Comparison of the RT3 Research Tracker and Tritrac R3D accelerometers during a backpacking expedition by a single subject

This study compared the RT3 Research Tracker accelerometer and the Tritrac R3D accelerometer in a field setting. A six-day backpacking expedition (122.4 km in length) was completed by a single subject in the Grand Canyon National Park, Arizona. The overall correlation between the counts of vector magnitude activity for the RT3 and R3D was moderate (r =.75, p<.001), with the overall calculated bias [mean difference (RT3 minus R3D) and standard deviation of the differences] across all six days estimated at 235+/-436 vector magnitude activity counts. However, agreement between the instruments is problematic; the RT3 might be 201 activity counts below or 671 activity counts above the R3D in assessing physical activity during backpacking.     

Reliability and validity of the tritrac-R3D accelerometer during backpacking: a case study.

This study investigated the utility of the Tritrac-R3D accelerometer as a reliable and valid instrument in the quantification of physical activity while backpacking in the field and to evaluate heart-rate responses and oxygen consumption to assess the feasibility of using the Tritrac-R3D to estimate caloric expenditure. Two 7-day backpacking expeditions were conducted in two consecutive years by a single subject at Grand Canyon National Park, Arizona. The average hiking heart rate ranged front 60% to 77% HRmax during the expeditions. The average rate of estimated caloric cost ranged from 6.8 to 11.7 kcals x min.(-1) (equivalent to 408 to 702 kcals x hr.(-1)), indicating a relatively moderate to high level of exertion. The Tritrac had adequate consistency and reliability in the field between the two expeditions in recorded activity counts. The Tritrac underestimated caloric expenditure during backpacking with changes in terrain, and hiking speed contributed to even greater disparity in accuracy.     

Walking Before and During a Sea Voyage

Stationary and moving surfaces impose different constraints on walking. In this study we investigated within-participants differences between walking on a ship before (at the dock) and during (at sea) a sea voyage. Four individuals participated in the study. While on the ship they wore a tri-axial accelerometer (ActiGraph GT3X+; ActiGraph LLC, Pensacola, FL) on their waists. Activity data were sampled at 30 Hz. Data were collected on the day before the voyage began and on several days at sea. The number of steps per day was greater at the dock than at sea. The net resultant force per day also was greater at the dock than at sea. However, resultant force per step was greater at sea (79.97 ± 8.50 vector magnitude counts/step) than on land (62.94 ± 10.03 vector magnitude counts/step). In addition, we observed variations in resultant force per step across days at sea. Ship motion decreased overall activity but increased the force per step.     

Relationship between a pulmonary function test (FEV1) and the ADAPT quality-of-life scale

In a previous study the Additive Daily Activities Profile Test (ADAPT) correlated .83 with maximum oxygen consumption among pulmonary rehabilitation patients. The present study expanded the pulmonary population base and compared the ADAPT scores of 41 patients at two independent centers with a more readily available parameter, the forced expiratory volume in the first second of forced exhalation (FEV1). The relationships between the two major ADAPT subscales and FEV1 were significant but lower in magnitude than that found with maximum oxygen consumption. The ADAPT continues to be sensitive to physical impairment and in translating the effect of impairment upon daily physical activity.     

Comparative interinstrument reliability of uniaxial and triaxial accelerometers in free-living conditions

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

Individual classification of elementary school children’s physical activity: A time-efficient,group-based approach to reference measurements

The objective measurement of physical activity using accelerometers is becoming increasingly popular. There is little consensus, however, about how to analyze acceleration data. One promising approach is the use of reference measurements in which the subjects conduct specific activities. This makes it possible to identify data patterns that indicate these activities for each subject. The drawback of this approach is its rather high cost, in terms of both time and money. We propose a new approach in which a group of children conduct the reference measurements at the same time. We trained support vector machine models on the accelerometer data of 70 children (ages 8–11 years) to predict their activities during those reference measurements. We correctly classified activities with an accuracy of 96.9 % when fitting the individual models for each subject, and 87.5 % when fitting general models for all subjects. The obtained accuracies were comparable to results reported in previous reference measurement studies, in which each subject was measured individually. They were higher than the accuracies obtained by the traditional approach, which transfers accelerometer data to counts and classifies those on the basis of predefined cut points. We concluded that our approach can yield a valuable contribution, particularly to studies with larger samples.     

Use of electronic games by young children and fundamental movement skills?

This study investigated associations between pre-school children's time spent playing electronic games and their fundamental movement skills. In 2009, 53 children had physical activity (Actigraph accelerometer counts per minute), parent proxy-report of child's time in interactive and non-interactive electronic games (min./week), and movement skill (Test of Gross Motor Development-2) assessed. Hierarchical linear regression, adjusting for age (range = 3-6 years), sex (Step 1), and physical activity (cpm; M=687, SD=175.42; Step 2), examined the relationship between time in (a) non-interactive and (b) interactive electronic games and locomotor and object control skill. More than half (59%, n=31) of the children were female. Adjusted time in interactive game use was associated with object control but not locomotor skill. Adjusted time in non-interactive game use had no association with object control or locomotor skill. Greater time spent playing interactive electronic games is associated with higher object control skill proficiency in these young children. Longitudinal and experimental research is required to determine if playing these games improves object control skills or if children with greater object control skill proficiency prefer and play these games.     

Sleep duration associates with moderate-to-vigorous intensity physical activity and body fat in 1- to 3-year-old children

Sleep during early childhood is important for many developmental outcomes and shows promise as an important correlate of both obesity risk and physical activity behaviors. This was a cross-sectional study concerning the relationships between sleep and moderate- to – vigorous intensity physical activity and body fat percentage in a sample of 1- to 3-year-old children (N = 50; ages 27.512 ± 10.363 months). Sleep was measured with a caregiver questionnaire. Sedentary time, light, moderate, vigorous, and moderate- to – vigorous intensity physical activity were measured with Actigraph wT3x-BT accelerometers. Body fat was measured using Air Displacement Plethysmography with the BodPod Pediatric Option. Moderate- to – vigorous intensity physical activity and body fat percentage both associated with sleep duration, controlling for age and accelerometer wear time. These factors combined explained 54.3 % of the variance in sleep duration present in the sample. These results suggest the presence of relationships between sleep and physical activity and body composition constructs in this sample. Sleep may be an important variable in efforts to both promote early childhood physical activity and healthy body composition.     

Physical fitness differences between athletes and nonathletes: Do changes occur as a function of age and sex?

The main objectives were to determine (a) if physical fitness superiority of athletes over nonathletes increases as a function of age, and (b) if the magnitude of athlete-nonathlete fitness differences are the same in males as in females, and if these differences are consistent across ages. Approximately 3,000 students in grades 3, 7, and 11 (ages 9, 13, and 17 years) were tested on measures of static and explosive muscular strength, static and dynamic muscular endurance, cardiovascular endurance, and flexibility. MANOVA and follow-up univariate ANOVAs indicated that the higher the grade, the better the performance; males outperformed females on all measures except flexibility; and athletes were superior to nonathletes on all six test items. Furthermore, (a) there was no difference between athletes and nonathletes at grade 3, athletes were considerably better than nonathletes by grade 7, and the magnitude of the difference was virtually the same at grade 11, (b) the fitness superiority of athletes over nonathletes was essentially of the same magnitude for males as for females at each grade level.     

International physical activity questionnaire: reliability and validity of the Turkish version

Physical inactivity is a global problem which is related to many chronic health disorders. Physical activity scales which allow cross-cultural comparisons have been developed. The goal was to assess the reliability and validity of a Turkish version of the International Physical Activity Questionnaire (IPAQ). 1,097 university students (721 women, 376 men; ages 18-32) volunteered. Short and long forms of the IPAQ gave good agreement and comparable 1-wk. test-retest reliabilities. Caltrac accelerometer data were compared with IPAQ scores in 80 participants with good agreement for short and long forms. Turkish versions of the IPAQ short and long forms are reliable and valid in assessment of physical activity.     

Psychosocial mediators of a lifestyle physical activity intervention in women

ObjectivesA lifestyle physical activity intervention in women based on the transtheoretical model and social–cognitive theory effectively increased physical activity. The aim of the present study was to examine possible mediators (perceived benefits and barriers of physical activity, self-efficacy, processes of change, and social support) of these physical activity changes.MethodsMembers of four units of a women's organization followed a six-month minimal-contact physical activity program. The intervention program included one group meeting, a self-help booklet and five monthly reminder letters. Members of two other units served as control group. Physical activity (accelerometer counts), and psychosocial constructs (self-report questionnaires) were assessed at baseline (pretest) and directly after the intervention (posttest). Women who completed all measurements (n = 101) were included in the mediation analyses.ResultsParticipants in the intervention group reported significantly greater increases in the use of behavioral processes from pretest to posttest than participants in the control group. None of the proposed psychosocial constructs showed a mediating effect on changes in physical activity.ConclusionsThe mechanisms proposed by the transtheoretical model and social–cognitive theory could not explain the positive effect of the intervention on physical activity. Identifying the working components of an intervention remains a challenging and necessary step in the development of effective low-cost and high-reach physical activity interventions.     

三维动静态场景下返回抑制的扩散

使用虚拟现实技术探讨三维动静态空间下返回抑制是否敏感于深度线索及返回抑制效应是否存在空间扩散。采用线索−靶子范式,分别设置三维静态和动态场景。结果发现：三维静态场景,不同深度及不同侧位置均发生返回抑制且产生效应大小有差异;三维动态场景,不同线索条件反应时无显著差异。结果表明,三维静态场景下,返回抑制敏感于深度线索,其效应在空间中存在扩散;客体运动破坏了返回抑制的产生及其效应的空间扩散。     

Consistency in physiological stress responses and electromyographic activity during induced stress exposure in women and men

Physiological responses serve the role as objective indicators of stress as well as a link between psychosocial stress and various health outcomes. The aim of the present exposure session was to compare different physiological stress responses (systolic and diastolic blood pressure, heart rate, urinary epinephrine and norepinephrine, salivary cortisol) as well as trapezius muscle activity, measured by surface electromyography, during mental and physical stress in 11 women and ten men. The results show significantly increased activity in all measures but cortisol and significant associations between sympathetic arousal and EMG activity. The association between sympathetic arousal and muscle activity is of importance for understanding the high prevalence of musculoskeletal disorders in mentally stressful but physically light work tasks. Men had higher blood pressure and a more pronounced increase in epinephrine output than women, whereas women had higher heart rate. It was concluded that sympathetic activity is more sensitive to moderately intense stress exposure than pituitary adrenocortical (cortisol) activity and that men respond to performance stress with more epinephrine output than women. Although the correlations between the different indicators of sympathetic arousal were high, together they could still only explain 30–70% of the inter-individual variance. Thus, several parameters are needed in order to obtain a reliable measure of sympathetic activity.     

Consistency in Physiological Stress Responses and Electromyographic Activity during Induced Stress Exposure in Women and Men

Physiological responses serve the role as objective indicators of stress as well as a link between psychosocial stress and various health outcomes. The aim of the present exposure session was to compare different physiological stress responses (systolic and diastolic blood pressure, heart rate, urinary epinephrine and norepinephrine, salivary cortisol) as well as trapezius muscle activity, measured by surface electromyography, during mental and physical stress in 11 women and ten men. The results show significantly increased activity in all measures but cortisol and significant associations between sympathetic arousal and EMG activity. The association between sympathetic arousal and muscle activity is of importance for understanding the high prevalence of musculoskeletal disorders in mentally stressful but physically light work tasks. Men had higher blood pressure and a more pronounced increase in epinephrine output than women, whereas women had higher heart rate. It was concluded that sympathetic activity is more sensitive to moderately intense stress exposure than pituitary adrenocortical (cortisol) activity and that men respond to performance stress with more epinephrine output than women. Although the correlations between the different indicators of sympathetic arousal were high, together they could still only explain 30-70% of the inter-individual variance. Thus, several parameters are needed in order to obtain a reliable measure of sympathetic activity.     

Does domain-specific time perspective predict accelerometer assessed physical activity? An examination of ecological moderators

ObjectivesThe primary objective of this study was to examine the association between time perspective (domain-general or domain-specific) and accelerometer-assessed physical activity behavior in ecological conditions (i.e., ambient temperature and precipitation levels) that vary in the implementational opportunities that they provide.DesignProspective observational study.MethodsThe study sample consisted of 208 community dwelling residents, free of functional impairments, stratified by age. Physical activity was assessed using a hip mounted tri-axial accelerometer worn during waking hours for 7 consecutive days. Participants completed the time perspective questionnaire, exercise version (TPQ-E) at baseline, to assess tendencies toward present versus future-oriented thinking about physical activity behavior. Ecological support for physical activity was assessed as average weekly temperature and precipitation patterns for the week that the accelerometer was worn by each participant.ResultsFindings revealed main effects of both temperature and time perspective on accelerometer-assessed physical activity. Most importantly, there was also a significant two way interaction between domain-specific time perspective and temperature, such that future-oriented individuals were more likely to increase their activity level when temperatures were warmer (and therefore more activity-supportive) than their less future-oriented counterparts. Precipitation level was not associated with activity level alone or in combination with time perspective.ConclusionsThe effect of domain specific-time perspective on accelerometer assessed physical activity is moderated by ambient temperature. In the current study, present and future-oriented participants were active at similar levels when temperatures were cool; when conditions were warmer (i.e., more supportive of physical activity) those with more future-oriented time perspectives were more active than their present-oriented counterparts. These effects were invariant by age group.     

On the nature and function of scoring protocols used in exercise motivation research: An empirical study of the behavioral regulation in exercise questionnaire

ObjectivesThe purpose of this study was to examine the effects of different scoring protocols used with instruments designed to assess motivation in line with Organismic Integration Theory (OIT; Deci & Ryan, 2002).DesignThis study used non-probability based sampling within a cross-sectional (survey) design.MethodsParticipants across four samples (N's ranged from 236 to 1200) completed either (a) the Behavioral Regulation in Exercise Questionnaire (BREQ), (b) the BREQ-2, or (c) the BREQ-2R in conjunction with a self-report assessment of physical activity behavior.ResultsParticipants endorsed more self-determined than controlled motives for physical activity. Identified regulation was the dominant correlate of more frequent physical activity behavior. The link between external regulation and physical activity was consistently weak. Multiple regression analyses revealed identified regulation was the strongest predictor of physical activity compared with other motives. Regression models using omnibus scoring protocols accounted for less variance in physical activity behavior in contrast to an item-aggregation scoring protocol.ConclusionsIdentified regulation may be a key source of physical activity motivation in adults. The scoring protocol used with OIT-based instruments represents an important consideration for advancing physical activity research.     

Timing and reaction time.

Because reaction time (RT) tasks are generally repetitive and temporally regular, participants may use timing strategies that affect response speed and accuracy. This hypothesis was tested in 3 serial choice RT experiments in which participants were presented with stimuli that sometimes arrived earlier or later than normal. RTs increased and errors decreased when stimuli came earlier than normal, and RTs decreased and errors increased when stimuli came later than normal. The results were consistent with an elaboration of R. Ratcliff's diffusion model (R. Ratcliff, 1978; R. Ratcliff & J. N. Rouder, 1998; R. Ratcliff, T. Van Zandt, & G. McKoon, 1999), supplemented by a hypothesis developed by D. Laming (1979a, 1979b), according to which participants initiate stimulus sampling before the onset of the stimulus at a time governed by an internal timekeeper. The success of this model suggests that timing is used in the service of decision making.     

情绪、情绪调节策略与情绪材料记忆的关系

研究采用实验法,以288名中小学生为被试,考察了不同情绪状态、不同情绪调节策略与不同类型情绪材料记忆的关系。结果表明:(1)快乐情绪的再认反应时短于悲伤情绪,快乐情绪的再认正确率高于悲伤情绪。(2)表达抑制策略下,词汇与图片的再认反应时无显著差异;认知重评策略下,词汇的再认反应时短于图片;对词汇和图片的再认反应时,认知重评组短于表达抑制组;认知重评组的再认正确率高于表达抑制组。(3)快乐材料再认反应时短于悲伤材料;快乐情绪下快乐材料的再认正确率高于悲伤材料,悲伤情绪下悲伤材料的再认正确率高于快乐材料。     

R34D1NG W0RD5 W1TH NUMB3R5

Letter identities and number identities are usually thought to imply different cortical mechanisms. Specifically, the left fusiform gyrus responds more to letters than to digits (T. A. Polk et al., 2002). However, a widely circulated statement on the internet illustrates that it is possible to use numbers (leet digits) as parts of words, 4ND TH3 R35ULT1NG S3NT3NC3 C4N B3 R34D W1TH0UT GR34T 3FF0RT. Two masked priming lexical decision experiments were conducted to determine whether leet digits produce (automatic) lexical activation. Results showed that words are identified substantially faster when they are preceded by a masked leet word (M4T3R14L-MATERIAL) than when they are preceded by a control condition with other letters or digits. In addition, there was only a negligible advantage of the identity condition over the related leet condition. This leet-priming effect is not specific to numbers: A prime in which leet digits are replaced by letter-like symbols (M(Delta symbol)T(euro symbol)R!(Delta symbol)L - MATERIAL) facilitates word processing to the same degree as an identity prime. Therefore, the cognitive system regularizes the shape of the leet digits and letter-like symbols embedded in words with very little cost.     

Agreement rates for sleep/wake judgments obtained via accelerometer and sleep diary: A comparison

Agreement rates for waking and sleeping obtained via sleep diary and accelerometer were evaluated, to compare the two methods. Sleep/wake data for consecutive days and nights were surveyed in 119 healthy university students. Accelerometer sleep/wake judgments obeyed the standard algorithm. Agreement rates for waking and sleeping according to accelerometer versus sleep diary, respectively, were calculated. Sleep diary data were set as a baseline. Seventy-six subjects (63.9%), 22 to 32 years of age, presented perfect data for the analysis. The mean sleep times, in minutes, judged by sleep diary and by accelerometer, were 482.3 and 629.6, respectively. The mean percentages and standard deviations of agreement on wake and sleep were 77.5% (SD=10.2) and 86.1% (SD=6.2), respectively. There was a significant negative relationship between the agreement rates for wake and sleep (r=−.482, p<.01). The accelerometer showed some measurement failure during waking, presumably because of the decrease in body movement. Sleep diary data during daytime appear to be more valid for detecting a sleep/wake cycle than are accelerometer data. In contrast, nocturnal sleep diary data might be supplemented by the use of an accelerometer as long as participants do not have insomnia.