Injury Prevalence Among Elite Adolescent Ballet Dancers is not Affected by Frequency of Questionnaire Administration: A 6-Month Exploratory Prospective Study.

INTRODUCTION: The Oslo Sports Trauma Research Centre Questionnaire on Health Problems (OSTRC-H) is a valid and reliable registration method for self-reported injuries and is regularly used among dancer populations. Monthly questionnaire administration is acceptable in athlete populations but has not been evaluated in dancers. The aim of this exploratory study was to assess the influence of weekly versus monthly administration of the OSTRC-H on estimated injury outcomes among elite adolescent ballet dancers. METHODS: Participants (n = 103) were prospectively followed for 6 months and completed the OSTRC-H online, evaluating perceived consequences of self-reported health problems during the previous week and the previous 4 weeks, respectively. Four definitions of dance-related injury were utilized: (1) all complaints, (2) substantial, (3) medical attention, and (4) time-loss injuries. Descriptive statistics estimated: (1) the number of injuries reported (count), (2) average injury prevalence [proportion, 95% confidence intervals (CI)], (3) average severity score (0-100), and (4) days of time loss (count) for each injury definition. The 4 outcome measures were then compared between weekly and monthly registration with paired sample t-tests (P < .05) and overlapping 95% CI. RESULTS: A significant difference between the number of all complaints injuries (weekly: 133; monthly: 94; P < .001) and substantial injuries (weekly: 64; monthly: 45; P = .012) was found. Regardless of injury definition, there were no significant differences between injury prevalence, severity scores, and days of time loss when reported weekly versus monthly. CONCLUSION: Monthly administration of the OSTRC-H is an acceptable method to estimate injury prevalence, severity scores, and days of time loss amongst elite adolescent ballet dancers.

Systematic review of methods used to measure training load in dance.

Dance is a popular physical activity. Increased dance training has been associated with an increased risk of injury. Given the established association between training load (TL) and injury in sport, knowledge of how TL is currently being measured in dance is critical. The objective of this study is to summarise published literature examining TL monitoring in dance settings. Six prominent databases (CINAHL, EMBASE, Medline, ProQuest, Scopus, SportDiscus) were searched and nine dance-specific journals were handsearched up to May 2022. Selected studies met inclusion criteria, where original TL data were collected from at least one dancer in a class, rehearsal and/or performance. Studies were excluded if TL was not captured in a dance class, rehearsal or performance. Two reviewers independently assessed each record for inclusion at title, abstract and full-text screening stages. Study quality was assessed using Joanna Briggs Institute Critical Appraisal Tool checklists for each study design. The 199 included studies reported on female dancers (61%), ballet genre (55%) and the professional level (31%). Dance hours were the most common tool used to measure TL (90%), followed by heart rate (20%), and portable metabolic systems (9%). The most common metric for each tool was mean weekly hours (n=381; median=9.5 hours, range=0.2-48.7 hours), mean heart rate (n=143) and mean oxygen consumption (n=93). Further research on TL is needed in dance, including a consensus on what tools and metrics are best suited for TL monitoring in dance.

Perceptions and Attitudes Toward the Use of Wearable Technology in the Dance Studio Environment.

Introduction: Wearable technology (WT) has become common place in sport. Increased affordability has allowed WT to reach the wrists and bodies of grassroots and community athletes. While WT is commonly used by sport populations to monitor training load, the use of WT among dancers and dance teachers is unknown. Therefore, the purpose of this study is to explore the perspectives of dancers, dance teachers, and dance parents on using WT in the dance studio environment. Methods: Dancers (aged 14+), dance teachers (aged 18+), and dance parents (with a child <18 years registered in a dance program) were recruited from local dance studios (including those offering vocational programs and/or professional training opportunities), and dance retail stores. Participants provided informed consent/assent and completed a one-time online survey about their attitudes, self-efficacy, motivations, barriers, and current practices of using WT in the studio. Results: Sixty-seven participants (19 dancers, 32 dance teachers, and 16 dance parents) completed the survey. Attitudes toward using WT were similar across all groups (mean score range = 34-38/45). Thirteen dancers (68%), 29 teachers (91%), and 7 dance parents reporting on behalf of their children (47%) were permitted to use WT in the studio. Smartwatches were the most common WT used in the studio by dancers (7/9) and teachers (13/17), while dance parents reported that their children primarily used wristband activity trackers (3/4). Among all groups, the primary reason for using WT was to track personalized training data, with calories, total duration, and heart rate being the most important perceived metrics for improving dancing. Conclusion: Across all groups, attitudes toward WT were modest. Prevalence of WT use in the dance studio varied, with wrist-based gadgets being the most common. As WT research continues in dance populations, it will be important for future studies to consider studio permissions as well as participants' existing WT use practices.

Global Prevalence of Meeting Screen Time Guidelines Among Children 5 Years and Younger: A Systematic Review and Meta-analysis.

IMPORTANCE: Pediatric guidelines suggest that infants younger than 2 years avoid screen time altogether, while children aged 2 to 5 years receive no more than 1 hour per day. Although these guidelines have been adopted around the world, substantial variability exists in adherence to the guidelines, and precise estimates are needed to inform public health and policy initiatives. OBJECTIVE: To derive the pooled prevalence via meta-analytic methods of children younger than 2 years and children aged 2 to 5 years who are meeting guidelines about screen time. DATA SOURCES: Searches were conducted in MEDLINE, PsycINFO, and Embase up to March 2020. STUDY SELECTION: Studies were included if participants were 5 years and younger and the prevalence of meeting (or exceeding) screen time guidelines was reported. DATA EXTRACTION AND SYNTHESIS: Data extraction followed Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Two independent reviewers extracted all relevant data. Random-effects meta-analyses were used to derive the mean prevalence rates. MAIN OUTCOMES AND MEASURES: Prevalence of meeting screen time guidelines. RESULTS: From 63 studies, 95 nonoverlapping samples with a total of 89 163 participants were included. For children younger than 2 years, the pooled prevalence of meeting the screen time guideline (0 h/d) was 24.7% (95% CI, 19.0%-31.5%). Moderator analyses revealed that prevalence of meeting screen time guidelines varied as a function of year of data collection (increased over time), measurement method (higher when questionnaires compared with interview), and type of device use (higher when a combination of screen use activities compared with television/movies only). For children aged 2 to 5 years, the mean prevalence of meeting the screen time guideline (1 h/d) was 35.6% (95% CI, 30.6%-40.9%). Moderator analyses revealed that the prevalence of meeting screen time guidelines varied as a function of type of device use (higher when screen time was television/movies only compared with a combination of screen use activities). CONCLUSIONS AND RELEVANCE: The findings of this meta-analysis indicate that only a minority of children 5 years and younger are meeting screen time guidelines. This highlights the need to provide support and resources to families to best fit evidence-based recommendations into their lives.

Genetic Influence on Frequencies of Myeloid-Derived Cell Subpopulations in Mouse.

Differences in frequencies of blood cell subpopulations were reported to influence the course of infections, atopic and autoimmune diseases, and cancer. We have discovered a unique mouse strain B10.O20 containing extremely high frequency of myeloid-derived cells (MDC) in spleen. B10.O20 carries 3.6% of genes of the strain O20 on the C57BL/10 genetic background. It contains much higher frequency of CD11b+Gr1+ cells in spleen than both its parents. B10.O20 carries O20-derived segments on chromosomes 1, 15, 17, and 18. Their linkage with frequencies of blood cell subpopulations in spleen was tested in F2 hybrids between B10.O20 and C57BL/10. We found 3 novel loci controlling MDC frequencies: Mydc1, 2, and 3 on chromosomes 1, 15, and 17, respectively, and a locus controlling relative spleen weight (Rsw1) that co-localizes with Mydc3 and also influences proportion of white and red pulp in spleen. Mydc1 controls numbers of CD11b+Gr1+ cells. Interaction of Mydc2 and Mydc3 regulates frequency of CD11b+Gr1+ cells and neutrophils (Gr1+Siglec-F- cells from CD11b+ cells). Interestingly, Mydc3/Rsw1 is orthologous with human segment 6q21 that was shown previously to determine counts of white blood cells. Bioinformatics analysis of genomic sequence of the chromosomal segments bearing these loci revealed polymorphisms between O20 and C57BL/10 that change RNA stability and genes' functions, and we examined expression of relevant genes. This identified potential candidate genes Smap1, Vps52, Tnxb, and Rab44. Definition of genetic control of MDC can help to personalize therapy of diseases influenced by these cells.

Internal Training Load Measures in Elite Adolescent Ballet Dancers.

Training load has been identified as a risk factor for musculoskeletal injury in sport, but little is known about the effects of training load in dance. The purpose of this study was to describe adolescent dancers' internal training load (ITL) and compare objective and subjective measures of ITL using heart rate (HR) training impulse methods and session Rating of Perceived Exertion (sRPE), respectively. Fifteen female elite adolescent ballet dancers at a vocational dance school volunteered to participate in the study. Internal training load data using HR and sRPE were collected over 9 days of multiple technique classes at the midpoint of the dancers' training year. Heart rate data were quantified using Edwards' training impulse (ETRIMP) and Banister's training impulse (BTRIMP), and sRPE was estimated from the modified Borg 0 to 10 scale and class duration. Descriptive statistics (median [M], and interquartile range [IQR]) were determined in arbitrary units (AU), and were as follows for all classes combined: ETRIMP: M = 134 AU (IQR = 79 to 244 AU); BTRIMP: M = 67 AU (IQR = 38 to 109); sRPE: M = 407 AU (IQR = 287 to 836 AU). The association and agreement between objective and subjective ITL measures in ballet and pointe class was assessed using Spearman correlations (rs) and adjusted Bland-Altman 95% limits of agreement (LOA), respectively, with alpha set at 0.05. A significant moderate positive correlation was found between ETRIMP and BTRIMP in pointe class (rρ = 0.8000, p = 0.0031). The mean difference (LOA) between ETRIMP and BTRIMP was 121 AU (33 to 210 AU) in ballet and 43 AU (-3 to 88 AU) in pointe. It is concluded that some, but not all, measures of ITL in elite adolescent ballet dancers are comparable. Additional research is needed to examine the utilization of ITL measures for evaluating dance-related injury risk, as well as the application of ITL to inform the development of effective injury prevention strategies for this high-risk population.

Workload a-WEAR-ness: Monitoring Workload in Team Sports With Wearable Technology. A Scoping Review.

OBJECTIVES: To (1) identify the wearable devices and associated metrics used to monitor workload and assess injury risk, (2) describe the situations in which workload was monitored using wearable technology (including sports, purpose of the analysis, location and duration of monitoring, and athlete characteristics), and (3) evaluate the quality of evidence that workload monitoring can inform injury prevention. DESIGN: Scoping review. LITERATURE SEARCH: We searched the CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, HealthSTAR, MEDLINE, PsycINFO, SPORTDiscus, and Web of Science databases. STUDY SELECTION CRITERIA: We included all studies that used wearable devices (eg, heart rate monitor, inertial measurement units, global positioning system) to monitor athlete workload in a team sport setting. DATA SYNTHESIS: We provided visualizations that represented the workload metrics reported, sensors used, sports investigated, athlete characteristics, and the duration of monitoring. RESULTS: The 407 included studies focused on team ball sports (67% soccer, rugby, or Australian football), male athletes (81% of studies), elite or professional level of competition (74% of studies), and young adults (69% of studies included athletes aged between 20 and 28 years). Thirty-six studies of 7 sports investigated the association between workload measured with wearable devices and injury. CONCLUSION: Distance-based metrics derived from global positioning system units were common for monitoring workload and are frequently used to assess injury risk. Workload monitoring studies have focused on specific populations (eg, elite male soccer players in Europe and elite male rugby and Australian football players in Oceania). Different injury definitions and reported workload metrics and poor study quality impeded conclusions regarding the relationship between workload and injury. J Orthop Sports Phys Ther 2020;50(10):549-563. doi:10.2519/jospt.2020.9753.

Novel Loci Controlling Parasite Load in Organs of Mice Infected With Leishmania major, Their Interactions and Sex Influence.

Leishmaniasis is a serious health problem in many countries, and continues expanding to new geographic areas including Europe and USA. This disease, caused by parasites of Leishmania spp. and transmitted by phlebotomine sand flies, causes up to 1.3 million new cases each year and despite efforts toward its functional dissection and treatment it causes 20-50 thousands deaths annually. Dependence of susceptibility to leishmaniasis on sex and host's genes was observed in humans and in mouse models. Several laboratories defined in mice a number of Lmr (Leishmania major response) genetic loci that control functional and pathological components of the response to and outcome of L. major infection. However, the development of its most aggressive form, visceral leishmaniasis, which is lethal if untreated, is not yet understood. Visceral leishmaniasis is caused by infection and inflammation of internal organs. Therefore, we analyzed the genetics of parasite load, spread to internal organs, and ensuing visceral pathology. Using a new PCR-based method of quantification of parasites in tissues we describe a network-like set of interacting genetic loci that control parasite load in different organs. Quantification of Leishmania parasites in lymph nodes, spleen and liver from infected F2 hybrids between BALB/c and recombinant congenic strains CcS-9 and CcS-16 allowed us to map two novel parasite load controlling Leishmania major response loci, Lmr24 and Lmr27. We also detected parasite-controlling role of the previously described loci Lmr4, Lmr11, Lmr13, Lmr14, Lmr15, and Lmr25, and describe 8 genetic interactions between them. Lmr14, Lmr15, Lmr25, and Lmr27 controlled parasite load in liver and lymph nodes. In addition, Leishmania burden in lymph nodes but not liver was influenced by Lmr4 and Lmr24. In spleen, parasite load was controlled by Lmr11 and Lmr13. We detected a strong effect of sex on some of these genes. We also mapped additional genes controlling splenomegaly and hepatomegaly. This resulted in a systematized insight into genetic control of spread and load of Leishmania parasites and visceral pathology in the mammalian organism.

A novel locus on mouse chromosome 7 that influences survival after infection with tick-borne encephalitis virus.

BACKGROUND: Tick-borne encephalitis (TBE) is the main tick-borne viral infection in Eurasia. Its manifestations range from inapparent infections and fevers with complete recovery to debilitating or fatal encephalitis. The basis of this heterogeneity is largely unknown, but part of this variation is likely due to host genetic. We have previously found that BALB/c mice exhibit intermediate susceptibility to the infection of TBE virus (TBEV), STS mice are highly resistant, whereas the recombinant congenic strain CcS-11, carrying 12.5% of the STS genome on the background of the BALB/c genome is even more susceptible than BALB/c. Importantly, mouse orthologs of human TBE controlling genes Oas1b, Cd209, Tlr3, Ccr5, Ifnl3 and Il10, are in CcS-11 localized on segments derived from the strain BALB/c, so they are identical in BALB/c and CcS-11. As they cannot be responsible for the phenotypic difference of the two strains, we searched for the responsible STS-derived gene-locus. Of course the STS-derived genes in CcS-11 may operate through regulating or epigenetically modifying these non-polymorphic genes of BALB/c origin. METHODS: To determine the location of the STS genes responsible for susceptibility of CcS-11, we analyzed survival of TBEV-infected F2 hybrids between BALB/c and CcS-11. CcS-11 carries STS-derived segments on eight chromosomes. These were genotyped in the F2 hybrid mice and their linkage with survival was tested by binary trait interval mapping. We have sequenced genomes of BALB/c and STS using next generation sequencing and performed bioinformatics analysis of the chromosomal segment exhibiting linkage with TBEV survival. RESULTS: Linkage analysis revealed a novel suggestive survival-controlling locus on chromosome 7 linked to marker D7Nds5 (44.2 Mb). Analysis of this locus for polymorphisms between BALB/c and STS that change RNA stability and genes' functions led to detection of 9 potential candidate genes: Cd33, Klk1b22, Siglece, Klk1b16, Fut2, Grwd1, Abcc6, Otog, and Mkrn3. One of them, Cd33, carried a nonsense mutation in the STS strain. CONCLUSIONS: The robust genetic system of recombinant congenic strains of mice enabled detection of a novel suggestive locus on chromosome 7. This locus contains 9 candidate genes, which will be focus of future studies not only in mice but also in humans.

Gene-specific sex effects on eosinophil infiltration in leishmaniasis.

BACKGROUND: Sex influences susceptibility to many infectious diseases, including some manifestations of leishmaniasis. The disease is caused by parasites that enter to the skin and can spread to the lymph nodes, spleen, liver, bone marrow, and sometimes lungs. Parasites induce host defenses including cell infiltration, leading to protective or ineffective inflammation. These responses are often influenced by host genotype and sex. We analyzed the role of sex in the impact of specific gene loci on eosinophil infiltration and its functional relevance. METHODS: We studied the genetic control of infiltration of eosinophils into the inguinal lymph nodes after 8 weeks of Leishmania major infection using mouse strains BALB/c, STS, and recombinant congenic strains CcS-1,-3,-4,-5,-7,-9,-11,-12,-15,-16,-18, and -20, each of which contains a different random set of 12.5% genes from the parental "donor" strain STS and 87.5% genes from the "background" strain BALB/c. Numbers of eosinophils were counted in hematoxylin-eosin-stained sections of the inguinal lymph nodes under a light microscope. Parasite load was determined using PCR-ELISA. RESULTS: The lymph nodes of resistant STS and susceptible BALB/c mice contained very low and intermediate numbers of eosinophils, respectively. Unexpectedly, eosinophil infiltration in strain CcS-9 exceeded that in BALB/c and STS and was higher in males than in females. We searched for genes controlling high eosinophil infiltration in CcS-9 mice by linkage analysis in F2 hybrids between BALB/c and CcS-9 and detected four loci controlling eosinophil numbers. Lmr14 (chromosome 2) and Lmr25 (chromosome 5) operate independently from other genes (main effects). Lmr14 functions only in males, the effect of Lmr25 is sex independent. Lmr15 (chromosome 11) and Lmr26 (chromosome 9) operate in cooperation (non-additive interaction) with each other. This interaction was significant in males only, but sex-marker interaction was not significant. Eosinophil infiltration was positively correlated with parasite load in lymph nodes of F2 hybrids in males, but not in females. CONCLUSIONS: We demonstrated a strong influence of sex on numbers of eosinophils in the lymph nodes after L. major infection and present the first identification of sex-dependent autosomal loci controlling eosinophilic infiltration. The positive correlation between eosinophil infiltration and parasite load in males suggests that this sex-dependent eosinophilic infiltration reflects ineffective inflammation.

Mapping the genes for susceptibility and response to Leishmania tropica in mouse.

BACKGROUND: L. tropica can cause both cutaneous and visceral leishmaniasis in humans. Although the L. tropica-induced cutaneous disease has been long known, its potential to visceralize in humans was recognized only recently. As nothing is known about the genetics of host responses to this infection and their clinical impact, we developed an informative animal model. We described previously that the recombinant congenic strain CcS-16 carrying 12.5% genes from the resistant parental strain STS/A and 87.5% genes from the susceptible strain BALB/c is more susceptible to L. tropica than BALB/c. We used these strains to map and functionally characterize the gene-loci regulating the immune responses and pathology. METHODS: We analyzed genetics of response to L. tropica in infected F2 hybrids between BALB/c×CcS-16. CcS-16 strain carries STS-derived segments on nine chromosomes. We genotyped these segments in the F2 hybrid mice and tested their linkage with pathological changes and systemic immune responses. PRINCIPAL FINDINGS: We mapped 8 Ltr (Leishmania tropica response) loci. Four loci (Ltr2, Ltr3, Ltr6 and Ltr8) exhibit independent responses to L. tropica, while Ltr1, Ltr4, Ltr5 and Ltr7 were detected only in gene-gene interactions with other Ltr loci. Ltr3 exhibits the recently discovered phenomenon of transgenerational parental effect on parasite numbers in spleen. The most precise mapping (4.07 Mb) was achieved for Ltr1 (chr.2), which controls parasite numbers in lymph nodes. Five Ltr loci co-localize with loci controlling susceptibility to L. major, three are likely L. tropica specific. Individual Ltr loci affect different subsets of responses, exhibit organ specific effects and a separate control of parasite load and organ pathology. CONCLUSION: We present the first identification of genetic loci controlling susceptibility to L. tropica. The different combinations of alleles controlling various symptoms of the disease likely co-determine different manifestations of disease induced by the same pathogen in individual mice.

Genetics of host response to Leishmania tropica in mice - different control of skin pathology, chemokine reaction, and invasion into spleen and liver.

BACKGROUND: Leishmaniasis is a disease caused by protozoan parasites of genus Leishmania. The frequent involvement of Leishmania tropica in human leishmaniasis has been recognized only recently. Similarly as L. major, L. tropica causes cutaneous leishmaniasis in humans, but can also visceralize and cause systemic illness. The relationship between the host genotype and disease manifestations is poorly understood because there were no suitable animal models. METHODS: We studied susceptibility to L. tropica, using BALB/c-c-STS/A (CcS/Dem) recombinant congenic (RC) strains, which differ greatly in susceptibility to L. major. Mice were infected with L. tropica and skin lesions, cytokine and chemokine levels in serum, and parasite numbers in organs were measured. PRINCIPAL FINDINGS: Females of BALB/c and several RC strains developed skin lesions. In some strains parasites visceralized and were detected in spleen and liver. Importantly, the strain distribution pattern of symptoms caused by L. tropica was different from that observed after L. major infection. Moreover, sex differently influenced infection with L. tropica and L. major. L. major-infected males exhibited either higher or similar skin pathology as females, whereas L. tropica-infected females were more susceptible than males. The majority of L. tropica-infected strains exhibited increased levels of chemokines CCL2, CCL3 and CCL5. CcS-16 females, which developed the largest lesions, exhibited a unique systemic chemokine reaction, characterized by additional transient early peaks of CCL3 and CCL5, which were not present in CcS-16 males nor in any other strain. CONCLUSION: Comparison of L. tropica and L. major infections indicates that the strain patterns of response are species-specific, with different sex effects and largely different host susceptibility genes.