reported compliance with the recommendation compared to 5% based on RT3 measurement (P = 0.002). Objectively-measured changes in MVPA from pre-op to 6 months post-op appear to be much smaller than self-reported changes. Further research involving larger samples is needed to confirm these findings and to determine whether self-report and objective PA measures are differentially associated with surgical weight loss outcomes.

RT3 accelerometer shoulder activity: Discrimination of activity levels by the RT3 accelerometer for the assessment of shoulder physical activity (SPA)

We investigated whether the RT3 accelerometer can be used to discriminate and characterize the different levels of shoulder physical activity (SPA) in both patients and healthy adults. Twenty healthy adults and 20 patients with shoulder disorders (SDs) performed activities at 5 levels of difficulty (easy, easy–moderate, moderate, hard–moderate, hard) with the same RT3 accelerometer fixed on the arm. The Vector Magnitude (VM) is the square root of the sum of squares from each axis to determine the overall magnitude of activity. The SPA counts of healthy group were significantly higher than the patient group in every level except easy (31–38 VM counts difference, p < 0.01). For both groups, the hard task demonstrated higher counts as compared to the other tasks. The easy task showed lower counts as compared to the other tasks. In the patient group, significant correlation between FLEX-SF scores and counts from the RT3 ( R = −0.72, p < 0.05) was found in the moderate tasks. The results of this study showed that RT3 can be a potential measurement tool to (1) characterize the difference of SPA between two groups; and (2) partially discriminate the different levels of SPA. The correlations between self-reported function scores and SPA RT3 counts are dependent on self-reported task difficulty.

Interinstrument reliability of the RT3 accelerometer

The objective of this study was to assess the interinstrument reliability of six RT3 accelerometers for measuring physical activities. Each of the six healthy participants, mean age 36.1 years (SD 9.4), carried six RT3 accelerometers (same type and same producer) simultaneously placed ventrally at the waist belt. The participants performed three standardized activities: walking on a treadmill at 3.0 km/h and 5.0 km/h, and sitting on a chair. Each activity lasted 5 min. The recordings of the accelerometers were compared with each other to assess interinstrument reliability. A correlation of 0.75 or higher was interpreted as sufficient. The mean Pearson correlation between the six accelerometers was r = 0.78 (0.46-0.97). The intraclass correlation between the accelerometers was 0.75 (95% confidence interval: 0.46-0.95, P <0.01). In conclusion, the interinstrument reliability of the RT3 accelerometer is sufficient. However, the lower limit of the confidence interval is low, indicating a challenge to the reliability.

Is Active Game A Possible Way to Promote Physical Activity in School?

Recently, involving physical activity (PA) in video games has been advocated in an attempt to enhance players' PA level. The combination of applying a technology device and engaging PA is called active game. It is assumed that the appealing effect of technology will attract children to be physically active with enjoyment. PURPOSE: To examine the physical activity level generated in an active game unit in elementary physical education. METHODS: Participants were 78 fourth grade students (35 males, 43 females) from four classes at an inner city elementary school in a southern metropolitan area in the United States. An active game lab was set up for research on school-based physical activity intervention. Nine different dual active games were included in the game lab, such as CYBEX Trazer. The physical education teacher received two-day training on incorporating active game into physical education. Students' in-class PA level was measured using RT3 accelerometers which provide tri-axial vector data in metabolic equivalent units (METs). A 30-minute Physical education class was offered twice a week. PA data were collected from four lessons randomly selected each week from the four week of active game unit. RESULTS: Descriptive analysis suggested that on average the PA level of active game unit (M = 2.13, SD =.65) did not meet the recommend moderate intensive level (MET ≥ 3.0). Specifically, 91.4% of students were lightly active and 8.6% of them were moderately active during the class. However, repeated measure analysis indicated that there was a significant time effect (p <.5). In other words, activity level gradually increased each week over the four weeks. CONCLUSION: Although active game did not seem to generate recommended PA level in this structured instructional unit, the finding should not be surprising as physical education is fundamentally different from any sole videogame playing settings. One possible reason for the low PA is that both the teacher and students were new (or inexperienced) to the active game as an instructional unit in physical education. Repeated measure analysis suggested that the PA level will increase and may eventually reach a moderate to vigorous level once students become familiar with the functions of the games. Future longitudinal study is needed for further investigation.