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OBJECTIVE: The circus professionalization process entails extensive training to mitigate the high-risk demands which increase stress in artists. In high-risk professions, everyday hassles (challenges) contribute greatly to overall stress. To capture the impact of daily challenges on student-artists, the aim of the current study was to describe the magnitude and pattern of daily challenges as well as their relationships with perceived coping, anxiety, fatigue, and psychological distress. METHODS: Ninety-two students at École Nationale de Cirque (ENC), in Montreal, Canada, completed the Circus Daily Challenges Questionnaire (CDCQ) and scales assessing perceived coping, state anxiety, and fatigue at four time points over 1 school year. The Kessler 6 Non-Specific Psychological Distress Scale (K6) was implemented at one time point. RESULTS: Findings revealed significant fluctuations in challenge level and management of challenges throughout the school year, with schedule, technical development, artistic expression, physical preparation, and sleep reported as high during the two examination periods. The lowest challenge-level scores were achieved following the extended breaks in the annual calendar. Daily challenge positively correlated to state anxiety and fatigue, and negatively correlated with perceived coping. The student-artists reported higher prevalence of moderate psychological distress to general populations. CONCLUSION: Befitting the Stress Process Model, a strong interplay between variables was observed, and the life challenges assessment provides a basis for interventions based upon commonalities across the group, as well as individually tailored.

Matched pre-during pandemic comparison (160 children) revealed a substantial reduction in physical activity (p < 0.001, rrb = 0.83), environmental participation (p = 0.046, rrb = 0.16), movement valuation (p < 0.001, rrb = 0.61), and parent perceptions of children’s physical literacy (p < 0.001, rrb = 0.56). Examining physical activity trajectories, higher pre-pandemic physical literacy protected children from pandemic related activity decline. Emerging from the pandemic, interventions should address children’s eroded belief in movement and consider physical literacy levels of children in individualizing movement opportunities for restoration of activity levels. Novelty: A substantial reduction in physical activity was associated with children who had lower physical literacy and resulted in reductions in children’s valuation of movement.

PLAYself is a tool designed for self-description of physical literacy in children and youth. We examined the tool using both the Rasch model and Classical Test Theory to explore its psychometric properties. A random selection of 300 children aged 8–14 years (47.3% female) from a dataset of 8513 Canadian children were involved in the Rasch analysis. The 3 subscales of the measure demonstrated good fit to the Rasch model, satisfying requirements of unidimensionality, having good fit statistics (item and person fit residuals = –0.17–1.47) and internal reliability (Person Separation Index = 0.70–0.82), and a lack of item bias and problematic local dependency. In a separate comparable sample, 297 children also aged 8–14 years (53.9% female) completed the PLAYfun, Physical Self-Description Questionnaire (PSDQ), Physical Activities Measure-Revised (MPAM-R), a physical activity inventory (PLAYinventory), and repeated the PLAYself 7 days later. The tests with this sample confirmed test–retest reliability (intraclass correlation coefficient = 0.81–0.84), and convergent and construct validity consistent with contemporary physical literacy definitions. Overall, the PLAYself demonstrated robust psychometric properties, and is recommended for researchers and practitioners who are interested in assessing self-reported physical literacy. Novelty: The PLAYself is a self-reported measure of physical literacy This study validates the measure using the Rasch model and classical test theory The PLAYself was found to have strong psychometric properties

The purpose of this study was to perform a longitudinal assessment of body composition of circus student-artists in an elite 3-year college training program. Ninety-two student-artists participated (age = 20.39 ± 2.42 years; height = 170.01 ± 8.01 cm; mass = 66.48 ± 11.07 kg; 36% female and 64% male), representing 92% of the student population. Body composi- tion was assessed using multi-frequency bioelectrical impedance at four strategic time points throughout the training year to evaluate changes over the two semesters (September to December and January to April) and winter vacation (December to January). Workloads were subjectively assessed using ratings of perceived exer- tion (RPE). Averaged over the academic terms, fat mass was 11.5 ± 4.8%, muscle mass was 50.2 ± 3.4%, and body mass index was 22.9 ± 2.2. Males and females differed significantly across all absolute and relative body composition variables. Muscle mass increased (semester one, +1.0%, p < 0.001; semester two, +0.4%, p < 0.05) while fat mass decreased during each semester (semester one, -1.6%, p < 0.001; semester two, -0.6%, p < 0.05) co-varying with changes in RPE (semester one, +2.3, p < 0.05; semester two, +1.7, p < 0.05). During the winter vacation period, percent fat mass increased (males, +1.0%; females, +2.0%) and percent muscle mass decreased (males, -0.6%; females, -0.9%). Discipline-specific differences in body composition were also detected, and significant differences were observed between student-artists grouped by years in school. Over the training year, there was a positive adaptation for muscle and fat mass despite the negative adaptation experienced during the winter vacation period.

Few assessment tools have been designed to assess motor creativity, and the existing tools have limitations. To bridge this gap, the current study aimed at designing a new movement creativity asses...

Matched pre-during pandemic comparison (160 children) revealed a substantial reduction in physical activity (p rb=0.83), environmental participation (p = 0.046, rrb=0.16), movement valuation (p rb=0.61), and parent perceptions of children’s physical literacy (p rb=0.56,). Examining physical activity trajectories, higher pre-pandemic physical literacy protected children from pandemic related activity decline. Emerging from the pandemic, interventions should address children’s eroded belief in movement, and consider physical literacy levels of children in individualizing movement opportunities for restoration of activity levels.

OBJECTIVE: To characterize clinical burden of injuries incurred by circus students enrolled in a 3-year college training program. METHODS: Student (n=334) injury data derived from an in situ clinic was examined over a 7.5-year time frame from August 2009 to December 2016. Injury incidence rate (per 1,000 training hours) was calculated and clinical incidence (injuries/year) was examined in relation to year in program, sex, age, and circus discipline. Weekly and monthly injury incidence were plotted with respect to milestones in the scholastic training year. Clinical burden (injury incidence and duration) was examined according to anatomic location and circus discipline. RESULTS: The overall injury incidence rate was 1.89 injuries/1,000 training hours and 0.94 injuries/1,000 training hours for injuries with a duration longer than 4 weeks. Clinical incidence decreased with year in program (p

Purpose: The purpose of this study was to examine the convergent validity of the PLAYfun tool, a physical literacy-based measure of movement competence, by examining its association with objectivel...

Purpose: Physical literacy (PL) has been proposed as a key construct for understanding participation in physical activity. However, the lack of an agreed-upon definition and measure has hindered re...

Objective: To examine the impact of circus arts instruction in physical education (PE) on the physical literacy of children in Grades 4 and 5. Methods: A clustered, quasi-experimental design was us...

While it is commonly thought that physical literacy is an early 21st-century construct and is often credited to Margaret Whitehead, in fact, the term physical literacy can be traced back to the late 1800s. In this narrative, the authors review descriptions of physical literacy that appeared in the late 19th and early to mid-20th century literature and show how physical literacy is historically tied to the reoccurring contextual issue of threats to active lifestyles and how definitional components of the construct have both remained consistent, while others changed over the course of the century. They conclude by discussing some tensions that have arisen with the Whiteheadian construction of the term, as well as the conflation of the term with fitness or physical education. In doing so, the authors hope to open up greater discussion of the multidisciplinary potential of this construct.

The COVID-19 pandemic resulted in the abrupt closure of circus schools, venues, and companies, introducing a myriad of novel stressors. Performers and students must now attempt to maintain their technical, physical, artistic, creative, and cognitive abilities without in-person support from their coaches and must manage the isolation from their training and performing spaces. For circus artists, the transposition of the work space to a home environment is not possible, which creates novel stressors that could lead to the exacerbation and escalation of mental health issues. The purpose of this study is to develop, implement and evaluate a holistic interventional program based on the socio-ecological model of resilience and operationalized through physical literacy. This will be a prospective longitudinal study with a retrospective comparison to data from a similar student cohort pre-pandemic. Interventions were designed using a population-specific, participant-based developmental model within a knowledge translation framework. The interventional program includes group webinars, small group information sessions, and one-on-one Zoom meetings, in addition to the distribution of electronic educational materials. The interventions will holistically provide psychological, physical, social, technical, artistic, and creative supports. Resources will be deployed throughout the closure period and through recovery, as transitions to return to training after prolonged hiatus will magnify known psychological and physical difficulties. Repeated, longitudinal assessment of students will be utilized to track changes over time at key transitions in the pandemic and school year and will be compared to a pre-pandemic school year. The framework for this program will be translatable to other performing arts and high-performance contexts. The program has implications for the mental health and overall wellbeing of artists and for cultural and economic recovery of the industry.

Introduction Physical Literacy Assessment for Youth (PLAYfun) is a measure of motor competence, comprehension, and confidence which is part of a suite of scales used to assess physical literacy in children and youth; however, its measurement properties have not been reported in the published literature. The purpose of this study is to examine the factor structure of PLAYfun, in addition to variations in PLAYfun subscale results by age and sex. Method In this study, we use a sample of children and youth 7 to 14 yr of age (n = 215) to test a proposed factor structure for the motor competence component of PLAYfun and to examine age and sex differences in subscale and total scores. The initial (n = 128) and secondary (n = 98) samples were drawn from a stratified (by geographic region), random sample of 27 after-school programs from a larger pool of 400 programs across the province of Ontario. Seven research assistants were initially trained on the administration of PLAYfun and rated a small pilot sample of 10 children. These trained assessors then assessed the full sample. Results Interrater agreement was very good (intraclass correlation, 0.87). The hypothesized five-factor structure of the scale was found to have an acceptable fit to the data (root mean square error of approximation, 0.055; 90% confidence interval, 0.03-0.075; comparative fit index, 0.95; Tucker-Lewis Index, 0.94). In general, PLAYfun scores increased with age as developmentally expected. There were few sex differences across skills, but girls did not perform as well as boys on upper and lower body object control skills. Conclusions The factor structure and patterns of results by age and sex support PLAYfun as a measure of motor competence. Continued evaluation of the tool and other subscales of PLAY is required.

The International Charter for Physical Education, Physical Activity, and Sport clearly states that vested agencies must participate in creating a strategic vision and identify policy options and priorities that enable the fundamental right for all people to participate in meaningful physical activity across their life course. Physical literacy is a rapidly evolving concept being used in policy making, but it has been limited by pre-existing and sometimes biased interpretations of the construct. The aim of this article is to present a new model of physical literacy policy considerations for key decision makers in the fields of public health, recreation, sport, and education. Internationally debated definitions of physical literacy and the wider construct of literacy were reviewed in order to establish common pillars of physical literacy in an applicable policy model. This model strives to be consistent with international understandings of what “physical literacy” is, and how it can be used to achie...

Spinal precautions are intended to limit motion of potentially unstable spinal segments. The efficacy of various treatment approaches for motion restriction in the cervical spine has been rigorously investigated using healthy volunteers and, to a lesser extent, cadaver samples. No previous studies have objectively measured this motion in trauma patients with potential spine injuries during prehospital care.Substantial single- and multi-plane H-N motion was observed among all participants. Maximum single-plane displacements were between 11.3 ± 3.0 degrees (rotation) and 19.0 ± 16.6 degrees (flexion-extension). Maximum multi-plane displacements averaged 31.2 ± 7.2 degrees (range: 7.2 to 82.1 degrees). Maximum multi-plane acceleration averaged 5.8 ± 1.4 m/s

Background: There is growing interest in the relationship between physical and psychosocial factors related to resilience to better understand the antecedents of health and successful adaptation to challenges in and out of school, and across the lifespan. To further this understanding, a trans-disciplinary approach was used to investigate the association between the multidimensional constructs of physical literacy and resilience in children at a key stage in their development. Methods: Cross-sectional data were collected from 227 school children aged 9-12 years old from five schools in Winnipeg, Manitoba, Canada. Resilience was measured using the Child and Youth Resilience Measure, and physical literacy through the Physical Literacy Assessment for Youth tools. Data were provided by self-report, surrogate assessors of the child (physical education teachers and parents), and trained assessors for movement skills. These data were analyzed using correlation and logistic regression. Results: Resilience was significantly correlated with numerous indicators of physical literacy, including movement capacity, confidence, and competence, environmental engagement, and overall perceptions of physical literacy. Regressions indicated that resilience could be predicted by movement confidence and competence, environmental engagement, and overall physical literacy. Conclusions: The findings of this study, using a constellation of sources, provide foundational evidence for the link between resilience and physical literacy among children, encouraging the importance of physical literacy development in schools. Longitudinal studies are required to further examine this relationship and how these previously unrelated fields may work together for a richer understanding of the interplay between the physical and psychological determinants of well-being.

To synthesize the available evidence on playground-related injuries and to determine the prevalence of these injuries in pediatric populations.A rapid systematic review was conducted using PubMed, EMBASE, and the Cochrane Library, as well as the gray literature.The search was limited to studies published between 2012 and 2016 and identified a total of 858 articles, of which 22 met our inclusion criteria: original quantitative studies published in peer-reviewed journals in the past 5 years, concerning unintentional injuries in playgrounds in children aged 0 to 18 years.Information was collected on study and injury characteristics, and the proportion of pediatric injuries related to playground activity was determined. Studies were performed in various countries and most were retrospective cohort studies. The prevalence of playground-related injury ranged from 2% to 34% (median 10%). Studies varied in the types of injuries investigated, including head injuries, genitourinary injuries, ocular and dental trauma, and various types of fractures. Most injuries were low severity.Although playgrounds are a common location where pediatric injuries occur, these injuries are relatively low in frequency and severity.

The term physical literacy has been embraced by a number of different countries around the world. Although the concept has regained momentum over the past few decades, little has been written about specific activities that may assist in providing the foundation for physical literacy as a life-long journey. This article introduces selected physical training concepts and activities based on national standards. Key benefits and teaching objectives related to both performance enhancement and injury prevention are provided.

The following commentary proposes that the current identification protocols for identifying children with neuro-developmental behavioral intellectual disorders (NDBIDs) are limited. Increasing prevalence of physical inactivity in children and those diagnosed with NDBIDs creating public health concerns, new methods of identification, and treatment may be warranted. We suggest the diagnostic and treatment protocols for all children (not just those with NDBIDs) may be enhanced by using the concept of physical literacy as a philosophical premise for assessment instrument design and strength-based treatment.

Physical literacy (PL) provides a powerful lens for examining movement in relation to physical activity (PA) and motor skill outcomes, environmental context, and broader social and affective learning processes. To date, limited consideration has been given to the role PL plays in promoting positive health behaviours. There is no clear conceptual framework based on existing empirical evidence that links PL to health, nor has an evidence-informed case been made for such a position. The purpose of this paper is to (1) present a conceptual model positioning PL as a health determinant, and (2) present evidence in support of PL as a health determinant, drawing on research largely from outside physical education. Viewing PL from the perspective of a multidimensional, experiential convergence process enables it to be differentiated from other models. However, parallels between our model and existing models that focus on movement competence are also drawn. Arguing from a pragmatic perspective on PL, we present evidence for positioning PL as a determinant of health from two literature sources: research on motor coordination disorders in children, and associations between motor competence, PA and health in typically developing children. Statistical modelling approaches consistent with the concept of PL are discussed. Results from these approaches-confirmatory factor analysis and cluster analysis-support the idea that measures related to motor competence, motivation and positive affect work in an integrative manner to produce differences in PA and subsequent health outcomes in children. There is increasing interest in PL, particularly in the field of public health. Presenting a model that explicitly links PL to health can lead to the generation of new research questions and the possibility of broadening impact beyond the context of physical education alone. To date, there has been little conceptual attention to what positioning PL as a determinant of health means. By providing an evidence-based model of PL as a determinant of health, we hope to further the discussion and stimulate increased empirical research in the field.

Objective: To determine the influence of ambulance motion on head-neck (H-N) kinematics and to compare the effectiveness of two spinal precaution (SP) protocols: spinal immobilization (SI) and spinal motion reduction (SMR). Methods: Eighteen healthy volunteers (7 females) underwent a series of standardized ambulance transport tasks, across various speeds, under the two SP protocols in a balanced order (n = 12 drivers, n = 7 ambulances). Inertial measurement units were placed on participants’ heads and sternums, with another affixed to the stretcher mattress frame. Outcome measures included H-N displacement and acceleration. Results: Ambulance accelerations varied across driving tasks (2.5–9.5 m/s2) and speeds (3.0–6.2 m/s2) and resulted in a wide range of H-N displacements (7.2–22.6 deg) and H-N accelerations (1.4–10.9 m/s2). Relative to SMR, SI resulted in reduced H-N motion during turning, accelerating, and speed bumps (1.9–10.7 deg; 0.4–2.6 m/s2), but increased H-N accelerations during abrupt starts/stops and some higher speed tasks (0.4–2.5 m/s2). Ambulance acceleration was moderately correlated to H-N acceleration (r = 0.68) and displacement (r = 0.42). Conclusion: H-N motion was somewhat coupled to ambulance acceleration and varied across a wide range, regardless of SP approach. In general, SI resulted in a modest reduction in H-N displacement and acceleration, with some exceptions. The results inform clinical decisions on SP practice during prehospital transport and demonstrate a novel approach to quantifying H-N motion in prehospital care.

AIMS: The development of elite circus artists requires extensive technical and artistic training, as well as a commensurate level of physical preparation in readiness for a demanding professional career as a performance artist. While sport research has identified the importance of monitoring sleep and fatigue in athletes to optimize performance and to prevent illness and injury, not a single study of circus artists exists. This study provides a longitudinal examination of sleep and fatigue in elite circus student-artists. METHODS: 92 student-artists (60 male, 32 female) were analyzed at 4 strategic time points over a preparatory year. At each time point, sleep parameters (duration, quality and latency), ratings of perceived exertion (RPE), wakefulness, and fatigue were obtained using questionnaires. RESULTS: Student-artists attained an average nightly sleep of 8 hours, 27 minutes, exceeding the recommended durations for general populations and those self-reported in athletes. The majority of the artists also indicated acceptable sleep latency (87%) and quality (83%) scores. Sleep parameters remained consistent throughout the year despite significant variations in training load and fatigue. Sleep parameters were not substantial predictors of overall fatigue. Fatigue covaried with yearly variation in sessional training loads. CONCLUSIONS: Although improvement in sleep could be postulated as a means to mitigate fatigue, it is likely that strategies aimed at optimizing the loading profile and additional recovery techniques be a first line approach.

The chronic effects of high-intensity endurance training on metabolic health outcomes in overweight adolescents remains poorly understood.To test the hypothesis that high-intensity endurance training (ET) is superior to moderate-intensity ET for improving risk factors for type 2 diabetes in overweight adolescents.In this randomized trial, 106 overweight and obese adolescents (15.2 years; 76% female; 62% Caucasian) were randomly assigned to high-intensity ET (70-85% of heart rate reserve, n=38), moderate-intensity ET (40-55% heart rate reserve; n=32) or control for 6 months (n=36). The primary and secondary outcome measures were insulin sensitivity assessed using a frequently sampled intravenous glucose tolerance test and hepatic triglyceride content with magnetic resonance spectroscopy. Exploratory outcomes were cardiorespiratory fitness, physical activity and MRI and dual x-ray absorptiometry-derived measures of adiposity.The study had 96% retention and attendance was 61±21% and 55±24% in the high- and moderate-intensity ET arms. Intention-to-treat analyses revealed that, at follow-up, insulin sensitivity was not different between high-intensity (-1.0 mU kg(-1) min(-1); 95% confidence interval (CI): -1.6, +1.4 mU kg(-1) min(-1)) and moderate-intensity (+0.26 mU kg(-1) min(-1); 95% CI: -1.3, +1.8 mU kg(-1) min(-1)) ET arms compared with controls (interaction, P=0.97). Similarly, hepatic triglyceride at follow-up was not different in high-intensity (-1.7% fat/water (F/W); 95% CI: -7.0, +3.6% F/W) and moderate-intensity (-0.40% FW; 95% CI: -6.0, +5.3% F/W) ET compared with controls. Both high intensity (+4.4 ml per kg-FFM (fat-free mass) per minute; 95% CI: 1.7, 7.1 ml kg-FFM(-1) min(-1)) and moderate intensity (+4.4 ml kg-FFM(-1) min(-1); 95% CI: 1.6, 7.3 ml kg-FFM(-1) min(-1)) increased cardiorespiratory fitness, relative to controls (interaction P0.001).ET improves cardiorespiratory fitness among obese adolescents; however, owing to lack of compliance, the influence of exercise intensity on insulin sensitivity and hepatic triglycerides remains unclear.

In this editorial, we provide a brief explanation of the physical literacy construct and its potential to contribute to the education, safety and overall development of a healthy life for the full lifespan. Although there has been a significant focus on teaching the competence component of being physically active, there has been a lack of focus on teaching people the confidence, desire, motivation, enjoyment and social benefits of physical activity.1–3 Therefore, we challenge the sports medicine and health-related professions to embrace and implement physical literacy’s holistic approach (both mind and body) to physical activity. The term physical literacy has been used in the academic literature since the 1930s1; however, it was not until the 1990s that the construct was re-introduced, embraced by several countries and gained significant attention.1–3 Following a number of iterations, the International Physical Literacy Association settled on the following definition: Physical Literacy is the motivation, confidence, physical competence, knowledge, and understanding to value and take responsibility for engagement in physical activities for life .4 Much of the available research thus far has focused on the sport and education sectors and specifically on the younger generation.1 3 5 Focusing on the younger generation can have a substantial impact on the health of future generations. However, as the definition indicates, physical literacy is …

Study design A cross-sectional study. Objective To identify the relationship between performance measures derived from accelerometry and subjective reports of pain, disability, and health in patients with lumbar spinal stenosis (LSS). Summary of background data Accelerometers have emerged as a measure of performance, providing the ability to characterize the pattern and magnitude of real-life activity, and sedentarism. Pain and loss of function, particularly ambulation, are common in LSS. The extent to which pain, perceived disability, and self-rated health relate to performance in patients with LSS is not well known. Methods Data regarding self-reported pain, disability (Oswestry Disability Index, Roland-Morris Disability Questionnaire, and Disabilities of the Arm, Shoulder, and Hand), and health (36-Item Short Form Health Survey [SF-36]) were collected from patients with LSS (n = 33). Physical activity, ambulation, and inactivity performance measures were derived from 7-day accelerometer records. Correlation and stepwise regression were used. Results The physical function subscale of the SF-36, a non-pathology-specific outcome, had the best overall correlation to physical activity and ambulation (average r = 0.53) compared with pain (average r = 0.32) and disability (average r = -0.45) outcomes. Stepwise regression models for performance were predominantly single-variable models (4 of 8 models); pain was not selected as a predictor. A second non-pathology-specific outcome, the Disabilities of Arm Shoulder and Hand, improved the prediction of performance in 5 of 8 models. Conclusion Subjective measures of pain and disability had limited ability to account for real-life performance in patients with LSS. Future research is required to identify determinants of performance in patients with LSS because barriers to activity may not be disease-specific.

Background The purpose of this study was to determine whether current post-operative rehabilitation protocols return the strength of the contralateral uninjured limb knee flexors and extensors after an anterior cruciate ligament (ACL) reconstruction to those of an uninjured control group. Methods Subjects with a hamstring tendon ACL reconstruction ( n = 12) were compared to an active control group ( n = 30). Comprehensive bilateral knee flexor and extensor isovelocity strength testing was performed (five speeds, 5–95°, concentric and eccentric contractions). Findings After hamstring tendon ACL reconstruction and rehabilitation, bilateral strength normalization (within 10% of the contralateral limb) is achieved by the knee extensors but not the knee flexors. When compared to the uninjured control group, large and statistically significant strength deficits were demonstrated in the knee extensors and knee flexors of both the anterior cruciate ligament reconstructed (extensors 24.8%; flexors 26.8%) and the contralateral uninjured (extensors 21%; flexors 13.5%) limbs. Interpretation These findings suggest that improvement can be made in knee flexor rehabilitation after ACL reconstruction and limit the validity of the use of a contralateral leg as a rehabilitation endpoint or as a control in the ACL reconstructed population.

Low levels of childhood physical activity (PA) are a contributing factor to obesity. The objective of this study was to determine the adherence of children to PA guidelines in relation to body composition. Body fat (Slaughter equation) and body mass index (BMI) were determined during the school year (n = 251, ages 8–11 y). Daily energy expenditure (EE, kcal·kg–1·d–1) and activity time (AT, min·d–1) above moderate and vigorous intensity thresholds were assessed (accelerometry). Using EE criteria, 35.9% expended < 3.0 kcal·kg–1·d–1, 27.9% expended between 3.0 and 5.9 kcal·kg–1·d–1, 13.5% expended between 6.0 and 7.9 kcal·kg–1·d–1, and 22.9% expended ≥ 8.0 kcal·kg–1·d–1. Using AT criteria, 52.2% accumulated < 30.0 min, 31.1% accumulated 30.0–59.9 min, 12.7% accumulated 60.0–89.9 min, and 4.0% accumulated ≥ 90.0 min of AT. The EE corresponding to accumulation of AT > 90 min was 14.8 kcal·kg–1·d–1. The AT corresponding to ≥ 8 kcal·kg–1·d–1 was 73.0 min. Inverse relationships were observed between EE and body fat (p = 0.0004), BMI (p = 0.002), mass (p = 0.008), and fat mass index (FMI) (p = 0.001), as well as between AT and body fat (p = 0.001), BMI (p = 0.008), mass (p = 0.017), and FMI (p = 0.002). Controlling for BMI, FMI was inversely related to EE (p = 0.049) and AT (p = 0.039). Fat-free mass index and AT were positively related (p = 0.038). Physical activity had beneficial effects on body composition for children independent of BMI. The relationship between AT and daily EE guidelines was rationalized (60 min·d–1 with 8 kcal·kg–1·d–1) and demonstrated association with acceptable body composition. The 60 min·d–1 of moderate activity may be a more suitable initial target than 90 min·d–1, as so few children met the upper tiers of PA guidelines.

Manufacturers of pedometers recommend wearing a pedometer on the midline of the right thigh and this recommendation is used in research. However, there is conflicting evidence regarding the effect of pedometer position on accuracy. The purpose of this study was to systematically evaluate the effect of pedometer position on accuracy for 3 modes of gait. The Yamax SW200 pedometer was evaluated in 20 subjects in 5 different positions simultaneously: left mid-axillary, left mid-thigh, umbilical, right mid-thigh, and right mid-axillary. Each subject was asked to walk on a treadmill (54, 80, and 107 m·min–1), to walk overground (slow, preferred, and fast speeds), and to ascend and descend stairs. Pedometer steps were recorded and compared with actual steps observed. Using the same protocol, instantaneous triaxial accelerometry was used to explain position-dependent differences in accuracy. At slow speeds, the left mid-axillary position demonstrated the lowest net mean (±SD) error across all modes of gait (7.7% (±11.6%%) overground; –0.6% (±2.2%) stairs). The right mid-thigh position had significantly (p < 0.01) higher error for treadmill (18.1% (±17.3%)), overground (12.9% (±15.2%)), and stairs (2.9% (±3.9%)). Pedometer position dependent error was demonstrated, with the left mid-axillary position superior to the recommended position of right mid-thigh. The greater accuracy on the left side was wholly explained by gait asymmetry evident in step-induced accelerations recorded at right and left pedometer positions. A model of absolute error based on the ratio of steps at different gait speeds was generated to demonstrate the importance of this finding in pedometer-based lifestyle intervention studies.

Objective. To determine the effect of trunk stabilization instruction on lumbar acceleration. Background. There is a paucity of information showing the impact of stabilization training and instruction on lumbar motion. Neuromuscular activation patterns have been implicated as an etiological factor in low back disorders. Knowledge of the short-term alterations in lumbar motion control, as assessed by acceleration, is an important first step to understanding the impact of trunk stabilization programs. Methods. A calibrated, uniaxial accelerometer was positioned over the L4 spinous process of subjects (n=33) to record anterior/posterior acceleration during 10 repetitions of lower and upper limb movements (hip flexion/extension and biceps curl) before and after standardized stabilization instruction. Results. Each repetition exhibited four stereotypical phases of acceleration. Instruction resulted in a substantial reduction in peak lumbar acceleration magnitude (P

The purpose of this study was to evaluate and characterize the agonist-antagonist strength balance (hamstring/quadriceps [H/Q] ratio and dynamic control ratio [DCR]) about the knee specific to velocity, range of motion, and contraction type. We hypothesized that there would be systematic variation in the H/Q ratio and DCR based on knee joint angle, angular velocity, and contraction type. We also hypothesized that these ratios would be altered in the anterior cruciate ligament (ACL)-reconstructed group in favor of protecting the ACL graft (relative knee flexor strength when strain on the ACL is the greatest).Cross-sectional design.A tertiary care sport medicine clinic.Sixteen subjects more than 1 year after hamstring tendon ACL reconstruction were compared with 30 active uninjured control subjects.Isokinetic strength testing was performed over 5 degrees to 95 degrees knee joint range of motion, 5 angular velocities (50, 100, 150, 200, 250 degrees/s), for concentric and eccentric contractions.Angle and velocity-matched H/Q ratio maps and DCR maps were produced for each group. Difference maps allowed quantification of the differences between the groups.Angle and velocity-matched H/Q ratio maps demonstrated systematic variation based on joint angle, velocity, and contraction type for both the control (H/Q, approximately 0-1.42; DCR, approximately 0-1.57) and the ACL-reconstructed group (H/Q, approximately 0-1.33; DCR, approximately 0-1.35). Difference maps demonstrate regional (angle and velocity-specific) alteration in the ratio between the ACL-reconstructed and control groups.Specific imbalances were demonstrated in the ACL-reconstructed group compared with control. In high knee flexion angles, the low H/Q ratio may represent a compromised ability of the hamstrings to stabilize the knee joint throughout the full range of motion. Near full knee extension shifts in favor of the knee flexors may represent an attempt to stabilize the knee at the angle of greatest ACL strain. These finding have implications for graft donor site selection and postoperative rehabilitation as well as provide insight into the neuromuscular control of the knee.

Nutraceuticals may induce doping infractions through contamination of the product itself or their ingestion might be metabolized within the body to create a positive doping control test. We tested this possibility using a commercially available, proprietary ginseng root extract (Cold-FX®, CV Technologies Inc., Edmonton, AB). After athletes ingested Cold-FX© for 28 d at 400 mg/d, urine samples were collected and processed under strict IOC doping control guidelines and then analyzed for a full screen of IOC banned/restricted substances by an IOC-approved laboratory. There were no positive tests for any banned substances in any of the subjects. Our study demonstrates that ingestion of Cold-FX® for 28 d at 400 mg/d does not represent a doping concern for athletes. Carefully controlled clinical studies like this one are necessary to provide the athlete, the nutraceutical industry and IOC regulatory bodies with information to avoid inadvertent exposure to banned/restricted or potentially unhealthy substances.

A paucity of objective outcome measures exists for assessing movement disorders, including degenerative lumbar spinal stenosis (LSS). Fitts's Law provides a novel approach to clinical outcome measurement since performance is resistant to learning, and task difficulty can be altered. The objective of the present study was to compare, using a Fitts's task, movement performance of individuals with and without LSS to determine if motor difficulties that arise with LSS impede the planning, initiation, or execution of deliberate lower limb movements. Twelve pre-surgical LSS patients and twelve control participants from the community performed a Fitts's Law (foot reaching) task, while LSS participants also completed pain and disability questionnaires. Fitts's Law was evident for both groups, however the LSS group's movements were more adversely impacted as task difficulty increased. Specifically, the LSS group's movement time and time to peak velocity (ttPV) increased as task index of difficulty increased, while peak velocity decreased. Correlations between ttPV and leg pain, and with stenosis impairment severity respectively, provided evidence that less support leg pain and less stenosis impairment severity yield faster ttPV in the moving leg at the highest index of difficulty. Therefore a lower extremity Fitts's Law task captured differences in the planning and execution of leg movements between healthy and LSS populations.

BACKGROUND: Individuals on hemodialysis have low physical function and activity levels. Clinical trials have shown improvements in these parameters with exercise programming. Pedometers have not been extensively evaluated in individuals on hemodialysis. This randomized clinical trial compared the effects of intradialytic cycling versus a pedometer program on physical function, physical activity and quality of life. METHODS: Sixty patients were randomly assigned to two study groups. The ergometer group cycled during each hemodialysis session for 24 weeks. Pedometer participants followed a home-based walking program for 24 weeks. The primary outcome was aerobic capacity [VO2peak and 6-minute walk (6MW) test]. Secondary outcomes included lower extremity strength [sit-to-stand (SS) test], flexibility [sit-and-reach (SR) test], physical activity (accelerometer) and health-related quality of life. Measurements were collected at baseline and at 12 and 24 weeks. RESULTS: At 12 and 24 weeks, there was no significant change in the VO2peak or 6MW test between or within study groups. SS testing in the ergometer group improved from 10.2 (SD 3.4) to 11.4 (SD 2.5) cycles from baseline to 24 weeks (P < 0.005). Similarly, in the pedometer group, SS cycles improved from 10.1 (SD 3.3) to 12.2 (SD 3.5) (P < 0.005). The SR test also significantly improved over time in both the study groups. No significant changes were noted for other secondary outcomes. CONCLUSIONS: Both intradialytic cycling and pedometer programming improved aspects of physical function. Neither intervention had a significant effect on aerobic capacity. No significant differences in any outcomes were identified between interventions groups.

There is a paucity of information regarding the impact of central adiposity on the inertial characteristics of body segments. Deriving low back loads during lifting requires accurate estimate of inertial parameters. The purpose was to determine the body segment inertial parameters of people with central adiposity using a photogrammetric technique, and then to evaluate the impact on lumbar spine loading. Five participants with central adiposity (waist:hip ratio>0.9, waist circumference>102 cm) were compared to a normal BMI group. A 3D wireframe model of the surface topography was constructed, partitioned into 8 body segments and then body segment inertial parameters were calculated using volumetric integration assuming uniform segment densities for the segments. Central adiposity dependent increases in body segment parameters ranged from 12 to 400%, varying across segments (greatest for trunk) and parameters. The increase in mass distribution to the trunk was accompanied by an anterior and inferior shift of the centre of mass. A proximal shift in centre of mass was detected for the extremities, along with a reduction in mass distribution to the lower extremity. L5/S1 torques (392 vs 263 Nm) and compressive forces (5918 vs 3986 N) were substantially elevated in comparison to the normal BMI group, as well as in comparison to torques and forces predicted using published BSIP equations. Central adiposity resulted in substantial but non-uniform increases in inertial parameters resulting in task specific increases in torque and compressive loads arising from different inertial and physical components.

The purpose of this study was to examine the strength of the knee flexors and knee extensors after two surgical techniques of ACL reconstruction and compare them to an age and activity level matched control group.Twenty-four subjects who had undergone ACL reconstruction greater than 1 yr previously were placed into one of two groups according to autograft donor site: patellar tendon (BPB; N = 8) and hamstring (H; N = 16), and compared with an active, control group (N = 30). Knee flexor and extensor strength was evaluated using isovelocity dynamometry (5 speeds, eccentric and concentric, 5-95 degrees ROM). Strength maps were used to graphically analyze strength over a broad operational domain of the neuromuscular system. Average strength maps were determined for each autograft group and compared with controls. A difference map (control minus graft group) and confidence (t-test) maps were used to quantitatively identify strength deficits.The combined ACL group (N = 24) revealed a global 25.5% extensor strength deficit, with eccentric regional (angle and velocity matched) deficits up to 50% of control. Strength deficits covered over 86% of the sampled strength map area (P0.01). These knee extensor strength deficits are greater than previously reported. In addition, the BPB group demonstrated a concentric, low velocity, knee extensor strength deficit at 60-95 degrees that was not observed in the H group. Significant graft site dependent, regional knee flexor deficits of up to 50% of control were observed for the H group.Strength deficits localized to specific contraction types and ranges of motion were demonstrated between the ACL and control groups that were dependent upon autograft donor site. Postoperative rehabilitation protocols specific to these deficits should be devised.