Search

Sleep is essential to life. Accurate measurement and classification of sleep/wake and sleep stages is important in clinical studies for sleep disorder diagnoses and in the interpretation of data from consumer devices for monitoring physical and mental well-being. Existing non-polysomnography sleep classification techniques mainly rely on heuristic methods developed in relatively small cohorts. Thus, we aimed to establish the accuracy of wrist-worn accelerometers for sleep stage classification and subsequently describe the association between sleep duration and efficiency (proportion of total time asleep when in bed) with mortality outcomes. We developed a self-supervised deep neural network for sleep stage classification using concurrent laboratory-based polysomnography and accelerometry. After exclusion, 1113 participant nights of data were used for training. The difference between polysomnography and the model classifications on the external validation was 48.2 min (95% limits of agreement (LoA): −50.3 to 146.8 min) for total sleep duration, −17.1 min for REM duration (95% LoA: −56.7 to 91.0 min) and 31.1 min (95% LoA: −67.3 to 129.5 min) for NREM duration. The sleep classifier was deployed in the UK Biobank with ~100,000 participants to study the association of sleep duration and sleep efficiency with all-cause mortality. Among 66,262 UK Biobank participants, 1644 mortality events were observed. Short sleepers (<6 h) had a higher risk of mortality compared to participants with normal sleep duration 6–7.9 h, regardless of whether they had low sleep efficiency (Hazard ratios (HRs): 1.36; 95% confidence intervals (CIs): 1.18 to 1.58) or high sleep efficiency (HRs: 1.29; 95% CIs: 1.04–1.61). Deep-learning-based sleep classification using accelerometers has a fair to moderate agreement with polysomnography. Our findings suggest that having short overnight sleep confers mortality risk irrespective of sleep continuity. [ABSTRACT FROM AUTHOR]

Advice to limit or avoid a flexed lumbar curvature during lifting is widely promoted to reduce the risk of low back pain (LBP), yet there is very limited evidence to support this relationship. To provide higher quality evidence this study compared intra-lumbar flexion in manual workers with (n = 21) and without a history of LBP (n = 21) during a repeated lifting task. In contrast to common expectations, the LBP group demonstrated less peak absolute intra-lumbar flexion during lifting than the noLBP group [adjusted difference −3.7° (95%CI −6.9 to −0.6)]. The LBP group was also further from the end of range intra-lumbar flexion and did not use more intra-lumbar range of motion during any lift condition (both symmetrical and asymmetrical lifts and different box loads). Peak absolute intra-lumbar flexion was more variable in the LBP group during lifting and both groups increased their peak absolute intra-lumbar flexion over the lift repetitions. This high-quality capture of intra-lumbar spine flexion during repeated lifting in a clinically relevant cohort questions dominant safe lifting advice. Practitioner summary: Lifting remains a common trigger for low back pain (LBP). This study demonstrated that people with LBP, lift with less intra-lumbar flexion than those without LBP. Providing the best quality in-vivo laboratory evidence, that greater intra-lumbar flexion is not associated with LBP in manual workers, raising questions about lifting advice. [ABSTRACT FROM AUTHOR]

Objective The purpose of this study was to determine whether sagittal neck sitting posture subgroup membership in late adolescence was a risk factor for persistent neck pain (PNP) in young adults. Methods There were 686 participants enrolled in the Raine Study at the 17- and 22-year follow-ups. At 17 years of age, posture was measured by photographs, and 4 subgroups of sitting neck posture were determined by cluster analysis. Height and weight were measured, and exercise frequency, depression, and PNP were assessed by questionnaire. At 22 years of age, participants answered questions about neck pain and occupation type. Logistic regression examined if neck posture subgroups at 17 years of age were a risk factor for PNP at 22 years of age, taking into account other factors. Results Female sex (odds ratio [OR] = 1.75, 95% CI = 1.16–2.65) and PNP at 17 years of age (OR = 3.78, 95% CI = 2.57–5.57) were associated with PNP at 22 years of age. In females, neck posture subgroup at 17 years of age was a risk factor for PNP at 22 years of age. Compared with the upright subgroup, both the slumped thorax/forward head subgroup groups and the intermediate subgroup had decreased odds for PNP at 22 years of age (OR = 0.24, 95% CI = 0.08–0.76; OR = 0.38, 95% CI = 0.15–0.99, respectively). No association was found in males. Conclusion After taking into account PNP at 17 years, sitting neck posture at 17 was not a risk factor for PNP at 22 years of age in males, whereas in females, more relaxed postures (slumped thorax/forward head and Intermediate postures) were protective of neck pain compared with upright posture. Impact Females in late adolescence who sat in slumped thorax/forward head or intermediate posture rather than upright sitting posture had a lower risk of PNP as a young adult. The practice of generic public health messages to sit up straight to prevent neck pain needs rethinking. [ABSTRACT FROM AUTHOR]

* OBJECTIVE: To evaluate whether lumbar spine flexion during lifting is a risk factor for low back pain (LBP) onset/persistence or a differentiator of people with and without LBP. * DESIGN: Etiology systematic review with metaanalysis. * LITERATURE SEARCH: Database search of ProQuest, CINAHL, MEDLINE, and Embase up to August 21,2018. * STUDY SELECTION CRITERIA: We included peer-reviewed articles that investigated whether lumbar spine position during lifting was a risk factor for LBP onset or persistence or a differentiator of people with and without LBP. * DATA SYNTHESIS: Lifting-task comparison data were tabulated and summarized. The meta-analysis calculated an n-weighted pooled mean ± SD of the results in the LBP and no-LBP groups. If a study contained multiple comparisons (ie, different lifting tasks that used various weights or directions), then only 1 result from that study was included in the meta-analysis. * RESULTS: Four studies (1 longitudinal study and 3 cross-sectional studies across 5 articles) included in meta-analysis measured lumbar flexion with intralumbar angles and found no difference in peak lumbar spine flexion when lifting (1.5°: 95% confidence interval [Cl]: -0.7°, 3.7°; P = .19 for the longitudinal study and -0.9°; 95% Cl: -2.5°, 0.7°; P = .29 for the cross-sectional studies). Seven cross-sectional studies measured lumbar flexion with thoracopelvic angles and found that people with LBP lifted with 5.0° less lumbar flexion than people without LBP (95% Cl: -11.2°, -0.9°; P = .02). Most (9/11) studies reported no significant between group differences in lumbar flexion during lifting. The included studies were of low quality. * CONCLUSION: There was low-quality evidence that greater lumbar spine flexion during lifting was not a risk factor for LBP onset/persistence or a differentiator of people with and without LBP. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study sought to explore factors in adults with cystic fibrosis (CF) that predicted whether (i) someone was engaged in full-time paid work, and (ii) those engaged in paid work reported problems with absenteeism and/or presenteeism. METHODS: Adults with cystic fibrosis who live in Western Australia completed absenteeism and presenteeism questions from the World Health Organization's Health Performance Questionnaire. The participants were grouped by work status (full time vs part time or unemployed) and by self-reported absenteeism and presenteeism (evidence of vs no evidence of). We explored whether factors such as air-flow obstruction, level of education, health-related quality of life (measured by using the Cystic Fibrosis Questionnaire--Revised), and treatment adherence predicted group membership. RESULTS: Of the 50 participants for whom data were available (median [interquartile range] age 30 [25-36] y; mean ± SD FEV1% predicted, 60 ± 18%); 34 (68%) worked full time. A higher education level increased the odds of working full time (odds ratio 1.74, 95% CI 1.36-1.89). Among the employed participants, problems with absenteeism and presenteeism were reported by 20 (47%) and 7 (16%), respectively. Both those who reported problems with absenteeism or presenteeism were characterized only by lower scores on the role domain of the Cystic Fibrosis Questionnaire--Revised (P = .02). CONCLUSIONS: In this study, the majority of adults with cystic fibrosis worked full time and a low percentage of the sample reported problems with absenteeism and presenteeism. [ABSTRACT FROM AUTHOR]

This study aimed to describe contemporary technology use, especially smartphones and tablets (mobile touch screen devices), and examine associations with musculoskeletal symptoms and visual health among adolescents in Singapore. A representative sample of 1884 adolescents (50.4% girls) from grades primary 5 to post-secondary (10–18 years old), recruited from 13 schools, completed an online questionnaire in class. Total technology use was high, with smartphone duration being highest (mean = 264 [SD = 243] min/day). Patterns of use, including multitasking and bout length, were influenced by gender, school level, type of device and activities. Musculoskeletal discomfort and visual symptoms were commonly reported. After adjusting for potential confounders, more hours/day of smartphone use was associated with increased risk of neck/shoulders, upper back, arms and wrist/hand discomfort (OR = 1.04[95%CI = 1.01–1.07] to 1.07[1.03–1.10]) and visual symptoms (OR = 1.05[1.02–1.08]), but was associated with decreased odds of myopia (OR = 0.97[0.94–0.99]). No significant associations were found for tablet use. Practitioner Summary: 1884 adolescents in Singapore completed an in-depth questionnaire regarding their use of technology. The smartphone was the device with the highest usage, and greater smartphone use was associated with increased odds of musculoskeletal and visual symptoms. High use of smartphones has physical health implications for adolescents. [ABSTRACT FROM AUTHOR]

Due to concerns about excessive sedentary exposure for office workers, alternate work positions such as standing are being trialled. However, prolonged standing may have health and productivity impacts, which this study assessed. Twenty adult participants undertook two hours of laboratory-based standing computer work to investigate changes in discomfort and cognitive function, along with muscle fatigue, movement, lower limb swelling and mental state. Over time, discomfort increased in all body areas (total body IRR [95% confidence interval]: 1.47[1.36-1.59]). Sustained attention reaction time (β = 18.25[8.00-28.51]) deteriorated, while creative problem solving improved (β = 0.89[0.29-1.49]). There was no change in erector spinae, rectus femoris, biceps femoris or tibialis anterior muscle fatigue; low back angle changed towards less  lordosis, pelvis movement increased, lower limb swelling increased and mental state decreased. Body discomfort was positively correlated with mental state. The observed changes suggest replacing office work sitting with standing should be done with caution. Practitioner Summary: Standing is being used to replace sitting by office workers; however, there are health risks associated with prolonged standing. In a laboratory study involving 2 h prolonged standing discomfort increased (all body areas), reaction time and mental state deteriorated while creative problem-solving improved. Prolonged standing should be undertaken with caution. [ABSTRACT FROM AUTHOR]

* STUDY DESIGN: Prospective cohort study of the Western Australian Pregnancy Cohort (Raine) Study. * BACKGROUND: Low back pain (LBP) commonly develops in adolescence and is a significant risk factor for adult LBP. A broad range of factors have been associated with the development of adolescent LBP, but prior literature has limitations related to characterization of LBP and the scope of risk factors considered. * OBJECTIVE: This study aimed to identify potential factors contributing to the development of LBP, with and without impact, at 17 years of age, utilizing a broad range of exposures at 14 years of age. * METHODS: Data from 1088 participants (52,1% female) with "no LBP," "LBP with minimal impact," and "LBP with impact" at 17 years of age and a range of measures from multiple domains, including spinal pain, physical, psychological, social, and lifestyle, at 14 years of age were collected for the study. Multivariable multinomial logistic regression was used to estimate the association of potential mechanistic factors at 14 years of age with LBP at 17 years of age. * RESULTS: Female sex and back pain at 14 years of age were strongly associated with LBP at 17 years of age. Potential mechanistic factors for LBP outcomes at 17 years of age included exposures from the pain (neck/shoulder pain) and physical domains (standing posture subgroup membership, back muscle endurance, throwing distance), psychological domain (somatic complaints, aggressive behavior), social domain (socioeconomic area), and lifestyle domain (exercise out of school). * CONCLUSION: The findings support the multidimensional nature of adolescent LBP and highlight the challenge this presents for epidemiological research, clinical practice, and prevention initiatives in the general population. * LEVEL OF EVIDENCE: Prognosis, level lb. [ABSTRACT FROM AUTHOR]

Background. There is conflicting evidence on the association between sagittal neck posture and neck pain. Objective. The purposes of this study were: (1) to determine the existence of clusters of neck posture in a cohort of 17-year-olds and (2) to establish whether identified subgroups were associated with biopsychosocial factors and neck pain. Design. This was a cross-sectional study. Methods. The adolescents (N= 1,108) underwent 2-dimensional photographic postural assessment in a sitting position. One distance and 4 angular measurements of the head, neck, and thorax were calculated from photo-reflective markers placed on bony landmarks. Subgroups of sagittal sitting neck posture were determined by cluster analysis. Height and weight were measured, and lifestyle and psychological factors, neck pain, and headache were assessed by questionnaire. The associations among posture subgroups, neck pain, and other factors were evaluated using logistic regression. Results. Four distinct clusters of sitting neck posture were identified: upright, intermediate, slumped thorax/forward head, and erect thorax/forward head. Significant associations between cluster and sex, weight, and height were found. Participants classified as having slumped thorax/forward head posture were at higher odds of mild, moderate, or severe depression. Participants classified as having upright posture exercised more frequently. There was no significant difference in the odds of neck pain or headache across the clusters. Limitations. The results are specific to 17-year-olds and may not be applicable to adults. Conclusion. Meaningful sagittal sitting neck posture clusters were identified in 17-year-olds who demonstrated some differences with biopsychosocial profiling. The finding of no association between cluster membership and neck pain and headaches challenges widely held beliefs about the role of posture in adolescent neck pain. [ABSTRACT FROM AUTHOR]

Fitness is an important component of health, and obese adolescents regularly have poor fitness. Unfortunately, few have assessed the impact of community-based lifestyle interventions on multiple components of fitness. The purpose of this study was to assess the impact of participation in a community-based intervention involving adolescents and parents on multiple components of fitness of obese adolescents. In a within-subject, waitlist controlled clinical trial with 12 months follow-up in Western Australia, participants (n = 56) completed multiple fitness measures at baseline, immediately prior to beginning an 8-week intervention and at 3, 6 and 12 months during a maintenance period. Performance on the shuttle walk was improved immediately post-intervention (increase of 42.8 m, 95% CI: 7.5, 78.2) and at 12 months post-intervention (increase of 44.6 m, 95% CI: 1.3, 87.8) compared with pre-intervention. Muscle performance of quadriceps and deltoids were improved post-intervention (increase of 1.1 (95% CI: 0.1, 2.1) kg · F and 1.0 (0.02, 2.1) kg · F, respectively) and all muscle performance measures were improved at 12 months following the intervention. There were no changes in waist circumference. A community-based lifestyle programme such as Curtin University’s Activity, Food and Attitudes Program (CAFAP) may be a viable strategy for improving fitness in overweight adolescents. [ABSTRACT FROM AUTHOR]

Background: To provide a detailed description of young adults' sedentary time and physical activity. Methods: 384 young women and 389 young men aged 22.1 ± 0.6 years, all participants in the 22 year old follow-up of the Raine Study pregnancy cohort, wore Actigraph GT3X+ monitors on the hip for 24 h/day over a one-week period for at least one 'valid' day (≥10 h of waking wear time). Each minute epoch was classified as sedentary, light, moderate or vigorous intensity using 100 count and Freedson cut-points. Mixed models assessed hourly and daily variation; t-tests assessed gender differences. Results: The average (mean ± SD) waking wear time was 15.0 ± 1.6 h/day, of which 61.4 ± 10.1 % was spent sedentary, 34.6 ± 9.1 % in light-, 3.7 ± 5.3 % in moderate- and, 0.3 ± 0.6 % in vigorous-intensity activity. Average time spent in moderate to vigorous activity (MVPA) was 36.2 ± 27.5 min/day. Relative to men, women had higher sedentary time, but also higher vigorous activity time. The 'usual' bout duration of sedentary time was 11.8 ± 4.5 min in women and 11.7 ± 5.2 min in men. By contrast, other activities were accumulated in shorter bout durations. There was large variation by hour of the day and by day of the week in both sedentary time and MVPA. Evenings and Sundays through Wednesdays tended to be particularly sedentary and/or inactive. Conclusion: For these young adults, much of the waking day was spent sedentary and many participants were physically inactive (low levels of MVPA). We provide novel evidence on the time for which activities were performed and on the time periods when young adults were more sedentary and/or less active. With high sedentary time and low MVPA, young adults may be at risk for the life-course sequelae of these behaviours. [ABSTRACT FROM AUTHOR]

Background: Relatively little is known about the relations between dietary patterns and bone health in adolescence, which is a period of substantial bone mass accrual. Objectives: We derived dietary patterns that were hypothesized to be related to bone health on the basis of their protein, calcium, and potassium contents and investigated their prospective associations with bone mineral density (BMD), bone area, and bone mineral content (BMC) in a cohort of young adults. Design: The study included 1024 young adults born to mothers who were participating in the Western Australian Pregnancy Cohort (Raine) Study. Dietary information was obtained from food-frequency questionnaires at 14 and 17 y of age. Dietary patterns were characterized according to protein, calcium, and potassium intakes with the use of reduced-rank regression. BMD, bone area, and BMC were estimated with the use of a total body dual-energy X-ray absorptiometry scan at 20 y of age. Results: We identified 2 major dietary patterns. The first pattern was positively correlated with intakes of protein, calcium, and potassium and had high factor loadings for low-fat dairy products, whole grains, and vegetables. The second pattern was positively correlated with protein intake but negatively correlated with intakes of calcium and potassium and had high factor loadings for meat, poultry, fish, and eggs. After adjustment for anthropometric, sociodemographic, and lifestyle factors, a higher z score for the first pattern at 14 y of age was positively associated with BMD and BMC at 20 y of age [differences: 8.6 mg/cm² (95% CI: 3.0, 14.1 mg/cm²) and 21.9 g (95% CI: 6.5, 37.3 g), respectively, per SD increase in z score]. The z score for this same pattern at 17 y of age was not associated with bone outcomes at 20 y of age. The second pattern at 14 or 17 y of age was not associated with BMD, BMC, or bone area. Conclusions: A dietary pattern characterized by high intakes of protein, calcium, and potassium in midadolescence was associated with higher BMD and BMC at 20 y of age. Our results indicate that high consumption of low-fat dairy products, whole grains, and vegetables in adolescence are associated with beneficial effects on bone development. [ABSTRACT FROM AUTHOR]

High impact forces during gymnastic landings are thought to contribute to the high rate of injuries. Lower limb joint flexion is currently limited within gymnastic rules, yet might be an avenue for reduced force absorption. This study investigated whether lower limb flexion during three gymnastic landings was related to force. Differences between landings were also explored. Twenty-one elite women's artistic gymnasts performed three common gymnastic techniques: drop landing (DL), front and back somersaults. Ankle, knee, and hip angles, and vertical ground reaction force [(vGRF) magnitude and time to peak], were measured using three-dimensional motion analysis and force platform. The DL had significantly smaller peak vGRF, greater time to peak vGRF and larger lower limb flexion ranges than landing from either somersault. Peak vGRF and time to peak vGRF were inversely related. Peak vGRF was significantly reduced in gymnasts who landed with greater hip flexion, and time to peak was significantly increased with increasing ankle, knee, and hip flexion. Increased range of lower limb flexion should be encouraged during gymnastic landings to increase time to peak vGRF and reduce high impact force. For this purpose, judging criteria limitations on lower limb flexion should be reconsidered. [ABSTRACT FROM PUBLISHER]

Background. Active virtual reality gaming (AVG) may be useful for children with developmental coordination disorder (DCD) to practice motor skills if their movement patterns are of good quality while engaged in AVG. Objective. This study aimed to examine: (1) the quality of motor patterns of children with DCD participating in AVG by comparing them with children with typical development (TD) and (2) whether differences existed in the motor patterns utilized with 2 AVG types: Sony PlayStation 3 Move and Microsoft Xbox 360 Kinect. Design. This was a quasi-experimental, biomechanical laboratory-based study. Methods. Twenty-one children with DCD, aged 10 to 12 years, and 19 age- and sex-matched children with TD played a match of table tennis on each AVG type. Hand path, wrist angle, and elbow angle were recorded using a motion analysis system. Linear mixed-model analyses were used to determine differences between DCD and TD groups and Move and Kinect AVG type for forehands and backhands. Results. Children with DCD utilized a slower hand path speed (backhand mean difference [MD] = 1.20 m/s; 95% confidence interval [95% Cl] =0.41, 1.98); greater wrist extension (forehand MD=34.3°; 95% 0 = 22.6, 47.0); and greater elbow flexion (forehand MD=22.3°; 95% 0 = 7 .4 , 37.1) compared with children with TD when engaged in AVG. There also were differences in movement patterns utilized between AVG types. Limitations. Only simple kinematic measures were compared, and no data regarding movement outcome were assessed. Conclusions. If a therapeutic treatment goal is to promote movement quality in children with DCD, clinical judgment is required to select the most appropriate AVG type and determine whether movement quality is adequate for unsupervised practice. [ABSTRACT FROM AUTHOR]

Background. Back pain beliefs (BPBs) are an important modifiable factor related to disability associated with low back pain (LBP). Back pain beliefs have not been characterized in baby boomers, a group at risk for decreased activity levels and reduced productivity. Objective. The aims of this study were: (1) to identify factors related to BPBs and (2) to evaluate the association between LBP disability and beliefs. Design. A cross-sectional survey of community-dwelling baby boomers (born 1946-1964) was conducted. M ethods. Nine hundred fifty-eight baby boomers (mean age=56.2 years) participating in the Busselton Healthy Aging Study provided their history of LBP, BPBs, LBP behaviors related to care seeking (taking medication, seeking professional help) and activity modification (missing work, interference with normal activities, interference with recreational activities), LBP-related disability, and additional covariates with known associations with BPBs. Regression analyses were used to: (1) identify' factors associated with more positive beliefs and (2) test the association between more positive BPBs and lower LBP disability, independent of other correlates of BPBs. Results. More positive BPBs were associated with younger age, better mental well-being, and higher income, whereas more negative BPBs were associated with receiving sickness or disability benefits and the experience of LBP in the previous month. In participants who reported experiencing LBP within the previous month, more positive BPBs were associated with lower disability' scale scores and a decreased probability of interference with usual activities, independent of pain intensity, age, mental well-being, income, and employment status. Limitations. Cross-sectional analysis limits assessment of causality. Conclusions. Poorer BPBs were associated with greater disability. Characterization of the relationships between BPBs and LBP-associated behaviors and disability in baby boomers can assist in developing interventions to improve activity participation and productivity, potentially reducing the burden of LBP in this age group. [ABSTRACT FROM AUTHOR]

Abstract: Question: Is exposure to non-music-related activities associated with playing-related musculoskeletal problems in young instrumentalists? Is non-music-activity-related soreness associated with playing-related musculoskeletal problems in this group of instrumentalists? Design: Observational study using a questionnaire and physical measures. Participants: 859 instrumentalists aged 7 to 17 years from the School of Instrumental Music program. Results: Of the 731 respondents who completed the questionnaire adequately, 412 (56%) experienced instrument-playing problems; 219 (30%) had symptoms severe enough to interfere with normal playing. Children commonly reported moderate exposure to non-music-related activities, such as watching television (61%), vigorous physical activity (57%), writing (51%) and computer use (45%). Greater exposure to any non-music activity was not associated with playing problems, with odds ratios ranging from 1.01 (95% CI 0.7 to 1.5) for watching television to 2.08 (95% CI 0.5 to 3.3) for intensive hand activities. Four hundred and seventy eight (65%) children reported soreness related to non-music activities, such as vigorous physical activity (52%), writing (40%), computer use (28%), intensive hand activities (22%), electronic game use (17%) and watching television (15%). Non-music-activity-related soreness was significantly associated with instrument playing problems, adjusting for gender and age, with odds ratios ranging from 2.6 (95% CI 1.7 to 3.9) for soreness whilst watching television, to 4.3 (95% CI 2.6 to 7.1) for soreness during intensive hand activities. Conclusion: Non-music-activity-related soreness co-occurs significantly with playing problems in young instrumentalists. The finding of significant co-occurrence of music and non-music-related soreness in respondents in this study suggests that intervention targets for young instrumentalists could include risk factors previously identified in the general child and adolescent population, as well as music-specific risk factors. This is an important consideration for the assessment and management of the musculoskeletal health of young musicians. [Ranelli S, Straker L, Smith A (2014) Soreness during non-music activities is associated with playing-related musculoskeletal problems: an observational study of 731 child and adolescent intrumentalists. Journal of Physiotherapy 60: 102–108]. [Copyright &y& Elsevier]

Purpose: This study aimed to quantify and compare lumbar region kinetics in kick and flat serves performed by elite, adolescent male players with and without a history of low back pain (LBP). Lumbar region kinematics, as well as racquet velocity and the position of the ball at impact, was described to facilitate kinetic data interpretation. Methods: Twenty Tennis Australia adolescent male players participated; 7 had a history of disabling LBP and confirmed L4/L5 injury and 13 were age-, height-, mass-, and performance-matched controls. The VICON motion analysis system was used to record racquet, upper and lower limb, trunk, and lumbar movement during three "flat" and three "kick" serves. A customized mathematical model calculated lumbar region kinetics/kinematics, racquet velocity, and ball position at impact, and these are reported as if all players were right-handed. A series of 2 x 2 mixed-model ANOVA were used to compare between pain/no pain and kick/flat serves. Results: There was no significant difference in racquet velocity or ball position at impact between pain groups or serve types. The players with LBP reported significantly greater (mean difference = 1.5 N-kg~') peak left lateral force than the control group. The flat serve was associated with significantly greater flexion moments (mean difference = 2.7 Nkg~ ') than the kick serve. Conclusions: The lumbar region undergoes substantial loading during both the kick and the flat tennis serves, including lateral flexion forces approximately eight times those experienced during running. Given that these left lateral flexion forces are significantly greater in players with a history of disabling LBP and occur simultaneous with peak vertical force and extension and right lateral rotations, this may be an important LBP mechanism in this population. [ABSTRACT FROM AUTHOR]

Background. Disability in adults with low back pain (LBP) is associated with negative back pain beliefs (BPBs). Adult BPBs can be positively influenced with education, resulting in reduced LBP disability. By late adolescence, the prevalence of LBP reaches adult levels. The relationship among LBP experience, LBP impact, and BPBs has not been investigated in late adolescence. Objective. The aim of this study was to document unknown relationships among LBP experience, LBP impact, and BPBs in 17-year-olds. Design. A cross-sectional study design was used. Methods. Adolescents (n= 1,126) in the Raine Study provided full information on LBP, LBP impact (sought professional advice or treatment, taken medication, missed school or work, interfered with normal activities, interfered with physical activities), BPBs, and a number of covariates. Results. Back pain beliefs were more positive in participants with experience of LBP (X=30.2, SD=5.6) than in those without experience of LBP (X=28.5, SD=5.1). Individuals with LBP without activity modification impacts had more positive BPBs than those with activity modification impacts, even after adjustment for mental well-being and sex. The adjusted difference in BPBs between participants with experience of LBP but no activity modification impacts and those reporting all 3 activity modification impacts was 2.9 points (95% confidence interval=1.7 to 4.2). Participants with no activity modification impacts had more positive BPBs than those with no experience of LBP (adjusted difference=2.2 points, 95% confidence interval 1.4 to 2.9). More positive BPBs also were associated with female sex, lower body mass index, higher family income, better 36-Item Short-Form Health Survey (SF-36) Mental Health scale scores, and more positive primary caregiver beliefs. Limitations. Cause and effect cannot be ascertained with the cross-sectional design. Conclusion. Differences in BPBs are associated with different levels of LBP impact at 17 years of age. This finding provides a potential target for intervention early during the life course. [ABSTRACT FROM AUTHOR]

Background. Conflicting evidence exists regarding relationships among sitting posture, factors that influence sitting posture, and back pain. This conflicting evidence may partially be due to the presence of multiple and overlapping factors associated with both sitting posture and back pain.Objective. The purpose of this study was to determine whether the degree ofslump in sitting was associated with sex and other physical, lifestyle, or psychosocial factors. Additionally, the relationship between the report of back pain made worse by sitting and the degree of slump in sitting and other physical, lifestyle, or psychosocial factors was investigated. Design. This was a cross-sectional study. Methods. Adolescents (n1,596) completed questionnaires to determine lifestyle and psychosocial profiles and the experience of back pain. Sagittal sitting posture, body mass index (BMI), and back muscle endurance (BME) were recorded. Standing posture subgroup categorization was determined. Results. Multivariate analysis revealed that the most significant factor associated with the degree of slump in sitting was male sex, followed by non-neutral standing postures, lower perceived self-efficacy, lower BME, greater television use, and higher BMI. Multivariable analysis indicated poorer Child Behaviour Checklist scores were the strongest correlate of report of back pain made worse by sitting, whereas degree of slump in sitting, female sex, and BME were more weakly related. Limitations. Causality cannot be determined from this cross-sectional study, and 60% of sitting posture variation was not explained by the measured variables. Conclusions. Slump in sitting was associated with physical correlates, as well as sex, lifestyle, and psychosocial factors, highlighting the complex, multidimensional nature of usual sitting posture in adolescents. Additionally, this study demonstrated that a greater degree of slump in sitting was only weakly associated with adolescent back pain made worse by sitting after adjustment for other physical and psychosocial factors. [ABSTRACT FROM AUTHOR]

Purpose: Sitting at work can be associated with musculoskeletal pain, but the effect of reductions in sitting is not well understood.We examined relationships with musculoskeletal pain of changes in sitting, standing, stepping, and short and long bouts of these behaviors. Methods: Analyses pooled data from 224 desk workers (68.4%women;mean ± SD age = 45.5 ± 9.4 yr; body mass index = 28.1 ± 6.1 kgm-2) in intervention trial.Device-assessed (activPAL3) sitting, standing, and stepping time andmultisite musculoskeletal pain (Nordic Questionnaire; 12 body areas) were assessed at baseline, 3months, and 12 months. Compositional data analyses in linear mixed-effects regressions examined relationships within 16 waking hours of the behaviors and their short and long bouts, with changes from baseline in acute and chronic multisite musculoskeletal pain at 3 and 12 months. Analyses were adjusted for initial group randomization and relevant covariates. Results: At 3 months, increased standing relative to changes in other compositions was significantly associated with increased multisite musculoskeletal pain (acute: β = 1.54, 95% confidence interval [CI] = 0.10 to 2.98; chronic: β = 1.49, 95% CI = 0.12 to 2.83). By contrast, increased stepping relative to changes in other compositions was significantly associated with reduced multisite musculoskeletal pain (acute: β = -1.49, 95% CI = -2.97 to -0.02; chronic: β = -1.87, 95% CI = -3.75 to -0.01). Neither sitting reduction relative to changes in other compositions nor changes in short bouts relative to long bouts of the behaviors were significantly associated with multisite musculoskeletal pain changes. At 12months, there were no significant associations for any of the compositional changes. Conclusions: In the short term, while increasing standing with reduced sitting time can be unfavorable, concurrently increasing stepping could potentially reducemusculoskeletal pain. In the longer term, musculoskeletal painmay not be increased by moderate reductions in sitting time through spending more time standing or stepping. [ABSTRACT FROM AUTHOR]

Objectives: This study investigated spinal pain-related absenteeism at age 17 as a potential precursor to work presenteeism at age 23. Methods: A longitudinal study was performed with Raine Study Gen2 participants (n = 451). Spinal pain-related absenteeism from school/work was collected at the 17 year follow-up. Presenteeism (due to ill-health or any other reason) was collected quarterly during one year around the age of 23. Zero-inflated binominal regression analysis was conducted. Results: Participants with adolescent spinal pain-related absenteeism reported higher work presenteeism in early adulthood than those without pain (155.7 h/y compared to 77.7 h/y), with an incident rate ratio (95% confidence interval) of 1.41 (1.04 to 1.92) after adjusting for sex, occupational class and multimorbidity count. Conclusions: Targeting factors associated with absenteeism behaviours during early life may have significant benefits for future work productivity. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to identify unique organized sport trajectories from early childhood to late adolescence in an Australian pregnancy cohort, the Raine Study. Methods: Participation in organized sport was assessed at ages 5, 8, 10,14, and 17 yr. Physical activity, body composition, and self-rated physical and mental health were assessed at the age of 20 yr. Latent class analysis was used to identify patterns of sport participation. To assess the internal validity of the trajectory classes, differences in health characteristics between trajectories were analyzed using generalized linear models. Results: For girls, three trajectory classes were identified: consistent sport participators (47.5%), sport dropouts (34.3%), and sport nonparticipators (18.1%). For boys, three trajectory classes were identified: consistent sport participators (55.2%), sport dropouts (36.9%), and sport joiners (8.1%). For girls, there were overall differences across trajectory classes in lean body mass (P = 0.003), lean mass index (P = 0.06), and physical health (P = 0.004). For boys, there were differences across classes in physical activity (P = 0.018), percent body fat (P = 0.002), lean body mass (P < 0.001), lean mass index (P < 0.001), physical health (P = 0.06), and depression scores (P = 0.27). Conclusion: This study identified unique, sex-specific trajectories of organized sport participation. The differences in health outcomes between trajectory classes, such as participants with consistent sport participation having more preferable health outcomes at the age of 20 yr, support the internal validity of the trajectories. Strategies are needed to identify and encourage those in the dropout trajectory to maintain their participation and those in the nonparticipator or joiner trajectories to join sport earlier. Specifically, interventions to encourage early sport participation in girls and help nonparticipating boys to join sport during adolescence may help more children receive the benefits of sport participation. [ABSTRACT FROM AUTHOR]

Active virtual games (AVG) may facilitate gross motor skill development, depending on their fidelity. This study compared the movement patterns of nineteen 10–12 yr old children, while playing table tennis on three AVG consoles (Nintendo Wii, Xbox Kinect, Sony Move) and as a real world task. Wrist and elbow joint angles and hand path distance and speed were captured. Children playing real table tennis had significantly smaller (e.g. Wrist Angle Forehand Real-Kinect: Mean Difference (MD): −18.2°, 95% Confidence Interval (CI): −26.15 to −10.26) and slower (e.g. Average Speed Forehand Real-Kinect: MD: −1.98 m s −1 , 95% CI: −2.35 to −1.61) movements than when using all three AVGs. Hand path distance was smaller in forehand and backhand strokes (e.g. Kinect-Wii: MD: 0.46 m, 95% CI: 0.13–0.79) during playing with Kinect than Move and Wii. The movement patterns when playing real and virtual table tennis were different and this may impede the development of real world gross motor skills. Several elements, including display, input and task characteristics, may have contributed to the differences in movement patterns observed. Understanding the interface components for AVGs may help development of higher fidelity games to potentially enhance the development of gross motor skill and thus participation in PA. [ABSTRACT FROM AUTHOR]