A Survey of Injuries Affecting Pre-Professional Ballet Dancers.

A cross-sectional design was employed retrospectively to evaluate injuries self-reported by 71 pre-professional ballet dancers over one season. Some of the descriptive findings of this survey were consistent with those of previous research and suggest particular demographic and injury trends in pre-professional ballet. These results include gender distribution, mean age and age range of participants, training hours, injury location, acute versus overuse injuries, as well as average number of physiotherapy treatments per dancer. Other results provide information that was heretofore unreported or inconsistent with previous investigations. These findings involved proportion of dancers injured, average number of injuries per dancer, overall injury incidence during an 8.5 month period, incidence rate by technique level, mean time loss per injury, proportion of recurrent injury, and activity practiced at time of injury. The results of univariate analyses revealed several significant findings, including a decrease in incidence rate of injury with increased months of experience in the pre-professional program, dancers having lower injury risk in rehearsal and performance than in class, and a reduced risk of injury for dancers at certain technique levels. However, only this latter finding remained significant in multivariate analysis. The results of this study underscore the importance of determining injury rates by gender, technique level, and activity setting in addition to overall injury rates. They also point to the necessity of looking at both overall and individual dancer-based injury risks.

Epidemiological Review of Injury in Pre-Professional Ballet Dancers.

The objective of this study was to provide an epidemiological review of the literature concerning ballet injuries affecting pre-professional ballet dancers. The literature search was limited to published peer-reviewed reports and involved an extensive examination of Scopus, SPORTDiscus, and CINAHL. The following search terms were used in various combinations: ballet, injury, epidemiology, risk factor, pre-professional, and intervention. Additional citations were located using the ancestry approach. Unlike some other athletic activities that have been the focus of recent intervention research, there is a paucity of intervention and translational research in pre-professional ballet, and sample sizes have often been small and have not accounted for the multivariate nature of ballet injury. Exposure-based injury rates in this population appear similar to those reported for professional ballet dancers and female gymnasts. A preponderance of injuries affect the lower extremity of these dancers, with sprains and strains being the most frequent type of injury reported. The majority of injuries appear to be overuse in nature. Injury risk factors have been tested in multiple studies and indicate a variety of potential injury predictors that may provide useful guidance for future research.

CLIMATE AND HABITAT INFLUENCE PREVALENCE OF MENINGEAL WORM INFECTION IN NORTH DAKOTA, USA.

The meningeal worm (Parelaphostrongylus tenuis) is a parasite of white-tailed deer (Odocoileus virginianus) and is also a significant pathogen of moose (Alces alces) and other ungulates. Changes in climate or habitat may facilitate range expansion or increase the prevalence of meningeal worm infection in white-tailed deer, resulting in increased exposure to susceptible ungulates. We examined 3,730 white-tailed deer during 2002-05 to determine the prevalence and range of meningeal worm infection in North Dakota, US, and investigated whether these had changed since earlier surveys. We used multiple logistic regression to model potential effects of habitat and climate on prevalence in white-tailed deer. We also examined how habitat influences intermediate hosts by comparing gastropod abundance and microclimate among habitat types. Prevalence in deer was 14% statewide, and prevalence and geographic range had increased since the early 1990 s. Natural woodlands provided the best habitat for intermediate hosts, and increases in prevalence of infection in deer may be due to recent patterns in growing-season precipitation. This study has redefined the geographic distribution of meningeal worm infection and increased understanding of how climate and habitat influence the prevalence and distribution of this parasite.

A prospective study of injury affecting competitive collegiate swimmers.

The purposes of this study were to determine the incidence and distribution of injuries affecting collegiate competitive swimmers and to test possible injury risk factors. A prospective cohort design was used to follow 34 swimmers (16 M, 18 F) from an NCAA Division I Midwest University over one academic year. Exposure-based injury rates were determined for both practice and competition. Risk of injury was assessed relative to gender, years swimming, and history of injury. Twenty of 34 swimmers sustained 31 injuries with overall injury rates of 5.55 injuries per 1000 athlete exposures and 3.04 injuries per 1000 hours exposure. Practice injury rates for female swimmers were higher than for women's practice injury rates in other NCAA sports. The most common injury locations were the shoulder, back, and knee. Risk factors that remained significant in the multivariate analysis were history of injury to the same anatomical location and history of injury at other anatomical sites.

Quantifying a dynamic risk landscape: heterogeneous predator activity and implications for prey persistence.

Spatial heterogeneity in predation risk can ameliorate impacts on prey populations, particularly for prey of generalists. Spatially heterogeneous risk implies the existence of refugia, and the spatial scale of those refugia and their persistence over time affect whether prey can avoid predation by aggregating therein. Our objective was to quantify the magnitude, spatial scale, and temporal persistence of heterogeneity in risk of predation by white-footed mice (Peromyscus leucopus), an abundant generalist predator of gypsy moths (Lymantria dispar) and songbirds. We used track plates to measure white-footed mouse activity at > 170 trees in each of three forest plots in upstate New York during summers of 2003-2005. We quantified the mean and coefficient of variation of track activity among trees by fitting the beta-binomial distribution to data from each plot and study period. We measured temporal persistence by disattenuated autocorrelation, and spatial scale by fitting exponential variograms. Mice were much less abundant in 2005 than the other two years, leading to lower overall track activity but higher coefficient of variation among trees. Mouse track activity at individual trees was positively autocorrelated between monthly study periods in 2003 and 2004, and even between the two years, whereas temporal autocorrelation in 2005 was much weaker. Track activity showed positive spatial autocorrelation over lag distances from approximately 30 to > 1000 m. These findings indicate that mouse activity, and hence risk to their prey, varies substantially in space at spatial and temporal scales that appear responsive to mouse population dynamics. The spatial scale and temporal persistence of that variation imply that prey may benefit from returning to, or failing to disperse from, refugia.

Spatial selection and inheritance: applying evolutionary concepts to population dynamics in heterogeneous space.

Organisms in highly suitable sites generally produce more offspring, and offspring can inherit this suitability by not dispersing far. This combination of spatial selection and spatial inheritance acts to bias the distribution of organisms toward suitable sites and thereby increase mean fitness (i.e., per capita population increase). Thus, population growth rates in heterogeneous space change over time by a process conceptually analogous to evolution by natural selection, opening avenues for theoretical cross-pollination between evolutionary biology and ecology. We operationally define spatial inheritance and spatial selective differential and then combine these two factors in a modification of the breeder's equation, derived from simple models of population growth in heterogeneous space. The modified breeder's equation yields a conservative criterion for persistence in hostile environments estimable from field measurements. We apply this framework for understanding gypsy moth population persistence amidst abundant predators and find that the predictions of the modified breeder's equation match initial changes in population growth rate in independent simulation output. The analogy between spatial dynamics and natural selection conceptually links ecology and evolution, provides a spatially implicit framework for modeling spatial population dynamics, and represents an important null model for studying habitat selection.