Kinematic parameters after repeated swimming efforts in higher and lower proficiency swimmers and para-swimmers

Purpose: The aim of this study was to determine changes in swimming parameters, stroke coordination, and symmetry after repeated high-intensity swimming efforts in swimmers of different performance levels and para-swimmers. Method: Forty swimmers (20 able-bodied, allocated to higher and lower performance groups—G1 and G2, respectively—and 20 impaired swimmers—S5 to S10) were recorded by four underwater cameras while performing repeated 50 m maximum front-crawl swimming with a ten-second interval for each time endured by the swimmer. A cycle stroke was digitized using SIMI Reality Motion Systems in the first and last trials to analyze the kinematic parameters. The comparison among groups and conditions was performed by Mixed ANOVA Models with p < .05. Results: For all groups, swimming velocity, stroke rate, and stroke index showed reduction over time, while stroke length and intracyclic velocity variation did not show significant changes. Conclusions: Training to maintain stroke rate is necessary to support performance since it is the main cause of velocity decrease. Stroke dimensions and individual underwater phases were not sufficient to distinguish groups or conditions. Hand velocity decreased probably due to a decline in energy capacity, propulsive force and passive drag caused by the fatigue process

The spatial context of clinic-reported sexually transmitted infection in Hong Kong

<p>Abstract</p> <p>Background</p> <p>The incidence and prevalence of sexually transmitted infection (STI) in China has been on the rise in the past decade. Delineation of epidemiologic pattern is often hampered by its uneven distribution. Spatial distribution is often a neglected aspect of STI research, the description of which may enhance epidemiologic surveillance and inform service development.</p> <p>Methods</p> <p>Over a one month-period, all first time attendees of 6 public STI clinics in Hong Kong were interviewed before clinical consultation using a standard questionnaire to assess their demographic, clinical and behavioural characteristics. A GIS (geographic information system)-based approach was adopted with mapping performed. The cases attending the clinics in different locations were profiled. A comparison was made between neighbourhood cases (patients living near a clinic) and distant cases (those farther off), by calculating the odds ratio for demographic, behavioural and geographic characteristics.</p> <p>Results</p> <p>Of the 1142 STI patients evaluated, the residence locations of 1029 (90.1%) could be geocoded, of which 95.6% were ethnic Chinese and 63.4% male. Geographically only about a quarter lived in the same district as the clinic. STI patients aged 55 or above were more likely to be living in the vicinity of the clinic, located in the same or adjacent tertiary planning unit (a small geographic unit below district level). A majority of patients came from locations a few kilometers from the clinic, the distance of which varies between clinics. Overall, more syphilis cases were reported in patients residing in the same or adjacent tertiary planning unit, while distant cases tended to give a higher risk of inconsistent condom use. There were otherwise no significant clinical and epidemiologic differences between neighbourhood and distant STI cases.</p> <p>Conclusions</p> <p>There was no specific relationship between STI and the residence location of patients as regards their clinical and epidemiologic characteristics in the territory of Hong Kong. Older STI patients were however more inclined to attend the nearby STI clinics. Most patients have travelled a variable distance to access the STI service. The relationship between STI clinic cases and distance could be a complex issue intertwined between psychosocial characteristics and STI service coverage.</p

A Spatial Analysis of County-level Variation in Syphilis and Gonorrhea in Guangdong Province, China

Sexually transmitted infections (STI) have made a resurgence in many rapidly developing regions of southern China, but there is little understanding of the social changes that contribute to this spatial distribution of STI. This study examines county-level socio-demographic characteristics associated with syphilis and gonorrhea in Guangdong Province.This study uses linear regression and spatial lag regression to determine county-level (n = 97) socio-demographic characteristics associated with a greater burden of syphilis, gonorrhea, and a combined syphilis/gonorrhea index. Data were obtained from the 2005 China Population Census and published public health data. A range of socio-demographic variables including gross domestic product, the Gender Empowerment Measure, standard of living, education level, migrant population and employment are examined. Reported syphilis and gonorrhea cases are disproportionately clustered in the Pearl River Delta, the central region of Guangdong Province. A higher fraction of employed men among the adult population, higher fraction of divorced men among the adult population, and higher standard of living (based on water availability and people per room) are significantly associated with higher STI cases across all three models. Gross domestic product and gender inequality measures are not significant predictors of reported STI in these models.Although many ecological studies of STIs have found poverty to be associated with higher reported STI, this analysis found a greater number of reported syphilis cases in counties with a higher standard of living. Spatially targeted syphilis screening measures in regions with a higher standard of living may facilitate successful control efforts. This analysis also reinforces the importance of changing male sexual behaviors as part of a comprehensive response to syphilis control in China

Individual-environment interactions in swimming: The smallest unit for analysing the emergence of coordination dynamics in performance?

Displacement in competitive swimming is highly dependent on fluid characteristics, since athletes use these properties to propel themselves. It is essential for sport scientists and practitioners to clearly identify the interactions that emerge between each individual swimmer and properties of an aquatic environment. Traditionally, the two protagonists in these interactions have been studied separately. Determining the impact of each swimmer’s movements on fluid flow, and vice versa, is a major challenge. Classic biomechanical research approaches have focused on swimmers’ actions, decomposing stroke characteristics for analysis, without exploring perturbations to fluid flows. Conversely, fluid mechanics research has sought to record fluid behaviours, isolated from the constraints of competitive swimming environments (e.g. analyses in two-dimensions, fluid flows passively studied on mannequins or robot effectors). With improvements in technology, however, recent investigations have focused on the emergent circular couplings between swimmers’ movements and fluid dynamics. Here, we provide insights into concepts and tools that can explain these on-going dynamical interactions in competitive swimming within the theoretical framework of ecological dynamics

Heterogeneity in the spatial distribution of bacterial sexually transmitted infections

Objectives: Detailed knowledge of the spatial distribution of disease is required to inform service delivery and plan effective interventions. In order to elucidate the spatial epidemiology of three common sexually transmitted infections (STI) further, any significant spatiotemporal clustering of gonorrhoea, chlamydia or syphilis cases in New South Wales (NSW) was detected and described. Methods: Eleven years of notified STI case data were analysed. Calculation of age and sex-stratified incidence rates was followed by spatiotemporal cluster analyses to investigate differences in the epidemiology of gonorrhoea, chlamydia and syphilis. Results: More than one-third of all gonorrhoea, chlamydia and syphilis cases in NSW were detected within cluster areas. Gonorrhoea cases were the most highly clustered, followed by syphilis, then chlamydia. Clusters were highly significant and relative risk estimates ranged from 1.6 to 22.9. Conclusion: The findings establish the high degree of geographical heterogeneity in STI incidence in NSW and indicate that the postal area of residence is an important predictor of STI incidence. Geographical surveillance could be incorporated into routine STI surveillance to identify populations in need of intervention. The evidence presented in this report indicates a need to implement geography-specific and phase-appropriate STI prevention and control strategies

Neural synchrony in caregiver-child interactions: The role of attachment and sensitivity

For attachment and emotion regulation, behavioral and affective attunement between caregiver and child are essential (Stern, 1985). Especially sensitive caregiving is associated with behavioral and physiological synchrony during mother-child interactions (Leclère, 2014). Interpersonal synchronization of brain activity, posited to be an underlying mechanism to behavioral synchrony, is only recently being addressed in developmental research (Reindl et al. 2018, Piazza et al., 2018). Neural synchrony is proposed to facilitate communication and temporal contingency (Hasson et al., 2012). Here, we present a dual functional near-infrared spectroscopy (dual-fNIRS) study looking at the relationship between quality of mother-child interaction during a problem-solving task and neural synchrony. In the present investigation, preschoolers and their mothers were tested simultaneously with dual-fNIRS (Figure 1). In the cooperation condition, mother and child were instructed to solve a tangram puzzle together where a template has to be recreated by arranging simple geometric shapes. In the individual condition, mother and child performed the same task alone with an opaque screen in between them. In a third condition, mother and child were engaged in a free verbal conversation. Finally, a resting phase (closed eyes) served as a baseline. The following self-reports and behavioral data were collected in order to test our hypothesis that maternal attachment, caregiving, and sensitivity affect mother-child neural synchrony: Experiences in Close Relationships, and Parental Sensitivity Questionnaire. In addition, we assessed quality of the mother-child interaction during the collaborative task with a customized coding scheme, including scales from the Parent-Child Interaction System (PARCHISY), the Coding System for Mother-Child Interactions (CSMCI), and INTAKT. Our sample consisted of 42 mother-child dyads (19 boys and 23 girls). Children’s mean age was 5;08 years (SD= 0;03 years; range=5;00-6;01 years). The mothers’ age averaged at 36.6 years (SD=4.29 years; range=28-46 years). 48% of mothers graduated from vocational school, the remaining mothers graduated with a university degree. Wavelet transform coherence (WTC) was used to assess the cross-correlation between the two fNIRS time series. For statistical analyses, WTC values were entered as the dependent variable in a linear mixed effects model with condition (cooperation vs. individual vs. talk vs. rest) and channel (16 per dyad) as fixed factors, and a random intercept. Results (Figure 2) revealed a main effect of condition due to increased coherence in frontal and temporal areas during the collaboration condition and free verbal conversation, t(2566)=3.77-4.47, p<.001 and t(2566)=5.02-5.71, p<.0001. Testing the hypothesis that neural synchrony facilitated task performance, coherence during collaboration indeed predicted the number of templates solved, t=1.95, p=.05. However, task performance was also predicted by coherence during rest, t=2.80, p=.005. Looking at the quality of mother-child interaction, mutual task engagement predicted coherence during the collaboration condition, F(1,35)=5.60, p=.02. Further analyses relating inter-brain coherence to differences in the quality of the parent-child interaction are underway. Data from the above study will be complemented with a follow-up investigation testing father-child neural synchrony with further measures of attachment. Results will be discussed in the context of variables affecting the quality of parent-child interactions and the potential functional role of interpersonal neural synchronization