Search Results (286)

Background/Objectives: Swimming requires precise motor control, sustained attention, and optimal cognitive–motor integration, making it an ideal model for investigating neural efficiency—the phenomenon whereby expert performers achieve optimal outcomes with reduced neural resource expenditure, operationalized as lower activation, sparser connectivity, and enhanced functional integration. This systematic review examined cognitive performance and neural adaptations in swimming athletes, investigating neuroimaging and behavioral outcomes distinguishing swimmers from non-athletes across performance levels. Methods: Following PRISMA 2020 guidelines, seven databases were searched (1999–2024) for studies examining cognitive/neural outcomes in swimmers using neuroimaging or validated assessments. A total of 24 studies (neuroimaging: n = 9; behavioral: n = 15) met the inclusion criteria. Risk of bias assessment used adapted Cochrane RoB2 and Newcastle–Ottawa Scale criteria. Results: Neuroimaging modalities included EEG (n = 4), fMRI (n = 2), TMS (n = 1), and ERP (n = 2). Key associations identified included the following: (1) Neural Efficiency: elite swimmers showed sparser upper beta connectivity (35% fewer connections, d = 0.76, p = 0.040) and enhanced alpha rhythm intensity (p ≤ 0.01); (2) Cognitive Performance: superior attention, working memory, and executive control correlated with expertise (d = 0.69–1.31), with thalamo-sensorimotor functional connectivity explaining 41% of world ranking variance (r² = 0.41, p < 0.001); (3) Attention: external focus strategies improved performance in intermediate swimmers but showed inconsistent effects in experts; (4) Mental Fatigue: impaired performance in young adult swimmers (1.2% decrement, d = 0.13) but not master swimmers (p = 0.49); (5) Genetics: COMT Val158Met polymorphism associated with performance differences (p = 0.026). Effect sizes ranged from small to large, with Cohen’s d = 0.13–1.31. Conclusions: Swimming expertise is associated with specific neural and cognitive characteristics, including efficient brain connectivity and enhanced cognitive control. However, cross-sectional designs (88% of studies) and small samples (median n = 36; all studies underpowered) preclude causal inference. The lack of spatially quantitative synthesis and visualization of neuroimaging findings represents a methodological limitation of this review and the field. The findings suggest potential applications for talent identification, training optimization, and mental health promotion through swimming but require longitudinal validation and development of standardized swimmer brain atlases before definitive recommendations. Full article

Fish passes are essential hydraulic structures that maintain longitudinal connectivity in regulated rivers, but their hydraulic performance may be affected by debris accumulation at chamber openings. This study investigates the influence of partial and total inlet blockage by plant debris on flow conditions within a semi-natural fish pass under field conditions. Hydraulic measurements were conducted at multiple locations along the fish pass, and the effects of debris covering were evaluated using statistical and mixed-effects modeling approaches. Field measurements demonstrated that the Froude number decreases systematically with increasing distance from the inlet, indicating progressive longitudinal dissipation of flow energy along the chamber sequence. Partial debris accumulation caused only marginal changes in the Froude number, remaining close to the threshold of statistical significance. In contrast, mean flow velocity decreased markedly with increasing inlet blockage, by approximately 17% at 50% covering and by about 36% under full blockage, indicating that debris primarily acts as a hydraulic damper rather than inducing a change in flow regime. The highest variability in hydraulic conditions was observed in chambers associated with changes in flow direction and local geometry. These results highlight the dominant role of longitudinal layout and chamber geometry in shaping hydraulic conditions in semi-natural fish passes, while moderate debris accumulation affects local velocities without fundamentally compromising hydraulic functionality. From an ecological perspective, transition zones with elevated hydraulic variability may represent critical locations influencing the swimming effort and passage efficiency of migrating fish. Full article

Background: Neuromuscular electrical stimulation (NMES) is an effective exogenous neuromuscular activation method widely used in sports training and rehabilitation. However, existing research primarily focuses on land-based sports or single-joint movements, with limited in-depth exploration of its intervention effects and underlying neuromuscular control mechanisms for complex, multi-joint coordinated aquatic activities like breaststroke swimming. This study aimed to investigate the effects of NMES combined with traditional resistance training on neuromuscular function during sport-specific technical movements in breaststroke athletes. Methods: A randomized controlled trial was conducted with 30 national-level or above breaststroke athletes assigned to either an experimental group (NMES combined with traditional squat resistance training) or a control group (traditional squat resistance training only) for an 8-week intervention. A specialized fully waterproof wireless electromyography (EMG) sensor system (Mini Wave Infinity Waterproof) was used to synchronously collect surface EMG signals from 10 lower limb and trunk muscles during actual swimming, combined with high-speed video for movement phase segmentation. Changes in lower limb explosive power were assessed using a force plate. Non-negative matrix factorization (NMF) muscle synergy analysis was employed to compare changes in muscle activation levels (iEMG, RMS) and synergy patterns (spatial structure, temporal activation coefficients) across different phases of the breaststroke kick before and after the intervention. Results: Compared to the control group, the experimental group demonstrated significantly greater improvements in single-leg jump height (Δ = 0.06 m vs. 0.03 m) and double-leg jump height (Δ = 0.07 m vs. 0.03 m). Time-domain EMG analysis revealed that the experimental group showed more significant increases in iEMG values for the adductor longus, adductor magnus, and gastrocnemius lateralis during the leg-retraction and leg-flipping phases (p < 0.05). During the pedal-clamp phase, the experimental group exhibited significantly reduced activation of the tibialis anterior alongside enhanced activation of the gastrocnemius. Muscle synergy analysis indicated that post-intervention, the experimental group showed a significant increase in the weighting of the vastus medialis and biceps femoris within synergy module 4 (SYN4, related to propulsion and posture) (p < 0.05), a significant increase in rectus abdominis weighting within synergy module 3 (SYN3, p = 0.033), and a significant shortening of the activation duration of synergy module 2 (SYN2, p = 0.007). Conclusions: NMES combined with traditional resistance training significantly enhances land-based explosive power in breaststroke athletes and specifically optimizes neuromuscular control strategies during the underwater breaststroke kick. This optimization is characterized by improved activation efficiency of key muscle groups, more economical coordination of antagonist muscles, and adaptive remodeling of inter-muscle synergy patterns in specific movement phases. This study provides novel evidence supporting the application of NMES in swimming-specific strength training, spanning from macroscopic performance to microscopic neural control. Full article

Background: Durative exercise-induced fatigue influences muscle structure and exercise performance. Dietary supplements combining bioavailable proteins with essential vitamins and minerals may help reduce fatigue. Compared with proteins, whey peptides, as easily absorbed energy sources, are regarded as better promoting the utilization of vitamins and minerals. This study investigated whether the combination of whey peptides and micronutrients could synergistically improve exercise-induced fatigue and exercise performance. Methods: Four-week-old male C57BL/6J mice were forced to exercise using a treadmill for four weeks to evaluate the supplemental effects of whey peptides and/or micronutrients on exercise performance. Results: Compared with mice receiving whey peptides or micronutrients alone, mice receiving a combination of whey peptides and micronutrients displayed increased muscle mass, muscle fiber cross-sectional area, muscle strength, and exercise performance, including running exhausting time and swimming exhausting time. Consistent results were obtained in detecting fatigue-associated serum metabolites and markers reflecting muscle injury. To elucidate the anti-fatigue mechanisms of whey peptides and micronutrients, RNA transcriptome in the muscle tissues were analyzed. Enrichment analysis results suggest that micronutrients and/or whey protein alleviate exercise-induced fatigue, not only via reducing oxidative stress but also repressing excessive immune activation in muscle tissue, thereby decreasing the tissue injury caused by strenuous exercise. Conclusions: Overall, the current study indicates that the combination of whey peptides and micronutrients produces a synergistic effect on promoting exercise performance. Our findings provide scientific evidence for the development of novel and efficient anti-fatigue functional foods using whey peptides and micronutrients. Full article

The purpose was to characterize and compare biomechanical and coordinative parameters at maximum velocity between swimmers with Down syndrome and intellectual disabilities and examine these in relation to their anthropometrics. Nine swimmers (four with Down syndrome and five with intellectual disabilities) performed three bouts of 25 m crawl stroke, each at maximum velocity, which were recorded with the Qualysis motion analysis system. Anthropometric variables, BMI, and percentage of body fat were also assessed. Swimmers with Down syndrome presented a smaller height, acromion height, sitting height, arm span, hand length, hand width, foot length, foot width, and velocity than swimmers with intellectual disabilities. Swimmers with Down syndrome have disadvantageous anthropometrics and slower swimming velocities compared to swimmers with intellectual disabilities. Those swimmers also appear to present distinctive coordination (catch-up for Down syndrome and superposition for intellectual disabilities) and intracyclic velocity variation (Down syndrome presented higher values) compared to swimmers with intellectual disabilities, suggesting a lower swimming efficiency. Full article

Shiga toxin-producing Escherichia coli (STEC) is a major foodborne pathogen, responsible for severe gastrointestinal disease and hemolytic uremic syndrome (HUS). Here, we report Click Detect, a novel diagnostic platform that leverages click display to efficiently produce sensing probes for sandwich-style antigen detection. Click display is an in vitro protein display technology that generates uniform and covalently linked protein–cDNA conjugates in a simple one-pot reaction format within 2 h. The captured sensing probe can be quantified by standard nucleic acid amplification assays. Using click displayed DARPin (D_#20) as the sensing probe and a high-affinity nanobody (N_G1) as the capture reagent, Click Detect reliably detected Shiga toxin 2 (Stx2) at 600 fM by quantitative PCR (qPCR) and 6 pM by loop-mediated isothermal amplification (LAMP). The assay maintained comparable sensitivity in matrices containing up to 40% public swimming pool water or lettuce extract, highlighting robustness for real-world surveillance applications. Key advantages of Click Detect include simple, rapid, and cost-effective (~USD 0.04 per assay) sensing probe preparation, as well as a versatile plug-and-play probe format for detecting other targets. We believe that Click Detect has great potential as a novel sensing platform for food/environmental monitoring and point-of-care diagnostics, with potentially broad applicability to other toxins and protein targets. Full article

Studies on autonomous underwater vehicles (AUVs) have gained momentum in recent years, and a special type of AUV, the robotic fish, has become a significant topic, with a superior maneuverability to traditional AUVs. In this paper, a prediction strategy for the hydrodynamic performance of a robotic fish to analyze undulatory swimming behaviors is proposed. The two-dimensional robotic fish model for computational fluid dynamics (CFD) simulations is constructed, and a dynamic network method is applied to orient the generated network based on the wavy motion. For the thrust force of the fin, a body traveling wave is derived. In the simulations, the effects of kinematic parameters such as flapping frequency and speed on swimming efficiency and drag are analyzed, and thrust force production, power expenditure, and overall efficiency of swimming are examined. Later, a deep learning-based prediction model is designed from the obtained parameters, and force predictions are performed. Long short-term memory (LSTM)-, convolutional neural network (CNN)-, and gated recurrent network (GRU)-based time series prediction models are used, and their variations are compared. In these experiments, while the CNN-GRU achieves the higher prediction performance for the root mean square error, with 0.0228, other approaches give a lower performance, between 0.0233 and 0.0359. The proposed method demonstrates a superior performance in CNN and LSTM models and exhibits lower prediction errors. Full article

The swimming crab (Portunus trituberculatus) is an economically important marine crab species in China. Understanding the structure and function of the male reproductive system in the swimming crab is crucial for increasing reproductive efficiency. Although studies on its reproductive biology have increased in recent years, the ultrastructure of the male copulatory system remains insufficiently explored. In this study, gonadal tissues [testes (T), anterior vas deferens (AVD), middle vas deferens (MVD), posterior vas deferens (PVD)] and copulatory organs [first gonopod (G1), second gonopod (G2), penis] of P. trituberculatus were sampled as experimental materials, and we systematically investigated the morphological and functional characteristics of male reproductive and copulatory organs in P. trituberculatus using anatomical, stereomicroscopic and scanning electron microscopic techniques. The results indicate that the male copulatory system comprises the G1, G2, and the penis. The G1 shows a tubular structure, with its endopodite bearing spines that anchor the female during copulation. The G2 is short, stout, solid and rod-shaped, with surface folds and blunt teeth, indicating its role in propelling the spermatophore within the G1. The penis is flexible and covered with elongated, rigid setae. Internally, the reproductive system displays a bilaterally symmetrical “H”-shaped architecture, consisting of the testes; anterior, middle, and posterior vas deferens; and the ejaculatory ducts. These segments have different structures and function in forming, storing, and transporting spermatophores. These findings provide important insights into the reproductive strategies and mating mechanisms of P. trituberculatus. Full article

The swimming crab, Portunus trituberculatus, is an important mariculture crustacean species in China. To quantitatively characterize its discontinuous and biphasic growth under intensive aquaculture conditions, we developed a modified growth model based on the dynamic energy budget (DEB) theory. The model incorporates a discontinuous growth representation that explicitly accounts for the molting process. Molting events were parameterized using a threshold ratio (α), defined as the carbon weight-to-wet weight ratio, with stage-dependent critical values derived from laboratory experiments and published datasets. Laboratory experiments were designed to estimate the energy-budget-related parameters together with data from the literature. In addition, by introducing a feedback mechanism for the energy demand of ovarian development, a set of κ values was calibrated with data from the literature to reproduce the stage-specific growth determined by ovarian development. The model was validated with growth data from several published studies related to the growth of P. trituberculatus, as well as measurements from the aquaculture ponds. Multiple goodness-of-fit indices (R-square, modeling efficiency, and Theil’s inequality coefficient) confirmed that the modified DEB model accurately reproduced both wet weight and ovarian growth trajectories, along with the characteristic non-continuous pattern of molting-driven wet weight increase. The individual growth model can be a useful tool for optimizing the intensive culture practice of the swimming crab in the aquaculture ponds and assessing the environmental impact of crab aquaculture. Full article

The locomotion of fish provides inspiration for designing efficient and agile underwater robots. Potamotrygon motoro propels itself by generating traveling waves along its pectoral fins. Inspired by its graceful swimming stroke, we design and fabricate a robotic fish, where the snap-through instability of elastic curved rods is exploited to produce the undulatory fin motion. In this design, the rotary input of two motors is transformed smoothly and continuously to controllable wave-like fin deformation. By changing the initial fin shape, motor speed, and friction at the releasing end, the propulsion performance and the maneuverability of the robotic fish can be significantly improved. The physical prototype of the robotic fish is fabricated, and its swimming performance is measured. Its maximum swimming speed reaches 0.76 BL/s, and it can achieve small-radius turns with a maximum angular speed of 1.25 rad/s. In contrast to the multi-actuator systems, the proposed dual-motor, elastic-snapping–driven design is featured by simple structural construction, low energy consumption, excellent maneuverability, and superb adaptation to environments. Our robotic fish holds promising applications in such areas as environmental monitoring, underwater inspection, and ocean exploration. The propulsion strategy presented in this work may pave a new way for the design of shape-morphing robots as well as other soft machines at multiple length scales. Full article

The search for therapeutic bioactive peptides has led to the utilization of marine byproducts as collagen sources. This study evaluated the effect of collagen hydrolysates (CH) obtained from the swim bladder (SB) of Totoaba macdonaldi on breast (MCF-7) and colorectal (Caco-2) adenocarcinoma cells and on human dermal fibroblasts (CRL-1474), considering the need for less invasive and less toxic treatment alternatives. Two pretreatment methods for the SB were compared: (1) NaOH and butanol (SBPT), and (2) hexane (SBDF). The pretreated tissues underwent direct enzymatic hydrolysis using bromelain. The resulting hydrolysates were characterized by SDS-PAGE, Raman spectroscopy, and chromatographic profiling. Both pretreatments preserved the structure of type I collagen. Bromelain hydrolysis was efficient, yielding peptides with molecular weights below 20 kDa for CH-SBPT and below 10 kDa for CH-SBDF. CH of Totoaba macdonaldi significantly reduced MCF-7 and Caco-2 cells viability, particularly at 20 mg/mL. In CRL-1474 fibroblasts, CH-SBDF stimulated cell proliferation, while CH-SBPT had neutral effects. Hexane pretreatment is a viable alternative to NaOH, reducing processing steps without compromising yield or bioactivity. CH derived from Totoaba macdonaldi exhibit promising anticancer and regenerative properties, suggesting potential biomedical applications. Further research is needed to isolate specifically active peptides and elucidate their mechanisms of action. Full article

Multi-object tracking (MOT) is a critical task in computer vision, with widespread applications in intelligent surveillance, behavior analysis, autonomous navigation, and marine ecological monitoring. In particular, accurate tracking of underwater fish plays a significant role in scientific fishery management, biodiversity assessment, and behavioral analysis of marine species. However, MOT remains particularly challenging due to low visibility, frequent occlusions, and the highly non-linear, burst-like motion of fish. To address these challenges, this paper proposes an improved tracking framework that integrates Interacting Multiple Model Kalman Filtering (IMM-KF) into DeepSORT, forming a self-adaptive multi-object tracking algorithm tailored for underwater fish tracking. First, a lightweight YOLOv8n (You Only Look Once v8 nano) detector is employed for target localization, chosen for its balance between detection accuracy and real-time efficiency in resource-constrained underwater scenarios. The tracking stage incorporates two complementary motion models—Constant Velocity (CV) for regular cruising and Constant Acceleration (CA) for rapid burst swimming. The IMM mechanism dynamically evaluates the posterior probability of each model given the observations, adaptively selecting and fusing predictions to maintain both responsiveness and stability. The proposed method is evaluated on a real-world underwater fish dataset collected from the East China Sea, comprising 19 species of marine fish annotated in YOLO format. Experimental results show that the IMM-DeepSORT framework outperforms the original DeepSORT in terms of MOTA, MOTP, and IDF1. In particular, it significantly reduces false matches and improves tracking continuity, demonstrating the method’s effectiveness and reliability in complex underwater multi-target tracking scenarios. Full article

5-hydroxymethylfurfural (5-HMF) has been shown to exert neuroprotective effects in a global cerebral ischemia mouse model in our previous study, where it demonstrated antioxidant and anti-inflammatory properties. However, studies on its antidepressant mechanisms remain scarce. Since oxidative stress and neuroinflammation are closely associated with depression, this study investigated the antidepressant effects of 5-HMF, focusing on its potential inhibition of oxidative stress via the Nrf2 pathway and its role in microglial M1 polarization-mediated neuroinflammation. An acute depression mouse model induced by intraperitoneal injection of lipopolysaccharide (LPS) was utilized. Mice received 5-HMF (12 mg/kg) or an equal volume of vehicle via intraperitoneal injection 30 min prior to and 5 min after LPS administration. At 24 h post-modeling, behavioral tests (sucrose preference, forced swim, and open field tests) were conducted to evaluate the antidepressant effect of 5-HMF. Histological damage in the hypothalamus was assessed using Nissl staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Immunofluorescence was performed to evaluate M1 polarization of hypothalamic microglia. Oxidative stress damage was assessed by measuring malondialdehyde (MDA), carbonyl groups, and 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels. Nrf2 DNA-binding activity was examined using an ELISA-based assay. The expression of inflammatory cytokines, Nrf2, and downstream antioxidant proteins was analyzed by ELISA kits and Western blotting. 5-HMF significantly alleviated LPS-induced depression-like behaviors, reduced hypothalamic neuronal damage, decreased oxidative stress, and inhibited microglial M1 polarization. It also regulated the expression of inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-4, and IL-10) and activated the Nrf2 signaling pathway, enhancing nuclear translocation efficiency. Notably, these effects were significantly attenuated by the Nrf2 inhibitor brusatol. In conclusion, 5-HMF exerts neuroprotective effects by modulating Nrf2-mediated oxidative stress responses and suppressing microglial M1 polarization-driven neuroinflammation. These findings suggest that 5-HMF may provide therapeutic potential for alleviating depression symptoms induced by acute inflammation. Full article

The changes in water flow caused by hydropower projects and river diversions have had a profound impact on aquatic ecosystems, especially due to artificial structures such as dams and bridge piers. This study investigates the swimming behavior differences between single and dual fish in the wake region behind a D-shaped obstacle, using Percocypris pingi as the experimental species. The results show that single fish efficiently utilize vortex energy through the Kármán gait, improving swimming efficiency, while the dual-fish group failed to maintain a stable Kármán gait, resulting in irregular swimming trajectories. However, the dual-fish group optimized wake utilization by maintaining a fore–aft linear alignment, improving swimming efficiency and resisting vortices. The conclusion indicates that mutual interference in group swimming affects swimming efficiency, with fish adjusting their swimming patterns to adapt to complex hydrodynamic conditions. By altering swimming formations, fish schools can adapt to the flow environment, offering new insights into the swimming behavior of fish and providing theoretical support for ecological conservation and hydropower project design. Full article

Clay minerals and other flocculants are used to mitigate the effects of some species that produce harmful algal blooms due to their physical and chemical characteristics. In this study, we applied calcium bentonite clay (Bca) and zeolite (Ze) to flocculate and remove cells of the dinoflagellate Gymnodinium catenatum (Graham), a producer of paralyzing toxins. The flocculants were characterized by scanning electron microscopy (SEM) in combination with an energy-dispersive X-ray spectroscopy (EDS) microanalysis system. During experiments, Bca and Ze were suspended in distilled water, deionized water, and seawater at concentrations of 0.25, 0.5, 1.0, 1.5, 2.0, 2.5, and 4.0 gL⁻¹. The percentage of removal efficiency (RE%) of biomass indicators of G. catenatum was calculated. The cell number and concentration of chlorophyll a and peridinin were analyzed using high-performance liquid chromatography (HPLC-UV and HPLC-DAD). The external effects on cells of G. catenatum were recorded. As a result, the maximum RE% of Bca was 79% with respect to the total number of cells, chlorophyll a was 69% and peridinin of 73%. The RE% of Ze was less than 40%. In the matrix of sedimented Bca, malformation of cells was observed, inhibiting their swimming, as well as death and rupture of cells with temporary cyst formation after 72 h. We conclude that Bca, suspended in deionized and distilled water, was more efficient in flocculating cells of G. catenatum. Full article