Advancing Use of DEXA Scans to Quantitatively and Qualitatively Evaluate Lateral Spinal Curves, for Preliminary Identification of Adolescent Idiopathic Scoliosis.

Dual-energy X-ray absorptiometry (DEXA) scan is an emerging screening method for identifying likely adolescent idiopathic scoliosis (AIS). Using DEXA in an unbiased population sample (the Raine Study), we aimed to report the inter-rater reliability and minimal detectable change (MDC95) for scoliosis curve angle measurement, identify likely AIS prevalence, and the concordance between reported AIS diagnosis and DEXA-identified likely AIS. Scoliosis curve angles were measured using the modified Ferguson method on DEXA scans (n = 1238) at age 20 years. For curve angle inter-rater reliability, two examiners measured angles (6-40°) on 41 scans. Likely, AIS was determined with quantitative and qualitative criteria (modified Ferguson angles ≥ 10° and expert review of spinal curves).The inter-rater reliability for scoliosis curve angle measurement was good-excellent (ICC: 0.82; 95% CI: 0.71-0.89; p < 0.001), and MDC95 was 6.2°. The prevalence of likely AIS was 2.1% (26/1238). Diagnosis of AIS was reported despite little or no scoliosis curve (< 3.8°) for 20 participants (1.6%), and diagnosis of AIS was not reported despite scoliosis curve ≥ 10° for 11 participants (0.9%). Results support the use of modified Ferguson method to measure scoliosis curve angles on DEXA. There is potential utility for using a combination of quantitative measurement and qualitative criteria to evaluate DEXA images, to identify likely AIS for reporting prevalence. Without formal school screening, the analysis of DEXA in this population sample suggested that relying on current health professional diagnosis alone could result in 2.5% of this cohort being at risk of false positive diagnosis or delay in necessary management due to non-diagnosis of AIS.

Physical activity trajectories from childhood to late adolescence and their implications for health in young adulthood.

Physical activity has been associated with physical and mental health across the life course, yet few studies have used group-based trajectory modeling to examine the effect of longitudinal patterns of physical activity during childhood and adolescence on adult health outcomes. The Raine Study data from Gen2 follow-ups at 8, 10, 14, 17, 20, and 22 years collected between 1998 and 2014 were used. Latent class analysis identified trajectories using parent-reported physical activity for ages 8 to 17. Associations between trajectories and physical and mental health outcomes at ages 20 and 22 were explored, adjusting for current physical activity and considering sex interactions. Analysis in 2019 identified three trajectories: low (13%), mid (65%) and high (22%) physical activity (n = 1628). Compared to the low-activity trajectory, those in the high-activity trajectory had lower adiposity, insulin, HOMA-IR and fewer diagnosed disorders, higher HDL-cholesterol, and faster cognitive processing. For example, those in the high-activity trajectory had lower percent body fat at age 20 compared to those in the mid-activity (-4.2%, 95%CI: -5.8, -2.7) and low-activity (-9.5%, 95%CI: -11.7, -7.2) trajectories. Physical activity trajectories showed different associations between sexes for self-reported physical and mental health, BMI, systolic blood pressure, and depression symptoms. Being in the high- or mid-activity trajectory was associated with a more favorable cardiometabolic and mental health profile in young adulthood. Strategies are needed to help less active children to increase physical activity throughout childhood and adolescence to improve young adult health outcomes.

Evaluating the effectiveness of organisational-level strategies with or without an activity tracker to reduce office workers' sitting time: a cluster-randomised trial.

BACKGROUND: Office workers engage in high levels of sitting time. Effective, context-specific, and scalable strategies are needed to support widespread sitting reduction. This study aimed to evaluate organisational-support strategies alone or in combination with an activity tracker to reduce sitting in office workers. METHODS: From one organisation, 153 desk-based office workers were cluster-randomised (by team) to organisational support only (e.g., manager support, emails; 'Group ORG', 9 teams, 87 participants), or organisational support plus LUMOback activity tracker ('Group ORG + Tracker', 9 teams, 66 participants). The waist-worn tracker provided real-time feedback and prompts on sitting and posture. ActivPAL3 monitors were used to ascertain primary outcomes (sitting time during work- and overall hours) and other activity outcomes: prolonged sitting time (≥30 min bouts), time between sitting bouts, standing time, stepping time, and number of steps. Health and work outcomes were assessed by questionnaire. Changes within each group (three- and 12 months) and differences between groups were analysed by linear mixed models. Missing data were multiply imputed. RESULTS: At baseline, participants (46 % women, 23-58 years) spent (mean ± SD) 74.3 ± 9.7 % of their workday sitting, 17.5 ± 8.3 % standing and 8.1 ± 2.7 % stepping. Significant (p < 0.05) reductions in sitting time (both work and overall) were observed within both groups, but only at 12 months. For secondary activity outcomes, Group ORG significantly improved in work prolonged sitting, time between sitting bouts and standing time, and overall prolonged sitting time (12 months), and in overall standing time (three- and 12 months); while Group ORG + Tracker, significantly improved in work prolonged sitting, standing, stepping and overall standing time (12 months). Adjusted for confounders, the only significant between-group differences were a greater stepping time and step count for Group ORG + Tracker relative to Group ORG (+20.6 min/16 h day, 95 % CI: 3.1, 38.1, p = 0.021; +846.5steps/16 h day, 95 % CI: 67.8, 1625.2, p = 0.033) at 12 months. Observed changes in health and work outcomes were small and not statistically significant. CONCLUSIONS: Organisational-support strategies with or without an activity tracker resulted in improvements in sitting, prolonged sitting and standing; adding a tracker enhanced stepping changes. Improvements were most evident at 12 months, suggesting the organisational-support strategies may have taken time to embed within the organisation. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry: ACTRN12614000252617 . Registered 10 March 2014.

An active video game intervention does not improve physical activity and sedentary time of children at-risk for developmental coordination disorder: a crossover randomized trial.

BACKGROUND: Children with developmental coordination disorder (DCD) are highly inactive and sedentary. The purpose of this study was to assess the impact of a home-based active video game intervention on objectively measured physical activity and sedentary behaviour in children at risk for DCD. METHODS: In a crossover randomized clinical trial, 21 children (mean age 11.0, SD 1.0; n = 11 girls) in Perth, Western Australia participated in two 16-week periods: no active video games (AVGs) control period and AVGs intervention period. Two active input consoles were provided to participants along with a selection of non-violent AVGs for participants to play at home. Participants wore accelerometers at baseline and following each period to determine minutes of sedentary, light, moderate and vigorous times in addition to self-reported types of activities in a diary. Linear mixed models, adjusted for the order of periods, compared physical activity and sedentary time during the last week of each period. RESULTS: There were no significant differences between the intervention and control periods in time spent in sedentary (decrease of -1.0 min/day during the intervention period, 95%CI -12.1, 10.1), light (increase of 2.2 min/day, 95%CI -8.8, 13.2), moderate (decrease of 0.7 min/day, 95%CI -4.6, 3.3) or vigorous (decrease of -0.6 min/day, 95%CI -1.6, 0.4). CONCLUSIONS: Among children at risk for DCD, participating in this AVG intervention did not improve objectively measured physical activity and sedentary time.

A crossover randomised and controlled trial of the impact of active video games on motor coordination and perceptions of physical ability in children at risk of Developmental Coordination Disorder.

BACKGROUND: Impaired motor development can significantly affect a child's life and may result in an increased risk of a range of physical and psychological disorders. Active video game (AVG) interventions have been demonstrated to enhance motor skills in children with Developmental Coordination Disorder (DCD); however a home-based intervention has not been assessed. OBJECTIVES: The primary aim of this study was to compare the changes in motor coordination between a 16 week period of AVG use, with 16 weeks of normal activities (NAG). The secondary aim was to compare the child and parent perceptions of their physical performance between the AVG and NAG conditions. METHODS: Twenty-one 9-12 year olds (10 males) were confirmed to be at risk of DCD (⩽ 16th percentile Movement Assessment Battery for Children-2nd edition (MABC-2) and ⩽ 15th percentile Developmental Coordination Disorder Questionnaire (DCDQ)) and participated in this crossover randomised and controlled trial. Data was collected at study entry, after the first 16 week condition and following the final 16 week condition, including; (1) the MABC-2, (2) three-dimensional motion analysis of single leg balance and finger-nose tasks, and (3) parent perception of physical skills. Participant perception of physical skills was collected only after the first and second conditions. RESULTS: There was no significant difference between AVG and NAG for any of the primary variables including the MABC-2, balance centre-of-mass path distance and finger-nose path distance. There was no significant intervention effect for secondary measures of motor coordination; however the children perceived their motor skills to be significantly enhanced as a result of the AVG intervention in comparison to the period of no intervention. CONCLUSION: A 16 week home based AVG intervention did not enhance motor skills in children with DCD, although they perceived their physical skills to be significantly improved. TRIAL REGISTRATION: Australia and New Zealand Clinical trials Registry (ACTRN 12611000400965).

Overweight adolescents eat what? And when? Analysis of consumption patterns to guide dietary message development for intervention.

BACKGROUND: Little is known about overweight adolescent dietary consumption patterns, with challenges to collecting meaningful data making it difficult to develop targeted obesity interventions. The present study aimed to examine the timing and consumption of fruit, vegetables and junk food by time of the day and day of the week. METHODS: Overweight adolescents (n = 61), aged 12-16 years, completed 3-day food records. Negative binomial and binary logistic regression using generalised estimating equations were used to compare the amount and likelihood of the consumption of each food group between time periods. RESULTS: Overweight adolescent girls were more likely to eat fruit on weekdays than weekends [odds ratio (OR) = 5.0. P < 0.001], as were boys (OR = 2.5, P = 0.034). Adolescents consumed more fruit at school than other meals [girls: incident rate ratio (IRR) = 7.5, P < 0.001; boys: IRR = 4.0, P = 0.050]. Weekday dinner was the meal where girls were most likely to consume vegetables (OR = 3.0, P = 0.009) and when boys consumed the most vegetables (IRR = 30.9, P = 0.006). Fast food consumption was most likely for girls at dinner on the weekend (OR = 9.6, P = 0.042), whereas fast food intake for boys increased overall on the weekend (IRR = 3.6, P = 0.001). Intake of 'other junk' (e.g. crisps) peaked during school hours for girls (IRR = 7.2, P < 0.001) and sugar-sweetened beverage consumption increased for boys on the weekend (IRR = 3.3, P = 0.001). Overall, trends in fruit intake showed opposing times for high and low consumption compared to vegetable intake. CONCLUSIONS: These results represent the next step in using time of day and day of week consumption patterns to develop targeted, evidence-based dietary messages for interventions in overweight adolescents.

A workplace exercise versus health promotion intervention to prevent and reduce the economic and personal burden of non-specific neck pain in office personnel: protocol of a cluster-randomised controlled trial.

INTRODUCTION: Non-specific neck pain is a major burden to industry, yet the impact of introducing a workplace ergonomics and exercise intervention on work productivity and severity of neck pain in a population of office personnel is unknown. RESEARCH QUESTION: Does a combined workplace-based best practice ergonomic and neck exercise program reduce productivity losses and risk of developing neck pain in asymptomatic workers, or decrease severity of neck pain in symptomatic workers, compared to a best practice ergonomic and general health promotion program? DESIGN: Prospective cluster randomised controlled trial. PARTICIPANTS AND SETTING: Office personnel aged over 18 years, and who work>30 hours/week. INTERVENTION: Individualised best practice ergonomic intervention plus 3×20 minute weekly, progressive neck/shoulder girdle exercise group sessions for 12 weeks. CONTROL: Individualised best practice ergonomic intervention plus 1-hour weekly health information sessions for 12 weeks. MEASUREMENTS: Primary (productivity loss) and secondary (neck pain and disability, muscle performance, and quality of life) outcome measures will be collected using validated scales at baseline, immediate post-intervention and 12 months after commencement. PROCEDURE: 640 volunteering office personnel will be randomly allocated to either an intervention or control arm in work group clusters. ANALYSIS: Analysis will be on an 'intent-to-treat' basis and per protocol. Multilevel, generalised linear models will be used to examine the effect of the intervention on reducing the productivity loss in dollar units (AUD), and severity of neck pain and disability. DISCUSSION: The findings of this study will have a direct impact on policies that underpin the prevention and management of neck pain in office personnel.

Reducing occupational sedentary time: a systematic review and meta-analysis of evidence on activity-permissive workstations.

Excessive sedentary time is detrimentally linked to obesity, type 2 diabetes, cardiovascular disease and premature mortality. Studies have been investigating the use of activity-permissive workstations to reduce sedentary time in office workers, a highly sedentary target group. This review systematically summarizes the evidence for activity-permissive workstations on sedentary time, health-risk biomarkers, work performance and feasibility indicators in office workplaces. In July 2013, a literature search identified 38 relevant peer-reviewed publications. Key findings were independently extracted by two researchers. The average intervention effect on sedentary time was calculated via meta-analysis. In total, 984 participants across 19 field-based trials and 19 laboratory investigations were included, with sample sizes ranging from n = 2 to 66 per study. Sedentary time, health-risk biomarkers and work performance indicators were reported in 13, 23 and 23 studies, respectively. The pooled effect size from the meta-analysis was -77 min of sedentary time/8-h workday (95% confidence interval = -120, -35 min). Non-significant changes were reported for most health- and work-related outcomes. Studies with acceptability measures reported predominantly positive feedback. Findings suggest that activity-permissive workstations can be effective to reduce occupational sedentary time, without compromising work performance. Larger and longer-term randomized-controlled trials are needed to understand the sustainability of the sedentary time reductions and their longer-term impacts on health- and work-related outcomes.

Gender differences in the relationships between lean body mass, fat mass and peak bone mass in young adults.

UNLABELLED: The relationships between fat mass and bone mass in young adults are unclear. In 1,183 young Australians, lean body mass had a strong positive relationship with total body bone mass in both genders. Fat mass was a positive predictor of total body bone mass in females, with weaker association in males. INTRODUCTION: Body weight and lean body mass are established as major determinants of bone mass, but the relationships between fat mass (including visceral fat) and peak bone mass in young adults are unclear. The aim of this study was to evaluate the associations between bone mass in young adults and three body composition measurements: lean body mass, fat mass and trunk-to-limb fat mass ratio (a surrogate measure of visceral fat). METHODS: Study participants were 574 women and 609 men aged 19-22 years from the Raine study. Body composition, total body bone mineral content (TBBMC), bone area and areal bone mineral density (TBBMD) were measured using DXA. RESULTS: In multivariate linear regression models with height, lean body mass, fat mass and trunk-to-limb fat mass ratio as predictor variables, lean mass was uniquely associated with the largest proportion of variance of TBBMC and TBBMD in males (semi-partial R(2) 0.275 and 0.345, respectively) and TBBMC in females (semi-partial R(2) 0.183). Fat mass was a more important predictor of TBBMC and TBBMD in females (semi-partial R(2) 0.126 and 0.039, respectively) than males (semi-partial R(2) 0.006 and 0.018, respectively). Trunk-to-limb fat mass ratio had a weak, negative association with TBBMC and bone area in both genders (semi-partial R(2) 0.004 to 0.034). CONCLUSIONS: Lean body mass has strong positive relationship with total body bone mass in both genders. Fat mass may play a positive role in peak bone mass attainment in women but the association was weaker in men; different fat compartments may have different effects.

Does the Animal Fun program improve motor performance in children aged 4-6 years?

The Animal Fun program was designed to enhance the motor ability of young children by imitating the movements of animals in a fun, inclusive setting. The efficacy of this program was investigated through a randomized controlled trial using a multivariate nested cohort design. Pre-intervention scores were recorded for 511 children aged 4.83 years to 6.17 years (M=5.42 years, SD=3.58 months). Six control and six intervention schools were compared 6 months later following the intervention, and then again at 18 months after the initial testing when the children were in their first school year. Changes in motor performance were examined using the Bruininks-Oseretsky Test of Motor Proficiency short form. Data were analyzed using multi-level-mixed effects linear regression. A significant Condition×Time interaction was found, F(2,1219)=3.35, p=.035, demonstrating that only the intervention group showed an improvement in motor ability. A significant Sex×Time interaction was also found, F(2,1219)=3.84, p=.022, with boys improving over time, but not girls. These findings have important implications for the efficacy of early intervention of motor skills and understanding the differences in motor performance between boys and girls.

The influence of age, gender and other information technology use on young people's computer use at school and home.

Young people are exposed to a range of information technologies (IT) in different environments, including home and school, however the factors influencing IT use at home and school are poorly understood. The aim of this study was to investigate young people's computer exposure patterns at home and school, and related factors such as age, gender and the types of IT used. 1351 children in Years 1, 6, 9 and 11 from 10 schools in metropolitan Western Australia were surveyed. Most children had access to computers at home and school, with computer exposures comparable to TV, reading and writing. Total computer exposure was greater at home than school, and increased with age. Computer activities varied with age and gender and became more social with increased age, at the same time parental involvement reduced. Bedroom computer use was found to result in higher exposure patterns. High use of home and school computers were associated with each other. Associations varied depending on the type of IT exposure measure (frequency, mean weekly hours, usual and longest duration). The frequency and duration of children's computer exposure were associated with a complex interplay of the environment of use, the participant's age and gender and other IT activities.

Genetic variation in the beta-2 adrenergic receptor is associated with chronic musculoskeletal complaints in adolescents.

BACKGROUND: There is significant evidence to suggest that psychological and stress-related factors are important predictors of the onset of chronic widespread pain (CWP) and fibromyalgia (FM). The hypothalamic-pituitary-adrenal axis, together with the efferent sympathetic/adrenomedullary system, influence all body organs (including muscles) during short- and long-term threatening stimuli. The aim of this study was to investigate the relationship between genetic variants in adrenergic candidate genes and chronic musculoskeletal complaints (MSCs) in adolescents. METHODS: Adolescents from the Western Australian Pregnancy (Raine) Cohort attending the 17-year cohort review completed a questionnaire containing a broad range of psychosocial factors and pain assessment (n = 1004). Blood samples were collected for DNA extraction and genotyping. Genotype data was obtained for 14 single nucleotide polymorphisms (SNPs) in two candidate genes - beta-2 adrenergic receptor (ADRB2) and catecholamine-O-methyltransferase (COMT). Haplotypes were reconstructed for all individuals with genotype data. RESULTS AND CONCLUSION: Both female gender and poor mental health were associated with (1) an increased risk for chronic, disabling comorbid neck and low back pain (CDCP); and (2) an increase in the number of areas of pain. Of the 14 SNPs evaluated, only SNP rs2053044 (ADRB2, recessive model) displayed an association with CDCP [odds ratio (OR) = 2.49; 95% confidence interval (CI) = 1.25, 4.98; p = 0.01] and pain in three to four pain areas in the last month (OR = 1.86; 95% CI = 1.13, 3.06; p = 0.02). These data suggest that genetic variants in ADRB2 may be involved in chronic MSCs.

'I am absolutely shattered': the impact of chronic low back pain on Australian Aboriginal people.

BACKGROUND: Aboriginal people in Australia have been uniquely identified as less susceptible to chronic low back pain (CLBP) disability when compared to non-Aboriginal populations, reportedly due to cultural beliefs about pain. A qualitative, culturally secure research approach was used to explore this assumption. METHODS: In-depth interviews were undertaken with 32 Aboriginal men and women with CLBP in regional and remote areas of Western Australia. Interviews were conducted collaboratively with male and female Aboriginal co-investigators, and with the support of local Aboriginal community organizations. A primary focus was to investigate the impact of CLBP from the perspective of Aboriginal people living with the condition. RESULTS: The experience of CLBP was found to be multidimensional, impacting on activities of daily life, employment, sport and family participation, emotional and cultural well-being. CONCLUSIONS: Contrary to previous assumptions, CLBP is profoundly disabling for some Aboriginal people and a priority health concern. Issues of gender, cultural obligations and the emotional consequences of CLBP are important consideration for health care. These findings, and the contextual approach used to gain an in-depth understanding of CLBP, may be relevant to populations elsewhere.

A proposed model representing the relationships between user characteristics, computer exposure and musculoskeletal symptoms in children.

UNLABELLED: Children's computer exposure is rapidly growing. Several studies have suggested children using computers may be at risk of developing musculoskeletal symptoms. General models and theories relating to the causality of negative musculoskeletal outcomes in adult workers demonstrated relationships between workplace factors and musculoskeletal outcomes. When examining children's computer exposure it is evident that their use is different. Even though risk factors may be similar, due to the nature of children and their computer environments, the potential risk factors and thus a proposed model of causal relationships between exposure and outcomes may differ. OBJECTIVE: To develop a model of factors influencing computer exposure and musculoskeletal symptoms in children. METHODS: 1351 children (or their parents for Year 1 children) in school Years 1, 6, 9 and 11 (ages ~ 6,11,14,16 years) from 10 schools in Western Australia were surveyed on a range of user characteristics, computer exposure and musculoskeletal symptoms. RESULTS: Potential risk factors for childrens' computer exposure and musculoskeletal outcomes were multivariable. Factors such as age, gender, somatic complaints, flow, computer anxiety, computer, TV and physical activity exposure, and SES were related to computer exposure and children's reports of musculoskeletal symptoms. SIGNIFICANCE: Developing a child-related computer exposure model to understand relationships between potential risk factors and musculoskeletal symptoms will assist academics, teachers and parents to develop a better understanding of the risk factors for children's computer exposure.

Differences in scapular and humeral head position between swimmers and non-swimmers.

The aims of this study were to determine differences between swimmers/non-swimmers, males/females and dominant/non-dominant sides for scapular and humeral head position, while accounting for size, and to determine the relationship between scapular and humeral head position. 46 teenage swimmers (30 females) and 43 non-swimmers (28 females) were measured. The distances between (a) medial spine of the scapula and T3/4 (Superior Kibler), (b) inferior scapula and T7/8 (Inferior Kibler) and (c) anterior acromion and anterior humeral head were recorded while teenagers stood with their hands-on hips. There was no main effect difference between swimmers and non-swimmers for scapular or humeral head position. There were interactions for swim status/dominance (Superior Kibler; P=0.005, Inferior Kibler; P<0.001) and swim status/gender (Superior Kibler; P=0.027). The humeral head was significantly further from the acromion on the dominant side (adjusted mean difference=1.4 mm, P=0.004). Little relationship between scapular and humeral head position was evident. Clinicians should be aware that swim status, in combination with gender or dominance may affect scapular position but does not affect humeral head position. Where swimming had an effect, it minimized differences between genders and sides. The small dominance effect on the humeral head position is unlikely to be clinically detectable.

Neck/shoulder pain is more strongly related to depressed mood in adolescent girls than in boys.

A cross-sectional study of 1258, 14 year old girls and boys used self-report and physical examination measures to assess neck/shoulder pain in the last month, depressed mood, physical fitness, body composition, self-efficacy, global self-worth, family functioning and social advantage. The data was used to compare the relationship between depressed mood and neck/shoulder pain (NSP) in adolescent girls and boys. The prevalence of NSP in girls (34%, 211/621) was significantly greater than in boys (21%, 134/637; p < .001). After controlling for covariates, girls with medium (OR = 4.28; CI = 2.31-7.92; p < .001) and high depressed mood (OR = 8.63; CI = 4.39-16.98; p < .001) were significantly more likely to report NSP than girls with low depressed mood. Depressed mood was also a significant correlate of NSP in boys after controlling for covariates, although the association was substantially weaker (OR = 2.44; CI = 1.29-4.61; p < .001). After controlling for relevant biological, psychological and social covariates, depressed mood was a significant correlate of NSP in both sexes; but the association between depressed mood and NSP was significantly stronger for girls than for boys.

Evidence-based guidelines for the wise use of computers by children: physical development guidelines.

Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.

Examining pacing profiles in elite female road cyclists using exposure variation analysis.

OBJECTIVE: In this study, the amplitude and time distribution of power output in a variety of competitive cycling events through the use of a new mathematical analysis was examined: exposure variation analysis (EVA). DESIGN: Descriptive field study. SETTING: Various professional road cycling events, including; a 5-day-eight-stage tour race, a 1-day World Cup event and the Australian National Individual Time Trial Championships. PARTICIPANTS: 9 elite female cyclists (mean (SD), mass = 57.8 (3.4) kg, height = 167.3 (2.8) cm, Vo(2)peak = 63.2 (5.2) ml kg(-1) min(-1)). INTERVENTIONS: None. MAIN OUTCOME MEASUREMENTS: The variation in power output and the quantification of the total time and acute time spent at various exercise intensities during competitive professional cycling were examined. Predefined levels of exercise intensity that elicited first ventilation threshold, second ventilation threshold and maximal aerobic power were determined from a graded exercise test performed before the events and compared with power output during each event. RESULTS: EVA exposed that power output during the time trial was highly variable (EVA(SD) = 2.81 (0.33)) but more evenly distributed than the circuit/criterium (4.23 (0.31)) and road race events (4.81 (0.96)). CONCLUSION: EVA may be useful for illustrating variations in the amplitude and time distribution of power output during cycling events. The specific race format influenced not only the overall time spent in various power bands, but also the acute time spent at these exercise intensities.

Principles for the wise use of computers by children.

Computer use by children at home and school is now common in many countries. Child computer exposure varies with the type of computer technology available and the child's age, gender and social group. This paper reviews the current exposure data and the evidence for positive and negative effects of computer use by children. Potential positive effects of computer use by children include enhanced cognitive development and school achievement, reduced barriers to social interaction, enhanced fine motor skills and visual processing and effective rehabilitation. Potential negative effects include threats to child safety, inappropriate content, exposure to violence, bullying, Internet 'addiction', displacement of moderate/vigorous physical activity, exposure to junk food advertising, sleep displacement, vision problems and musculoskeletal problems. The case for child specific evidence-based guidelines for wise use of computers is presented based on children using computers differently to adults, being physically, cognitively and socially different to adults, being in a state of change and development and the potential to impact on later adult risk. Progress towards child-specific guidelines is reported. Finally, a set of guideline principles is presented as the basis for more detailed guidelines on the physical, cognitive and social impact of computer use by children. The principles cover computer literacy, technology safety, child safety and privacy and appropriate social, cognitive and physical development. The majority of children in affluent communities now have substantial exposure to computers. This is likely to have significant effects on child physical, cognitive and social development. Ergonomics can provide and promote guidelines for wise use of computers by children and by doing so promote the positive effects and reduce the negative effects of computer-child, and subsequent computer-adult, interaction.

Effect of visual display height on modelled upper and lower cervical gravitational moment, muscle capacity and relative strain.

Head and neck posture is an important factor in neck pain related to computer use; however, the evidence for an optimal posture is unconvincing. This study measured the 3-D postures of 36 young adults during use of three different display heights. Cervical extensor muscle strain was estimated using modelled gravitational load moments and muscle capacities. The influence of more or less upper vs. lower cervical movement was also explored across a broad range of potential postures. Overall cervical extensor muscle capacity diminished away from a neutral posture whilst gravity moment increased with flexion. Overall cervical extensor muscle strain increased with head flexion but remained stable into head extension. Individual differences in the amount of upper and lower cervical movement had an important effect on strain, particularly for some muscles. Computer display height guidelines are an important component of ergonomics practice, yet the relative strain on neck extensor muscles as a function of display height has not been examined. The current findings provide more detailed biomechanical evidence that ergonomists can incorporate with usability and other evidence to determine appropriate display height recommendations.