Are Jumping Asymmetries Associated with Prospective Injury Risk in Pre-Professional Ballet?

Background: Pre-professional ballet dancers are exposed primarily to injury risk in the lower extremities with most injuries occurring during jumping and landing activities. Inter-limb asymmetry during jumping and landing activities has been associated with injury risk in adolescent athletes but this has not been examined in dancers. Purpose: To investigate associations between interlimb asymmetry in double-leg (DL-CMJ) and single leg (SLJ), countermovement jump performance and prospective injury risk in pre-professional adolescent ballet dancers. Study Design: Cohort-Study. Methods: Pre-professional adolescent ballet dancers (n=255) performed 3 DL-CMJ’s and 3 SLJ’s on force plates during of annual profiling. Absolute and directional (separate values for left and right dominance) asymmetries in a range of DL-CMJ kinetic variables and in SLJ height were calculated. Each variable was dichotomised as “high” or “normal” asymmetry according to whether % asymmetry was > or ≤ mean + 0.5 SD, based on the present sample. Risk ratios (RR) and 95% confidence intervals (95% CI) were calculated based on injury incidence in the subsequent academic year. Results: Of 242 dancers, 128 injuries were observed in the subsequent academic year. In the full sample, two absolute, six left limb dominant and one right limb dominant kinetic asymmetries across eccentric, concentric and landing phases of the DL-CMJ, and left limb dominant jump height asymmetry in the SLJ were associated with a significant (p=<0.001) increase in injury risk (RR= between 1.48 and 1.71, 95% CI = 1.01 to 2.48). Separating by sex, eccentric DL-CMJ asymmetries were not significant in boys, while in girls RR’s for eccentric asymmetries increased and SLJ height was not significant. Conclusions: Higher asymmetries in specific DL-CMJ kinetic variables and in SLJ height were associated with an elevated risk of injury in elite pre-professional ballet dancers with some specific sex differences. Associations were mainly identified for high left limb dominant asymmetry in the take-off phase suggesting that risk may be specific to a relative right limb deficit. Clinical Relevance: This study provides detailed and thorough initial research investigating associations between jumping asymmetry and prospective injury risk in pre-professional ballet dancers. This may lead to the introduction of more proactive injury reduction strategies in the future. This research also highlights that jump-land asymmetry-risk analyses should not only consider absolute values, but also left and right limb dominant asymmetries separately as associations are missed if directional asymmetries are not considered. Key Words: Injuries, Jumping, Limb asymmetry, Dance, Risk Factors, Biomechanics, Knee Injury, Ankle Injury, Foot Injury What is already known on the topic: Pre-professional adolescent ballet dancers face significant exposure to injury in the lower extremities and jumping and landing during dance is the most common mechanism of injury. Associations between SLJ height asymmetry and injury risk have been reported in team sports. What this study adds: High (relative to population norms), jump-land double leg CMJ and single leg jump height asymmetries, predominantly left dominance (right limb deficits) are associated with prospective injury risk in pre-professional ballet dancers. In addition, using internal descriptive statistics to classify asymmetry and analysis of directional asymmetries may provide a useful method to investigate interactions between asymmetry and injury

Measuring the quality and quantity of professional intrapartum support: Testing a computerised systematic observation tool in the clinical setting

Background: Continuous support in labour has a significant impact on a range of clinical outcomes, though whether the quality and quantity of support behaviours affects the strength of this impact has not yet been established. To identify the quality and quantity of support, a reliable means of measurement is needed. To this end, a new computerised systematic observation tool, the &lsquo;SMILI' (Supportive Midwifery in Labour Instrument) was developed. The aim of the study was to test the validity and usability of the &lsquo;Supportive Midwifery in Labour Instrument' (SMILI) and to test the feasibility and acceptability of the systematic observation approach in the clinical intrapartum setting. Methods: Systematic observation was combined with a postnatal questionnaire and the collection of data about clinical processes and outcomes for each observed labour. The setting for the study was four National Health Service maternity units in Scotland, UK. Participants in this study were forty five midwives and forty four women. The SMILI was used by trained midwife observers to record labour care provided by midwives. Observations were undertaken for an average of two hours and seventeen minutes during the active first stage of labour and, in 18 cases, the observation included the second stage of labour. Content validity of the instrument was tested by the observers, noting the extent to which the SMILI facilitated the recording of all key aspects of labour care and interactions. Construct validity was tested through exploration of correlations between the data recorded and women's feelings about the support they received. Feasibility and usability data were recorded following each observation by the observer. Internal reliability and construct validity were tested through statistical analysis of the data. Results: One hundred and four hours of labour care were observed and recorded using the SMILI during forty nine labour episodes. Conclusion: The SMILI was found to be a valid and reliable instrument in the intrapartum setting in which it was tested. The study identified that the SMILI could be used to test correlations between the quantity and quality of support and outcomes. The systematic observational approach was found to be an acceptable and feasible method of enquiry

Efficacy of aerobic exercise and a prudent diet for improving selected lipids and lipoproteins in adults: a meta-analysis of randomized controlled trials

Background Studies addressing the effects of aerobic exercise and a prudent diet on lipid and lipoprotein concentrations in adults have reached conflicting conclusions. The purpose of this study was to determine the effects of aerobic exercise combined with a prudent diet on lipid and lipoprotein concentrations in adults. Methods Studies were located by searching nine electronic databases, cross-referencing, and expert review. Two independent reviewers selected studies that met the following criteria: (1) randomized controlled trials, (2) aerobic exercise combined with diet recommendations (saturated/trans fat intake less than 10% of total calories and cholesterol less than 300 mg/day and/or fiber intake ≥25 g/day in women and ≥35 grams per day in men), (3) intervention ≥4 weeks, (4) humans ≥18 years of age, (5) published studies, including dissertations and Master\u27s theses, (6) studies published in any language, (7) studies published between January 1, 1955 and May 1, 2009, (8) assessment of one or more of the following lipid and lipoprotein concentrations: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), ratio of TC to HDL-C, non-HDL-C, low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG). Two reviewers independently extracted all data. Random-effects models that account for heterogeneity and 95% confidence intervals were used to pool findings. Results Of the 1,401 citations reviewed, six studies representing 16 groups (8 intervention, 8 control) and up to 559 men and women (282 intervention, 277 control) met the criteria for analysis. Statistically significant intervention minus control reductions were found for TC (-15.5 mg/dl, 95% CI, -20.3 to -10.7), TC:HDL-C (-0.4 mg/dl, 95% CI, -0.7 to -0.2), LDL-C (-9.2 mg/dl, 95% CI, -12.7 to -5.8) and TG (-10.6 mg/dl, 95% CI, -17.2 to -4.0) but not HDL-C (-0.5 mg/dl, 95% CI, -4.0 to 3.1). Changes were equivalent to reductions of 7.5%, 6.6%, 7.2% and 18.2% respectively, for TC, TC:HDL-C, LDL-C and TG. Because of missing variance statistics, non-HDL-C was excluded. Conclusions Aerobic exercise combined with a prudent diet is highly efficacious for improving TC, TC:HDL-C, LDL-C and TG, but not HDL-C concentrations, in adults. However, additional studies are needed, including effectiveness studies using intention-to-treat analysis

Rescue of neuropsychiatric phenotypes in a mouse model of 16p11.2 duplication syndrome by genetic correction of an epilepsy network hub

Neuropsychiatric disorders (NPDs) are frequently co-morbid with epilepsy, but the biological basis of shared risk remains poorly understood. The 16p11.2 duplication is a copy number variant that confers risk for diverse NPDs including autism spectrum disorder, schizophrenia, intellectual disability and epilepsy. We used a mouse model of the 16p11.2 duplication (16p11.2dup/+) to uncover molecular and circuit properties associated with this broad phenotypic spectrum, and examined genes within the locus capable of phenotype reversal. Quantitative proteomics revealed alterations to synaptic networks and products of NPD risk genes. We identified an epilepsy-associated subnetwork that was dysregulated in 16p11.2dup/+ mice and altered in brain tissue from individuals with NPDs. Cortical circuits from 16p11.2dup/+ mice exhibited hypersynchronous activity and enhanced network glutamate release, which increased susceptibility to seizures. Using gene co-expression and interactome analysis, we show that PRRT2 is a major hub in the epilepsy subnetwork. Remarkably, correcting Prrt2 copy number rescued aberrant circuit properties, seizure susceptibility and social deficits in 16p11.2dup/+ mice. We show that proteomics and network biology can identify important disease hubs in multigenic disorders, and reveal mechanisms relevant to the complex symptomatology of 16p11.2 duplication carriers