1.Clinical and pathological characteristics of pediatric tumors with DICER1 mutations detected by Sanger sequencing
Meng ZHANG ; Xingfeng YAO ; Nan ZHANG ; Chao JIA ; Yaqian WU ; Baofeng YANG ; Shen YANG ; Lejian HE
Chinese Journal of Pathology 2025;54(12):1288-1296
Objective:To investigate the clinicopathological and molecular genetic characteristics of pediatric tumors with DICER1 mutations.Methods:A total of 90 patients diagnosed with various types of pediatric tumors at Beijing Children′s Hospital, Capital Medical University, Beijing, China from July 2023 to September 2025 were included in this study. PCR amplification and Sanger sequencing were performed to detect the coding-region mutations of the DICER1 gene. The clinical, histopathological, and molecular genetic features of the cases with DICER1 mutation were then analyzed.Results:Among the 90 patients, 39 were male and 51 were female, with an age of onset ranging from 1 month to 17 years [median 7.13 (2.77, 10.37) years]. DICER1 mutations were detected in 37 patients (37/90, 41.1%). Among them, 9 cases harbored one mutation [6 pleuropulmonary blastomas (PPBs), 2 sex cord stromal tumors (SCSTs), and 1 cystic nephroma (CN)], 27 cases carried two mutations [10 PPBs, 3 anaplastic sarcomas of the kidney (ASKs), 3 SCSTs, 3 thyroid adenoma, 2 nodular thyroid goiters, 2 thyroid follicular lesions, 2 CN, 1 embryonal rhabdomyosarcoma, and 1 case with multiple primary tumors], and 1 case exhibited three mutations (bilateral ASKs). Despite variations in the site of origin, DICER1-mutant tumors shared several morphological features. Grossly, they presented as multilocular cystic, cystic-solid to solid masses. Microscopically, they exhibited a subepithelial layer of mesenchymal cells, with focal rhabdomyoblastic/chondroid/chondrosarcomatous differentiation, as well as cellular anaplasia. Germline testing using peripheral blood in the 31 patients with DICER1 mutation confirmed germline origin in 61.3% (19/31) of them. Parental analysis ( n=12) demonstrated genetic inheritance in 8 cases, predominantly from families with tumor history. Germline variants scattered throughout DICER1 and consisted of loss-of-function mutations (nonsense, frameshift, and splice-site). Somatic mutations showed distinct clustering in exons 24 and 25 hotspots (codons 1705, 1709, 1809, 1810 and 1813), primarily missense variants. Notably, one multiple primary tumor case harbored a somatic mosaic p.E1705K mutation. Conclusions:DICER1 mutations are frequently detected in pediatric PPB, CN, SCST, ASK, nodular thyroid goiter, thyroid adenoma, and genitourinary rhabdomyosarcoma, which often represent as the index case of DICER1 syndrome. Performing DICER1 mutation testing in these patients not only facilitates tumor diagnosis and secondary cancer surveillance, but also enables the comprehensive genetic risk assessment and management for patient′s family members.
2.Mechanism of central analgesia in rats with myofascial pain syndrome by intervention of"trigger points"with stagnant moving needles
Liping ZHAO ; Yibo CHEN ; Yaqian WANG ; Zhitong LI ; Qi ZHANG ; Bo GOU
Chinese Journal of Tissue Engineering Research 2025;29(17):3614-3623
BACKGROUND:The analgesic effect of stagnant moving needle on myofascial pain syndrome is remarkable,but the analgesic mechanism is still unclear.OBJECTIVE:To investigate the analgesic mechanism of stagnant moving needle acupuncture in the treatment of myofascial pain syndrome.METHODS:Fifty-four SD rats were randomly divided into a blank group(n=16)and a modeling group(n=38).The models of leftmyofascial pain syndrome in the modeling group were prepared by using the method of"striking combined with centrifugal movement".Twelve weeks after modeling,six mice were randomly selected to verify the success of the modeling.The rest of the 32 rats were randomly divided into the model group and the stagnant moving needle group,with 16 rats in each group.The stagnant needle moving group was treated by stagnant moving needle into the local excitation point nodule of the left medial vastus muscle fascia in rats,twice a week,for 4 weeks.The mechanical foot contraction reflex threshold of the leftfoot were measured weekly in the pre/post modeling and post-intervention groups of rats.At 4 weeks after treatment,hematoxylin-eosin staining was used to observe the morphological changes in the muscle tissue of the leftmedial femoral muscle of rats,ELISA was used to detect the levels of substance P and β-endorphin in the serum and the gray matter around the midbrain aqueduct.Immunohistochemistry was used to detect positive expression of microglia markers(Iba-1)and c-fos in the gray matter around the midbrain aqueduct.Western blot assay was used to detect the expression level of brain-derived neurotrophic factor protein in the periaqueductal gray.RESULTS AND CONCLUSION:Compared with the blank group,the mechanical pain threshold of the rats in the model group and the stagnant moving needle group decreased after modeling(P<0.05).After 4 weeks of treatment,the mechanical pain threshold of the rats in the stagnant moving needle group was higher than that in the model group(P<0.05).Hematoxylin-eosin staining results showed that in the model group,the muscle fibers of the leftlower limb medial femoral muscle of rats were disorganized,unequal in thickness,myocytes were enlarged,with inward movement of the nucleus,rounded contracture nodules and tension bands;whereas in the stagnant moving needle group,the muscle fibers were arranged in a neat way,the myocytes were angular,and the contracture nodules were occasionally seen.Compared with the blank group,the expression of substance P in the serum of the model group was significantly higher(P<0.05),while the levels of β-endorphin in serum and substance P and β-endorphin in brain were decreased(P<0.01).Compared with the model group,the level of serum substance P in the stagnant moving needle group was decreased(P<0.05),and the levels of serum β-endorphin and brain substance P and β-endorphin were increased(P<0.05).Compared with the blank group,the positive expression of c-fos and Iba-1 and the protein of brain-derived neurotrophic factor in the model group were increased(P<0.05).Compared with the model group,the positive expression of c-fos in the stagnant moving needle group was increased(P<0.05),and the positive expression of Iba-1 and the protein of brain-derived neurotrophic factor were decreased(P<0.05).These findings suggest that stagnant moving needle may indirectly promote the release of β-endorphin by microglia polarized to the M2 phenotype and increase the excitability of c-fos neurons by inhibiting the activity of microglia in the gray matter around the periaqueductal gray and downregulating the expression of brain-derived neurotrophic factor protein,thereby reducing the degree of central sensitization and effectively relieving myofascial pain syndrome.
3.Quorum-sensing inhibition of flavonoid glycosides from Epimedium brevicornum
Xianrui JIANG ; Yaqian DUAN ; Chang LIU ; Chengzhong ZHANG
Journal of Pharmaceutical Practice and Service 2025;43(4):169-173
Objective To identify flavonoid glycosides with quorum sensing inhibitory activity from Epimedium brevicornum and evaluate their bioactivity. Methods The minimum inhibitory concentrations (MICs) of five major flavonoid glycosides (baohuoside, icariin, epimedin A/B/C) and the extract of E. brevicornum were firstly determined. Subsequently, the inhibitory effects on the production of purple pigments in Chromobacterium violaceum CV026 were measured. Additionally, the biofilm formation and chitin quantification of Pseudomonas aeruginosa PAO1 were assessed. Results The extract of E. brevicornum and its primary components exhibited significant quorum sensing inhibitory activity. Particularly, icariin and epimedin C demonstrated superior inhibitory activity. Conclusion E. brevicornum demonstrates the ability to inhibit the quorum sensing system of Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1. Furthermore, icariin and epimedin C (100 μg/ml) show promise for development into novel drugs for quorum sensing inhibitor.
4.Effects of acupuncture on the hypothalamic-pituitary-ovarian axis and FSH/cAMP signaling pathway in aged rats.
Yaoyao ZHU ; Yaqian YIN ; Huanfang XU ; Li YANG ; Weixin LI ; Chenchen SU ; Rong ZHANG ; Yigong FANG
Chinese Acupuncture & Moxibustion 2025;45(2):200-208
OBJECTIVE:
To explore the mechanism of acupuncture on improving ovarian hypofunction in aged rats from two perspectives: the overall regulation of the hypothalamic-pituitary-ovarian (HPO) axis and the local ovarian follicle stimulating hormone (FSH)/cyclic adenosine monophosphate (cAMP) signaling pathway.
METHODS:
Six 3-month-old female SPF-grade Sprague-Dawley (SD) rats were selected as the blank group. Another twelve 9-month-old female SD rats were randomly divided into a model group and an acupuncture group, with six rats in each. The acupuncture group received acupuncture at "Baihui" (GV20), "Guanyuan" (CV4), and bilateral "Ciliao" (BL32) for 20 min per session, once every other day, for a total of 10 sessions. Vaginal smear tests were performed daily to observe the estrous cycle of the rats. Ovarian morphology was observed using HE staining, and follicles at various stages were counted. ELISA was used to detect levels of serum FSH, luteinizing hormone (LH), estradiol (E2), anti-müllerian hormone (AMH), hypothalamic gonadotropin-releasing hormone (GnRH), pituitary FSH and LH, and ovarian cAMP. Immunohistochemistry and Western blot were used to detect the protein expression of ovarian cAMP protein kinase catalytic subunit, FSH receptor (FSHR), and P450. Real-time quantitative PCR was used to measure mRNA expression levels of FSHR and P450 in ovarian tissue.
RESULTS:
Compared with the blank group, the model group showed an increased rate of estrous cycle disorder (P<0.01), reduced granulosa cell layers with blurred boundaries and disordered arrangement, decreased numbers of developing follicles at all stages, and increased numbers of atretic follicles (P<0.01); the serum levels of FSH and LH were increased (P<0.01), while E2 and AMH levels were decreased (P<0.01); the hypothalamic GnRH and pituitary FSH and LH levels were elevated (P<0.01), and ovarian cAMP level was decreased (P<0.01); the positive expression and protein expression of ovarian P450, cAMP protein kinase catalytic subunit, and FSHR were reduced (P<0.01), and ovarian FSHR and P450 mRNA expression was decreased (P<0.01). Compared with the model group, the acupuncture group showed a reduced rate of estrous cycle disorder (P<0.01), clear granulosa cell margins, increased numbers of primordial and secondary follicles, and decreased numbers of atretic follicles (P<0.01); the serum FSH and LH levels were decreased (P<0.01, P<0.05), while E2 and AMH levels were increased (P<0.05, P<0.01); the hypothalamic GnRH and pituitary FSH and LH levels were decreased (P<0.01, P<0.05), and ovarian cAMP level was increased (P<0.01); the positive expression and protein expression of ovarian P450, cAMP protein kinase catalytic subunit, and FSHR were elevated (P<0.01), and ovarian FSHR and P450 mRNA expression was increased (P<0.01).
CONCLUSION
Acupuncture could delay ovarian hypofunction in aged rats, possibly through regulating the HPO axis and the FSH/cAMP signaling pathway.
Animals
;
Female
;
Rats
;
Rats, Sprague-Dawley
;
Follicle Stimulating Hormone/genetics*
;
Acupuncture Therapy
;
Ovary/metabolism*
;
Signal Transduction
;
Humans
;
Cyclic AMP/metabolism*
;
Hypothalamo-Hypophyseal System/metabolism*
;
Aging/metabolism*
;
Hypothalamus/metabolism*
;
Pituitary Gland/metabolism*
;
Gonadotropin-Releasing Hormone/metabolism*
5.Spicy food consumption and risk of vascular disease: Evidence from a large-scale Chinese prospective cohort of 0.5 million people.
Dongfang YOU ; Dianjianyi SUN ; Ziyu ZHAO ; Mingyu SONG ; Lulu PAN ; Yaqian WU ; Yingdan TANG ; Mengyi LU ; Fang SHAO ; Sipeng SHEN ; Jianling BAI ; Honggang YI ; Ruyang ZHANG ; Yongyue WEI ; Hongxia MA ; Hongyang XU ; Canqing YU ; Jun LV ; Pei PEI ; Ling YANG ; Yiping CHEN ; Zhengming CHEN ; Hongbing SHEN ; Feng CHEN ; Yang ZHAO ; Liming LI
Chinese Medical Journal 2025;138(14):1696-1704
BACKGROUND:
Spicy food consumption has been reported to be inversely associated with mortality from multiple diseases. However, the effect of spicy food intake on the incidence of vascular diseases in the Chinese population remains unclear. This study was conducted to explore this association.
METHODS:
This study was performed using the large-scale China Kadoorie Biobank (CKB) prospective cohort of 486,335 participants. The primary outcomes were vascular disease, ischemic heart disease (IHD), major coronary events (MCEs), cerebrovascular disease, stroke, and non-stroke cerebrovascular disease. A Cox proportional hazards regression model was used to assess the association between spicy food consumption and incident vascular diseases. Subgroup analysis was also performed to evaluate the heterogeneity of the association between spicy food consumption and the risk of vascular disease stratified by several basic characteristics. In addition, the joint effects of spicy food consumption and the healthy lifestyle score on the risk of vascular disease were also evaluated, and sensitivity analyses were performed to assess the reliability of the association results.
RESULTS:
During a median follow-up time of 12.1 years, a total of 136,125 patients with vascular disease, 46,689 patients with IHD, 10,097 patients with MCEs, 80,114 patients with cerebrovascular disease, 56,726 patients with stroke, and 40,098 patients with non-stroke cerebrovascular disease were identified. Participants who consumed spicy food 1-2 days/week (hazard ratio [HR] = 0.95, 95% confidence interval [95% CI] = [0.93, 0.97], P <0.001), 3-5 days/week (HR = 0.96, 95% CI = [0.94, 0.99], P = 0.003), and 6-7 days/week (HR = 0.97, 95% CI = [0.95, 0.99], P = 0.002) had a significantly lower risk of vascular disease than those who consumed spicy food less than once a week ( Ptrend <0.001), especially in those who were younger and living in rural areas. Notably, the disease-based subgroup analysis indicated that the inverse associations remained in IHD ( Ptrend = 0.011) and MCEs ( Ptrend = 0.002) risk. Intriguingly, there was an interaction effect between spicy food consumption and the healthy lifestyle score on the risk of IHD ( Pinteraction = 0.037).
CONCLUSIONS
Our findings support an inverse association between spicy food consumption and vascular disease in the Chinese population, which may provide additional dietary guidance for the prevention of vascular diseases.
Humans
;
Male
;
Female
;
Prospective Studies
;
Middle Aged
;
Aged
;
Vascular Diseases/etiology*
;
Risk Factors
;
China/epidemiology*
;
Adult
;
Proportional Hazards Models
;
Cerebrovascular Disorders/epidemiology*
;
East Asian People
6.Effects of Huoxue Xiaoyi Formula (活血消异方) on Tfh Cells and the JAK/STAT Pathway in Ectopic Tissues of Ovarian Endometriosis Model Rats
Weisen FAN ; Yongjia ZHANG ; Yaqian WANG ; Hong LEI ; Huiting YAN ; Ruijie HOU ; Xin WANG ; Yu TAO ; Ruihua ZHAO
Journal of Traditional Chinese Medicine 2025;66(14):1473-1480
ObjectiveTo explore the potential mechanism of Huoxue Xiaoyi Formula (活血消异方, HXF) in treating ovarian endometriosis (OEM) from the perspective of T follicular helper (Tfh) cells and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. MethodsForty-five female SD rats with normal estrous cycles were randomly divided into three groups, HXF group, model group, and normal group, with 15 rats in each group. A rat model of OEM was established by autologous endometrial tissue implantation. After successful modeling, the treatment group received HXF at 5.85 g/(kg·d) by gavage for 14 consecutive days. The model group and normal group received 1 mL/d of normal saline by gavage. RNA-sequencing data from human proliferative-phase endometriotic and normal endometrial tissues were downloaded from the GEO database. Transcriptomic sequencing was used to analyze gene expression in rat ovarian ectopic tissues and normal uterine tissues, and comparisons were made with human data to verify JAK/STAT pathway activation in proliferative-phase ectopic tissues. Immunohistochemistry was used to detect the positive expression of CXC chemokine receptor 5 (CXCR5) and interleukin-21 (IL-21) in rat ovarian ectopic and normal uterine tissues. Western Blotting was performed to detect the protein levels of IL-21, IL-21 receptor (IL-21R), Janus kinase 1 (JAK1), signal transducer and activator of transcription 6 (STAT6), and B-cell lymphoma 2 (Bcl-2). Tfh cell infiltration was analyzed using immune cell infiltration methods. ResultsGene set enrichment analysis showed that the JAK/STAT pathway was significantly activated in human proliferative-phase endometriotic tissues compared to normal endometrial tissues. Similarly, the JAK/STAT pathway was markedly activated in rat ovarian ectopic tissues in the model group compared to the normal group, but suppressed in the HXF group compared to the model group. Compared with normal uterine tissues, ovarian ectopic tissues in the model group showed increased Tfh cell infiltration scores, higher CXCR5 and IL-21 expression, and elevated levels of IL-21, IL-21R, JAK1, STAT6, and Bcl-2 proteins. Compared with the model group, HXF group showed reduced CXCR5 and IL-21 expression and decreased protein levels of IL-21, IL-21R, JAK1, STAT6, and Bcl-2. ConclusionHXF may suppress activation of the JAK/STAT signaling pathway in ovarian endometriotic tissues by inhibiting IL-21 secretion from Tfh cells.
7.Developing a polygenic risk score for pelvic organ prolapse: a combined risk assessment approach in Chinese women.
Xi CHENG ; Lei LI ; Xijuan LIN ; Na CHEN ; Xudong LIU ; Yaqian LI ; Zhaoai LI ; Jian GONG ; Qing LIU ; Yuling WANG ; Juntao WANG ; Zhijun XIA ; Yongxian LU ; Hangmei JIN ; Xiaowei ZHANG ; Luwen WANG ; Juan CHEN ; Guorong FAN ; Shan DENG ; Sen ZHAO ; Lan ZHU
Frontiers of Medicine 2025;19(4):665-674
Pelvic organ prolapse (POP), whose etiology is influenced by genetic and clinical risk factors, considerably impacts women's quality of life. However, the genetic underpinnings in non-European populations and comprehensive risk models integrating genetic and clinical factors remain underexplored. This study constructed the first polygenic risk score (PRS) for POP in the Chinese population by utilizing 20 disease-associated variants from the largest existing genome-wide association study. We analyzed a discovery cohort of 576 cases and 623 controls and a validation cohort of 264 cases and 200 controls. Results showed that the case group exhibited a significantly higher PRS than the control group. Moreover, the odds ratio of the top 10% risk group was 2.6 times higher than that of the bottom 10%. A high PRS was significantly correlated with POP occurrence in women older than 50 years old and in those with one or no childbirths. As far as we know, the integrated prediction model, which combined PRS and clinical risk factors, demonstrated better predictive accuracy than other existing PRS models. This combined risk assessment model serves as a robust tool for POP risk prediction and stratification, thereby offering insights into individualized preventive measures and treatment strategies in future clinical practice.
Humans
;
Female
;
Pelvic Organ Prolapse/epidemiology*
;
Middle Aged
;
Risk Assessment/methods*
;
China/epidemiology*
;
Multifactorial Inheritance
;
Aged
;
Risk Factors
;
Genome-Wide Association Study
;
Genetic Predisposition to Disease
;
Case-Control Studies
;
Adult
;
Polymorphism, Single Nucleotide
;
Genetic Risk Score
;
East Asian People
8.Diagnostic value of urine gene methylation combined with folate metabolism gene polymorphism in bladder cancer
Juanjuan HOU ; Yaqian NIU ; Dan ZHANG ; Jianlong ZHENG ; Guoping ZHANG ; Junqiang TIAN ; Zhenyun WANG
Chinese Journal of Immunology 2025;41(7):1574-1580
Objective:To investigate the application value of combined detection of urine genes Twist1,Onecut2,VIM methyl-ation and folate metabolism related genes MTHFR(C677T/A1298C),MTRR(A66G)polymorphisms in the screening and diagnosis of bladder cancer.Methods:A total of 134 patients with primary bladder cancer admitted to the Department of Urology of Qingyang Peo-ple's Hospital and the Second Hospital of Lanzhou University from January 2023 to January 2024 were selected(bladder cancer group),and a total of 130 patients with common benign urinary system diseases and other malignant tumors of urinary system treated with cystoscopy were admitted during the same period(control group).Methylation-specific polymerase chain reaction was used to de-tect the methylation of Twist1,Onecut2 and VIM genes in urine shed cells.PCR fluorescence probe fusion was used to detect the poly-morphism of folate metabolism-related genes in peripheral blood of patients,and collected the clinical data and immunological indica-tors,and to all the data for statistical analysis.Results:The methylation rates of hematuria,bladder irritation,Twist1,Onecut2 and VIM genes were significantly different between two groups(P<0.05).The area under ROC curve(AUC)of Twist1,Onecut2 and VIM genes methylation and their combined detection were 0.721,0.675,0.674 and 0.772,respectively.Sensitivity and specificity were 73.20%and 71.00%,56.10%and 79.00%,48.80%and 86.00%,80.50%and 69.00%,respectively.The AUC of hematuria and blad-der irritation were 0.661 and 0.652.The sensitivity and specificity were 60.20%and 72.00%,41.50%and 89.00%,respectively.The combined AUC of all indicators were the largest(0.858),and the sensitivity and specificity were higher.The frequencies of CC,CT,TT,and T alleles of MTHFR C677T in bladder cancer group were 21.64%,41.79%,36.56%and 57.46%,respectively.Compared with the control group,the difference was statistically significant(P<0.05).The T allele frequency was significantly different between methylated and unmethylated Twist1 groups(P<0.05).Others differences were not statistically significant,and there was no signifi-cant association with gene methylation(P>0.05).Conclusion:The methylation of Twist1,Onecut2 and VIM genes are highly ex-pressed in the urine cells of patients with bladder cancer,and the combination of hematuria and bladder irritation has a high predictive value for the diagnosis of bladder cancer.The MTHFR(C677T)T allele is associated with the methylation of Twist1 gene and may be one of the risk factors for bladder cancer.
9.Simulation of Fluid Resistance at Different Drafting Positions in Marathon Swimming
Yaqian QI ; Kaiyang SUN ; Defeng ZHAO ; Peng ZHANG ; Xiangbo FAN
Journal of Medical Biomechanics 2025;40(5):1288-1294
Objective To analyze the fluid resistance characteristics of different drafting formations in marathon swimming using computational fluid dynamics(CFD)method,and provide theoretical guidance for selecting optimal drafting strategies in competitions and training.Methods Multi-swimmer models were established via three-dimensional body scanning technology,and various formation models(I-,A-,V-,L-,H-type)were created by adjusting lateral and longitudinal distances between swimmers.The ANSYS Discovery Live software was used to simulate the overall resistance of different models and the resistance of individual swimmers within formations.Results The I3-type formation exhibited an overall drag reduction effect,reducing total resistance by 55.21%,whereas other formations increased overall resistance.The V-type formation showed the most significant resistance increase(31.88%).During drafting,the lowest resistance position was the rear position in the I3-type formation,while the highest resistance position was the middle position in the L-type formation.When leading,the fluid resistance of the leading swimmer in the A-type formation was significantly greater than that of an individual swimmer(P<0.05).Conclusions Longitudinal drafting formations demonstrated superior drag reduction effects,with the rear position in a three-person longitudinal arrangement showing the optimal drag reduction.Considering both tactical considerations and drag reduction effects,swimmers are advised to avoid the middle position in lateral formations.
10.Simulation of Fluid Resistance at Different Drafting Positions in Marathon Swimming
Yaqian QI ; Kaiyang SUN ; Defeng ZHAO ; Peng ZHANG ; Xiangbo FAN
Journal of Medical Biomechanics 2025;40(5):1288-1294
Objective To analyze the fluid resistance characteristics of different drafting formations in marathon swimming using computational fluid dynamics(CFD)method,and provide theoretical guidance for selecting optimal drafting strategies in competitions and training.Methods Multi-swimmer models were established via three-dimensional body scanning technology,and various formation models(I-,A-,V-,L-,H-type)were created by adjusting lateral and longitudinal distances between swimmers.The ANSYS Discovery Live software was used to simulate the overall resistance of different models and the resistance of individual swimmers within formations.Results The I3-type formation exhibited an overall drag reduction effect,reducing total resistance by 55.21%,whereas other formations increased overall resistance.The V-type formation showed the most significant resistance increase(31.88%).During drafting,the lowest resistance position was the rear position in the I3-type formation,while the highest resistance position was the middle position in the L-type formation.When leading,the fluid resistance of the leading swimmer in the A-type formation was significantly greater than that of an individual swimmer(P<0.05).Conclusions Longitudinal drafting formations demonstrated superior drag reduction effects,with the rear position in a three-person longitudinal arrangement showing the optimal drag reduction.Considering both tactical considerations and drag reduction effects,swimmers are advised to avoid the middle position in lateral formations.

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