Negative prior aquatic experiences and children's aquatic competency: Do parent perceptions differ from reality?

ISSUE ADDRESSED: Achieving aquatic competence is recommended for preventing childhood drownings, yet many children in Victoria, Australia do not meet aquatic benchmarks despite participating in swimming and water safety programs. While few studies have explored factors influencing aquatic competency development, negative prior aquatic experiences (NPAE) have surfaced as a potential influence. Research on children's NPAE has primarily focused on parental perceptions rather than the child's actual experiences. METHODS: Parents and children (aged 10-12 years) completed reliable surveys for background information and NPAE-related data. Children also completed aquatic competency assessments against benchmark standards. Chi-square tests determined relationships between NPAE and aquatic competency, and thematic analysis categorised themes related to perceptions of the child's NPAE. RESULTS: Most parents (82.9%) indicated their child had not had NPAE, while only half (51.0%) of children did not report NPAE. Children reporting NPAE often perceived incidents as nearly drowning (41%), encompassing swimming pool environments and underwater submersion. Similarly, parents reported varied situations, noting NPAE involving open water and the child's loss of control. Parent-reported NPAE was associated with children less likely to achieve knowledge, continuous swimming, and survival competency benchmarks (p < .05). Children reporting NPAE were less likely to achieve underwater competencies (p < .05). CONCLUSIONS: The disparity between parent and child perspectives of NPAE demonstrates the importance of considering both perspectives. This should assist in providing appropriate support for children to develop aquatic competencies. SO WHAT?: Using NPAE data, practitioners can customise swim teaching approaches to address and prevent NPAE, particularly as many children associate their NPAE with pools, the common setting for aquatic education.

Tolerance threshold of a pelagic species in China to total dissolved gas supersaturation: from the perspective of survival characteristics and swimming ability.

Total dissolved gas (TDG) supersaturation downstream of dams can occur in the Yangtze River basin and is known to cause stress and even death in fish. Consequently, it is important to establish tolerance thresholds of endemic fish to protect local aquatic resources. We conducted experiments to assess survival characteristics and swimming ability of bighead carp, an important commercial fish dwelling in the Yangtze River, to evaluate its tolerance threshold to TDG supersaturation. The typical external symptoms of gas bubble trauma (GBT) were observed and the time when the fish lost equilibrium and died were recorded. The results showed that the mortality occurred when TDG level exceeded 125%, with obvious symptoms such as exophthalmos and bubbles on the head. The interval between loss of equilibrium and mortality decreased with an increase in TDG level. Neither exposure time nor TDG level significantly affected the critical swimming speed (Ucrit) of fish exposed to non-lethal exposure (110%, 120% and 125% TDG) over a 7 day period. Significant reductions in Ucrit were found under 130% and 135% TDG conditions when the exposure lasted 52.0 h and 42.9 h, respectively. The Ucrit also significantly decreased after exposure of 1.6 h under 140% TDG condition. Moreover, after exposure to 140% TDG for 39.2 h, 135% TDG for 56.5 h and 130% TDG for 95.9 h, bighead carp were transferred into air saturated water to recover for 24 h or 48 h; however, swimming performance remained impaired. The results of this study indicate that 125% TDG was the highest TDG level where limited mortality was observed and the swimming ability was not impaired, showing that 125% TDG can be set as the tolerance threshold of this species to guide the operation of dams in the Yangtze River Basin.

Swimming ability of Schizothoracinae fishes in Yarlung Zangbo River of China.

The Yarlung Zangbo River is a river with abundant hydropower resources but fragile biodiversity in China. As an important benchmark for both research and ecological management, there is still a lack of knowledge about the swimming ability of fishes in the Yarlung Zangbo River. The induced flow velocity (Uind), critical swimming speed (Ucrit), and burst swimming speed (Uburst) of five Schizothoracinae species were tested in this study. Relative swimming ability related to body length and body shape was calculated. The results indicated that the average absolute swimming speeds (Uind-a, Ucrit-a, and Uburst-a) of all the experimental fish were 10.20 ± 0.01, 57.58 ± 3.28, and 69.54 ± 2.94 cm/s, respectively, and the corresponding relative Uind, Ucrit, and Uburst related to body length (Uind-l, Ucrit-l, Uburst-l) were 1.15 ± 0.07, 5.04 ± 0.26, and 7.23 ± 0.28 BL/s, respectively. Moreover, relative Uind, Ucrit, and Uburst related to body shape (Uind-s, Ucrit-s, and Uburst-s) were 0.80 ± 0.13, 2.49 ± 0.51, and 4.32 ± 0.57 cm-2/s, respectively. No significantly differences in relative swimming speeds existed among five species. Only Oxygymnocypris stewartii was significantly weaker in Uburst-s than Schizothorax o'connori. The body shape showed a stronger relationship with swimming speed than the body length did. Schizothoracinae fish in the Yarlung Zangbo River basin are less sensitive to the water flow and performed weaker Ucrit and Uburst compared to those in the Yangtze River basin, indicating that Schizothoracinae fish in the Yarlung Zangbo River may be more susceptible to threats from environmental changes. The paper enriched the research on the swimming ability of Schizothoracinae fishes and provided efficient data for the fish conservation in the Yarlung Zangbo River.

A design of a nature-like fishway to solve the fractured river connectivity caused by small hydropower based on hydrodynamics and fish behaviors.

Achieving a harmonious alignment between the biological characteristics of fish and hydrodynamics patterns is crucial for ensuring the efficacy of fish passage facilities. In this study, based on the hydrodynamic characteristics of the river and the biological characteristics of fish, we evaluated the internal flow field in the nature-like fishway of Congen II hydropower station located along the Chabao river and explored methods to improve the operation efficiency. Based on comprehensive considerations of the flow field, turbulent kinetic energy, and the migration pathways of fish, it is found that the implementation of a continuous oblique bottom slope represents a more cost-effective and operationally convenient solution. The influence of different permutation of bulkheads in the nature-like fishway on operational efficiency was further examined. Our investigation revealed that the nature-like fishway with the continuous slope of 2% and the arrangement of three bulkheads in each row (model 3) exhibited a relatively simple velocity distribution and linear flow line, which poses challenges for fish in locating resting areas. In addition, the distribution of low turbulence kinetic energy area in the mainstream made it less favorable for fish to transition from the mainstream to the rest area within the fishway. The nature-like fishway with the continuous slope of 2% and the arrangement of two or three bulkheads in staggered rows (model 4) demonstrated better performance. Several potential fish migration routes for both model 3 and model 4 were proposed based on the numerical simulation results. In model 3, fish exhibited a continuous sprint through the concentrated high-speed area, which was less favorable for fish to rest and forage. In contrast, model 4 exhibited a diversified flow velocity distribution, enabling fish to make timely changes in their direction during migration. This feather proved to be advantageous in enhancing fish migration within the passage. The design of nature-like fishway in this study provides an important reference and technical support for the construction and optimization of the nature-like fishway for low dams, and is of great significance for restoring river connectivity destroyed by small hydropower construction and improving fish migration.

Phosphatidylcholine-deficient suppressor mutant of Sinorhizobium meliloti, altered in fatty acid synthesis, partially recovers nodulation ability in symbiosis with alfalfa (Medicago sativa).

Rhizobial phosphatidylcholine (PC) is thought to be a critical phospholipid for the symbiotic relationship between rhizobia and legume host plants. A PC-deficient mutant of Sinorhizobium meliloti overproduces succinoglycan, is unable to swim, and lacks the ability to form nodules on alfalfa (Medicago sativa) host roots. Suppressor mutants had been obtained which did not overproduce succinoglycan and regained the ability to swim. Previously, we showed that point mutations leading to altered ExoS proteins can reverse the succinoglycan and swimming phenotypes of a PC-deficient mutant. Here, we report that other point mutations leading to altered ExoS, ChvI, FabA, or RpoH1 proteins also revert the succinoglycan and swimming phenotypes of PC-deficient mutants. Notably, the suppressor mutants also restore the ability to form nodule organs on alfalfa roots. However, nodules generated by these suppressor mutants express only low levels of an early nodulin, do not induce leghemoglobin transcript accumulation, thus remain white, and are unable to fix nitrogen. Among these suppressor mutants, we detected a reduced function mutant of the 3-hydoxydecanoyl-acyl carrier protein dehydratase FabA that produces reduced amounts of unsaturated and increased amounts of shorter chain fatty acids. This alteration of fatty acid composition probably affects lipid packing thereby partially compensating for the previous loss of PC and contributing to the restoration of membrane homeostasis.

Effect of total dissolved gas supersaturation and flow velocity on survival and swimming ability of juvenile Schizothorax prenanti.

Although developing large-scale hydropower cascades in the upper Yangtze River effectively improves the hydropower resource utilization, it produces total dissolved gas (TDG) supersaturation. In the flood season, the high level of TDG supersaturation (TDGS) frequently occurs in the downstream of dams, causing migratory fish to suffer from gas bubble trauma (GBT) and reducing their survival and swimming ability. Currently, there is a deficiency in particular approaches to evaluate the ecological hazard posed by TDGS on migratory fish as they traverse different flow velocities within their migratory routes. This study assessed the vulnerability of juvenile Schizothorax prenanti (S. prenanti) to GBT from the static setting to 9.0 BL/s during exposure to nominal levels of 100%, 110%, 120% and 130% TDG. The mortality occurs when the flow velocity surpasses 6.0 and 7.5 BL/s in 100% and 110% TDG levels, respectively. For fish exposed to 120% and 130% TDG levels, the relationship between survival time and flow velocity is an approximately inverse bell-shaped curve with increasing velocity. The optimal velocity of maximal survival time of juvenile S. prenanti is 3.0 and 4.5 BL/s in 120% and 130% TDG-supersaturated water. Both TDG level and flow velocity significantly affect burst swimming speed (Uburst) and critical swimming speed (Ucrit). The cases involving GBT showed substantial declines in Uburst and Ucrit, exceeding 6.0 BL/s and TDG levels greater than 120%. The results may contribute to formulating a specific management strategy for hydropower operation during the migratory period and conserving vulnerable species in the Yangtze River.

Swimming ability of cyprinid species (subfamily schizothoracinae) at high altitude.

The primary objective of this investigation was to study the effect of altitude on fish swimming ability. Different species were tested to ensure that the differences observed are not associated with a single species. Fish critical swimming speed and burst speed were determined using stepped-velocity tests in a Brett-type swimming respirometer. Based on the effects of water temperature and dissolved oxygen, it is clear that the swimming ability of fish decreases as altitude increases. Further, because the effects of high altitude on fish physiology go beyond the effects of lower temperature and dissolved oxygen, we recommend that fish swimming ability be tested at an altitude similar to the target fishway site to ensure the validity of fish data used for fishway design.

Restoration of a fish-attracting flow field downstream of a dam based on the swimming ability of endemic fishes: A case study in the upper Yangtze River basin.

The construction of fish passage facilities can mitigate the negative effects of dams and other water engineering construction on river connectivity and have a significant positive effect on the conservation of local fish diversity. To attract target fishes into fish passage facilities effectively, the optimal flow velocity range to attract fish must be determined. Three local endemic species of the Mishi Reservoir were considered as the protection targets. However, their swimming abilities remain unclear. Therefore, the induced swimming speed (Uind), critical swimming speed (Ucrit) and burst swimming speed (Uburst) of three fish species were tested. Based on these results, we identified the optimal flow velocity to attract fish, which falls within the range of 0.15-0.51 m/s. A validated three-dimensional hydrodynamic model was used to simulate different schemes. By comparing the flow field simulation results of different schemes, we obtained the optimal measure to restore the flow field, namely, a multiple engineering measure combining increased the fish attraction flow in the fish collection pond and the construction of a spur dike. This study offers a solution for the specific case and enhances the database of swimming characteristics of endemic fish in the upstream reaches of the Yangtze River. It also provides a valuable reference for designing fish-attracting flows and potential measures for restoring flow fields in similar future projects.

Young children's motivations and social cognitions toward swimming: Testing direct and moderation effects of sport competence in two large-scale studies.

Direct and moderation effects of swimming competence using an integrated model of self-determination theory (SDT) and theory of planned behaviour (TPB) were examined in two large-scale studies among young children. Specifically, we examined whether swimming competence had direct and moderation effects on social psychological variables of perceived need support, autonomous motivation, TPB social cognition constructs, and intention. In Study 1, using a cross-sectional survey of 4959 primary school children, swimming competence formed significant positive relationships with all model variables (ß =.061 to.330, p < .05) except intention (ß = -.009, p > .05), and its moderation effect on model parameters were small in size or not statistically significant. In Study 2, using a pre-post-test quasi-experiment among 1,609 primary school children, improvement of swimming competence was associated with change-scores in all model variables (ß =.046 to.230, p < .05) except subjective norm (ß =.049, p > .05). Swimming competence did not significantly moderate the parameter estimates of the integrated model (p > .05) at the change-score level. Findings indicate that swimming competence is associated with higher autonomous motivation; TPB social cognitions of attitude, subjective norm, and perceived behavioural control; and intention. However, swimming competence did not moderate the parameter estimates of the integrated model.

ompX contribute to biofilm formation, osmotic response and swimming motility in Citrobacter werkmanii.

Citrobacter werkmanii, an aerobe and mesophilic Proteobacterium, is universal in industrial putrefaction, coastal water, and human blood. Our previous studies have discovered that outer membrane protein X (OmpX) of C. werkmanii is involved in calcium response, but the underlying mechanisms and its molecular characteristics remain elusive. To that end, the ompX gene was deleted from the genome of C. werkmanii and its phenotypic variations were thoroughly investigated in conjunction with the wild type (WT) and complementary strains using biochemical and molecular techniques such as RNA-Seq, respectively. The results demonstrated that deleting ompX reduces biofilm formation on polystyrene and glass surfaces. Meanwhile, ΔompX's swimming ability but not for its twitching or swarming abilities, was also reduced on semi-solid plates compared with WT, which was caused by inhibition of flagellar assembly genes, such as flgC, flhB, and fliE, etc. Furthermore, ompX inactivation altered susceptibility to various bactericide classes, as well as responses to Ca2+ and Mg2+ stress. In addition, when compared to WT, ΔompX captures a total of 1,357 deferentially expressed genes (DEGs), of which 465 were up-regulated and 892 were down-regulated, which can be enriched into various GO ontology and KEGG pathway terms. Furthermore, ompX, as well as ompD and ompW, can be modulated at the transcriptional levels by rbsR and tdcA. Overall, the ompX gene contributed to a variety of biological functions in C. werkmanii and could be served as a targeted site for controlling biofilm formation and developing new bactericides.

Determining the position of a fish passage facility entrance based on endemic fish swimming abilities and flow field.

Hydropower development can significantly mitigate climate change and reduce carbon emissions, but it can also have substantial negative impacts on river environments and fish biodiversity. Fish passage facilities are built to ensure sustainable hydropower development and the biodiversity of fish populations. The locations of the entrances to these facilities play a key role in their efficiency. This study presents a reliable approach that combines the swimming ability of fish and a numerical flow field simulation to determine the optimal location for a fish passage facility entrance. In this study, we used the Gujun Reservoir upstream of the Yangtze River as a case study. A field experiment was conducted, and the swimming abilities of eight endemic fish species in the upstream region of the Yangtze River were measured. Among the tested species, the fastest induced swimming speed (0.14 m/s) was achieved by Glyptothorax sinense, while the slowest critical swimming speed (0.30 m/s) was observed for Paracobitis potanini. We propose that the velocity near the fish passage facility entrance should be higher than the maximum induced swimming speed and lower than the minimum critical swimming speed, making the suitable range between 0.14 and 0.30 m/s. On this basis, velocity fields 500 m downstream of the dam of the Gujun Reservoir under 4 operating conditions with discharge flows of 5.7 m3/s, 23.3 m3/s, 32.5 m3/s, and 41.1 m3/s were calculated. The results showed that the flow field variation downstream of the dam was between 0.1 and 0.9 m/s. After comparing the suitable areas for the target species, the left bank at location 2 was recommended as the optimal location for the fish passage facility entrance in the Gujun Reservoir.

Outer membrane protein of OmpF contributes to swimming motility, biofilm formation, osmotic response as well as the transcription of maltose metabolic genes in Citrobacter werkmanii.

Bacterial outer membrane proteins (Omps) are essential for environmental sensing, stress responses, and substance transport. Our previous study discovered that OmpA contributes to planktonic growth, biocide resistance, biofilm formation, and swimming motility in Citrobacter werkmanii, whereas the molecular functions of OmpF in this strain are largely unknown. Thus, in this study, the ompF gene was firstly knocked out from the genome of C. werkmanii using a homologous recombination method, and its phenotypical alternations of ∆ompF were then thoroughly characterized using biochemical and molecular approaches with the parental wild type (WT) and complementary (∆ompF-com) strains. The results demonstrated that the swimming ability of ∆ompF on semi-solid plates was reduced compared to WT due to the down-regulation of flgC, flgH, fliK, and fliF. Meanwhile, ompF deletion reduces biofilm formation on both glass and polystyrene surfaces due to decreased cell aggregation. Furthermore, ompF inactivation induced different osmotic stress (carbon sources and metal ions) responses in its biofilms when compared to WT and ∆ompF-com. Finally, a total of 6 maltose metabolic genes of lamB, malE, malK, malG, malM, and malF were all up-regulated in ∆ompF. The gene knockout and HPLC results revealed that the MalEFGK2 cluster was primarily responsible for maltose transport in C. werkmanii. Furthermore, we discovered for the first time that the upstream promoter of OmpF and its transcription can be combined with and negatively regulated by MalT. Overall, OmpF plays a role in a variety of biochemical processes and molecular functions in C. werkmanii, and it may even act as a targeted site to inhibit biofilm formation.

Relationship between Swimming Ability of College Students and Their Regular Exercise Habits.

BACKGROUND: This study examined the relationship between the five-level swimming ability of college students and their regular exercise habits. METHODS: This study applied to Academia Sinica for permission to use the raw data from the Survey on the Sports Participation Situations of Students in All Levels of Education, which was conducted by the Sports Administration, Ministry of Education, Taiwan; a secondary data analysis of the obtained data was then conducted. RESULTS: Overall, 18,515 pieces of data were selected for analysis, and the results revealed that 85.9% of the surveyed students had learned to swim; those who had regular exercise habits exhibited a higher level of swimming ability than those without such habits. A logistic regression analysis showed that progressing to a higher level of swimming ability increased the likelihood of having regular exercise habits by 20%. CONCLUSIONS: The present study showed that level of swimming ability was significantly correlated with regular exercise habits. In the future, exercise self-efficacy theories can be applied to explore the relationship between exercise skill proficiency and regular exercise habits.

Sub-acute exposure to nanoplastics via two-chain trophic transfer: From brine shrimp Artemia franciscana to small yellow croaker Larimichthys polyactis.

This study investigated the trophic transfer of nanoplastics in marine food chains. We fed nanoplastic-exposed Artemia franciscana (brine shrimp) to Larimichthys polyactis (small yellow croaker) daily for eight days. Subsequently, the overall health condition, histopathological damage to the liver and digestive tract, and swimming ability of the fish were measured. After the sub-acute exposure to nanoplastics via trophic transfer, the fish showed inhibited growth, severe liver damage, as well as a poorer swimming ability compared to the control. The swimming ability was especially affected, in terms of the overall movement as well as thigmotaxis. The results thus clarified that even an indirect exposure to nanoplastics could induce neurotoxic effects and affect the swimming ability of the fish. As fish are well-known human food resources, the possibility of such trophic transfers affecting higher trophic level organisms, such as humans, cannot be ruled out.

A comparison of two methods for estimating critical swimming speed (Ucrit) in larval fathead minnows: the laminar flow assay and the spinning task assay.

Critical swimming speed (Ucrit) is considered a good predictor of swimming capabilities in fish. To estimate Ucrit, a fish is exposed to an incrementally increasing laminar flow of water until it cannot maintain its position against the current. The spinning task assay has been proposed as an alternative method to traditional laminar flow methods; however, these methods have not been directly compared. Thus, the goal of this study was to determine whether the spinning task assay is a suitable alternative to traditional laminar flow assays. To that end, the performance of fathead minnows in each assay was compared at three time points (14, 19 and 24 days post-fertilization, dpf). In 14 dpf fish, Ucrit estimates were similar regardless of the assay used. However, at 19 and 24 dpf, Ucrit estimates derived from the two assay types were significantly different. This indicates that the assays are not equivalent to one another and that the spinning task assay is not a suitable alternative to the laminar flow assay for the determination of Ucrit.

Roles of ompA of Citrobacter werkmanii in bacterial growth, biocide resistance, biofilm formation and swimming motility.

The genus Citrobacter is commonly found in environmental and industrial settings, some members of which have been used for bioremediation of heavy metals owing to the absorption ability of their biofilms. Although our previous studies have found that the outer membrane protein A (OmpA) contributes to the process of Citrobacter werkmanii biofilm formation, the underlying mechanisms remain elusive. Therefore, we deleted ompA from the genome of C. werkmanii and investigated its phenotypes in comparison to the wild type strain (WT) and the complementary strain using biochemical and molecular techniques including RNA-Seq. Our results demonstrated that the deletion of ompA led to an increase in biofilm formation on both polystyrene and glass surfaces due to upregulation of some biofilm formation related genes. Meanwhile, swimming ability, which is mediated by activation of flagellar assembly genes, was increased on semi-solid plates in the ∆ompA strain when compared with WT. Additionally, inactivation of ompA also caused increased 1,2-benzisothiazolin-3-one (BIT) resistance, differential responses to Ca2+ stress, curli protein expression and cellulose production. Finally, ∆ompA caused differential expression of a total of 1470 genes when compared with WT, of which 146 were upregulated and 1324 were downregulated. These genes were classified into different Gene Ontology (GO) and KEGG pathways. In summary, ompA in C. werkmanii contributes to a variety of biological functions and may act as a target site to modulate biofilm formation. KEY POINTS: • ompA is a negative regulator for biofilm formation by C. werkmanii. • ompA inhibits swimming motility of C. werkmanii. • ompA deletion causes different expression profiles in C. werkmanii.

Adolescent Water Safety Behaviors, Skills, Training and Their Association with Risk-Taking Behaviors and Risk and Protective Factors.

Background: Drowning remains the third leading cause of unintentional injury death for adolescents in the United States. Aims: This study described adolescent swimming lessons, behaviors (life jacket wear while boating) and comfort (swimming in deep water) and their association with protective and risk factors and risk-taking behaviors reported by Washington State students in Grades 8, 10, 12, primarily comprised of youth ages 13 to 18 years. Methods: This study used the 2014 Washington State Healthy Youth Survey (HYS), a publicly available dataset. Results: Most students reported having had swimming lessons, using life jackets, and comfort in deep water. Differences reflected racial, ethnic and socioeconomic disparities: being White or Caucasian, speaking English at home and higher maternal education. Lowest rates of comfort in deep water were among Hispanics or Latino/Latinas followed by Blacks or African Americans. Greater life jacket wear while boating was reported by females, those in lower grades and negatively associated with alcohol consumption, sexual activity and texting while driving. Having had swimming lessons was associated with fewer risk-taking behaviors. Conclusions: The HYS was useful to benchmark and identify factors associated with drowning risk among adolescents. It suggests a need to reframe approaches to promote water safety to adolescents and their families. Multivariate analysis of this data could identify the key determinants amongst the racial, ethnic, and socioeconomic disparities noted and provide stronger estimation of risk-taking and protective behaviors.

A Miniature Intermittent-Flow Respirometry System with a 3D-Printed, Palm-Sized Zebrafish Treadmill for Measuring Rest and Activity Metabolic Rates.

Zebrafish are a preferred vertebrate model for evaluating metabolism during development, and for toxicity studies. However, commercially available intermittent-flow respirometry systems (IFRS) do not provide a suitable zebrafish-scaled swimming tunnel with a low water volume and proper flow velocities. We developed a miniature IFRS (mIFRS) with a 3D-printed, palm-sized zebrafish treadmill for measuring the swimming ability and metabolic rate of a single one- or three-month-old zebrafish with and without toxicity treatment. The 3D-printed zebrafish treadmill consists of discrete components assembled together which enables the provision of a temporary closed circulating water flow. The results showed that three-month-old zebrafish of normal physiological status had higher energetic efficiency and could swim at a higher critical swimming speed (Ucrit) of 16.79 cm/s with a lower cost of transport (COTopt) of 0.11 µmol g-1m-1. However, for a single three-month-old zebrafish treated with an antibacterial agent, Ucrit decreased to 45% of normal zebrafish and the COTopt increased to 0.24 µmol g-1m-1, due to the impairment of mitochondria. Our mIFRS provides a low-cost, portable, and readily adaptable tool for studying the swimming performance and energetic metabolism of zebrafish.

Anthropometric and Motor Competence Classifiers of Swimming Ability in Preschool Children-A Pilot Study.

Swimming is a form of physical activity and a life-saving skill. However, only a few studies have identified swimming ability classifiers in preschool children. This pilot cross-sectional study aimed to find anthropometric (AM) and motor competence (MC) predictors of swimming ability in preschool children, by building classifiers of swimming ability group (SAG) membership. We recruited 92 children (girls n = 45) aged 5-6 years and took the AM and MC measurements in accordance with the reference manual and using the KTK battery test (motor quotient, MQ), respectively. A linear discriminant analysis tested a classification model of preschoolers' swimming ability (SAG: POOR, GOOD, EXCELLENT) based on gender, age, AM, and MC variables and extracted one significant canonical discriminant function (model fit: 61.2%) that can differentiate (group centroids) POOR (-1.507), GOOD (0.032), and EXCELLENT (1.524). The MQ total was identified as a significant classifier, which absolutely contributed to the discriminant function that classifies children's swimming ability as POOR (standardized canonical coefficient: 1.186), GOOD (1.363), or EXCELLENT (1.535) with an accuracy of 64.1%. Children with higher MQ total ought to be classified into higher SAG; thus, the classification model of SAG based on the MQ total is presented.

Descriptive epidemiology and correlates of children's swimming competence.

This study examined the swimming competence of primary school children, and how it was related to swimming activity, non-fatal aquatic events, and demographic factors. Primary school students (N = 4959; female = 2705, male = 2241; age range = 5 to 14 years) across 28 schools in the 15 districts of Hong Kong completed the Swimming Competence Questionnaire, and questions about their swimming experience, non-fatal aquatic events, and demographic variables. Descriptive statistics showed that over 60% of children could swim more than 5m, but less than 50% could swim over 25m. Over 50% of children were able to perform some basic swimming skills (e.g., holding breath underwater, floating, poolside/kickboard kicking, and treading water). Swimming competence was positively predicted by the demographic factors (i.e., age, sex, family income, and parents' highest education level), swimming experience, learning experience, and swimming location. Treading water was the only factor of swimming competence that established asignificant negative association with non-fatal aquatic events. Current results can be used to target key groups to improve children's swimming competence and reduce non-fatal aquatic events; children from lower socio-economic backgrounds and with less swimming experience should be encouraged to participate in more formal learn to swim lessons.