Accelerometry

To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on academic performance in 10-year-old children. In total, 1129 fifth-grade children from 57 elementary schools in Sogn og Fjordane County, Norway, were cluster-randomized by school either to the intervention group or to the control group. The children in the 28 intervention schools participated in a physical activity intervention between November 2014 and June 2015 consisting of three components: 1) 90min/week of physically active educational lessons mainly carried out in the school playground; 2) 5min/day of physical activity breaks during classroom lessons; 3) 10min/day physical activity homework. Academic performance in numeracy, reading and English was measured using standardized Norwegian national tests. Physical activity was measured objectively by accelerometry. We found no effect of the intervention on academic performance in primary analyses (standardized difference 0.01-0.06, p&gt...

Theoretical and laboratory studies generally show that ectotherm performance increases with temperature to an optimum, and subsequently declines. Several physiological mechanisms probably shape thermal performance curves, but responses of free-ranging animals to temperature variation will represent a compromise between these mechanisms and ecological constraints. Thermal performance data from wild animals balancing physiology and ecology are rare, and this represents a hindrance for predicting population impacts of future temperature change. We used internally implanted accelerometers near the middle of a species' geographical distribution and gill-net catch data near the species' latitudinal extremes to quantify temperature-related activity levels of a wild predatory fish (Platycephalus fuscus). We examined our data in…

Eleven subjects (33.6 +/- 4.5 years) were enrolled in this pilot validation study. Each subject semi-trained, i.e. had incorporated running into their training regimen with weekly mileage ranging 10 to 60 miles. Most participants had previously completed a half-marathon. Subjects’ race experience ran the distance gamut (marathons, 10k races, Half Ironmans, 0bstacle  races).  Subjects self-enrolled in a 6-week program designed with training loads to deliberately induce fatigue levels that
could be deemed counter-productive to performance (i.e. non-functional over-reaching). Training was divided into three 2-week phases: baseline training, overload training, and active recovery.  Participants were surveyed each weekday as to their perceived level of stress, sleep quality, muscle soreness, and general
fatigue. Subjects also performed Under Armour's patented jump-test -- a cued series of 6 countermovement jumps (hands kept upon hips) before and after a 3-minute warm-up. Finally, heartrate (HR) measures were captured, including resting HR, running HR (85% estimated VO2max), and recovery HR (recorded 60s after a steady-state treadmill run)

The eff ect of a wristband on the dynamic balance of young adults was assessed. Twenty healthy young adults wore a commercial Power Balance TM or fake silicone wristband. A 3D accelerometer was attached to their lumbar region to measure body sway. They played the video game Tightrope (Wii ® video game console) with and without a wristband; body sway acceleration was measured. Mean balance sway acceleration and its variability were the same in all conditions, so silicone wristbands do not modify dynamic balance control.

Changes in stride frequency and length with speed are key parameters in animal locomotion research. They are commonly measured in a laboratory on a treadmill or by filming trained captive animals. Here, we show that a clustering approach can be used to extract these variables from data collected by a tracking collar containing a GPS module and tri-axis accelerometers and gyroscopes. The method enables stride parameters to be measured during free-ranging locomotion in natural habitats. As it does not require labelled data, it is particularly suitable for use with difficult to observe animals. The method was tested on large data sets collected from collars on free-ranging lions and African wild dogs and validated using a domestic dog.

Rev Esp Cardiol. 2008;61(2):123-9 123 Introducción y objetivos. Se considera que la capacidad cardiovascular (CCV) es un marcador de salud en todas las edades. La finalidad principal de este estudio fue examinar si las recomendaciones actuales de actividad física (AF) están relacionadas con un mejor CCV en los adolescentes.

Numerous recent studies have aimed to improve myoelectric control of prostheses. However, the majority of these studies is characterized by two problems that could be easily fulfilled with recent resources supplied by the scientific literature. First, the majority of these studies use only intact subjects, with the unproved assumption that the results apply equally to amputees. Second, usually only electromyography data are used, despite other sensors (e.g., accelerometers) being easy to include into a real life prosthesis control system. In this paper we analyze the mentioned problems by the classification of 40 hand movements in 5 amputated and 40 intact subjects, using both sEMG and accelerometry data and applying several different state of the art methods. The datasets come from the NinaPro database, which supplies publicly available sEMG data to develop and test machine learning algorithms for prosthetics. The number of subjects can seem small at first sight, but it is not cons...

The purpose of this study was to investigate the utility of peak outward acceleration (POA) measured from an inertial sensor worn at the wrist as an indicator of the critical end point of the bowling action - ball release, a critical element when assessing illegal actions. Twenty-one finger-spin and fast bowlers from nine countries were recruited from the ICC under-19 Cricket World Cup to take part in this research. Bowlers delivered a cross section of their standard deliveries while wearing an inertial sensor placed on their wrists. Ball release was determined by a validated motional analysis ball release (MABR) protocol and compared to the simultaneously collected POA. POA was shown to be highly correlated with MABR (R(2) = 0.98) and a Bland-Altman plot indicated that all 148 trials were within the 3.42 frame (0.014 s) limits of agreement. POA when measured by an inertial sensor worn on the wrist during bowling had a close relationship with an established method of identifying bal...

The use of contemporary technology is widely recognised as a key tool for enhancing competitive performance in swimming. Video analysis is traditionally used by coaches to acquire reliable biomechanical data about swimming performance; however, this approach requires a huge computational effort, thus introducing a delay in providing quantitative information. Inertial and magnetic sensors, including accelerometers, gyroscopes and magnetometers, have been recently introduced to assess the biomechanics of swimming performance. Research in this field has attracted a great deal of interest in the last decade due to the gradual improvement of the performance of sensors and the decreasing cost of miniaturised wearable devices. With the aim of describing the state of the art of current developments in this area, a systematic review of the existing methods was performed using the following databases: PubMed, ISI Web of Knowledge, IEEE Xplore, Google Scholar, Scopus and Science Direct. Twenty...

Objectives: The correct assessment of energy expenditure in very active individuals is important to ensure that dietary energy intake is sufficient. We aimed to validate a combined heart rate (HR) and motion sensor in estimating total (TEE) and activity energy expenditure (AEE) in males and females with high physical activity levels. Design: Cross-sectional. Methods: Doubly-labelled water (DLW) was used to assess 7-day TEE in 12 male and female elite junior basketball players, aged 16-17 years. Resting energy expenditure (REE) was assessed with indirect calorimetry and AEE was calculated (AEE = TEE-RMR-0.1 × TEE). Simultaneously, TEE and AEE were measured by combined HR and motion sensing. Individual HR calibration was performed with step-test. TEE and AEE were estimated from accelerometry and HR with individual (ACC + HR step ) and group calibration (ACC + HR group ). Results: No mean differences were found between TEE and AEE from the ACC + HR step and ACC + HR group with DLW. TEE values (kJ/day) from ACC + HR group and ACC + HR step explained TEE from DLW by ∼60% and 53%, respectively whereas AEE (kJ/day) estimated by ACC + HR group and ACC + HR step explained 53% and 41% of the variability of AEE from the reference method. Concordance correlation coefficients for TEE and AEE using ACC + HR group were 0.74 and 0.69, correspondingly while for ACC + HR step values of 0.69 and 0.45 were found. Large limits of agreement were found for TEE and AEE using both ACC + HR group and ACC + HR step . Conclusions: ACC + HR models are a valid alternative to estimate TEE but not AEE in a group of highly active individuals however the considerable rate of equipment failure (∼50%) limits its usefulness.

Both scientists and the general public assume that physical activity (PA) is an effective, nonpharmacological approach to improvement in sleep quality. However, objective and reliable data on this relationship are scarce, particularly for adolescents. Therefore, the aims of the present study were to test the relationship by assessing both PA and sleep subjectively and objectively. A total of 56 adolescent vocational school students (Mean age=17.98, SD=1.36; 28 males, 28 females) participated in the study. Sleep and PA were subjectively assessed via questionnaires. Accelerometers objectively assessed PA, while sleep-EEG devices objectively assessed sleep. The data supported our prediction that adolescents with high PA levels would have longer TST, fewer wakening at night (WASO), fewer symptoms of insomnia, and higher sleep quality. However, gender influenced this pattern of results in that significant findings were only found between high self-reported PA levels and shorter perceived sleep onset latency (SOL). Though self-reported PA levels were a better predictor of good sleep than objectively assessed PA levels, gender was associated with sleep complaints; females reported more sleep complaints. Results indicate that among a non-clinical sample of adolescents increased PA is favorably associated with restoring sleep. Therefore, PA seems beneficial not only for physical and mental health, but also for sleep restoration.

Although proof-of-concept for mobile health (mHealth) lifestyle programs targeting physical inactivity and overweight/obesity has been established in randomized trials, the feasibility and impact of globally distributed, large-scale mass-participation mHealth implementation has not been investigated. To determine the impact of Stepathlon, an international low-cost mass-participation mHealth intervention, on physical activity, sitting and weight. The study was an analysis of prospectively collected cohort data from participants completing Stepathlon, an annual 100-day global event in 2012, 2013, and 2014. (ACTRN12615001310550). Participants were organized in worksite-based teams, issued pedometers, and encouraged to increase daily steps and physical activity as part of team-based race. The program was conducted via an interactive multi-platform app available on mobile devices and the worldwide web. Analysis was performed according to a pre-specified plan. N=69,219 subjects participat...

Assessment of the functional capacity of the cardiovascular system is essential in sports medicine. For athletes, the maximal oxygen uptake ð _ VO 2max Þ provides valuable information about their aerobic power. In the clinical setting, the _ VO 2max provides important diagnostic and prognostic information in several clinical populations, such as patients with coronary artery disease or heart failure. Likewise, _ VO 2max assessment can be very important to evaluate fitness in asymptomatic adults. Although direct determination of _ VO 2max is the most accurate method, it requires a maximal level of exertion, which brings a higher risk of adverse events in individuals with an intermediate to high risk of cardiovascular problems. Estimation of _ VO 2max during submaximal exercise testing can offer a precious alternative. Over the past decades, many protocols have been developed for this purpose. The present review gives an overview of these submaximal protocols and aims to facilitate appropriate test selection in sports, clinical, and home settings. Several factors must be considered when selecting a protocol: (i) The population being tested and its specific needs in terms of safety, supervision, and accuracy and repeatability of the _ VO 2max estimation. (ii) The parameters upon which the prediction is based (e.g. heart rate, power output, rating of perceived exertion [RPE]), as well as the need for additional clinically relevant parameters (e.g. blood pressure, ECG). (iii) The appropriate test modality that should meet the above-mentioned requirements should also be in line with the functional mobility of the target population, and depends on the available equipment. In the sports setting, high repeatability is crucial to track training-induced seasonal changes. In the clinical setting, special attention must be paid to the test modality, because multiple physiological parameters often need to be measured during test execution. When estimating _ VO 2max , one has to be aware of the effects of medication on heart Electronic supplementary material The online version of this article (

By definition, physical computing deals with the study and development of interactive systems that sense and react to the analog world. In an analogous way, physiological computing can be defined as the field, within physical computing, that deals with the study and development of systems that sense and react to the human body. While physical computing has seen significant advancements leveraged by the popular Arduino platform, no such equivalent can yet be found for physiological computing. In this paper we present a novel, low-cost and versatile platform, targeted at multimodal biosignal acquisition and that can be used to support classroom activities, interface with other devices, or perform rapid prototyping of end-user applications in the field of physiological computing. We build on previous work developed by our group, by presenting an improved version of the BITalino platform, emphasizing on the hardware characterization, benchmarking and design principles.

Both timbre and dynamics of isolated piano tones are determined exclusively by the speed with which the hammer hits the strings. This physical view has been challenged by pianists who emphasize the importance of the way the keyboard is touched. This article presents empirical evidence from two perception experiments showing that touch-dependent sound components make sounds with identical hammer velocities but produced with different touch forms clearly distinguishable. The first experiment focused on finger-key sounds: musicians could identify pressed and struck touches. When the finger-key sounds were removed from the sounds, the effect vanished, suggesting that these sounds were the primary identification cue. The second experiment looked at keykeyframe sounds that occur when the key reaches key-bottom. Key-bottom impact was identified from key motion measured by a computer-controlled piano. Musicians were able to discriminate between piano tones that contain a key-bottom sound from those that do not. However, this effect might be attributable to sounds associated with the mechanical components of the piano action. In addition to the demonstrated acoustical effects of different touch forms, visual and tactile modalities may play important roles during piano performance that influence the production and perception of musical expression on the piano.

Objective To modify the self-administered, short version of the International Physical Activity Questionnaire (IPAQ) for adults to be used in the elderly (aged 65 years and above), and to validate this modified IPAQ for the elderly (IPAQ-E). Design A direct validity study using accelerometer-measured physical activity (PA) as the criterion measure, and an indirect criterion validity study using high-sensitivity C-reactive protein (hs-CRP) as a biological marker of activity. Setting Organisations for retired persons in Sweden. Subjects The direct validity study consisted of fifty-four participants and the indirect criterion validity study consisted of 359 participants. All participants were retired persons (66–91 years) living independently. Results All self-reported activity domains (sitting, walking, moderate and vigorous) were positively correlated with the corresponding variable objectively assessed by an accelerometer (ρ = 0·277–0·471), but a systematic error was observed. The s...

Detection and quantification of lameness in horses consists primarily of a subjective assessment, whereby both intra-and inter-observer disagreements exist, especially with low grade lameness. Therefore, clinically applicable methods are needed for reliable, objective assessments. The aim of this study was to describe three symmetry indices derived from a simple accelerometric method and investigate these in sound trotting horses. The indices describe the overall symmetry of the gait, the symmetry of loads placed on the limbs and the symmetry in timing between left and right steps. These symmetry indices were able to quantify the high degree of symmetry of the trot in sound horses that has been described in earlier studies using other gait analysis methods. Also, we have analysed the variances and have found high repeatability for all three indices.

Skate é uma das culturas mais populares no Brasil, com mais de 8.5 milhões de adeptos. O movimento esportivo atualmente se encontra em uma fase de grande crescimento, dada inclusive a estréia da modalidade nos Jogos Olímpicos em Tóquio 2020.
O presente estudo teve como objetivo desenvolver técnicas de detecção e classificação de manobras de Street Skate, utilizando sensores inerciais IMU (Inertial Module Unit) e Redes Neurais Artificiais (RNA).
Utilizando conhecimento do estado da arte em detecção de movimentos no Skate, foram gerados 181 registros artificiais, resultando em 543 sinais de aceleração (X, Y e Z) divididos entre 5 classes de manobras. Foi desenvolvida uma heurística de classificação utilizando coeficientes de correlação cruzada para discriminar cada classe, e com a Neural Network Toolbox foi criada uma Multilayer Feed Forward Network de três camadas treinada através de um algoritmo de aprendizagem supervisionado (scaled conjugate gradient backpropagation).
Os resultados mostraram que com a utilização de RNAs treinadas especificamente para cada eixo, sendo o eixo Z o maior discriminador, podemos alcançar um percentual de erro inferior a 0.05%, com uma eficiência computacional que disponibiliza respostas em tempo real.
Aprendizado de máquina é uma podersoa ferramenta na classificação de padrões de movimento complexos, contanto que os classificadores sejam arquitetados de maneira eficiente e o problema proposto de maneira clara, essa técnica possui promissoras aplicações para Exergames e detecção de movimentos.

Microelectromechanical Systems (MEMS) technology is playing a key role in the design of the new generation of smartphones. Thanks to their reduced size, reduced power consumption, MEMS sensors can be embedded in above mobile devices for increasing their functionalities. However, MEMS cannot allow accurate autonomous location without external updates, e.g., from GPS signals, since their signals are degraded by various errors. When these sensors are fixed on the user's foot, the stance phases of the foot can easily be determined and periodic Zero velocity UPdaTes (ZUPTs) are performed to bound the position error. When the sensor is in the hand, the situation becomes much more complex. First of all, the hand motion can be decoupled from the general motion of the user. Second, the characteristics of the inertial signals can differ depending on the carrying modes. Therefore, algorithms for characterizing the gait cycle of a pedestrian using a handheld device have been developed. A classifier able to detect motion modes typical for mobile phone users has been designed and implemented. According to the detected motion mode, adaptive step detection algorithms are applied. Success of the step detection process is found to be higher than 97% in all motion modes.

Background: Assessment of hand kinematics is important when evaluating hand functioning. Major drawbacks of current sensing glove systems are lack of rotational observability in particular directions, labour intensive calibration methods which are sensitive to wear and lack of an absolute hand orientation estimate. Methods: We propose an ambulatory system using inertial sensors that can be placed on the hand, fingers and thumb. It allows a full 3D reconstruction of all finger and thumb joints as well as the absolute orientation of the hand. The system was experimentally evaluated for the static accuracy, dynamic range and repeatability. Results: The RMS position norm difference of the fingertip compared to an optical system was 5 ± 0.5 mm (mean ± standard deviation) for flexion-extension and 12.4 ± 3.0 mm for combined flexion-extension abduction-adduction movements of the index finger. The difference between index and thumb tips during a pinching movement was 6.5 ± 2.1 mm. The dynamic range of the sensing system and filter was adequate to reconstruct full 80 degrees movements of the index finger performed at 116 times per minute, which was limited by the range of the gyroscope. Finally, the reliability study showed a mean range difference over five subjects of 1.1 ± 0.4 degrees for a flat hand test and 1.8 ± 0.6 degrees for a plastic mold clenching test, which is smaller than other reported data gloves. Conclusion: Compared to existing data gloves, this research showed that inertial and magnetic sensors are of interest for ambulatory analysis of the human hand and finger kinematics in terms of static accuracy, dynamic range and repeatability. It allows for estimation of multi-degree of freedom joint movements using low-cost sensors.

Purpose: To describe the physical activity (PA) levels of children attending after-school programs, 2) examine PA levels in specific after-school sessions and activity contexts, and 3) evaluate after-school PA differences in groups defined by sex and weight status. Methods: One hundred forty-seven students in grades 3-6 (mean age: 10.1 T 0.7, 54.4% male, 16.5 % overweight (OW), 22.8% at-risk for OW) from seven after-school programs in the midwestern United States wore Actigraph GT1M accelerometers for the duration of their attendance to the program. PA was objectively assessed on six occasions during an academic year (three fall and three spring). Stored activity counts were uploaded to a customized data-reduction program to determine minutes of sedentary (SED), light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous (MVPA) physical activity. Time spent in each intensity category was calculated for the duration of program attendance, as well as specific after-school sessions (e.g., free play, snack time). Results: On average, participants exhibited 42.6 min of SED, 40.8 min of LPA, 13.4 min of MPA, and 5.3 min of VPA. The average accumulation of MVPA was 20.3 min. Boys exhibited higher levels of MPA, VPA, and MVPA, and lower levels of SED and LPA, than girls. OW and at-risk-for-OW students exhibited significantly less VPA than nonoverweight students, but similar levels of LPA, MPA, and MVPA. MVPA levels were significantly higher during free-play activity sessions than during organized or structured activity sessions. Conclusion: After-school programs seem to be an important contributor to the PA of attending children. Nevertheless, ample room for improvement exists by making better use of existing time devoted to physical activity.

Background: Childhood overweight/obesity and inadequate physical activity burden Western countries, and now, pose a growing threat to the health of children in low and middle income countries. Behavioural transitions toward more sedentary lifestyles coupled with increased consumption of high calorie foods has resulted in rising proportions of overweight/obesity and decreasing levels of physical activity in school-aged children. The objective of this study was to determine the prevalence and to investigate factors associated with overweight/obesity and physical activity in Kenyan children aged 9 to 11 years. Methods: Body composition and physical activity measures of participating children were accomplished by anthropometric assessment, accelerometry, and administration of questionnaires related to diet and lifestyle, and the school and neighbourhood environments. Data collection was conducted in the city of Nairobi as part of a larger International Study of Childhood Obesity, Lifestyle and Environment.

For many children, physical activity (PA) during physical education (PE) lessons provides an important opportunity for being physically active. Although PA during PE has been shown to be low, little is known about the contribution of PA during PE to overall PA. The aim was therefore to assess children's PA during PE and to determine the contribution of PE to overall PA with special focus on overweight children. Accelerometer measurements were done in 676 children (9.3 ± 2.1 years) over 4-7 days in 59 randomly selected classes. Moderate-and-vigorous PA (MVPA; ≥ 2000 counts/min) during PE (MVPAPE), overall MVPA per day (MVPADAY), and a comparison of days with and without PE were calculated by a regression model with gender, grade, and weight status (normal vs overweight) as fixed factors and class as a random factor. Children spent 32.8 ± 15.1% of PE time in MVPA. Weight status was not associated to MVPAPE . MVPAPE accounted for 16.8 ± 8.5% of MVPADAY, and 17.5 ± 8.2% in overweigh...

Background: Precise measurement of physical activity (PA) is required to identify current levels and changes in PA within a population, and to gauge effectiveness of interventions. Methods: The Online Self-reported Walking and Exercise Questionnaire (OSWEQ) was developed for monitoring PA via the Web. Forty-nine participants (mean ± SD; age = 27 ± 11.9yrs) completed the OSWEQ and International PA Questionnaire (IPAQ) short form 3 times [T1/T2/T3 (separated by 7-days)] and wore an Actigraph-GT3X-accelerometer for 7-days between T2-T3. For each measure, estimates of average MET·min·day -1 and time spent in moderate PA (MPA), vigorous PA (VPA) and moderate and vigorous PA (MVPA) were obtained. Results: The OSWEQ and IPAQ demonstrated test-retest reliability for MPA, VPA, and MVPA minutes and average MET·min·day -1 between T1-T2 (OSWEQ range, r = .71-.77; IPAQ range, r = .59-.79; all, P < .01). The OSWEQ and IPAQ, compared with the GT3X, had lower estimates (mean error ± 95% PI) of MVPA MET·min·day -1 by 150.4 ± 477.6 and 247.5 ± 477.5, respectively. Conclusions: The OSWEQ demonstrates good test-retest reliability over 7-days and better group level estimates of MET·min·day -1 than the IPAQ, compared with the GT3X. These results suggest that the OSWEQ is a reliable and valid measure among young/working age adults and could be useful for monitoring PA trends over time.

Given the obesity epidemic, it is critical to understand factors associated with youth physical activity and sedentary behavior at home, where youth spend significant time. We examined relationships between these child behaviors and home environment factors. Data were obtained from 713 children aged 6 to 11 in Washington and California 2007-2009. Multivariate regression analyses controlling for socio-demographics examined associations between parent-reported home environment factors and child&#39;s accelerometer-measured moderate-to-vigorous physical activity (MVPA) and sedentary time, overall and at home, and parent-reported child screen time. Children averaged 47.2% of time at home, which included 43.6% and 46.4% of overall MVPA and sedentary behavior, respectively. Parental support for physical activity and having a basketball hoop were positively associated with MVPA and negatively associated with sedentary behavior. Combined parental support and a basketball hoop was associated...

To study correlates of change in BMI percentile and body fat among adolescent girls. A longitudinal prospective study following 265 girls from the Trial of Activity for Adolescent Girls (TAAG) cohort measured in 8th grade and during 10 and 11th grade or 11th and 12th grade. Twice during 2009-2011 girls wore an accelerometer and completed a food frequency questionnaire and 7-day diary documenting trips and food eaten away from home and school. Physical activity, BMI, and percent body fat were objectively measured at each time point. Moderate to vigorous physical activity (MVPA) declined, but the change was not independently associated with changes in BMI percentile. Increased vigorous physical activity was associated with reductions in body fat. Diet was associated with both changes in BMI percentile and body fat. Girls who increased the percentage of caloric intake from snacks and desserts reduced their BMI percentile and body fat. Some relationships between energy balance behaviors...

The study aimed to establish the test-retest reliability and convergent validity of PlayerLoad™ (triaxial-accelerometer data) during a standardized bout of treadmill running. Forty-four team-sport players performed 2 standardized incremental treadmill running tests (7-16 km/h) 7 d apart. Players&#39; oxygen uptake (VO2; n = 20), heart rate (n = 44), and triaxialaccelerometer data (PlayerLoad; n = 44) measured at both the scapulae and at the center of mass (COM), were recorded. Accelerometer data from the individual component planes of PlayerLoad (anteroposterior [PLAP], mediolateral [PLML], and vertical [PLV]) were also examined. Moderate to high test-retest reliability was observed for PlayerLoad and its individual planes (ICC .80-.97, CV 4.2-14.8%) at both unit locations. PlayerLoad was significantly higher at COM vs scapulae (223.4 ± 42.6 vs 185.5 ± 26.3 arbitrary units; P = .001). The percentage contributions of individual planes to PlayerLoad were higher for PLML at the COM (sc...

The five-times-sit-to-stand test (FTSS) is an established assessment of lower limb strength, balance dysfunction and falls risk. Clinically, the time taken to complete the task is recorded with longer times indicating increased falls risk. Quantifying the movement using tri-axial accelerometers may provide a more objective and potentially more accurate falls risk estimate. 39 older adults, 19 with a history of falls, performed four repetitions of the FTSS in their homes. A tri-axial accelerometer was attached to the lateral thigh and used to identify each sit-stand-sit phase and sit-stand and stand-sit transitions. A second tri-axial accelerometer, attached to the sternum, captured torso acceleration. The mean and variation of the root-mean-squared amplitude, jerk and spectral edge frequency of the acceleration during each section of the assessment were examined. The test-retest reliability of each feature was examined using intra-class correlation analysis, ICC(2,k). A model was developed to classify participants according to falls status. Only features with ICC > 0.7 were considered during feature selection. Sequential forward feature selection within leave-one-out cross-validation resulted in a model including four reliable accelerometer-derived features, providing 74.4% classification accuracy, 80.0% specificity and 68.7% sensitivity. An alternative model using FTSS time alone resulted in significantly reduced classification performance. Results suggest that the described methodology could provide a robust and accurate falls risk assessment. ß

Jackhammer manufacturers have recently developed lightweight (45-60 lbs) jackhammers intended to reduce the required lifting and pushing forces during operation. However, the vibration characteristics of the lightweight jackhammers and their effect on muscle activity are currently unknown. The objective of this study was to compare the measured vibration and muscle activity between: (i) conventional (90 lb) and light weight (60 lb) jackhammers, (ii) different pavement type/thickness combinations, and (iii) pneumatic and hydraulic jackhammers. Five jackhammers were tested on 4 and 6 inch thick asphalt and concrete pavements by four experienced operators. Analysis of the results revealed that both weight classes averaged 9.7 m/s(2) at the 20 Hz weighted 1/3 octave band frequency, and the TLV of daily exposure for either weight class of jackhammer was less than 1.5 hours/per day. There was an approximately 33% difference in vibration measured on the hand of the operators due to pavemen...

Posttraumatic stress disorder (PTSD) is reportedly associated with lower rates of physical activity participation despite the known benefits of regular physical activity for improving both mental and physical health. However, no studies have evaluated the validity or feasibility of assessing physical activity within this population resulting in uncertainty around the reported lower rates of physical activity participation. This study aimed to evaluate the feasibility and concurrent validity of the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and the Actigraph accelerometer (an objective physical activity monitor) among inpatients with PTSD. Fifty-nine adult hospital inpatients with a Diagnostic Statistical Manual Mental Disorder-IV-TR diagnosis of primary PTSD (mean age = 49.9 years; 85% male) participated in the study. Participants were asked to wear an Actigraph accelerometer for seven consecutive days then complete the IPAQ-SF. The Spearman rho correlation c...

There is no universally accepted definition of human joint stability, particularly in nonperiodic general activities of daily living. Instability has proven to be a difficult parameter to define and quantify, since both spatial and temporal measures need to be considered to fully characterize joint stability. In this preliminary study, acceleration-based parameters were proposed to characterize the joint stability. Several time-statistical parameters of acceleration and jerk were defined as potential stability measures, since anomalous acceleration or jerk could be a symptom of poor control or stability. An inertial measurement unit attached at the level of the tibial tubercle of controls and patients following total knee arthroplasty was used to determine linear acceleration of the knee joint during several activities of daily living. The resulting accelerations and jerks were compared with patient-reported instability as determined through a standard questionnaire. Several parameters based on accelerations and jerks in the anterior/posterior direction during the step-up/step-down activity were significantly different between patients and controls and correlated with patient reports of instability in that activity. The range of the positive to negative peak acceleration and infinity norm of acceleration, in the anterior/posterior direction during the step-up/step-down activity, proved to be the best indicators of instability. As time derivatives of displacement, these acceleration-based parameters represent spatial and temporal information and are an important step forward in developing a definition and objective quantification of human joint stability that can complement the subjective patient report.

Background. Body worn accelerometry has been shown to be reliable in measuring training Intensity in several sports including
MMA and has been used to assign training intensity in sports such as football and rugby, but not in MMA.
Material and methods. Eight male MMA trained participants (age 25.5 ± 4.5 yrs) were equipped with a Catapult Minimax x3
accelerometer between the T3 and T4 vertebrae and completed a series of MMA specific movements in isolation and a MMA
sparring bout each (3 x 5 minute rounds). Mean playerload was recorded for each isolated movement and the equivalent movements
in the sparring bouts.
Results. Paired sample t tests (p≤ 0.05) found that jabs, crosses and left hooks had significantly higher playerload in isolation
that in sparring, single leg takedowns have higher playerload than double leg takedowns in isolation but not in sparring, whilst
takedowns cause significantly greater playerload than strikes in both isolation and sparring according to one way ANOVA (p≤
0.05). It was also found that there is no difference in playerload between an unsuccessful takedown and a successful takedown
in sparring, either for the offensive participant or the defensive participant.
Conclusions. These results demonstrate the differences in movements in MMA and can be used to more accurately prescribe
training intensity.

Wearable and accompanied sensors and devices are increasingly being used for user activity recognition. However, typical GPS-based and accelerometer-based (ACC) methods face three main challenges: a low recognition accuracy; a coarse recognition capability, i.e., they cannot recognise both human posture (during travelling) and transportation mode simultaneously, and a relatively high computational complexity. Here, a new GPS and Foot-Force (GPS + FF) sensor method is proposed to overcome these challenges that leverages a set of wearable FF sensors in combination with GPS, e.g., in a mobile phone. User mobility activities that can be recognised include both daily user postures and common transportation modes: sitting, standing, walking, cycling, bus passenger, car passenger (including private cars and taxis) and car driver. The novelty of this work is that our approach provides a more comprehensive recognition capability in terms of reliably recognising both human posture and transportation mode simultaneously during travel. In addition, by comparing the new GPS + FF method with both an ACC method (62% accuracy) and a GPS + ACC based method (70% accuracy) as baseline methods, it obtains a higher accuracy (95%) with less computational complexity, when tested on a dataset obtained from ten individuals.