Walk this way: validity evidence of iphone health application step count in laboratory and free-living conditions

Several attempts have been made to demonstrate the accuracy of the iPhone pedometer function in laboratory test conditions. However, no studies have attempted to evaluate evidence of convergent validity of the iPhone step counts as a surveillance tool in the field. This study takes a pragmatic approach to evaluating Health application derived iPhone step counts by measuring accuracy of a standardized criterion iPhone SE and a heterogeneous sample of participant owned iPhones (6 or newer) in a laboratory condition, as well as comparing personal iPhones to accelerometer derived steps in a free-living test. During lab tests, criterion and personal iPhones differed from manually counted steps by a mean bias of less than ±5% when walking at 5km/h, 7.5km/h and 10km/h on a treadmill, which is generally considered acceptable for pedometers. In the free-living condition steps differed by a mean bias of 21.5% or 1340 steps/day when averaged across observation days. Researchers should be cautioned in considering the use of iPhone models as a research grade pedometer for physical activity surveillance or evaluation, likely due to the iPhone not being continually carried by participants; if compliance can be maximized then the iPhone might be suitable.     

Wear compliance,sedentary behaviour and activity in free-living children from hip-and wrist-mounted ActiGraph GT3X+ accelerometers

The GT3X+ worn at the wrist promotes greater compliance than at the hip. Minutes in SB and PA calculated from raw accelerations at the hip and wrist provide contrasting estimates and cannot be directly compared.

Wear-time for the wrist (15.6 to 17.4 h.d^?1) was greater than the hip (15.2 to 16.8 h.d^?1) across several wear-time criteria (all P < 0.05). Moderate-strong associations were found between time spent in SB (r = 0.39), LPA (r = 0.33), MPA (r = 0.99), VPA (r = 0.82) and MVPA (r = 0.81) between the two device placements (All P < 0.001). The wrist device detected more minutes in LPA, MPA, VPA and MVPA whereas the hip detected more SB (all P = 0.001). Estimates of time in SB and all activity outcomes from the wrist and hip lacked equivalence.

One hundred and eighty-eight 9–12-year-old children wore a wrist- and hip-mounted accelerometer for 7 days. Data were available for 160 (hip) and 161 (wrist) participants. Time spent in SB and PA was calculated using GGIR.

This study examined the compliance of children wearing wrist- and hip-mounted ActiGraph GT3X+ accelerometers and compared estimates of sedentary behaviour (SB) and physical activity (PA) between devices.     

基于加速度计与GPS探索儿童青少年在不同场所的身体活动情况

目的 探索儿童青少年在不同场所的身体活动,为国内儿童青少年身体活动环境的营造提供依据.方法 采用系统文献综述法,以关键词"physical activity""GPS""accelerometer/accelerometry""children/adoles-cents/young people"在SportDiscu...     

Running patterns for male and female competitive and recreational runners based on accelerometer data

The purpose of this study was to classify runners in sex-specific groups as either competitive or recreational based on center of mass (CoM) accelerations. Forty-one runners participated in the study (25 male and 16 female), and were labeled as competitive or recreational based on age, sex, and race performance. Three-dimensional acceleration data were collected during a 5-minute treadmill run, and 24 features were extracted. Support vector machine classification models were used to examine the utility of the features in discriminating between competitive and recreational runners within each sex-specific subgroup. Competitive and recreational runners could be classified with 82.63 % and 80.4 % in the male and female models, respectively. Dominant features in both models were related to regularity and variability, with competitive runners exhibiting more consistent running gait patterns, but the specific features were slightly different in each sex-specific model. Therefore, it is important to separate runners into sex-specific competitive and recreational subgroups for future running biomechanical studies. In conclusion, we have demonstrated the ability to analyze running biomechanics in competitive and recreational runners using only CoM acceleration patterns. A runner, clinician, or coach may use this information to monitor how running patterns change as a result of training.     

Physical activity levels,game performance and friendship goals using two different pedagogical models: Sport Education and Direct Instruction

Background: Advances in technology have changed children’s lifestyle so much that the majority of them do not meet the recommended 60 min of moderate to vigorous physical activity every day. Compulsory Physical Education has been highlighted as an ideal context to achieve the suggested physical activity (PA) goals, since it could be the only place where some students become truly physically active. In those classes, the teacher selects a pedagogical approach and this selection could be vital to meet the advised PA levels.

Purpose: The goal was to assess the effects of two instructional approaches, Sport Education Model (SEM) and Direct Instruction (DI) in Primary Education students’ physical activity intensity levels, game performance, and friendship goals.

Method: A total of 88 students with an average age of 11.16?±?0.63 years, enrolled in two year-5 (from 10 to11 years) and two year-6 (from 11 to 12 years) Physical Education classes of the same school agreed to participate. The number of participants in the SEM was 47 and in DI was 41. The schools’ administration distributed one class of each grade to the experimental group, which experienced SEM, and to the non-equivalent group, which experienced DI. The content selected for both study groups was the same: Handball. Both study groups experienced a 15-session learning unit (45 min per class, three sessions per week). The goal was to conduct the experiment in a non-manipulated (intact) educational context. It followed a pre-test, post-test, experimental, non-equivalent group design. Participants wore Actigraph GT3X accelerometers in order to monitor physical activity levels, answered questionnaires to assess friendship goals, and their game performance was assessed using the Game Performance Assessment instrument (GPAI).

Results: Results showed that students who experienced the SEM had significantly higher light and moderate physical activity levels, friendship-approach and friendship-avoidance goals, while the ones who experienced DI had significantly higher sedentary physical activity levels. The GPAI scores showed significant gains in students’ game performance in both study groups, but these were larger in the SEM one.

Conclusions: The SEM could be considered more effective than DI to improve Primary Education students’ PA levels, game performance and friendship goals.     

Comparing the standards of one metabolic equivalent of task in accurately estimating physical activity energy expenditure based on acceleration

The purpose of the study is to analyse how the standard of resting metabolic rate (RMR) affects estimation of the metabolic equivalent of task (MET) using an accelerometer. In order to investigate the effect on estimation according to intensity of activity, comparisons were conducted between the 3.5 ml O₂ · kg^?1 · min^?1 and individually measured resting VO₂ as the standard of 1 MET. MET was estimated by linear regression equations that were derived through five-fold cross-validation using 2 types of MET values and accelerations; the accuracy of estimation was analysed through cross-validation, Bland and Altman plot, and one-way ANOVA test. There were no significant differences in the RMS error after cross-validation. However, the individual RMR-based estimations had as many as 0.5 METs of mean difference in modified Bland and Altman plots than RMR of 3.5 ml O₂ · kg^?1 · min^?1. Finally, the results of an ANOVA test indicated that the individual RMR-based estimations had less significant differences between the reference and estimated values at each intensity of activity. In conclusion, the RMR standard is a factor that affects accurate estimation of METs by acceleration; therefore, RMR requires individual specification when it is used for estimation of METs using an accelerometer.     

女子羽毛球运动员后场击球后不同场区单脚落地的生物力学差异——基于三维加速度计的分析

为了探寻女子羽毛球运动员后场击球后单脚落地对膝关节前十字韧带损伤的影响,通过比较正手、反手场区头顶击球单脚落地时躯干加速度及运动变量的差异,寻求运动风险的变量因素。10名优秀女子羽毛球运动员穿戴三维加速计进行单打比赛,使用同步摄像机记录产生超过4g加速度的时刻,分析了加速度>4g时着陆点躯干倾斜角和髋关节外展角。结果显示:在头顶击球过程中,正手场区和反手场区的躯干侧弯及躯干加速度存在差异,反手区头顶击球时横向加速度大于正手区(P<0.05,es=0.706);反手场区单脚落地时躯干倾斜角(24°±7°)大于正手侧(17°±13°);正反手两侧躯干倾斜角均大于先前报道的受伤角度,反手侧的髋外展角(23°±11°)大于正手侧的髋外展角(-1°±8°);反手场区的3个轴的加速度与躯干侧弯、髋外展角度均呈显著相关性。反手场区头顶击球后,单脚落地姿势与前交叉韧带损伤的落地姿势相似,反手侧躯干过度侧弯和高风险落地姿势可能与羽毛球比赛中膝关节前十字韧带损伤有关。     

Physical activity and lipidomics in a population at high risk of type 2 diabetes mellitus

ABSTRACT

The aim was to investigate how measurements of the lipidome differ according to the level and intensity of physical activity in a population at high risk of type 2 diabetes (T2DM). A targeted metabolomics platform provided quantitative molecular data on lipid species. Linear regression examined the associations between plasma lipid concentrations, particle size and time spent in objectively measured physical activity intensity domains, in increments of 500 counts per minute (cpm) (up to >4500 cpm (~>5.6METs)). Results are presented as % difference in the concentration (lower/higher) or particle size (smaller/larger) per 10 min of activity within each intensity. Five hundred and nine participants were included. Time spent in the lowest physical activity intensity domain (<500 cpm) was unfavourably associated with VLDL (2%), HDL (?2%) and Apolipoprotein A-1 particle concentrations (?2%) and HDL diameter (?2%). Conversely, time spent in intensities ≥1000 cpm were favourably associated with HDL subclass concentrations; with stronger associations seen at moderate intensities (2000-3999 cpm (~4.5METs)). For Apolipoprotein-B concentration and VLDL particle concentration and size, a negative association was consistently observed at the highest physical activity intensity only. If these associations are causal, HDL subclasses appear sensitive to light-intensities whereas only the high category of physical activity intensity was consistently associated with VLDL subclasses.     

加速度计在儿童体力活动测量中的应用

加速度计是一种客观测量体力活动的工具,因其小巧轻便且不受受试者回忆准确性和认知水平的限制,近年来在儿童体力活动测量中得到广泛应用。然而到目前为止,较少有研究关注加速度计使用方法的标准化,如加速度计的选择、采样间隔、佩戴部位、佩戴时间的确定、数据处理等。针对儿童体力活动的特点,就上述问题做一综述,以期提供一些在加速度计使用中的实用性参考。