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Thalmann, Tomas, Manuel Zechner, and Hans Neuner. "Accelerometer Triad Calibration for Pole Tilt Compensation Using Variance Based Sensitivity Analysis." Sensors 20, no. 5 (March 8, 2020): 1481. http://dx.doi.org/10.3390/s20051481.
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In Engineering Geodesy, most coordinate frames are aligned with the local vertical. For many measurement tasks, it is therefore necessary to manually (or arithmetically) align sensors or equipment with the local vertical, which is a common source of errors and it is very time consuming. Alternatively, accelerometer triads as part of inertial measurement units (IMUs) are used in several applications for horizon leveling. In this contribution we analyze and develop a method to use accelerometer triads for pole tilt compensation with total stations. Several triad sensor models are investigated and applied in a calibration routine using an industrial robot arm. Furthermore a calibration routine to determine the orientation of the IMU mounted on the pole is proposed. Using variance based sensitivity analysis we investigate the influence of different model parameters on leveling and pole tilt compensation. Based on this inference the developed calibration routines are adjusted. The final evaluation experiment shows an RMS of 2.4 mm for the tilt compensated measured ground point with tilts up to 50 gon.
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Filatov, Yu V., A. M. Boronakhin, V. B. Dao, V. Ch Le, and L. N. Podgornaya. "Studying the Static Errors of MEMS Accelerometer Triad in Quasiharmonic Oscillation Mode." Giroskopiya i Navigatsiya 95, no. 4 (December 2016): 35–46. http://dx.doi.org/10.17285/0869-7035.2016.24.4.035-046.
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Jie Yang, Wenqi Wu, Yuanxin Wu, and Junxiang Lian. "Thermal Calibration for the Accelerometer Triad Based on the Sequential Multiposition Observation." IEEE Transactions on Instrumentation and Measurement 62, no. 2 (February 2013): 467–82. http://dx.doi.org/10.1109/tim.2012.2212608.
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Filatov, Yu V., A. M. Boronakhin, V. B. Dao, V. Ch Le, and L. N. Podgornaya. "Studying the static errors of MEMS accelerometer triad in quasiharmonic oscillation mode." Gyroscopy and Navigation 8, no. 2 (April 2017): 121–28. http://dx.doi.org/10.1134/s2075108717020055.
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Sharygin, B. L. "Marine Inertial Navigation and Stabilization System. 20 Years of Development." Giroskopiya i Navigatsiya 28, no. 3 (2020): 122–31. http://dx.doi.org/10.17285/0869-7035.0045.
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The paper presents the history of creation and development of Ladoga-M marine inertial navigation and stabilization system (INSS). The major steps of testing and modifications are covered. The system architecture and key features are given: semianalytical inertial navigation system, rotation of azimuth platform, single degree of freedom floating gyros, accelerometer triad, application of Kalman type filter, use of Baget computer. INSS reliability parameters by the results of operation in real conditions are demonstrated.
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Silva, Felipe O., Lucas P. S. Paiva, and Gustavo S. Carvalho. "Error Analysis of Accelerometer- and Magnetometer-Based Stationary Alignment." Sensors 21, no. 6 (March 14, 2021): 2040. http://dx.doi.org/10.3390/s21062040.
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This paper revisits the stationary attitude initialization problem, i.e., the stationary alignment, of Attitude and Heading Reference Systems (AHRSs). A detailed and comprehensive error analysis is proposed for four of the most representative accelerometer- and magnetometer-based stationary attitude determination methods, namely, the Three-Axis Attitude Determination (TRIAD), the QUaternion ESTimator (QUEST), the Factored Quaternion Algorithm (FQA), and the Arc-TANgent (ATAN). For the purpose of the error analysis, constant biases in the accelerometer and magnetometer measurements are considered (encompassing, hence, the effect of hard-iron magnetism), in addition to systematic errors in the local gravity and Earth magnetic field models (flux density magnitude, declination angle, and inclination angle). The contributions of this paper are novel closed-form formulae for the residual errors (normality, orthogonality, and alignment errors) developed in the computed Direction Cosine Matrices (DCM). As a consequence, analytical insight is provided into the problem, allowing us to properly compare the performance of the investigated alignment formulations (in terms of ultimate accuracy), as well as to remove some misleading conclusions reported in previous works. The adequacy of the proposed error analysis is validated through simulation and experimental results.
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Estevez-Urra, Aida, Jordi Llumà, Ramón Jerez-Mesa, and Jose Antonio Travieso-Rodriguez. "Monitoring of Processing Conditions of an Ultrasonic Vibration-Assisted Ball-Burnishing Process." Sensors 20, no. 9 (April 30, 2020): 2562. http://dx.doi.org/10.3390/s20092562.
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Although numerous references present the beneficial effects on surface integrity of ultrasonic vibration-assisted ball burnishing (UVABB), nothing has been reported about the dynamic behavior of the UVABB tool, workpiece, and machine triad during the process. In this paper, a dynamic monitorization through a set of 5 accelerometers is tested to analyze the interactions between the tool–workpiece–machine mechanical assembly. A UVABB tool attached to a milling machine and equipped with a piezoelectric stack that is able to assist the process with a 40-kHz vibration is tested on a milled C45 steel surface. First, the natural frequencies of the mechanical system are obtained through hammer impact tests. Then, the vibratory signals transmitted during the execution of the process are monitored and compared to those: two feed velocities and two burnishing preloads, all with and without vibration-assistance. Results show that the proposed accelerometer set is valid to assess the behavior of a UVABB process. The system’s natural frequencies are not varied by vibration-assistance and are not excited when the piezoelectric is functioning. It is confirmed that UVABB is safe for the machine and the tool, and there is no unexpected excited frequencies due to the piezoelectric excitation.
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Jiang, Wei, Weiguo Zhang, Jingping Shi, Yongxi Lyu, and Huakun Chen. "Globally Asymptotic Stable Attitude Estimation with Application to MEMS Sensors." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 3 (June 2020): 550–57. http://dx.doi.org/10.1051/jnwpu/20203830550.
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Aiming at the requirement of attitude information module with high precision, small size and low power consumption for the control of miniature UAV, a practical attitude estimation algorithm based on the micro-electro-mechanical sensor is proposed in this paper, which realizes the accurate estimation of the attitude of the UAV under the condition of low acceleration. A low-cost MEMS gyroscope, accelerometer, and magnetometer are used in the system. The Euler angle is obtained by the state observer method based on Direction Cosine Matrix (DCM) which can be got by fusing the sensor data. Firstly, based on the basic idea of TRIAD algorithm, a method to determine the attitude rotation matrix by accelerometer and magnetometric measurement is proposed. Compared with the traditional method, this method does not have to calculate the inverse of the matrix. Secondly, a state observer is intended to estimate the attitude of the system. The state observer doesn't have to observe the bias of the gyroscope, but still ensures the convergence of the Euler angle. Finally, the simulation based on the actual sampling data of the MEMS sensor shows that the output of the state observer designed in this paper still has high accuracy and good dynamic characteristics under the condition of gyroscope noise and bias.
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Crane, Tracy E., Meghan B. Skiba, Austin Miller, David O. Garcia, and Cynthia A. Thomson. "Development and Evaluation of an Accelerometer-Based Protocol for Measuring Physical Activity Levels in Cancer Survivors: Development and Usability Study." JMIR mHealth and uHealth 8, no. 9 (September 24, 2020): e18491. http://dx.doi.org/10.2196/18491.
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Background The collection of self-reported physical activity using validated questionnaires has known bias and measurement error. Objective Accelerometry, an objective measure of daily activity, increases the rigor and accuracy of physical activity measurements. Here, we describe the methodology and related protocols for accelerometry data collection and quality assurance using the Actigraph GT9X accelerometer data collection in a convenience sample of ovarian cancer survivors enrolled in GOG/NRG 0225, a 24-month randomized controlled trial of diet and physical activity intervention versus attention control. Methods From July 2015 to December 2019, accelerometers were mailed on 1337 separate occasions to 580 study participants to wear at 4 time points (baseline, 6, 12, and 24 months) for 7 consecutive days. Study staff contacted participants via telephone to confirm their availability to wear the accelerometers and reviewed instructions and procedures regarding the return of the accelerometers and assisted with any technology concerns. Results We evaluated factors associated with wear compliance, including activity tracking, use of a mobile app, and demographic characteristics with chi-square tests and logistic regression. Compliant data, defined as ≥4 consecutive days with ≥10 hours daily wear time, exceeded 90% at all study time points. Activity tracking, but no other characteristics, was significantly associated with compliant data at all time points (P<.001). This implementation of data collection through accelerometry provided highly compliant and usable activity data in women who recently completed treatment for ovarian cancer. Conclusions The high compliance and data quality associated with this protocol suggest that it could be disseminated to support researchers who seek to collect robust objective activity data in cancer survivors residing in a wide geographic area.
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Zmitri, Fourati, and Vuillerme. "Human Activities and Postures Recognition: From Inertial Measurements to Quaternion-Based Approaches." Sensors 19, no. 19 (September 20, 2019): 4058. http://dx.doi.org/10.3390/s19194058.
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This paper presents two approaches to assess the effect of the number of inertial sensors and their location placements on recognition of human postures and activities. Inertial and Magnetic Measurement Units (IMMUs)—which consist of a triad of three-axis accelerometer, three-axis gyroscope, and three-axis magnetometer sensors—are used in this work. Five IMMUs are initially used and attached to different body segments. Placements of up to three IMMUs are then considered: back, left foot, and left thigh. The subspace k-nearest neighbors (KNN) classifier is used to achieve the supervised learning process and the recognition task. In a first approach, we feed raw data from three-axis accelerometer and three-axis gyroscope into the classifier without any filtering or pre-processing, unlike what is usually reported in the state-of-the-art where statistical features were computed instead. Results show the efficiency of this method for the recognition of the studied activities and postures. With the proposed algorithm, more than 80% of the activities and postures are correctly classified using one IMMU, placed on the lower back, left thigh, or left foot location, and more than 90% when combining all three placements. In a second approach, we extract attitude, in term of quaternion, from IMMUs in order to more precisely achieve the recognition process. The obtained accuracy results are compared to those obtained when only raw data is exploited. Results show that the use of attitude significantly improves the performance of the classifier, especially for certain specific activities. In that case, it was further shown that using a smaller number of features, with quaternion, in the recognition process leads to a lower computation time and better accuracy.
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Trisno, Roth, Parvathy Nair, Daniel Martin, Maryam S. Baghini, Hoam Chung, Gita Pendharkar, and Jayashri Kulkarni. "Using accelerometer as a diagnostic tool to detect drug-induced parkinsonism (DIP) secondary to first-generation anti-psychotic medications." Australasian Psychiatry 28, no. 3 (February 24, 2020): 348–53. http://dx.doi.org/10.1177/1039856220901467.
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Objective: The objective of this study is to examine the effectiveness of an accelerometer-based compact system in detecting and quantifying drug-induced parkinsonism (DIP) in patients with schizophrenia. Method: A pilot study controlled clinical trial comprising 6 people with schizophrenia and 11 control subjects was conducted at Alfred Health, Melbourne. Participants had their movements assessed using Barnes Akathisia Rating Scale (BARS), Simpson Angus Scale (SAS) and Movement Disorder Society Unified Parkinson’s Disease Rating Scale Part III (MDS-UPDRS III) followed by an assessment of gait using three triaxial accelerometers. Results: Median BARS, SAS, MDS-UPDRS III and accelerometer scores were significantly higher for patients with schizophrenia than controls. Accelerometers detected three times more rest tremor than clinical rating scales. Patients with schizophrenia had 70% of their dynamic acceleration at frequencies between 4 and 10 Hz, which is almost twice that observed in the control population (38%). Accelerometer scores were significantly correlated with BARS scores. Conclusion: Accelerometers were able to accurately detect patients with DIP better than some clinical rating scale including the SAS. Further larger-scale studies must be conducted to further demonstrate the accuracy of accelerometers in detecting DIP.
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Zmitri, Makia, Hassen Fourati, and Christophe Prieur. "Magnetic Field Gradient-Based EKF for Velocity Estimation in Indoor Navigation." Sensors 20, no. 20 (October 9, 2020): 5726. http://dx.doi.org/10.3390/s20205726.
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This paper proposes an advanced solution to improve the inertial velocity estimation of a rigid body, for indoor navigation, through implementing a magnetic field gradient-based Extended Kalman Filter (EKF). The proposed estimation scheme considers a set of data from a triad of inertial sensors (accelerometer and gyroscope), as well as a determined arrangement of magnetometers array. The inputs for the estimation scheme are the spatial derivatives of the magnetic field, from the magnetometers array, and the attitude, from the inertial sensors. As shown in the literature, there is a strong relation between the velocity and the measured magnetic field gradient. However, the latter usually suffers from high noises. Then, the novelty of the proposed EKF is to develop a specific equation to describe the dynamics of the magnetic field gradient. This contribution helps to filter, first, the magnetic field and its gradient and second, to better estimate the inertial velocity. Some numerical simulations that are based on an open source database show the targeted improvements. At the end of the paper, this approach is extended to position estimation in the case of a foot-mounted application and the results are very promising.
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Kirby, Joanna, Carly Tibbins, Claire Callens, Beckie Lang, Margaret Thorogood, William Tigbe, and Wendy Robertson. "Young People's Views on Accelerometer Use in Physical Activity Research: Findings from a User Involvement Investigation." ISRN Obesity 2012 (November 20, 2012): 1–7. http://dx.doi.org/10.5402/2012/948504.
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The use of accelerometers to objectively measure physical activity is important in understanding young people's behaviours, as physical activity plays a key part in obesity prevention and treatment. A user-involvement qualitative study with young people aged 7–18 years (n=35) was carried out to investigate views on accelerometer use to inform an obesity treatment research study. First impressions were often negative, with issues related to size and comfort reported. Unwanted attention from wearing an accelerometer and bullying risk were also noted. Other disadvantages included feeling embarrassed and not being able to wear the device for certain activities. Positive aspects included feeling “special” and having increased attention from friends. Views on the best time to wear accelerometers were mixed. Advice was offered on how to make accelerometers more appealing, including presenting them in a positive way, using a clip rather than elastic belt to attach, personalising the device, and having feedback on activity levels. Judgements over the way in which accelerometers are used should be made at the study development stage and based on the individual population. In particular, introducing accelerometers in a clear and positive way is important. Including a trial wearing period, considering practical issues, and providing incentives may help increase compliance.
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Price, Lisa, Katrina Wyatt, Jenny Lloyd, Charles Abraham, Siobhan Creanor, Sarah Dean, and Melvyn Hillsdon. "Children’s Compliance With Wrist-Worn Accelerometry Within a Cluster-Randomized Controlled Trial: Findings From the Healthy Lifestyles Programme." Pediatric Exercise Science 30, no. 2 (May 1, 2018): 281–87. http://dx.doi.org/10.1123/pes.2017-0179.
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Purpose: The purpose of this study was to assess children’s compliance with wrist-worn accelerometry during a randomized controlled trial and to examine whether compliance differed by allocated condition or gender. Methods: A total of 886 children within the Healthy Lifestyles Programme trial were randomly allocated to wear a GENEActiv accelerometer at baseline and 18-month follow-up. Compliance with minimum wear-time criteria (≥10 h for 3 weekdays and 1 weekend day) was obtained for both time points. Chi-square tests were used to determine associations between compliance, group allocation, and gender. Results: At baseline, 851 children had usable data, 830 (97.5%) met the minimum wear-time criteria, and 631 (74.1%) had data for 7 days at 24 hours per day. At follow-up, 789 children had usable data, 745 (94.4%) met the minimum wear-time criteria, and 528 (67%) had complete data. Compliance did not differ by gender (baseline: χ2 = 1.66, P = .2; follow-up: χ2 = 0.76, P = .4) or by group at follow-up (χ2 = 2.35, P = .13). Conclusion: The use of wrist-worn accelerometers and robust trial procedures resulted in high compliance at 2 time points regardless of group allocation, demonstrating the feasibility of using precise physical activity monitors to measure intervention effectiveness.
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O'Neil, Margaret E., Maria Fragala-Pinkham, Nancy Lennon, Ameeka George, Jeffrey Forman, and Stewart G. Trost. "Reliability and Validity of Objective Measures of Physical Activity in Youth With Cerebral Palsy Who Are Ambulatory." Physical Therapy 96, no. 1 (January 1, 2016): 37–45. http://dx.doi.org/10.2522/ptj.20140201.
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Background Physical therapy for youth with cerebral palsy (CP) who are ambulatory includes interventions to increase functional mobility and participation in physical activity (PA). Thus, reliable and valid measures are needed to document PA in youth with CP. Objective The purpose of this study was to evaluate the inter-instrument reliability and concurrent validity of 3 accelerometer-based motion sensors with indirect calorimetry as the criterion for measuring PA intensity in youth with CP. Methods Fifty-seven youth with CP (mean age=12.5 years, SD=3.3; 51% female; 49.1% with spastic hemiplegia) participated. Inclusion criteria were: aged 6 to 20 years, ambulatory, Gross Motor Function Classification System (GMFCS) levels I through III, able to follow directions, and able to complete the full PA protocol. Protocol activities included standardized activity trials with increasing PA intensity (resting, writing, household chores, active video games, and walking at 3 self-selected speeds), as measured by weight-relative oxygen uptake (in mL/kg/min). During each trial, participants wore bilateral accelerometers on the upper arms, waist/hip, and ankle and a portable indirect calorimeter. Intraclass coefficient correlations (ICCs) were calculated to evaluate inter-instrument reliability (left-to-right accelerometer placement). Spearman correlations were used to examine concurrent validity between accelerometer output (activity and step counts) and indirect calorimetry. Friedman analyses of variance with post hoc pair-wise analyses were conducted to examine the validity of accelerometers to discriminate PA intensity across activity trials. Results All accelerometers exhibited excellent inter-instrument reliability (ICC=.94–.99) and good concurrent validity (rho=.70–.85). All accelerometers discriminated PA intensity across most activity trials. Limitations This PA protocol consisted of controlled activity trials. Conclusions Accelerometers provide valid and reliable measures of PA intensity among youth with CP.
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Wang, Xin, Jie Yan, Dongzhu Feng, Yonghua Fan, and Dongsheng Yang. "Flight motion tracking with new configuration of hybrid inertial sensors." Engineering Computations 37, no. 5 (January 10, 2020): 1683–701. http://dx.doi.org/10.1108/ec-11-2018-0542.
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Purpose This paper aims to describe a novel hybrid inertial measurement unit (IMU) for motion capturing via a new configuration of strategically distributed inertial sensors, and a calibration approach for the accelerometer and gyroscope sensors mounted in a flight vehicle motion tracker built on the inertial navigation system. Design/methodology/approach The hybrid-IMU is designed with five accelerometers and one auxiliary gyroscope instead of the accelerometer and gyroscope triads in the conventional IMU. Findings Simulation studies for tracking with both attitude angles and translational movement of a flight vehicle are conducted to illustrate the effectiveness of the proposed method. Originality/value The cross-quadratic terms of angular velocity are selected to process the direct measurements of angular velocities of body frame and to avoid the integration of angular acceleration vector compared with gyro-free configuration based on only accelerometers. The inertial sensors are selected from the commercial microelectromechanical system devices to realize its low-cost applications.
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Saunders, Nathan W., Panagiotis Koutakis, Anne D. Kloos, Deborah A. Kegelmeyer, Jessica D. Dicke, and Steven T. Devor. "Reliability and Validity of a Wireless Accelerometer for the Assessment of Postural Sway." Journal of Applied Biomechanics 31, no. 3 (June 2015): 159–63. http://dx.doi.org/10.1123/jab.2014-0232.
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Clinicians are in need of valid and objective measures of postural sway. Accelerometers have been shown to be suitable alternatives to expensive and stationary force plates. We evaluated the test-retest reliability and balance task discrimination capability of a new wireless triaxial accelerometer (YEI 3-Space Sensor). Four testing conditions (eyes open or closed, while on a firm or compliant surface) were used to progressively challenge the static balance of 20 healthy male (n = 8) and female (n = 12) older adults (mean age 81 ± 4.3 y). Subjects completed 2 blocks of three 30-second trials per condition. The accelerometer was positioned on the lower back to acquire mediolateral (M-L) and anterior-posterior (A-P) accelerations. Intraclass correlation coefficients were all good to excellent, with values ranging from .736 to .972 for trial-to-trial and from .760 to .954 for block-to-block. A significant stepwise increase in center of mass acceleration root mean square values was found across the 4 balance conditions (F[1.49, 28.26] = 39.54, P < .001). The new accelerometer exhibited good to excellent trial-to-trial and block-to-block reliability and was sensitive to differences in visual and surface conditions and acceleration axes.
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Brage, Søren, Niels Wedderkopp, Lars Bo Andersen, and Karsten Froberg. "Influence of Step Frequency on Movement Intensity Predictions with the CSA Accelerometer: A Field Validation Study in Children." Pediatric Exercise Science 15, no. 3 (August 2003): 277–87. http://dx.doi.org/10.1123/pes.15.3.277.
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Four Computer Science and Applications (CSA, Model 7164) accelerometers were validated against speed and heart rate in a field trial, consisting of two walking and two preset running speeds, and 3 min of running at freely chosen speeds. Fifteen children (9–11 years) were recruited from a suburban school in Denmark. Mean CSA output was calculated and converted to acceleration by calibration to sinusoidal accelerations in a mechanical setup, the latter variable being independent of frequency-based filtering. Mean CSA output and estimated acceleration both correlated significantly with speed (r2 = 0.55 and r2 = 0.76, respectively) and heart rate (r2 = 0.60 and r2 = 0.81, respectively), controlled for gender. ANOVA post hoc test failed to show significant differences in accelerometer output between running speeds. Inter-individual variability of CSA output and acceleration could not be explained by differences in step frequency in walking but running values correlated significantly with step frequency (r = −0.86 and r = −0.47 for CSA output and acceleration, respectively). Conversion of CSA output to average acceleration provides more precise estimates of intensity with less inter-individual variability than raw CSA output. Different running intensities, however, are generally not well differentiated with vertical accelerometry.
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Wetten, Alexander Allan, Marijka Batterham, Sze Yen Tan, and Linda Tapsell. "Relative Validity of 3 Accelerometer Models for Estimating Energy Expenditure During Light Activity." Journal of Physical Activity and Health 11, no. 3 (March 2014): 638–47. http://dx.doi.org/10.1123/jpah.2011-0167.
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Background:With physical inactivity inextricably linked to the increasing prevalence of obesity, there is a need for validated methods that measure free-living energy expenditure (EE) within sedentary environments. While accelerometers enable these measurements, few studies have compared device accuracy in such settings. The aim of this study was to investigate the relative validity of the Actigraph, RT3 and SenseWear Armband (SWA).Methods:Twenty-three (11 male, 12 female) participants (age: 25.3 ± 6.3 yr; BMI: 22.6 ± 2.7) wore 3 accelerometers at designated sites during a 4-hour stay in the Whole Room Calorimeter (WRC). Participants performed 2 10-minute bouts of light-intensity exercise (stepping and stationary cycling) and engaged in unstructured sedentary activities. EE estimated by accelerometers was compared with WRC EE derived from measurements of gaseous exchange.Results:The Actigraph and SWA both accurately estimated EE during the stepping exercise. EE estimated by the RT3 during stepping was significantly lower than the WRC value (31.2% ± 15.6%, P < .001). All accelerometers underestimated cycling and unstructured activity EE over the trial period (P < .001).Conclusions:The Actigraph and SWA are both valid tools for quantifying EE during light-intensity stepping. These results provide further valuable information on how accelerometer devices may be appropriately used.
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Everson, Bethan, Kelly A. Mackintosh, Melitta A. McNarry, Charlotte Todd, and Gareth Stratton. "Can Wearable Cameras be Used to Validate School-Aged Children’s Lifestyle Behaviours?" Children 6, no. 2 (February 1, 2019): 20. http://dx.doi.org/10.3390/children6020020.
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Wearable cameras combined with accelerometers have been used to estimate the accuracy of children’s self-report of physical activity, health-related behaviours, and the contexts in which they occur. There were two aims to this study; the first was to validate questions regarding self-reported health and lifestyle behaviours in 9–11-year-old children using the child’s health and activity tool (CHAT), an accelerometer and a wearable camera. Second, the study sought to evaluate ethical challenges associated with taking regular photographs using a wearable camera through interviews with children and their families. Fourteen children wore an autographer and hip-worn triaxial accelerometer for the waking hours of one school and one weekend day. For both of these days, children self-reported their behaviours chronologically and sequentially using the CHAT. Data were examined using limits of agreement and percentage agreement to verify if reference methods aligned with self-reported behaviours. Six parent–child dyads participated in interviews. Seven, five, and nine items demonstrated good, acceptable, and poor validity, respectively. This demonstrates that the accuracy of children’s recall varies according to the behaviour or item being measured. This is the first study to trial the use of wearable cameras in assessing the concurrent validity of children’s physical activity and behaviour recall, as almost all other studies have used parent proxy reports alongside accelerometers. Wearable cameras carry some ethical and technical challenges, which were examined in this study. Parents and children reported that the autographer was burdensome and in a few cases invaded privacy. This study demonstrates the importance of adhering to an ethical framework.
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Brown, Theodore R., and Virginia I. Simnad. "A Randomized Crossover Trial of Dalfampridine Extended Release for Effect on Ambulatory Activity in People with Multiple Sclerosis." International Journal of MS Care 18, no. 4 (July 1, 2016): 170–76. http://dx.doi.org/10.7224/1537-2073.2015-035.
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Background: Dalfampridine extended release (D-ER) is indicated to improve walking in people with multiple sclerosis (MS) as demonstrated by an increase in walking speed. This study assessed the effects of D-ER on accelerometer-based measures in people with MS, including intensity of walking and total amount of walking during daily activities. Methods: In this double-blind placebo-controlled crossover study, people with MS-related walking difficulty were randomized (1:1) to receive 4 weeks of D-ER 10 mg twice daily and 4 weeks of placebo in either order separated by a 2-week washout. Participants wore accelerometers for 7 days at baseline and week 3 of each on-drug period. The primary outcome was the peak activity index (PAI), defined as the most intense 30 individual minutes of the day (strides per minute). Secondary outcomes included daily step count, 6-Minute Walk Test (6MWT), Timed Up and Go (TUG) test, and patient-reported outcomes. A mixed-effects repeated-measures statistical model was used. Results: Forty-three participants were randomized (mean Expanded Disability Status Scale score, 5.17). Least squares mean (standard error) change from baseline on the PAI was 0.6 (0.54) strides/min on D-ER and 0.3 (0.55) strides/min on placebo and in daily step count was 148.7 (222.4) on D-ER and 128.0 (225.4) on placebo. Other accelerometer-based measures and the 6MWT showed no significant differences between D-ER and placebo. The TUG test (P = .042) favored D-ER. There were no serious adverse events. Conclusions: Dalfampridine did not show an effect on accelerometer-measured ambulatory activity in people with MS-related walking difficulty. More work is needed to confirm these results.
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Bammann, Karin, Nicola K. Thomson, Birte Marie Albrecht, Duncan S. Buchan, and Chris Easton. "Generation and validation of ActiGraph GT3X+ accelerometer cut-points for assessing physical activity intensity in older adults. The OUTDOOR ACTIVE validation study." PLOS ONE 16, no. 6 (June 3, 2021): e0252615. http://dx.doi.org/10.1371/journal.pone.0252615.
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The study of physical activity in older adults is becoming more and more relevant. For evaluation of physical activity recommendations, intensity-specific accelerometer cut-points are utilized. However, research on accelerometer cut-points for older adults is still scarce. The aim of the study was to generate placement-specific cut-points of ActiGraph GT3X+ activity counts and raw measures of acceleration to determine physical activity intensity in older adults. A further aim was to compare the validity of the generated cut-points for a range of different physical activities. The study was a single experimental trial using a convenience sample. Study participants were 20 adults aged 59 to 73 years. Accelerometers were worn at six different placements (one on each wrist, one on each ankle, and two at the hip) and breath-by-breath indirect calorimetry was used as the reference for energy. The experiment comprised of two parts; a) The first required participants to walk on a treadmill at incremental speeds (3.0–5.0 km·h-1), and b) Five different everyday activities (reading, cleaning, shopping, cycling, aerobics) were staged in the laboratory setting. Accelerometer cut-points (activity counts, raw data) were derived for each of the investigated placements by linear regression using the treadmill part. Performance of the cut-points was assessed by applying the cut-points to the everyday activities. We provide cut-points for six placements and two accelerometer metrics in the specific age group. However, the derived cut-points did not outperform published ones. More research and innovative approaches are needed for improving internal and external validity of research results across populations and age groups.
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Garnotel, M., T. Bastian, H. M. Romero-Ugalde, A. Maire, J. Dugas, A. Zahariev, M. Doron, et al. "Prior automatic posture and activity identification improves physical activity energy expenditure prediction from hip-worn triaxial accelerometry." Journal of Applied Physiology 124, no. 3 (March 1, 2018): 780–90. http://dx.doi.org/10.1152/japplphysiol.00556.2017.
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Accelerometry is increasingly used to quantify physical activity (PA) and related energy expenditure (EE). Linear regression models designed to derive PAEE from accelerometry-counts have shown their limits, mostly due to the lack of consideration of the nature of activities performed. Here we tested whether a model coupling an automatic activity/posture recognition (AAR) algorithm with an activity-specific count-based model, developed in 61 subjects in laboratory conditions, improved PAEE and total EE (TEE) predictions from a hip-worn triaxial-accelerometer (ActigraphGT3X+) in free-living conditions. Data from two independent subject groups of varying body mass index and age were considered: 20 subjects engaged in a 3-h urban-circuit, with activity-by-activity reference PAEE from combined heart-rate and accelerometry monitoring (Actiheart); and 56 subjects involved in a 14-day trial, with PAEE and TEE measured using the doubly-labeled water method. PAEE was estimated from accelerometry using the activity-specific model coupled to the AAR algorithm (AAR model), a simple linear model (SLM), and equations provided by the companion-software of used activity-devices (Freedson and Actiheart models). AAR-model predictions were in closer agreement with selected references than those from other count-based models, both for PAEE during the urban-circuit (RMSE = 6.19 vs 7.90 for SLM and 9.62 kJ/min for Freedson) and for EE over the 14-day trial, reaching Actiheart performances in the latter (PAEE: RMSE = 0.93 vs. 1.53 for SLM, 1.43 for Freedson, 0.91 MJ/day for Actiheart; TEE: RMSE = 1.05 vs. 1.57 for SLM, 1.70 for Freedson, 0.95 MJ/day for Actiheart). Overall, the AAR model resulted in a 43% increase of daily PAEE variance explained by accelerometry predictions.NEW & NOTEWORTHY Although triaxial accelerometry is widely used in free-living conditions to assess the impact of physical activity energy expenditure (PAEE) on health, its precision and accuracy are often debated. Here we developed and validated an activity-specific model which, coupled with an automatic activity-recognition algorithm, improved the variance explained by the predictions from accelerometry counts by 43% of daily PAEE compared with models relying on a simple relationship between accelerometry counts and EE.
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Chen, Chuhe, Gerald J. Jerome, Daniel LaFerriere, Deborah Rohm Young, and William M. Vollmer. "Procedures Used to Standardize Data Collected by RT3 Triaxial Accelerometers in a Large-Scale Weight-Loss Trial." Journal of Physical Activity and Health 6, no. 3 (May 2009): 354–59. http://dx.doi.org/10.1123/jpah.6.3.354.
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Background:Accelerometers measure intensity, frequency, and duration of physical activity. However, the scarcity of reports on data reduction makes comparing accelerometer results across studies difficult.Methods:Participants were asked to wear a triaxial accelerometer (RT3) for ≥10 hours for at least 4 days, including one weekend day. We summarize our data-cleaning procedures and assess the impact of defining a usable day of measurements as at least 6, 8, or 10 hours of wear time, and of standardizing data to a 12-hour day.Results:Eighty-two percent of participants met wear time requirements; 93% met requirements when we defined a day as 8-or-more hours of wear time. Normalization of data to a 12-hour day had little impact on estimates of daily moderate-to-vigorous physical activity (MVPA; 16.9 vs. 17.1 minutes); restricting MVPA to activities occurring in bouts of 10 minutes or longer had greater impact (16.9 vs. 6.3 minutes per day).Conclusion:Our account of accelerometry quality-control and data-cleaning procedures documents the small impact of variations in daily wear time requirements on MVPA estimates, and the larger impact of evaluating total MVPA vs. MVPA occurring in extended bouts. This paper should allow other researchers to duplicate or revise our methods as needed.
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Rudolf, Kevin, Bianca Biallas, Lea A. L. Dejonghe, Christopher Grieben, Lisa-Marie Rückel, Andrea Schaller, Gerrit Stassen, Holger Pfaff, and Ingo Froböse. "Influence of Health Literacy on the Physical Activity of Working Adults: A Cross-Sectional Analysis of the TRISEARCH Trial." International Journal of Environmental Research and Public Health 16, no. 24 (December 6, 2019): 4948. http://dx.doi.org/10.3390/ijerph16244948.
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Studies show that high health literacy (HL) can support the promotion and maintenance of healthy behavior such as physical activity (PA). However, most studies rely on subjective data. The aim of the present study is to investigate the relationship between HL and PA, not only with subjectively but also with objectively measured PA data. The present study is a pooled analysis of baseline data from the research association TRISEARCH (2015–2018), which focused on the HL of working adults. HL was measured by Lenartz’ questionnaire, and PA by the Global Physical Activity Questionnaire (GPAQ; n = 1056). A subsample (n = 124) also received accelerometers (Actigraph GT3X+) to provide more objective PA data. Partial correlations and regression models were used to investigate the relationship between HL and questionnaire- and accelerometer-derived PA. Very low and medium partial correlations could be found for HL subscales and daily PA by questionnaire (r = −0.06, p < 0.05) and accelerometer (r = 0.26, p < 0.01). No subscale of HL made a significant contribution to the amount of daily PA (all p > 0.05). Not all subscales of HL seem to have an influence on the occurrence of healthy behavior, such as PA. This should be considered when HL-based interventions are designed. Further investigation of the relationship between HL and PA is needed. Objective assessments of both HL and PA can provide additional information for this task.
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Kadar, Julianna P., Monique A. Ladds, Joanna Day, Brianne Lyall, and Culum Brown. "Assessment of Machine Learning Models to Identify Port Jackson Shark Behaviours Using Tri-Axial Accelerometers." Sensors 20, no. 24 (December 11, 2020): 7096. http://dx.doi.org/10.3390/s20247096.
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Movement ecology has traditionally focused on the movements of animals over large time scales, but, with advancements in sensor technology, the focus can become increasingly fine scale. Accelerometers are commonly applied to quantify animal behaviours and can elucidate fine-scale (<2 s) behaviours. Machine learning methods are commonly applied to animal accelerometry data; however, they require the trial of multiple methods to find an ideal solution. We used tri-axial accelerometers (10 Hz) to quantify four behaviours in Port Jackson sharks (Heterodontus portusjacksoni): two fine-scale behaviours (<2 s)—(1) vertical swimming and (2) chewing as proxy for foraging, and two broad-scale behaviours (>2 s–mins)—(3) resting and (4) swimming. We used validated data to calculate 66 summary statistics from tri-axial accelerometry and assessed the most important features that allowed for differentiation between the behaviours. One and two second epoch testing sets were created consisting of 10 and 20 samples from each behaviour event, respectively. We developed eight machine learning models to assess their overall accuracy and behaviour-specific accuracy (one classification tree, five ensemble learners and two neural networks). The support vector machine model classified the four behaviours better when using the longer 2 s time epoch (F-measure 89%; macro-averaged F-measure: 90%). Here, we show that this support vector machine (SVM) model can reliably classify both fine- and broad-scale behaviours in Port Jackson sharks.
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Goldfield, Gary S., Risa Mallory, Denis Prud’homme, and Kristi B. Adamo. "Gender Differences in Response to a Physical Activity Intervention in Overweight and Obese Children." Journal of Physical Activity and Health 5, no. 4 (July 2008): 592–606. http://dx.doi.org/10.1123/jpah.5.4.592.
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Background:This study evaluated the effects of gender on response to a behavioral intervention that rewarded increases in physical activity (PA) with increases in access to TV viewing.Methods:We performed a secondary analysis of a clinical trial that randomized 30 overweight or obese, 8- to 12-year-old children to an intervention (8 boys, 6 girls) or control (7 boys, 9 girls) group. Participants wore accelerometers every day for 8 weeks and attended biweekly meetings to download the activity monitors. For the intervention group, accumulating 400 counts of PA on accelerometers earned 1 hour of TV time, which was controlled by a Token TV electronic device. Controls wore activity monitors but had free access to T V.Results:Compared with girls, boys in the intervention group exhibited greater increases in overall daily PA counts (110% versus 40%, P < .05) and minutes per day of moderate-to-vigorous physical activity (MVPA; +18.1 versus +2.7, P < .05). Neither boys nor girls in the control group showed significant changes in overall PA or intensity of PA.Conclusion:Wearing an accelerometer in combination with rewarding PA with TV might be a more effective intervention for increasing overall PA and time spent in MVPA in overweight and obese boys than it is for overweight or obese girls.
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Vasankari, Ville, Jari Halonen, Pauliina Husu, Henri Vähä-Ypyä, Kari Tokola, Jaana Suni, Harri Sievänen, et al. "Personalised eHealth intervention to increase physical activity and reduce sedentary behaviour in rehabilitation after cardiac operations: study protocol for the PACO randomised controlled trial (NCT03470246)." BMJ Open Sport & Exercise Medicine 5, no. 1 (July 2019): e000539. http://dx.doi.org/10.1136/bmjsem-2019-000539.
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IntroductionPersonalized intervention to increase physical Activity and reduce sedentary behaviour in rehabilitation after Cardiac Operations (PACO) is a smartphone-based and accelerometer-based eHealth intervention to increase physical activity (PA) and reduce sedentary behaviour (SB) among patients recovering from cardiac surgery.DesignProspective randomised controlled trial.Methods and analysisThe present protocol describes a randomised controlled clinical trial to be conducted in the Heart Centres of Kuopio and Turku university hospitals. The trial comprises 540 patients scheduled for elective coronary artery bypass grafting, aortic valve replacement or mitral valve repair. The patients will be randomised into two groups. The control group will receive standard postsurgical rehabilitation guidance. The eHealth intervention group will be given the same guidance together with personalised PA guidance during 90 days after discharge. These patients will receive personalised daily goals to increase PA and reduce SB via the ExSedapplication. Triaxial accelerometers will be exploited to record patients’ daily accumulated PA and SB, and transmit them to the application. Using the accelerometer data, the application will provide online guidance to the patients and feedback of accomplishing their activity goals. The data will also be transmitted to the cloud, where a physiotherapist can monitor individual activity profiles and customise the subsequent PA and SB goals online. The postoperative improvement in patients’ step count, PA, exercise capacity, quality of sleep, laboratory markers, transthoracic echocardiography (TTE) parameters and quality of life, and reduction in SB and incidence of major cardiac events are investigated as outcomes.ConclusionsThe PACO intervention aims to build a personalised eHealth tool for the online tutoring of cardiac surgery patients.Trial registration numberNCT03470246.
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Rizun, Peter. "Optimal Wiener Filter for a Body Mounted Inertial Attitude Sensor." Journal of Navigation 61, no. 3 (June 26, 2008): 455–72. http://dx.doi.org/10.1017/s0373463308004736.
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An optimal attitude estimator is presented for a human body-mounted inertial measurement unit employing orthogonal triads of gyroscopes, accelerometers and magnetometers. The estimator continuously fuses gyroscope and accelerometer measurements together in a manner that minimizes the mean square error in the estimate of the gravity vector, based on known spectral characteristics for the gyroscope noise and the linear acceleration of points on the human body. The gyroscope noise is modelled as a white noise process of power spectral density δn2/2 while the linear acceleration is modelled as the derivative of a band-limited white noise process of power spectral density δv2/2. The estimator is robust to centripetal acceleration and guaranteed to have zero mean error regardless of the motion of the sensor. The mean square angular error in attitude is shown to be independent of the module's angular velocity and equal to 21/2g−1/2δn3/2δv1/2.
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Hwang, Young Sub, and Jeong-Yi Kwon. "Effects of Modified Constraint-Induced Movement Therapy in Real-World Arm Use in Young Children with Unilateral Cerebral Palsy: A Single-Blind Randomized Trial." Neuropediatrics 51, no. 04 (March 6, 2020): 259–66. http://dx.doi.org/10.1055/s-0040-1702220.
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Abstract Objective To determine whether modified constraint-induced movement therapy (mCIMT) with continuous restraint is feasible and effective in improving the use of the paretic arm in the real world among infants and toddlers with unilateral cerebral palsy (CP). Design Single-blind randomized controlled trial. Setting Tertiary hospital. Participants Children aged 7 to 36 months with unilateral CP (N = 24; 16 boys, 8 girls). Intervention The experimental group received 2-hour clinic-based mCIMT sessions (5 days per week for 3 weeks), and a continuous restraint was applied. Main Outcome Measures Standardized assessments were conducted. Peabody Developmental Motor Scales-2 (PDMS-2), Gross Motor Function Measure-66, Pediatric Motor Activity Log (PMAL), and Pediatric Evaluation of Disability Inventory were measured pre- and postintervention. Children who agreed to participate in the accelerometer study additionally wore accelerometers on both their wrists for 3 days before and after the intervention. Results The mCIMT group exhibited greater improvement in PMAL-how often (p = 0.048; ηp2 = 0.173), PMAL-how well (p = 0.008; ηp2 = 0.289), and PDMS-2 visual motor integration (p = 0.014; ηp2 = 0.256) posttreatment than the control group. The percentage of time in moderate-to-vigorous physical activity (z = –2.24; p = 0.03) and vector magnitude average counts (z = –2.52; p = 0.01) significantly increased in children in who wore accelerometers (N = 8) after the 3-week mCIMT protocol. Conclusion mCIMT with continuous restraint applied to infants and toddlers with unilateral CP appeared to have a positive effect on paretic hand use in the real world. Clinical Trial Registration Number NCT03418519
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Santos-Lozano, A., G. Torres-Luque, and N. Garatachea. "Inter-trial variability of GT3X accelerometer." Science & Sports 29, no. 3 (June 2014): e7-e10. http://dx.doi.org/10.1016/j.scispo.2014.03.002.
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Fortier, Michelle S., William Hogg, Tracey L. O’Sullivan, Christopher Blanchard, Ronald J. Sigal, Robert D. Reid, Pierre Boulay, et al. "Impact of integrating a physical activity counsellor into the primary health care team: physical activity and health outcomes of the Physical Activity Counselling randomized controlled trial." Applied Physiology, Nutrition, and Metabolism 36, no. 4 (August 2011): 503–14. http://dx.doi.org/10.1139/h11-040.
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The purpose of this paper was to report the physical activity and health outcomes results from the Physical Activity Counselling (PAC) trial. Patients (n = 120, mean age 47.3 ± 11.1 years, 69.2% female) who reported less than 150 min of physical activity per week were recruited from a large community-based Canadian primary care practice. After receiving brief physical activity counselling from their provider, they were randomized to receive 6 additional patient-centered counselling sessions over 3 months from a physical activity counsellor (intensive-counselling group; n = 61), or no further intervention (brief-counselling group; n = 59). Physical activity (self-reported and accelerometer) was measured every 6 weeks up to 25 weeks (12 weeks postintervention). Quality of life was also assessed, and physical and metabolic outcomes were evaluated in a randomly selected subset of patients (33%). In the intent-to-treat analyses of covariance, the intensive-counselling group self-reported significantly higher levels of physical activity at 6 weeks (p = 0.009) and 13 weeks (p = 0.01). There were no differences in self-reported physical activity between the groups after the intervention in the follow-up period, nor was there any increase in accelerometer-measured physical activity. Finally, the intensive-counselling patients showed greater decreases in percent body fat and total fat mass from 13 weeks to 25 weeks. Results for physical activity depended on the method used, with positive short-term results with self-report and no effects with the accelerometers. Between-group differences were found for body composition in that the intensive-counselling patients decreased more. A multisite randomized controlled trial with a longer intensive intervention and follow-up is warranted.
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Bierling-sørensen, F., H. Ryde, F. Bojsen-møller, and E. Lyquist. "Shock absorbing material on the shoes of long leg braces for paraplegic walking." Prosthetics and Orthotics International 14, no. 1 (April 1990): 27–32. http://dx.doi.org/10.3109/03093649009080313.
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A study was designed to evaluate if shock absorbing material (ethyl vinyl acetate (EVA)) on the shoes of long leg braces could decrease the accelerations and consequent shock forces transmitted through the leg and brace during paraplegic walking. Six male paraplegics (26–55 years old) took part, four using a “swing-to” and two a “swing-through” technique when walking. Recordings comprised accelerometry of leg and brace, force platform measurement, and still photography of the trajectories of the leg segments. Each experimental condition was tested three times with a coefficient of variation (CV) for the measurements ranging from 5–22%. Compared to hard heels, shoes equipped with 20mm EVA soles decreased the acceleration amplitude in the first 10 msec as well as at maximum for shoe-to-ground contact. With the accelerometer at the malleolus reduction of the amplitude averaged 22% and 12% respectively, and 35% and 21% respectively with the accelerometer on the caliper (p: 0.03–0.1). In a second trial the two “swing-through” walkers had new shoes made with a 10mm thick EVA heel built in. After 3 months of walking with these shoes tests were carried out with the accelerometer attached to the malleolus both when the new and the former shoes were put on the calipers. CV for these measurements were 15–24%. It was found that the new shoes decreased the amplitudes by up to 62% and 26% on average (all pc0.01). The experimental subjects indicated that the EVA soles/heels gave a more comfortable and silent walk, e.g. the “bump” transmitted up through the body to the head diminished. In future, shock absorbing material should be built into the heels of shoes provided to long leg braces for paraplegic walking.
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Malone, Quinn, Steven Passmore, and Michele Maiers. "Comparing Two Moderate-to-Vigorous Physical Activity Accelerometer Cut Points in Older Adults With Neck and Back Disabilities Undergoing Exercise and Spinal Manipulation Interventions." Journal of Aging and Physical Activity 28, no. 2 (April 1, 2020): 255–61. http://dx.doi.org/10.1123/japa.2018-0447.
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Different techniques used to analyze and reduce accelerometer data may impact its interpretation. To determine which variables were impacted by changing analysis parameters, the authors performed a secondary analysis of data gained from a clinical trial conducted on older adults (aged ≥65 years; M = 71.1 and SD = 5.3; n = 100) with neck and back disabilities and compared the effects of two different cut- point sets (Matthews and Freedson sets) commonly used to analyze older adult accelerometry data. The Matthews set was found to assign significantly greater moderate-to-vigorous physical activity per day than the Freedson set in all comparisons. This suggests that, if moderate-to-vigorous physical activity per unit time is a primary outcome measure, the choice of which analysis method is used should be carefully considered. Further results from analyses of dependent variables, time in moderate-to-vigorous physical activity bouts of >10 min/day, mean bout length, and number of bouts per day are discussed.
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Loprinzi, Paul D., and Meghan K. Edwards. "Pilot Experimentation of the Accuracy of Accelerometer Activity Count-Derived Breaks in Sedentary Time." Journal of Health Sciences 8, no. 1 (April 3, 2018): 62–67. http://dx.doi.org/10.17532/jhsci.2018.514.
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Introduction: The purpose of this study was toconduct a pilot experimentation of the accuracy of the ActiGraph GT9X model in detecting breaks from sedentary behavior.
Methods: Participants completed six transitional-based sedentary break activities while wearing an ActiGraph GT9X accelerometer. Data were processed using both the default filter and low-frequency extension filter. Direct observation was used as the criterion to observe a break in sedentary behavior. Trial 1 included the transition from sitting to standing; trial 2, sitting to walking for 30 sec; trial 3, sitting to walking for 1 min; trial 4, standing to walking for 30 sec; trial 5, standing to walking for 1 min; and trial 6, standing to sitting. Results: For both the default and low-frequency filter, the accelerometer only detected a break 10% of the time for trial 1. Accuracy was also low (<40%) for trial 6. However, accuracy was perfect (100%) for trials 2-5. Conclusion: The ActiGraph GT9X accelerometer was inaccurate in detecting a sedentary break when transitioning from a sitting to standing position but was accurate for other transitional shifts.
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Schopp, Patrick, Hagen Graf, Michael Maurer, Michailas Romanovas, Lasse Klingbeil, and Yiannos Manoli. "Observing Relative Motion With Three Accelerometer Triads." IEEE Transactions on Instrumentation and Measurement 63, no. 12 (December 2014): 3137–51. http://dx.doi.org/10.1109/tim.2014.2327472.
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Van Dyck, Delfien, Karel Herman, Louise Poppe, Geert Crombez, Ilse De Bourdeaudhuij, and Freja Gheysen. "Results of MyPlan 2.0 on Physical Activity in Older Belgian Adults: Randomized Controlled Trial." Journal of Medical Internet Research 21, no. 10 (October 7, 2019): e13219. http://dx.doi.org/10.2196/13219.
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Background The beneficial effects of physical activity (PA) for older adults are well known. However, few older adults reach the health guideline of 150 min per week of moderate-to-vigorous PA (MVPA). Electronic health (eHealth) interventions are effective in increasing PA levels in older adults in the short term but, rarely, intermediate-term effects after a period without the support of a website or an app have been examined. Furthermore, current theory-based interventions focus mainly on preintentional determinants, although postintentional determinants should also be included to increase the likelihood of successful behavior change. Objective This study aimed to investigate the effect of the theory-based eHealth intervention, MyPlan 2.0, focusing on pre- and postintentional determinants on both accelerometer-based and self-reported PA levels in older Belgian adults in the short and intermediate term. Methods This study was a randomized controlled trial with three data collection points: baseline (N=72), post (five weeks after baseline; N=65), and follow-up (three months after baseline; N=65). The study took place in Ghent, and older adults (aged ≥65 years) were recruited through a combination of random and convenience sampling. At all the time points, participants were visited by the research team. Self-reported domain-specific PA was assessed using the International Physical Activity Questionnaire, and accelerometers were used to objectively assess PA. Participants in the intervention group got access to the eHealth intervention, MyPlan 2.0, and used it independently for five consecutive weeks after baseline. MyPlan 2.0 was based on the self-regulatory theory and focused on both pre- and postintentional processes to increase PA. Multilevel mixed-models repeated measures analyses were performed in R (R Foundation for Statistical Computing). Results Significant (borderline) positive intervention effects were found for accelerometer-based MVPA (baseline−follow-up: intervention group +5 min per day and control group −5 min per day; P=.07) and for accelerometer-based total PA (baseline−post: intervention group +20 min per day and control group −24 min per day; P=.05). MyPlan 2.0 was also effective in increasing self-reported PA, mainly in the intermediate term. A positive intermediate-term intervention effect was found for leisure-time vigorous PA (P=.02), moderate household-related PA (P=.01), and moderate PA in the garden (P=.04). Negative intermediate-term intervention effects were found for leisure-time moderate PA (P=.01) and cycling for transport (P=.07). Conclusions The findings suggest that theory-based eHealth interventions focusing on pre- and postintentional determinants have the potential for behavior change in older adults. If future studies including larger samples and long-term follow-up can confirm and clarify these findings, researchers and practitioners should be encouraged to use a self-regulation perspective for eHealth intervention development. Trial Registration Clinicaltrials.gov NCT03194334; https://clinicaltrials.gov/ct2/show/NCT03783611.
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Napolitano, Melissa A., Kelley E. Borradaile, Beth A. Lewis, Jessica A. Whiteley, Jaime L. Longval, Alfred F. Parisi, Anna E. Albrecht, et al. "Accelerometer use in a physical activity intervention trial." Contemporary Clinical Trials 31, no. 6 (November 2010): 514–23. http://dx.doi.org/10.1016/j.cct.2010.08.004.
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Cappa, Paolo, Lorenzo Masia, and Fabrizio Patanè. "Numerical Validation of Linear Accelerometer Systems for the Measurement of Head Kinematics." Journal of Biomechanical Engineering 127, no. 6 (July 11, 2005): 919–28. http://dx.doi.org/10.1115/1.2049329.
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The purpose of this study was to analytically exploit the capabilities of head-mounted systems instrumented with linear accelerometers (ACs) for field use in redundant configurations. We simulated different headsets equipped with uni-, bi- or triaxial sensors with a number of axes that lie in the range of 12–24; the ACs were located on a hemispherical surface by adopting a priori criterion while their orientation was randomized. In addition, for a comparative purpose the nine accelerometer scheme (one triaxial AC and three biaxial ACs addressed in the following as “3-2-2-2 configuration”) was also analyzed in the present paper. We simulated and statistically assessed the performances of hemispherical headsets in the test case of a healthy subject walking freely at normal pace over level ground. The numerical results indicated that a well designed instrumented headset can retrieve the angular acceleration and (a0−g) component with rms errors of about 2% and 0.5%, respectively, and angular velocity with a drift error of about 20% in a 6s trial. On the contrary, the pose of the headset cannot be evaluated because of the drift induced by the integration process. In general, we can state that headsets with uni-, bi- or triaxial ACs have comparable performances. The main implications of the above-mentioned observations are (a) neither expensive triaxial ACs nor assembling procedure based on the use of orthogonal mounting blocks are needed; (b) redundant arrays of low-cost uni- or biaxial ACs can effectively be used to reach adequate performances in biomechanical studies where head acceleration and velocity are investigated; (c) while estimates of angular acceleration with accelerometers are accurate, estimations of angular velocities, linear velocities and pose are not.
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Spielvogel, Andrew R., and Louis L. Whitcomb. "Adaptive bias and attitude observer on the special orthogonal group for true-north gyrocompass systems: Theory and preliminary results." International Journal of Robotics Research 39, no. 2-3 (November 5, 2019): 321–38. http://dx.doi.org/10.1177/0278364919881689.
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This article reports an adaptive sensor bias observer and attitude observer operating directly on [Formula: see text] for true-north gyrocompass systems that utilize six-degree-of-freedom inertial measurement units (IMUs) with three-axis accelerometers and three-axis angular rate gyroscopes (without magnetometers). Most present-day low-cost robotic vehicles employ attitude estimation systems that employ microelectromechanical system (MEMS) magnetometers, angular rate gyros, and accelerometers to estimate magnetic attitude (roll, pitch, and magnetic heading) with limited heading accuracy. Present-day MEMS gyros are not sensitive enough to dynamically detect the Earth’s rotation, and thus cannot be used to estimate true-north geodetic heading. Relying on magnetic compasses can be problematic for vehicles that operate in environments with magnetic anomalies and those requiring high-accuracy navigation as the limited accuracy ([Formula: see text] error) of magnetic compasses is typically the largest error source in underwater vehicle navigation systems. Moreover, magnetic compasses need to undergo time-consuming recalibration for hard-iron and soft-iron errors every time a vehicle is reconfigured with a new instrument or other payload, as very frequently occurs on oceanographic marine vehicles. In contrast, the gyrocompass system reported herein utilizes fiber optic gyroscope (FOG) IMU angular rate gyro and MEMS accelerometer measurements (without magnetometers) to dynamically estimate the instrument’s time-varying true-north attitude (roll, pitch, and geodetic heading) in real-time while the instrument is subject to a priori unknown rotations. This gyrocompass system is immune to magnetic anomalies and does not require recalibration every time a new payload is added to or removed from the vehicle. Stability proofs for the reported bias and attitude observers, preliminary simulations, and a full-scale vehicle trial are reported that suggest the viability of the true-north gyrocompass system to provide dynamic real-time true-north heading, pitch, and roll utilizing a comparatively low-cost FOG IMU.
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Sanders, Sarah G., Elizabeth Yakes Jimenez, Natalie H. Cole, Alena Kuhlemeier, Grace L. McCauley, M. Lee Van Horn, and Alberta S. Kong. "Estimated Physical Activity in Adolescents by Wrist-Worn GENEActiv Accelerometers." Journal of Physical Activity and Health 16, no. 9 (September 1, 2019): 792–98. http://dx.doi.org/10.1123/jpah.2018-0344.
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Background: Reports of physical activity (PA) measured via wrist-worn accelerometers in adolescents are limited. This study describes PA levels in adolescents at baseline of an obesity prevention and weight management trial. Methods: Adolescents (n = 930) at 8 high schools wore an accelerometer for 7 days, with average acceleration values of <50 mg, >150 mg, and >500 mg categorized as sedentary, moderate, and vigorous PA, respectively. In a 3-level mixed-effects generalized linear model, PA was regressed on sex, weight status, and day of week. Daily PA was nested within students, and students within schools, with random effects included for both. Results: Adolescents accumulated a median of 40 minutes daily of moderate to vigorous PA (MVPA). MVPA was significantly different for teens with obesity versus teens with normal weight (−5.4 min/d, P = .03); boys versus girls (16.3 min/d, P < .001); and Sundays versus midweek (−16.6 min/d, P < .001). Average sedentary time increased on weekends (Saturday: 19.1 min/d, P < .001; Sunday: 44.8 min, P < .001) relative to midweek but did not differ by sex or weight status. Conclusions: Interventions to increase PA in adolescents may benefit from focusing on increasing weekend PA and increasing MVPA in girls.
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Pulakka, A., Y. B. Cheung, K. Maleta, K. G. Dewey, C. Kumwenda, J. Bendabenda, U. Ashorn, and P. Ashorn. "Effect of 12-month intervention with lipid-based nutrient supplement on the physical activity of Malawian toddlers: a randomised, controlled trial." British Journal of Nutrition 117, no. 4 (February 28, 2017): 511–18. http://dx.doi.org/10.1017/s0007114517000290.
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AbstractPhysical activity is beneficial for children’s well-being. The effect of dietary supplementation on children’s physical activity in food-insecure areas remains little studied. We examined the effects of a lipid-based nutrient supplement (LNS) on children’s objectively measured physical activity in a randomised, controlled, outcome-assessor-blinded trial. Mothers of the children received one capsule daily of Fe-folic acid (IFA), one capsule containing eighteen micronutrients (MMN) or one 20 g sachet of LNS (containing twenty-two MMN, protein, carbohydrates, essential fatty acids and 494 kJ (118 kcal)) during pregnancy and for 6 months thereafter. Children in the IFA and MMN groups received no supplementation, and these groups were collapsed into a single control group; children in the LNS group received 20 g LNS from 6 to 18 months. We measured physical activity with accelerometers over 1 week at 18 months. The main outcome was mean vector magnitude counts/15 s. Of the 728 children at the beginning of child intervention at 6 months, 570 (78 %) provided sufficient data for analysis. The mean accelerometer counts for the 190 children in the LNS group and for the 380 children in the control group were 303 (sd 59) and 301 (sd 56), respectively (Pfor difference=0·65). LNS, given to mothers during pregnancy and 6 months postpartum and to their infants from 6 to 18 months of age, did not increase physical activity among 18-month-old children.
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Fanning, Jason, W. Jack Rejeski, Shyh-Huei Chen, Barbara J. Nicklas, Michael P. Walkup, Robert S. Axtell, Roger A. Fielding, et al. "A Case for Promoting Movement Medicine: Preventing Disability in the LIFE Randomized Controlled Trial." Journals of Gerontology: Series A 74, no. 11 (February 19, 2019): 1821–27. http://dx.doi.org/10.1093/gerona/glz050.
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Abstract Background The movement profile of older adults with compromised function is unknown, as is the relationship between these profiles and the development of major mobility disability (MMD)—a critical clinical outcome. We first describe the dimensions of movement in older adults with compromised function and then examine whether these dimensions predict the onset of MMD. Methods Older adults at risk for MMD (N = 1,022, mean age = 78.7 years) were randomized to receive a structured physical activity intervention or health education control. We assessed MMD in 6-month intervals (average follow-up of 2.2 years until incident MMD), with activity assessed at baseline, 6-, 12- and 24-month follow-up via accelerometry. Results A principal components analysis of 11 accelerometer-derived metrics yielded three components representing lifestyle movement (LM), extended bouts of moderate-to-vigorous physical activity (MVPA), and stationary body posture. LM accounted for the greatest proportion of variance in movement (53%). Within health education, both baseline LM (HR = 0.74; 95% CI 0.62 to 0.88) and moderate-to-vigorous physical activity (HR = 0.69; 95% CI 0.54 to 0.87) were associated with MMD, whereas only LM was associated with MMD within physical activity (HR = 0.74; 95% CI 0.61 to 0.89). There were similar nonlinear relationships present for LM in both physical activity and health education (p < .04), whereby risk for MMD was lower among individuals with higher levels of LM. Conclusions Both LM and moderate-to-vigorous physical activity should be central in treatment regimens for older adults at risk for MMD. Trial Registration clinicaltrials.gov Identifier NCT01072500
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Tarp, Jakob, Lars B. Andersen, and Lars Østergaard. "Quantification of Underestimation of Physical Activity During Cycling to School When Using Accelerometry." Journal of Physical Activity and Health 12, no. 5 (May 2015): 701–7. http://dx.doi.org/10.1123/jpah.2013-0212.
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Background:Cycling to and from school is an important source of physical activity (PA) in youth but it is not captured by the dominant objective method to quantify PA. The aim of this study was to quantify the underestimation of objectively assessed PA caused by cycling when using accelerometry.Methods:Participants were 20 children aged 11 to 14 years from a randomized controlled trial performed in 2011. Physical activity was assessed by accelerometry with the addition of heart rate monitoring during cycling to school. Global positioning system (GPS) was used to identify periods of cycling to school.Results:Mean minutes of moderate-to-vigorous physical activity (MVPA) during round-trip commutes was 10.8 (95% CI: 7.1−16.6). Each kilometer of cycling meant an underestimation of 9314 (95% CI: 7719−11238) counts and 2.7 (95% CI: 2.1−3.5) minutes of MVPA. Adjusting for cycling to school increased estimates of MVPA/day by 6.0 (95% CI: 3.8−9.6) minutes.Conclusions:Cycling to and from school contribute substantially to levels of MVPA and to mean counts/min in children. This was not collected by accelerometers. Using distance to school in conjunction with self-reported cycling to school may be a simple tool to improve the methodology.
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Kelechi, Teresa J., Margaret A. Prentice, Martina Mueller, Mohan Madisetti, and Alexey Vertegel. "A Lower Leg Physical Activity Intervention for Individuals With Chronic Venous Leg Ulcers: Randomized Controlled Trial." JMIR mHealth and uHealth 8, no. 5 (May 15, 2020): e15015. http://dx.doi.org/10.2196/15015.
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Background Individuals with venous leg ulcers (VLUs) suffer disproportionately with multiple chronic conditions, are often physically deconditioned, and demonstrate high levels of physical inactivity. Objective The primary objective of this randomized controlled trial was to establish the feasibility of a mobile health (mHealth) physical activity exercise app for individuals with VLUs to improve lower leg function. Methods In a 6-week study, adults with VLUs were recruited from 2 wound centers in South Carolina, United States, and enrolled if they were aged 18 years or older with impaired functional mobility and an ankle-brachial index between 0.8 and 1.3. Participants were randomized 1:1 to receive evidence-based, phased, nonexertive physical conditioning activities for lower leg function (FOOTFIT) or FOOTFIT+ with an added patient-provider communication feature. The mHealth Conditioning Activities for Lower Leg Function app also provided automated educational and motivational messages and user reports. Foot movement on the VLU-affected leg was tracked by a Bluetooth-enabled triaxial accelerometer. The study was guided by the Reach, Effectiveness, Adoption, Implementation, and Maintenance framework to assess the feasibility of reach, adherence, acceptability, implementation, and maintenance. Results A total of 24 patients were recruited, enrolled, and randomized in the study. Most patients reported difficulty following the protocol for exercising and using the accelerometer and mobile phone and did not use the provider contact feature. However, all patients were adherent to the 6-week exercise program more than 85% of the time for duration, whereas 33% (8/24) of patients adhered more than 85% for the frequency of performing the exercises. Across the three exercise levels, adherence did not differ between the two groups. Confidence limits around the difference in proportions ranged from −0.4 to 0.7. Providers in FOOTFIT+ were inconsistent in checking participant progress reports because of lack of time from competing work commitments. The technology became outdated quickly, making maintenance problematic. Participants said they would continue to exercise their foot and legs and liked being able to follow along with the demonstrations of each level of exercise provided through the app. Conclusions The findings of this study suggest that despite initial interest in using the app, several components of the program as originally designed had limited acceptability and feasibility. Future refinements should include the use of more modern technology including smaller wearable accelerometers, mobile phones or tablets with larger screens, an app designed with larger graphics, automated reporting for providers, and more engaging user features. Trial Registration ClinicalTrials.gov NTC02632695; https://clinicaltrials.gov/ct2/show/NCT02632695
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Celano, Christopher M., Taylor A. Gianangelo, Rachel A. Millstein, Wei-Jean Chung, Deborah J. Wexler, Elyse R. Park, and Jeff C. Huffman. "A positive psychology–motivational interviewing intervention for patients with type 2 diabetes: Proof-of-concept trial." International Journal of Psychiatry in Medicine 54, no. 2 (August 16, 2018): 97–114. http://dx.doi.org/10.1177/0091217418791448.
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Objective Eighteen million Americans with type 2 diabetes (T2D) do not follow recommended guidelines for physical activity. Motivational interviewing (MI) has had modest effects on activity and related behaviors in T2D. Positive psychological attributes (e.g., optimism) are associated with superior medical outcomes in T2D, and positive psychology (PP) interventions promote such attributes. There had been no study in T2D of a combined PP–MI intervention to promote well-being and health behavior adherence. We developed a novel, telephone-delivered, 16-week PP–MI intervention and explored its feasibility and impact in T2D patients in a single-arm, proof-of-concept trial. Method Participants completed PP-based exercises and MI-based physical activity goal-setting activities and reviewed these activities weekly with a study trainer for 16 weeks. Feasibility and acceptability were assessed via exercise completion rates and post-exercise ratings of ease/utility (0–10 scales). Impact was explored by examining changes in physical activity (via accelerometers and self-report), other health behaviors, psychological measures, and medical outcomes (e.g., hemoglobin A1c (A1C)) from baseline to 16 weeks, using paired t tests. Results Twelve participants enrolled, and 10 provided follow-up data. Seventy-eight percent of PP–MI activities were completed, and participants rated the PP–MI content and sessions as easy (mean = 8.2/10, standard deviation (SD) = 1.9) and useful (mean = 9.1/10, SD = 1.5). PP–MI was associated with improved adherence to health behaviors and overall self-care, variable effects on accelerometer-measured activity and psychological outcomes, and modest beneficial effects on body mass index and A1C. Conclusion Further testing of this intervention is warranted in a larger, controlled trial to assess its effects on important health outcomes.
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Lee, Winnie Y. H., Bronwyn K. Clark, Elisabeth Winkler, Elizabeth G. Eakin, and Marina M. Reeves. "Responsiveness to Change of Self-Report and Device-Based Physical Activity Measures in the Living Well With Diabetes Trial." Journal of Physical Activity and Health 12, no. 8 (August 2015): 1082–87. http://dx.doi.org/10.1123/jpah.2013-0265.
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Background:This study evaluated the responsiveness to change in physical activity of 2 self-report measures and an accelerometer in the context of a weight loss intervention trial.Methods:302 participants (aged 20 to 75 years) with type 2 diabetes were randomized into telephone counseling (n = 151) or usual care (n = 151) groups. Physical activity (minutes/week) was assessed at baseline and 6-months using the Active Australia Survey (AAS), the United States National Health Interview Survey (USNHIS) walking for exercise items, and accelerometer (Actigraph GT1M; ≥1952 counts/minute). Responsiveness to change was calculated as responsiveness index (RI), Cohen’s d (postscores) and Cohen’s d (change-scores).Results:All instruments showed significant improvement in the intervention group (P < .001) and no significant change for usual care (P > .05). Accelerometer consistently ranked as the most responsive instrument while the least responsive was the USHNIS (responsiveness index) or AAS (Cohen’s d). RIs for AAS, USNHIS and accelerometer did not differ significantly and were, respectively: 0.45 (95% CI: 0.26–0.65); 0.38 (95% CI: 0.20–0.56); and, 0.49 (95% CI: 0.23–0.74).Conclusions:Accelerometer tended to have the highest responsiveness but differences were small and not statistically significant. Consideration of factors, such as validity, feasibility and cost, in addition to responsiveness, is important for instrument selection in future trials
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Davey, Neil, Megan Anderson, and Daniel A. James. "Validation trial of an accelerometer‐based sensor platform for swimming." Sports Technology 1, no. 4-5 (January 2008): 202–7. http://dx.doi.org/10.1080/19346182.2008.9648474.
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Kanai, Masashi, Kazuhiro P. Izawa, Miki Kobayashi, Akira Onishi, Hiroki Kubo, Masafumi Nozoe, Kyoshi Mase, and Shinichi Shimada. "Effect of accelerometer-based feedback on physical activity in hospitalized patients with ischemic stroke: a randomized controlled trial." Clinical Rehabilitation 32, no. 8 (February 5, 2018): 1047–56. http://dx.doi.org/10.1177/0269215518755841.
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Objective: To evaluate the effect of accelerometer-based feedback on physical activity in hospitalized patients with ischemic stroke. Design: Randomized controlled trial. Setting: Acute care hospital. Subjects: A total of 55 patients with ischemic stroke who could walk without assistance were randomly assigned to the intervention group ( n = 27) or the control group ( n = 28). Interventions: At the baseline measurement, patients did not receive accelerometer-based feedback. At follow-up, a physical therapist provided instruction on accelerometer-based feedback, discussed physical activity targets and encouraged the patients to walk more until discharge. Main measures: The average daily number of steps taken was used as the index of daily hospitalized physical activity. Results: The study sample consisted of 48 patients, of whom 23 patients comprised the intervention group and 25 patients comprised the control group. Although there were no significant differences in physical activity values between the two groups at the baseline measurement, the values in the intervention group at follow-up were significantly higher than those in the control group (5180.5 ± 2314.9 vs. 3113.6 ± 1150.9 steps/day, P = 0.0003). The effect size of physical activity values (Cohen’s d = 1.15) at follow-up was large between the two groups. Conclusion: Exercise training combined with accelerometer-based feedback effectively increased physical activity in hospitalized patients with ischemic stroke.
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Li, Ying, and P. Barker. "Field Evaluation of a Portable Whispering Gallery Mode Accelerometer." Sensors 18, no. 12 (November 29, 2018): 4184. http://dx.doi.org/10.3390/s18124184.
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An accelerometer utilising the optomechanical coupling between an optical whispering gallery mode (WGM) resonance and the motion of the WGM cavity itself was prototyped and field-tested on a vehicle. We describe the assembly of this portable, battery operated sensor and the field-programmable gate array automation. Pre-trial testing using an electrodynamic shaker demonstrated linear scale-factors with <0.3% standard deviation ( ± 6 g range where g = 9.81 ms − 2 ), and a strong normalised cross-correlation coefficient (NCCC) of r ICP / WGM = 0.997 when compared with an integrated circuit piezoelectric (ICP) accelerometer. A noise density of 40 μ g Hz − 1 / 2 was obtained for frequencies of 2–7 kHz, increasing to 130 μ g Hz − 1 / 2 at 200 Hz, and 250 μ g Hz − 1 / 2 at 100 Hz. A reduction in the cross-correlation was found during the trial, r ICP / WGM = 0.36, which we attribute to thermal fluctuations, mounting differences, and the noisy vehicle environment. The deployment of this hand-fabricated sensor, shown to operate and survive during ±60 g shocks, demonstrates important steps towards the development of a chip-scale device.