Validation of a body-worn accelerometer to measure activity patterns in octogenarians

OBJECTIVE: To determine the validity of a triaxial body-worn accelerometer for detection of gait and postures in people aged >80 years. DESIGN: Participants performed a range of activities (sitting, lying, walking, standing) in both a controlled and a home setting while wearing the accelerometer. Activities in the controlled setting were performed in a scripted sequence. Activities in the home setting were performed in an unscripted manner. Analyzed accelerometer data were compared against video observation as the reference measure. SETTING: Independent-living and long-term-care retirement village. PARTICIPANTS: Older people (N=22; mean age ± SD, 88.1±5y) residing in long-term-care and independent-living retirement facilities. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The level of agreement between video observation and the accelerometer for the total duration of each activity, and second-by-second correspondence between video observation and the accelerometer for each activity. RESULTS: The median absolute percentage errors between video observation and the accelerometer were <1% for locomotion and lying. The absolute percentage errors were higher for sitting (median, -22.3%; interquartile range [IQR], -62.8% to 10.7%) and standing (median, 24.7%; IQR, -7.3% to 39.6%). A second-by-second analysis between video observation and the accelerometer found an overall agreement of ≥85% for all activities except standing (median, 56.1%; IQR, 34.8%-81.2%). CONCLUSIONS: This single-device accelerometer provides a valid measure of lying and locomotion in people aged >80 years. There is an error of approximately 25% when discriminating sitting from standing postures, which needs to be taken into account when monitoring longer-term habitual activity in this age group.

Factors associated with higher sitting time in general, chronic disease, and psychologically-distressed, adult populations: findings from the 45 & up study

This study examined factors associated with higher sitting time in general, chronic disease, and psychologically-distressed, adult populations (aged ≥45 years). A series of logistic regression models examined potential socio-demographic and health factors associated with higher sitting (≥6hrs/day) in adults from the 45 and Up Study (n = 227,187), including four separate subsamples for analysis comprising those who had ever had heart disease (n = 26,599), cancer (n = 36,381), diabetes (n = 19,550) or psychological distress (n = 48,334). Odds of higher sitting were significantly (p<.01) associated with a number of factors across these groups, with an effect size of ORs≥1.5 observed for the high-income ≥$70,000AUD, employed full-time and severe physical limitations demographics. Identification of key factors associated with higher sitting time in this population-based sample will assist development of broad-based, public health and targeted strategies to reduce sitting-time. In particular, those categorized as being high-income earners, full-time workers, as well as those with severe physical limitations need to be of priority, as higher sitting appears to be substantial across these groups.

The impact and feasibility of introducing height-adjustable desks on adolescents' sitting in a secondary school classroom

Children spend over 60% of their school day sitting; much of this occurs in the classroom. Emerging research has examined the impact of environmental interventions on classroom sitting. While this research is promising, it has predominantly focused on the primary school setting. This study examined the impact and feasibility of height-adjustable desks on time spent sitting/standing during classroom lessons in a secondary school. Traditional desks in a Melbourne secondary school classroom were replaced with 27 height-adjustable desks (intervention classroom). Forty-three adolescents (51% male; mean age 13.7 ± 1.4 years) from Grades 7, 9 and 10 wore an inclinometer and accelerometer for schooldays and completed a survey after using the desks during lessons for seven weeks. Ten teachers (50% male) completed a survey. Time spent sitting, standing, and the length of sitting bouts were compared between periods when adolescents were in the intervention classroom versus traditional classrooms (matched on teacher and subject). Compared to the traditional classroom, adolescents spent 25% less time sitting and 24% more time standing in the intervention classroom (effect size > 0.8), and had a greater frequency of short sitting bouts and fewer longer bouts. The majority of teachers (71%) and students (70%) reported wanting to continue to use the height-adjustable desks. When standing during lessons, adolescents reported working well (69%); however, a third reported difficulties paying attention (28%) and becoming distracted (36%). Few teachers reported negative influences on adolescents’ ability to work (14%) and concentrate (14%). Half the adolescents reported leg, or back pain with standing. Introducing height-adjustable desks resulted in lower levels of sitting compared with traditional classrooms, was acceptable and had some adverse effects on concentration and discomfort. The study provides preliminary evidence that height-adjustable desks may help reduce prolonged sitting in school among adolescents. Future research should incorporate a control group and explore behavioural and academic outcomes.

Office workers' objectively assessed total and prolonged sitting time: individual-level correlates and worksite variations

Sedentary behavior is highly prevalent in office-based workplaces; however, few studies have assessed the attributes associated with this health risk factor in the workplace setting. This study aimed to identify the correlates of office workers' objectively-assessed total and prolonged (≥ 30 min bouts) workplace sitting time. Participants were 231 Australian office workers recruited from 14 sites of a single government employer in 2012-13. Potential socio-demographic, work-related, health-related and cognitive-social correlates were measured through a self-administered survey and anthropometric measurements. Associations with total and prolonged workplace sitting time (measured with the activPAL3) were tested using linear mixed models. Worksites varied significantly in total workplace sitting time (overall mean [SD]: 79% [10%] of work hours) and prolonged workplace sitting time (42% [19%]), after adjusting for socio-demographic and work-related characteristics. Organisational tenure of 3-5 years (compared to tenure > 5 years) was associated with more time spent in total and prolonged workplace sitting time, while having a BMI categorised as obese (compared to a healthy BMI) was associated with less time spent in total and prolonged workplace sitting time. Significant variations in sitting time were observed across different worksites of the same employer and the variation remained after adjusting for individual-level factors. Only BMI and organisational tenure were identified as correlates of total and prolonged workplace sitting time. Additional studies are needed to confirm the present findings across diverse organisations and occupations.

A cluster randomized controlled trial to reduce office workers' sitting time: impact on activity outcomes

PURPOSE: To evaluate, compared to usual practice, the initial and long-term effectiveness of a workplace intervention targeting reducing sitting on activity outcomes.

METHODS: Office worksites (≥1km apart) from a single organization in Victoria, Australia were cluster randomized to intervention (n=7) or control (n=7). Participants were 231 desk-based office workers (5 to 39 participants per worksite) working at least 0.6 full time equivalent. The workplace-delivered intervention addressed organizational, physical environment, and individual behavioural change to reduce sitting time. Assessments occurred at baseline, three-, and 12-months, with the primary outcome participants' objectively measured (activPAL3 device) workplace sitting time (mins/8-h workday). Secondary activity outcomes were: workplace time spent standing, stepping (light, moderate-vigorous and total) and in prolonged (≥30min) sitting bouts (h/8-h workday); usual duration of workplace sitting bouts; and, overall sitting, standing and stepping time (mins/16-h day). Analysis was by linear mixed models, accounting for repeated measures and clustering and adjusting for baseline values and potential confounders.

RESULTS: At baseline, on average, participants (68% women; mean±SD age = 45.6±9.4 years) sat, stood and stepped for 78.8±9.5%, 14.3±8.2%, and 6.9±2.9% of work hours respectively. Workplace sitting time was significantly reduced in the intervention group compared to the controls at three months (-99.1 [95% CI -116.3 to -81.8] min/8-h workday) and 12 months (-45.4 [-64.6 to -26.2] min/8-h workday). Significant intervention effects (all favoring intervention) were observed for standing, prolonged sitting, and usual sitting bout duration at work, as well as overall sitting and standing time, with no significant nor meaningful effects observed for stepping.

CONCLUSIONS: This workplace-delivered multicomponent intervention was successful at reducing workplace and overall daily sitting time in both the short- and long- term.

Analysis of compressive load on intervertebral joint in standing and sitting postures

BACKGROUND: There have been some disagreements on the comparison of disc pressures in the standing and sitting postures in literature. Most research on in vivo pressure needle measurement found higher disc pressure in sitting than in standing. The disc pressure data can help to advocate better postures for clinical advice. OBJECTIVE: The aim of this paper is to develop a procedure to study the compressive load on intervertebral joint in the standing and sitting postures through the approach of motion capture and musculoskeletal modeling. METHODS: The marker data of six subjects performing various standing and sitting postures was obtained during the motion capture experiment and used to train the musculoskeletal model with an enhanced discretized spine developed for subject in the inverse and forward simulations. RESULTS: Compressive loads on L3-L4 and L4-L5 joints are found higher in upright sitting than in upright standing. Slumped sitting, cross-legged sitting and flexion sitting can introduce higher compressive loads on intervertebral joints compared with upright sitting. CONCLUSIONS: These findings indicate the effects of standing and sitting postures on the spinal joint loads. The results can provide doctors and therapists with more information on clinical advice on better postures for people with spinal problems.

Criterion validity of the activPAL™ and ActiGraph for assessing children's sitting and standing time in a school classroom setting

BACKGROUND: Few studies have investigated the accuracy of the ActiGraph (AG) GTX3 accelerometer for assessing children's sitting and standing time. The activPAL (aP) has an inclinometer function that enables it to distinguish between sitting/lying and standing; however, its accuracy for assessing sitting and standing in older children is unknown. This study validated the accuracy of these devices for estimating sitting and standing time in a school classroom against a criterion measure of direct observation (DO).

FINDINGS: Forty children in grades 5-7 wore both devices while being video recorded during two school lessons. AG and aP data were simultaneously collected in 15-s epochs. Individual participant DO and aP data were recorded as total time spent sitting/lying, standing and stepping. AG data were converted into time spent sitting and standing using previously established cut-points. Compared with DO, the aP underestimated sitting time (mean bias = -1.9 min, 95 % LoA = -8.9 to 5.2 min) and overestimated standing time (mean bias = 1.8 min, 95% LoA = -9.6 to 13.3 min). The best-performing AG cut-point across both sitting and standing (<75 counts/15 s) was more accurate than the aP, underestimating sitting time (mean bias = -0.8 min, 95 % LoA = -10.5 to 9.9 min) and standing time (mean bias = -0.4 min, 95% LoA = -9.8 to 9.1 min), but was less precise as evidenced by wider LoAs and poorer correlations with DO (sitting r = 0.86 aP vs 0.80 AG; standing r = 0.78 aP vs 0.60 AG).

CONCLUSIONS: The aP demonstrated good accuracy and precision for assessing free-living sitting and standing time in classroom settings. The AG was most accurate using a cut-point of < 75 counts/15 s. Further studies should validate the monitors in settings with greater inter- and intra-individual variation in movement patterns.

Impact of an 8-month trial using height-adjustable desks on children's classroom sitting patterns and markers of cardio-metabolic and musculoskeletal health

During school hours, children can sit for prolonged and unbroken periods of time. This study investigated the impact of an 8-month classroom-based intervention focusing on reducing and breaking-up sitting time on children's cardio-metabolic risk factors (i.e., body mass index, waist circumference, blood pressure) and perceptions of musculoskeletal discomfort. Two Year-6 classes (24 students per class) in one primary school were assigned to either an intervention or control classroom. The intervention classroom was equipped with height-adjustable desks and the teacher was instructed in the delivery of pedagogical strategies to reduce and break-up sitting in class. The control classroom followed standard practice using traditional furniture. At baseline, and after 8-months, time spent sitting, standing, stepping, and sitting-bouts (occasions of continuous sitting) as well as the frequency of sit-to-stand transitions were obtained from activPAL inclinometers and the time spent in light-intensity physical activity was obtained from ActiGraph accelerometers. Demographics and musculoskeletal characteristics were obtained from a self-report survey. Hierarchical linear mixed models found that during class-time, children's overall time spent sitting in long bouts (>10 min) were lower and the number of sit-to-stand transitions were higher in the intervention group compared to the control group, while no changes were observed for musculoskeletal pain/discomfort. No significant intervention effects were found for the anthropometrics measures and blood pressure. Height-adjustable desks and pedagogical strategies to reduce/break-up sitting can positively modify classroom sitting patterns in children. Longer interventions, larger and varied sample size may be needed to show health impacts; however, these desks did not increase musculoskeletal pain/discomfort.

Who does not gain weight? Prevalence and predictors of weight maintenance in young women

OBJECTIVE: To investigate the prevalence and predictors of weight maintenance over time in a large sample of young Australian women.

DESIGN: This population study examined baseline and 4 y follow-up data from the cohort of young women participating in the Australian Longitudinal Study on Women's Health.

SUBJECTS: A total of 8726 young women aged 18-23 y at baseline.

MEASURES: Height, weight and body mass index (BMI); physical activity; time spent sitting; selected eating behaviours (eg dieting, disordered eating, takeaway food consumption); cigarette smoking, alcohol consumption; parity; and sociodemographic characteristics.

RESULTS: Only 44% of the women reported their BMI at follow-up to be within 5% of their baseline BMI (maintainers); 41% had gained weight and 15% had lost weight. Weight maintainers were more likely to be in managerial or professional occupations; to have never married; to be currently studying; and not to be mothers. Controlling for sociodemographic factors, weight maintainers were more likely to be in a healthy weight range at baseline, and to report that they spent less time sitting, and consumed less takeaway food, than women who gained weight.

CONCLUSIONS: Fewer than half the young women in this community sample maintained their weight over this 4 y period in their early twenties. Findings of widespread weight gain, particularly among those already overweight, suggest that early adulthood, which is a time of significant life changes for many women, may be an important time for implementing strategies to promote maintenance of healthy weight. Strategies which encourage decreased sitting time and less takeaway food consumption may be effective for encouraging weight maintenance at this life stage.

Growth of highly versus moderately trained competitive female artistic gymnasts

Purpose: To investigate whether growth was adversely affected in 137 young competitive female artistic gymnasts involved in different training volumes.

Methods: This was a 2-yr prospective cohort study in which height, sitting height, leg length, weight, skinfolds, and pubertal status were measured in competitive advanced (20–27 h·wk-1) and intermediate (7.5–22 h·wk-1) training level female gymnasts every 6–12 months. Biological parameters of the adolescent growth curve were estimated using the Preece–Baines growth model. Growth rates were estimated for both groups from the mixed-longitudinal data.

Results: Estimated ages at peak height velocity (PHV) (13–13.5 yr) and mean PHV (6.2–6.4 cm·yr-1) for the advanced- and intermediate-level gymnasts suggest that these gymnasts were later maturing and experienced a blunting of the growth spurt relative to reference values for U.S. youth. Comparison of growth velocities by pubertal status revealed that height velocity was lower in the advanced- versus the intermediate-level peripubertal gymnasts, which was due to a significant reduction in sitting height velocity (2.3 vs 3.1 cm·yr-1, P. < 0.05). No marked acceleration in height or sitting height velocity was detected in the advanced-level gymnasts from pre- to peripuberty. Inspection of individual growth rates revealed that over 35% of the pre- and peripubertal gymnasts experienced growth faltering (height velocity less than 4.5 cm·yr-1) during follow-up.

Conclusion: Advanced–and intermediate–training level competitive female gymnasts tend to exhibit an adolescent growth spurt that is similar in timing and tempo to short, normal, slowly maturing girls, but the high frequency of growth faltering suggests that training may alter the tempo of growth and maturation in some, but not all, female gymnasts.

Gait termination : a review of experimental methods and the effects of aging and gait pathologies

The study of human gait has expanded and diversified to the extent that it is now possible to identify a substantive literature concerning a variety of gait tasks, such as gait initiation [Halliday SE, Winter DA, Frank JS, Patla AE, Prince F. The initiation of gait in young, elderly, and Parkinson's disease subjects. Gait Posture 1998;8:8–14; Mickelborough J, van der Linden ML, Tallis RC, Ennos AR. Muscle activity during gait initiation in normal elderly people. Gait Posture 2004;19:50–57], stepping over and across obstacles [Patla AE, Prentice SD, Robinson C, Newfold J. Visual control of locomotion: strategies for changing direction and for going over obstacles. J Exp Psych 1991;17:603–34; Chen, HC, Ashton-Miller JA, Alexander NB, Schultz AB. Effect of age and available response time on ability to step over an obstacle. J Gerontol 1994;49:227–33; Sparrow WA, Shinkfield AJ, Chow S, Begg RK. Gait characteristics in stepping over obstacles. Hum Mov Sci 1996;15:605–22; Begg RK, Sparrow WA, Lythgo ND. Time-domain analysis of foot–ground reaction forces in negotiating obstacles. Gait Posture 1998;7:99–109; Patla AE, Rietdyk S. Visual control of limb trajectory over obstacles during locomotion: effect of obstacle height and width. Gait Posture 1993;1:45–60] negotiating raised surfaces such as curbs and stairs [Begg RK, Sparrow WA. Gait characteristics of young and older individuals negotiating a raised surface: implications for the prevention of falls. J Gerontol Med Sci 2000;55A:147–54; Mcfayden BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech 1988;21:733–44]. In addition, increasing research interest in age-related declines in gait that might predispose individuals to falls has engendered a very extensive literature concerning ageing effects on gait. While rapid locomotor adjustments are common in the course of daily activities there has been no previous review of the findings concerning gait adaptations when walking is terminated both rapidly and unexpectedly. The aims of this review were first, to summarise the key research findings and methodological considerations from studies of termination. The second aim was to demonstrate the effects of ageing and gait pathologies on termination with respect to the regulation of step characteristics, lower-limb muscle activation patterns and foot–ground reaction forces.

Penetration testing professional ethics : a conceptual model and taxonomy

In an environment where commercial software is continually patched to correct security flaws, penetration testing can provide organisations with a realistic assessment of their security posture. Penetration testing uses the same principles as criminal hackers to penetrate corporate networks and thereby verify the presence of software vulnerabilities. Network administrators can use the results of a penetration test to correct flaws and improve overall security. The use of hacking techniques, however, raises several ethical questions that centre on the integrity of the tester to maintain professional distance and uphold the profession. This paper discusses the ethics of penetration testing and presents our conceptual model and revised taxonomy.

Experimental study of ostensibly shamanic journeying imagery in naďve participants I: antecedents

The purpose of the present study was to investigate experimentally the antecedents of ostensibly shamanic journeying imagery associated with the Lower World in naïve participants. Forty six participants completed a composite questionnaire consisting of demographic items and the Tellegen Absorption Scale (Tellegen and Atkinson 1974). Participants were randomly assigned to one of five conditions: Harner's (1990) shamanic journeying to the Lower World instructions coupled with monotonous percussion drumming at either 4 or 8 beats-per-second for either 10 or 15 minutes; and sitting quietly with eyes closed for 15 minutes. Participants' phenomenology was retrospectively assessed using the Phenomenology of Consciousness Inventory (Pekala 1991) and a mental imagery checklist. The results indicated that there was a statistically significant difference between conditions with regards to the number of ostensibly shamanic journeying images. After adjusting for Harner's (1990) instructions, a significant main effect was found for both beats-per-second and time with regards to the number of ostensibly shamanic journeying images reported. There was a statistically significant relationship between condition and the tendency to report mental imagery associated with rocky ravines, predatory creatures, and rivers. Religious devotion was found to be a significant predictor of the number of ostensibly shamanic journeying images reported. Religious exposure and trait absorption were significant predictors of altered experience. Implications of the findings are discussed and suggestions for future research advanced.

Phenomenological analysis of experimentally induced visual mental imagery associated with shamanic journeying to the lower world

This study explored ostensibly shamanic journeying imagery by (a) assessing visual images across induction techniques (i.e., sonic driving, Ganzfeld, relaxation, and sitting with eyes open); (b) determining combination(s) of induction technique and instructions most associated with religious imagery; and (c) investigating the origins of visual imagery. Six participants were randomly assigned to factorial combinations of a 3 x 4 mixed design (levels of instruction x levels of induction) and were administered the Modified Affect Bridge to explore the origins of mental imagery reported during the experimental conditions. Phenomenological analysis yielded comprehensive constituent themes. Harner’s (1990) shamanic journeying, coupled with religious, instructions were associated with the highest religious imagery, while visual images associated with shamanic journeying were derived primarily from autobiographical memories.

Experimental study of ostensibly shamanic journeying imagery in naďve participants II: phenomenological mapping and modified affect bridge

This study develops the methodological framework advanced in Rock, Baynes, and Casey's (2005) experimental study of ostensibly shamanic journeying imagery in naïve participants. Specifically, the present study experimentally investigates the impact of the word landscape, featured in Harner's (1990) shamanic journeying to the Lower World instructions, on the number of landscape-related images reported; examines the origins of ostensibly shamanic journeying images; and maps the phenomenological state effects of shamanic journeying to the Lower World. Sixtyeight naïve participants were randomly assigned to one of three conditions: either the original or a revised version of Harner's (1990) instructions coupled with monotonous percussion drumming at 8 beats-per-second for 15 minutes, or sitting quietly with eyes open for 15 minutes. Each participant's subjective experience was retrospectively assessed using the Phenomenology of Consciousness Inventory (PCI) (Pekala 1991) and a mental imagery checklist. Subsequently, participants were administered the Modified Affect Bridge for the purpose of exploring the origins of mental imagery experienced during the experimental conditions. The results indicated that there was a statistically significant difference between conditions with regard to the number of ostensibly shamanic journeying images reported, but not between treatment conditions with regard to the number of landscaperelated images reported. There were no significant relationships between condition and mental imagery derived from autobiographical memories. There were statistically significant differences between conditions with regard to the PCI dimensions of fear, altered state of awareness, and arousal.