Objective To establish the regression equation for the maximum oxygen uptake(VO2max)of male young endurance athletes at altitudeby modeling relevant indicators.Methods A total of 81 young male endurance athletes(long-distance runner,marathoner,and race walker)aged 15～18 years old were selected as the research subjects.The VO2max,3000-meter timed run,400-meter timed run,body morphology,body composition,hematological indicators,and cardiac function of the ath-letes were tested in Kunming,Yunnan Province(1890 meters altitude high)in four consecutive days.The testing sequence of the exercise was randomly arranged.The data of the first 65 athletes were used for multiple linear regression modeling,while those of the rest 16 were employed for the verifica-tion of the established model.Results Based on the data of 65 athletes,the multiple linear regression equation of VO2max was:VO2max=2616.661+60.389×lean body mass(kg)-3.108×3000-meter run-ning time(s)-16.665×lower limb length A(cm)+6.356×maximum heart rate(bpm),R2=0.858,and that of the relative VO2max was:relative VO2max=119.685-0.058×3000-meter running time(s)-0.224×body weight(kg)-0.452×Achilles tendon length(cm),R2=0.681.Accord-ing to the data of the rest 16 athletes,there was no significant difference in the calculated values of VO2max and relative VO2max.Moreover,the calculated values and the direct test values of VO2max and rel-ative VO2max were positively correlated(r=0.735,P=0.001;r=0.509,P=0.044).Conclusion A regression model of VO2max and relative VO2max for young male endurance athletes at altitude(1890 meters altitude high)was established and verified through direct testing.The model established is worth popularization and application,and can provide references for indicators selection of young male endurance athletes at altitude(1890 meters altitude high).

Objective To analyze the technical movement characteristics of female table tennis play-ers with shoulder impingement syndrome when hitting a forehand topspin loop ball,in order to explore the reasons for shoulder impingement syndrome.Methods Thirteen female table tennis athletes with shoulder impingement syndrome were recruited for the shoulder impingement group(age 20.31±2.56 years,height 165.69±4.00 cm,weight 56.62±6.00 kg)and 13 healthy female table tennis athletes(age 21.54±2.78 years,height 165.54±4.45 cm,weight 60.08±8.02 kg)were selected for the healthy group.Kinematic and electromyographic data of the upper limbs were collected during six tri-als of forehand topspin strokes using a three-dimensional motion capture system and a wireless surface electromyographic system.The data were then averaged and compared between the groups.Results The shoulder impingement group had a greater shoulder flexion angular velocity at the end of the forward swing compared to the healthy group(t=-3.689,P=0.001).In addition,the shoulder impingement group showed significantly smaller trunk torsion angular amplitude(t=2.614,P=0.015)and average an-gular velocity of trunk torsion(t=3.958,P=0.001).Furthermore,the peak activation level of the anteri-or serratus muscle was smaller in the shoulder impingement group compared to the healthy group(t=2.363,P=0.027).Finally,the deactivation duration of both the triceps brachii and brachioradialis mus-cles was shorter in the shoulder impingement group compared to the latter(t=3.705,P=0.002;t=3.29,P=0.004).Conclusion Female table tennis players with shoulder impingement syndrome exhibit the fol-lowing characteristics in their forehand topspin:1)insufficient trunk rotation and premature deactiva-tion of the brachioradialis muscle,which lead to excessive loading on the shoulder during flexion;2)inadequate activation of the serratus anterior muscle,resulting in compromised scapular stability;3)premature deactivation of the triceps brachii muscle,which negatively affects the control of eccentric contraction velocity at the shoulder joint.

Objective To determine 32 anabolic agents in tablets,capsules and injections using liquid chromatography-high resolution mass spectrometry(LC-HRMS),so as to provide technical support in the fields of anti-doping and judicial identification.Methods The tablet grinded into powder,capsule samples extracted using a methanol∶water(7∶3)solution and injection underwent centrifugation and filtration.The separation was performed on a Waters Acquity UPLC HSS T3 column(100 mm×2.1 mm,1.8 μm),followed by gradient elution using ammonium acetate(20 mmol/L)solution containing 0.1%formic acid,5%acetonitrile and acetonitrile system as mobile phases,and detection by heated electrospray ionization in positive mode with a primary full-scan/data-dependent secondary scan mode.The established analytical method was subjected to methodological validation and parameters such as se-lectivity,sensitivity,matrix effect and delay effect were investigated.Meanwhile,the method was ap-plied to the detection of anabolic agents in 20 samples of tablets,capsules and injections provided by the authorities.Results The detection limits for 32 anabolic agents ranged from 1～200 μg/mg in the powder and 1～200 ng/mL in the injection.When this method was applied to the analysis of actual samples,five anabolic agents,including methandrostenolone and stanozolol,were identified among the 20 samples,disconsistent with labels on the package.Conclusion The LC-HRMS method is simple in pretreatment,sensitive and suitable for the detection of anabolic agents in tablet,capsule and injec-tion samples in the fields of anti-doping and judicial identification.

Objective To explore adhering to 24-hour movement guidelines of disabled athletes,and its correlation to psychological resilience and subjective well-being.Methods A convenience sampling method was used to survey 192 disabled athletes from 17 provinces in China,to collect their demo-graphic information,compliance with 24-hour movement guidelines,psychological resilience and subjec-tive well-being.Ultimately,180 valid samples were obtained.Generalized linear models were used to analyze the relationship of meeting 24-hour movement guidelines to psychological resilience and subjec-tive well-being,and the roles of gender and type of disability were explored.Results On the average,disabled athletes spent 3.68 h on physical activities every week,but 4.89 h and 8 h on sedentary be-havior and sleep every day.The proportions of meeting 3 guidelines,2,and 1 were 26.1%,47.8%and 22.2%,respectively.Moreover,there was a dose-response relationship of the number of guide-lines met to psychological resilience(B=5.184,P<0.001)and subjective well-being(B=2.806,P<0.01).In other words,disabled athletes meeting more guidelines exhibited higher levels of psychological resil-ience(B=8.407,P<0.001)and subjective well-being(B=6.122,P<0.001).Conclusion Meeting 24-hour movement guidelines is of positive relation to psychological resilience and subjective well-being.There-fore,it is recommended to promote adherence to 24-hour movement guidelines among disabled ath-letes to promote their psychological health.

Objective To explore the effect of aerobic calisthenics on sleep quality in children with attention-deficit/hyperactivity disorder(ADHD).Methods Forty children with ADHD(aged 9～11 years;mean age 9.83±0.76 years)were recruited from the pediatric outpatient department of some class-3 grade-A hospital in Beijing.They were randomized into an intervention group(n=21)and a control group(n=19).Both groups participated in standard school physical education programs,while the intervention group underwent 60-minute aerobic calisthenics exercise sessions three times weekly for 8 weeks.Before and after the intervention,the sleep condition was measured using the children's sleep habits questionnaire(CSHQ)and the three-axis acceleration recorder.The inter-group differenc-es in sleep dimensions were analyzed using independent samples t-tests,while the intra-group ones were evaluated using paired t-tests.Results(1)Inter-group comparison:Before the experiment,no sig-nificant differences were detected between the two groups in sleep characteristics.After the experi-ment,in comparison with the control group,there was a significant decrease in awakening time,aver-age awakening time,and sleep latency time of the intervention group,but a significant increase in sleep efficiency(P<0.05).Moreover,the total score of CSHQ,as well as the sleep resistance and sleep delay scores,were significantly lower in the intervention group(P<0.05).(2)Intra-group com-parison:In the intervention group,after the experiment,there were significant reductions in awakening time and sleep latency time,and a significant enhancement in sleep efficiency(P<0.05).Moreover,the total score of CSHQ,along with the scores of sleep resistance,sleep delay,and daytime sleepi-ness,decreased significantly(P<0.05).In the control group,the daytime sleepiness score decreased af-ter the experiment(P<0.05).Conclusion An 8-week aerobic calisthenics exercise(60 minutes/session,3 sessions/week)significantly improves overall sleep quality in children with ADHD.Therefore,it is worth application in the clinical practice.

Objective To explore the effect of aerobic exercise on sarcopenia in CT26 tumor mice through the gut microbiota-skeletal muscle axis and its potential mechanism.Methods Forty-eight SPF BALB/c male mice aged 8 weeks were randomly divided into a normal control group(group NC,n=12),a normal control+aerobic exercise group(group NA,n=12),a CT26 tumor-associated sarco-penia group(group TS,n=12)and a CT26 tumor-associated sarcopenia+aerobic exercise group(group TSA,n=12).After a 2-week adaptive exercise period,CT26 cell suspension(0.2 mL,1×107 cells/mL)was subcutaneously injected into the dorsal region of mice in group TS and group TSA,while group NC and group NA were inoculated with 0.2 mL normal saline.One day later,group NA and group TSA underwent a 4-week aerobic treadmill running intervention(14 m/min,60 min/day,6 days/week).If a mouse failed to complete the target intensity on a given day,its running speed was reduced by 20%the following day.Moreover,group NA and group TSA received no exercise interven-tion.General health status of all groups was monitored throughout the study.The forelimb gripping force,rotarod walking time and the cross-sectional area of gastrocnemius muscle fibers were measured.Moreover,the ultrastructural changes of gastrocnemius were observed by transmission electron micro-scope,while the cecum contents were observed by 16S rRNA sequencing.Meanwhile,the pathological morphological changes of small intestine wall were observed using HE,while the contents of tumor ne-crosis factor-α(TNF-α),interleukin-6(IL-6),interleukin-1β(IL-1β)and lipopoly saccharide(LPS)of serum and gastrocnemius muscle were determined by using ELISA.Moreover,small intestine zonula occludens-1(ZO-1),Occludin and muscle ring finger 1(MuRF1),muscle atrophy F-box(MAF-bx),Toll-like receptor 4(TLR4)/myeloid differentiation factor 8(MyD88)/nuclear transcription factor-κB(NF-κB)signal pathway related proteins expression levels of gastrocnemius muscle,as well as muscle ring finger 1(MuRF1)and muscle atrophy F-box(MAF-bx)were detected using Western blot.Results(1)Subcutaneous tumors were prominent in group TS.The forelimb gripforce,wet weight and cross-sectional area of gastrocnemius,and rotarod walking time in group TS at the 5th and 6th weekends were significantly lower than group NC(P<0.01),while the relative expression levels of MuRF1 and MAF-bx proteins in the gastrocnemius muscle in group TS were significantly higher than the latter group(P<0.05,P<0.01).Moreover,transmission electron microscopy revealed sparse and dis-organized muscle fiber arrangement in group TS,with visible Z-lines but indistinct M-lines,as well as shortened,poorly defined,and thin sarcomeres.(2)The group TSA exhibited significantly higher α-diversity indices(Shannon,Chao1,and Observed species)in gut microbiota compared to group TS(P<0.05,P<0.01,P<0.05),while the β-diversity differed to some extent between the two groups.At phylum level,the F/B ratio was lower in group NA than that group NC,with that of group TSA low-er than group TS.At genus level,the relative abundances of Muribaculaceae,Bacteroides,Roseburia,and Alistipes in group NA were higher than group NC,and those of Alloprevotellaand Helicobacter were significantly lower,while those of Muribaculaceae,Lachnospiraceae_NK4A136_group,Roseburia,Bacteroides,Lachnospiraceae_UCG-001 of group TSA were significantly higher than group TS.Nota-bly,Roseburia and Alistipes were the most significantly enriched genera in group TSA and group TS(LDA score>4 for both).(3)The inflammatory cells of the small intestine wall in group TSA signifi-cantly reduced than those in group TS(P<0.05).Moreover,the expression level of ZO-1 proteins in the small intestine wall were significantly higher in group NA than group NC,and that of ZO-1 and Occludin proteins in the small intestine wall was significantly higher in group TSA than those in group TS(P<0.05).(4)The group NA exhibited significantly lower LPS concentrations in the gastrocne-mius muscle compared to group NC(P<0.05).Similarly,the group TSA showed reduced LPS levels in both serum and gastrocnemius compared to group TS(P<0.05).The relative protein expression of p-IκBα and p-NF-κB p65 significantly decreased in group TSA compared to group TS(P<0.05).The group TS displayed elevated concentrations of pro-inflammatory cytokines(TNF-α,IL-1β)in serum and gastrocnemius compared to group NC(P<0.01,P<0.05).The group TSA demonstrated significantly lower levels of TNF-α and IL-6 in these tissues in comparison with group TS(P<0.05,P<0.01).Conclusion Aerobic exercise can improve gut microbiota α diversity,adjusting its composition,improv-ing intestinal mucosal barrier function,reducing the LPS-induced pro-inflammatory response,and delay-ing skeletal muscle atrophy.The underlying mechanism may involve down regulation of TLR4/MyD88/NF-κB signaling in skeletal muscle,which has a positive effect on Gut-Muscle Axis.

Objective To explore the effect of back-pushing manipulation on motor ability and skele-tal muscle mitochondrial function in rats with chronic fatigue syndrome(CFS).Methods Twenty-four male Sprague-Dawley rats were randomly divided into a blank group of 8 and a modeling group of 16.The CFS rat model was established using forced weight-bearing swimming combined with chronic stress stimulation for 21 days.After successful modeling,the modeling group was further divided into the modeling control(MC)group and the back-pushing manipulation(BPM)group,each of 8.In the back-pushing manipulation group,all rats were given daily 20-minute back pushing for 14 consecu-tive days after modeling.Then,all groups were recorded semi-quantitative scores of general conditions(SQS-GC),body mass,and exhaustion swimming time(EST).Moreover,the grasping ability of limbs was assessed by using the mesh screen test(MST).After the intervention,the tissue of the erector spinae muscle was taken to detect the adenosine triphosphate(ATP)content using the biochemi-cal method,and the activities of mitochondrial respiratory chain complexes Ⅰ to Ⅳ were detected by using the spectrophotometric method.Results After modeling,compared with the blank group,the SQS-GC of the MC group and BPM groups were higher(P<0.01),while EST was shorter and the MST score was lower(P<0.01 or P<0.05).However,after intervention,compared with the MC group,the SQS-GC of the BPM group was lower(P<0.01),while EST and the MST score was higher(P<0.01 or P<0.05).Compared with the blank group,the ATP content of the modelling group was significantly lower(P<0.01),and the activities of mitochondrial respiratory chain complexes I,II,III,and IV de-creased significantly(P<0.01).However,after intervention,all the above values of the BPM group in-creased significantly,compared with the MC group(P<0.01 or P<0.05).Conclusion The back-pushing manipulation can improve the mitochondrial function and energy metabolism,as well as the exercise ca-pacity,and alleviate fatigue of CFS rats,which may be related to the improvement of the activities of mitochondrial respiratory chain complexes I,II,III,and IV,and the increase of ATP content in the skeletal muscles.

Objective To explore the association between knee torsion and multiple bony abnormali-ties of the lower limb in patients with recurrent patellar dislocation(RPD).Methods The preoperative imaging data of RPD patients treated in our institution between May 2020 and October 2024 were col-lected retrospectively.A total of 238 patients were included in this study,with 83.6%being females.All patients underwent standard hip-knee-ankle CT scans,and lower limb bony structural parameters were reconstructed and measured using Mimics 20.0,focusing on variables such as knee torsion,femo-ral anteversion(FAA),femoral distal torsion angle(DFTA),supratrochlear spur,tibial tuberosity to trochlear groove distance(TT-TG),Caton-Deschamps index,and tibial torsion.Bony abnormalities were categorized based on previously established risk thresholds.Moreover,chi-square tests were em-ployed to compare the composition ratio differences between knee torsion and multiple lower limb osse-ous abnormalities.Results Among all affected knees,the proportion of excessive knee torsion was 33.6%,while in cases with osseous abnormalities,the value was over 40%.Compared with cases of low knee torsion,patients with excessive knee torsion showed significantly higher proportions of FAA(41.3%vs.27.2%,P=0.028),excessive DFTA(60%vs.32.9%,P<0.001),supratrochlear spur(55%vs.38.6%,P=0.016),trochlear dysplasia(93.8%vs.73.4%,P<0.001),excessive TT-TG(68.8%vs.43.7%,P<0.001),and patella alta(50%vs.22.2%,P<0.001).Additionally,95%of knees with excessive torsion exhibited two or more bony risk factors,whereas 55%had four or more bony structural abnormalities,which was significantly higher than those of low knee torsion(55%vs.21.5%,P<0.001).Conclusion In RPD patients,excessive knee torsion is associated with multiple low-er limb bony abnormalities.Moreover,patients with high knee torsion(>12°)are significantly more likely to have multiple bony abnormalities than those with low torsion.Therefore,in surgical decision-making for such patients,lower limb bony abnormalities should be assessed comprehensively.

Objective To establish the regression equation for the maximum oxygen uptake(VO2max)of male young endurance athletes at altitudeby modeling relevant indicators.Methods A total of 81 young male endurance athletes(long-distance runner,marathoner,and race walker)aged 15～18 years old were selected as the research subjects.The VO2max,3000-meter timed run,400-meter timed run,body morphology,body composition,hematological indicators,and cardiac function of the ath-letes were tested in Kunming,Yunnan Province(1890 meters altitude high)in four consecutive days.The testing sequence of the exercise was randomly arranged.The data of the first 65 athletes were used for multiple linear regression modeling,while those of the rest 16 were employed for the verifica-tion of the established model.Results Based on the data of 65 athletes,the multiple linear regression equation of VO2max was:VO2max=2616.661+60.389×lean body mass(kg)-3.108×3000-meter run-ning time(s)-16.665×lower limb length A(cm)+6.356×maximum heart rate(bpm),R2=0.858,and that of the relative VO2max was:relative VO2max=119.685-0.058×3000-meter running time(s)-0.224×body weight(kg)-0.452×Achilles tendon length(cm),R2=0.681.Accord-ing to the data of the rest 16 athletes,there was no significant difference in the calculated values of VO2max and relative VO2max.Moreover,the calculated values and the direct test values of VO2max and rel-ative VO2max were positively correlated(r=0.735,P=0.001;r=0.509,P=0.044).Conclusion A regression model of VO2max and relative VO2max for young male endurance athletes at altitude(1890 meters altitude high)was established and verified through direct testing.The model established is worth popularization and application,and can provide references for indicators selection of young male endurance athletes at altitude(1890 meters altitude high).

Objective To analyze the technical movement characteristics of female table tennis play-ers with shoulder impingement syndrome when hitting a forehand topspin loop ball,in order to explore the reasons for shoulder impingement syndrome.Methods Thirteen female table tennis athletes with shoulder impingement syndrome were recruited for the shoulder impingement group(age 20.31±2.56 years,height 165.69±4.00 cm,weight 56.62±6.00 kg)and 13 healthy female table tennis athletes(age 21.54±2.78 years,height 165.54±4.45 cm,weight 60.08±8.02 kg)were selected for the healthy group.Kinematic and electromyographic data of the upper limbs were collected during six tri-als of forehand topspin strokes using a three-dimensional motion capture system and a wireless surface electromyographic system.The data were then averaged and compared between the groups.Results The shoulder impingement group had a greater shoulder flexion angular velocity at the end of the forward swing compared to the healthy group(t=-3.689,P=0.001).In addition,the shoulder impingement group showed significantly smaller trunk torsion angular amplitude(t=2.614,P=0.015)and average an-gular velocity of trunk torsion(t=3.958,P=0.001).Furthermore,the peak activation level of the anteri-or serratus muscle was smaller in the shoulder impingement group compared to the healthy group(t=2.363,P=0.027).Finally,the deactivation duration of both the triceps brachii and brachioradialis mus-cles was shorter in the shoulder impingement group compared to the latter(t=3.705,P=0.002;t=3.29,P=0.004).Conclusion Female table tennis players with shoulder impingement syndrome exhibit the fol-lowing characteristics in their forehand topspin:1)insufficient trunk rotation and premature deactiva-tion of the brachioradialis muscle,which lead to excessive loading on the shoulder during flexion;2)inadequate activation of the serratus anterior muscle,resulting in compromised scapular stability;3)premature deactivation of the triceps brachii muscle,which negatively affects the control of eccentric contraction velocity at the shoulder joint.