Objective To investigate the effects of strength training and flexibility training on the strategy of crossing obstacles for the elderly women and the risk of tripping over obstacles.Methods Twenty five elderly women were randomly divided into strength training group(n=13)and flexibility training group(n=12),and received corresponding intervention training for 12 weeks.The kinematics data of obstacle crossing were collected using an infrared three-dimensional(3D)motion capture system before and after training.Results Both strength training and flexibility training could significantly improve the gait speed(P=0.033),stride length(P=0.020)and toe distance(P=0.014)during 25 cm obstacle crossing.The interactive effect of training and time was significant for the crossing height(15 cm:P=0.025;25 cm:P=0.019).The interactive effect of training and time was significant for the margin of stability(MOS)in the internal-external direction during 25 cm obstacle crossing(P<0.05).The minimum MOS in the first single support period(P=0.046)and the MOS at the time when the toe crossed directly above the obstacle(P=0.043)in strength training group were significantly increased.Conclusions Both strength training and flexibility training can improve the spatiotemporal characteristics of the elderly women during obstacle crossing.Compared with flexibility,muscle strength is the most important reason that restricts the crossing height of the elderly women.Strength training can effectively reduce the risk of tripping over obstacles by improving the crossing height and dynamic stability of elderly women.

Objective To examine and compare the effect of personalized progressive aerobic-exercise and resistance-training prescriptions on anxiety of undergraduates.Methods This was a randomized controlled trial.Sixty-six undergraduates with anxiety were recruited and randomized into an aerobic ex-ercise(AE)group,a resistance exercise(RE)group and a control group,each of 22.The aerobic and resistance exercise groups underwent 12-week aerobic and resistance exercise respectively,while the control group only received health education.Before as well as after 4-,8-and 12-week interven-tion,and 4 weeks after the intervention,all groups were evaluated using Self-Rating Anxiety Scale(SAS)and Chinese College Students Mental Health Scale--Anxiety Subscale(CCSMHS-AS).More-over,before and 16 weeks after the intervention,all groups were assessed physical activity(PA)us-ing the International Physical Activity Questionnaire-Short Form(IPAQ-SF).Results The average SAS scores of the AE and RE groups decreased significantly from 6.95±6.32 and 56.41±5.45 before the intervention to 38.29±5.82 and 41.18±7.51 after 12-week exercise,while the average CC-SMHS-AS score decreased significantly from 20.00±5.66 and 19.41±3.70,to 13.18±4.81 and 14.32±4.16 during the same period of time(P<0.01 for all).Four weeks after the intervention,the SAS score of the AE group was significantly higher than 4 weeks earlier(49.18±11.84 vs.38.29±5.82,P<0.01),while that of the RE group increased without significant differences compared with 4 weeks earlier(42.50±9.57 vs.41.18±7.51,P>0.05),with the value of both groups significantly lower than right after the intervention(P<0.01,P<0.05).In the control group,the SAS score de-creased significantly from 55.73±5.27 before the intervention to 47.09±5.55 right after the interven-tion,and further to 46.95±9.70 4 weeks later(P<0.05),but no significant differences were ob-served in the CCSMHS-AS score(P>0.05).Meanwhile,right after the intervention,the average SAS scores of the AE and RE groups were significantly lower than the control group(P<0.01,P<0.05),without significant differences among the three groups 4 weeks after the intervention(P>0.05).The CC-SMHS-AS scores of AE group right after and 4 weeks after the intervention were significantly higher than the control group(P<0.01),but no significant differences were found in it between either the AE and RE group,or the RE and control group(P>0.05).Besides,the PA levels of the AE and RE groups 4 weeks after the intervention were significantly higher than before the intervention,while no significant changes were observed in the PA level of the control group(P>0.05).Conclusion Twelve-week personalized progressive aerobic-exercise and resistance-training prescriptions both result in a similar effect on relieving anxiety and improving spontaneous PA of college students.However,the prognosis of aerobic exercise is poorer than the other.

Objective:To compare the effects of 8 weeks of aerobic exercise(AE),resistance exercise(RE)and com-bined exercise(CE)on cardiac function,hemodynamics and vascular stiffness in young women with obesity,and to provide theoretical and practical basis for exercise prescription in this population.Method:Forty-seven women with obesity(body fat percentage≥30％)were screened and randomly divided in-to AE,RE and CE group.Exercise intervention consisted of 8 weeks,60 min per session,3 sessions per week.The AE group exercised on a running platform at 70％—75％of the heart rate reserve for 50 min.The RE group completed squats,bench presses and pull-ups sequentially at 75％of the 1 repetition maximum for 10 reps per set,with a 2 min break between sets and 2 min for the change of the movement interval.The CE group performed 25min of resistance training followed by 25min of aerobic training with the same content and intensity as the AE and RE exercise group.Changes in body composition,cardiac function,hemodynam-ics and vascular stiffness were detected before,during and after exercise using a dual-energy X-ray detector,color Doppler ultrasound and arterial stiffness detector.Result:Body fat percentage decreased significantly in all three groups after 8 weeks of exercise compared to pre-exercise(P<0.05).Lean mass significantly decreased in the AE group(P=0.02)at week 4,whereas in-creased significantly in the RE and CE groups at week 8 compared to baseline and exercise(P<0.05).Left ventricular end-diastolic volume(P<0.01),stroke volume(P<0.01),and short-axis foreshortening rate(AE:P<0.01,RE:P=0.01,CE:P=0.047)increased significantly in all three groups after exercise compared to pre-exer-cise.Peak blood flow velocity(AE:P=0.04,CE:P<0.01)and blood flow shear(AE:P=0.01,CE:P<0.01)were significantly higher in the AE and CE groups than in the pre-exercise period,and only the increase in Wall shear stress was statistically significant in the RE group(P=0.02).The left and right brachial-ankle pulse wave conduction velocity(baPWV)of the AE group decreased significantly after 8 weeks of exercise(P<0.05).BaPWV of the RE group did not change significantly(P>0.05).The right baPWV of the CE group de-creased gradually with the increase of the duration of exercise,and the decrease appeared to be statistically significant in the 8 weeks(P=0.03).Conclusion:Eight weeks of aerobic,resistance and combined exercise all improved body composition,cardiac function and hemodynamic indices in young women with obesity.Aerobic and combined exercise not only re-duced body fat but also baPWV.Both combined and resistance exercise increased muscle mass,and resistance exercise had no effect on baPWV in young women with obesity.

Objective Based on statistical parametric mapping(SPM),to analyze the variability characteristics of lower limb in females with generalized joint hypermobility(GJH)during drop jump.Methods Fifteen females with GJH(GJH group)were recruited based on the Beighton scores,and 15 healthy females(control group)were matched.Kinematic and kinetic data were synchronously collected using the Qualisys infrared motion capture system and Kistler three-dimensional(3D)force platform.Joint angles and torques were computed using OpenSim.Custom Matlab scripts were used to calculate the standard deviation curves of joint angles,and SPM was applied to analyze differences in movement variability between the two groups during the eccentric,coupling,and concentric phases of drop jumps.The maximum joint flexion angles and torques(mean and standard deviation)were calculated to support the findings,and effect sizes were evaluated using Cohen's d.Results Significant differences were observed between the two groups during various phases of drop jumps.In all statistically significant periods,the GJH group exhibited higher joint angle standard deviations compared to the control group(P＜0.05).Differences were primarily concentrated in joint flexion movements.During the coupling phase at different heights,the standard deviation of knee joint flexion angles in GJH group consistently exceeded that of control group(P＜0.001).Discrete variables showed significant differences in the standard deviation of the maximum knee flexion angles at different heights:At 30 cm,P=0.001,Cohen's d=2.520;at 40 cm,P=0.014,Cohen's d=1.739;and at 50 cm,P=0.005,Cohen's d=1.768.No significant group differences were found in the mean values or standard deviations of the maximum joint flexion angles and torques.Conclusions Females with GJH exhibit higher movement variability during drop jumps compared to healthy females,particularly in knee flexion movements during the coupling phase.Excessive variability reflects insufficient motor control,reducing their ability to resist external disturbances and leading to high-risk movement patterns(e.g.,excessive flexion or knee valgus).

Objective To compare the effectiveness of the heart rate variability threshold(HRVT),muscle oxygenation threshold(MOT),and their combined threshold(COMT)in predicting the ventila-tory threshold(VT)and lactate threshold(LT).Methods Twenty male athletes at or above the nation-al level were recruited to perform an incremental exercise test to determine VT and LT,during which gas exchange,muscle oxygenation,and heart rate variability were collected.The HRVT,MOT,and COMT methods were then applied,and their predictive validity was evaluated by comparing the correla-tions and agreements between heart rate(HR)and power output(PO)at VT and LT.Results For HR,VT1 showed strong correlation and agreement with MOT1(r=0.958,ICC=0.944)and COMT1(r=0.957,ICC=0.951),with COMT1 having the smallest mean bias(1.4 bpm)and the narrowest limits of agreement(LOA)(-5.4 to 8.2 bpm).Moreover,VT2 demonstrated the highest correlation and agree-ment with COMT2(r=0.985,ICC=0.982),with a mean bias of-0.7 bpm and LOA of-5.0 to 3.7 bpm.Meanwhile,LT showed high correlation and good agreement with COMT2(r=0.884,ICC=0.754)and MOT2(r=0.886,ICC=0.738),with mean biases of-6.8 bpm and-7.3 bpm,and LOA of-17.5 to 3.8 bpm and-17.9 to 3.2 bpm,respectively.For PO,VT1 had the best correlation and agreement with MOT1(r=0.836,ICC=0.808),with a mean bias of-0.2 W and LOA of-11.7 to 11.3 W.VT2 performed best correlation and agreement with COMT2(r=0.910,ICC=0.900),with a mean bias of 2.3 W and LOA of-8.9 to 13.5 W.In LT prediction,MOT2(r=0.736,ICC=0.692)outperformed COMT2(r=0.635,ICC=0.618),with mean biases of-2.6 W and 0.2 W,and LOA of-26.0 to 20.7 W and-26.6 to 27.1 W,respectively.Conclusion All three indicators—HRVT,MOT,and COMT—demonstrates high validity in predicting VT and LT.MOT1 performs best for predicting PO at VT1,while COMT2 shows the highest consistency for predicting both HR and PO at VT2.Howev-er,for LT prediction,MOT2 is more advantageous for predicting PO,whereas COMT2 is more accu-rate for predicting HR.Therefore,method selection should be tailored to the specific threshold type and measurement target.

BACKGROUND:The hippocampus is crucial for cognitive function,and exercise holds promise for enhancing cognition and alleviating cognitive decline.However,the molecular mechanisms underlying these effects remain unclear.Bioinformatics,by analyzing the impact of exercise on molecular expression in the hippocampus,helps reveal key mechanisms,providing new insights into how exercise promotes cognition and informing the development of intervention strategies.OBJECTIVE:Using bioinformatics methods to conduct an in-depth analysis of the gene expression profiles of hippocampal tissue in mice subjected to voluntary exercise interventions and by examining the biological functions of differentially expressed genes and their potential regulatory networks to elucidate the molecular mechanisms by which exercise modulates neural function in the hippocampus.METHODS:Gene expression microarray datasets(GSE42904 and GSE29075)from the Gene Expression Omnibus(GEO)database were obtained for hippocampal tissue in mice subjected to voluntary exercise interventions.Strict differential gene analysis was performed using the Limma and DESeq2 packages in R,and the results were visually presented using volcano plots generated by the ggplot2 package.Common differentially expressed genes were identified using the FunRich software.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyses were conducted using the clusterProfiler package in R.Protein-protein interaction networks of differentially expressed genes were analyzed using the online tool STRING,and core targets were further screened using Cytoscape software.RESULTS AND CONCLUSION:In the GSE42904 dataset,voluntary exercise intervention led to the differential expression of 123 genes in the hippocampus of mice,primarily involved in rhythmic processes,glycosylation,and other GO biological processes.These genes were also associated with multiple KEGG pathways,including interleukin-17,calcium,and ethanol signaling.Key hub genes identified in the protein-protein interaction network included Npy,Mapk3,Mapk11,and Chgb.In the GSE29075 dataset,voluntary exercise resulted in the differential expression of 455 genes in the hippocampus,mainly involved in the positive regulation of cellular projection organization,negative regulation of apoptotic signaling,and other GO biological processes.These genes were significantly enriched in pathways related to neurodegenerative diseases.Key hub genes identified in the protein-protein interaction network included Eed,Bptf,and Nedd8.To conclude,voluntary exercise significantly regulates the expression of key genes such as Chrm1,Eed,Npy,Mapk3,Mapk11,and Map2k1 in the hippocampus of mice.These genes play a core regulatory role in biological processes such as neurodegenerative diseases and calcium signaling.Voluntary exercise may promote cognitive function by influencing neurogenesis and synaptic plasticity.

Objective To explore the effect of hypoxic exercise on Irisin secretion of obese rats with a palmitic acid-induced lipid accumulation in L6 myotubes and a high-fat diet-induced model.Methods L6 myotubes were treated with 750 μmol/L palmitic acid to induce lipid accumulation and subsequently divided into four groups of normoxia(N),exercise(E),hypoxia(H),and hypoxic exer-cise(HE).Hypoxic conditions(1%O2)were used to simulate a low-oxygen environment,while AICAR stimulation was applied to the E and HE groups to mimic exercise.Eighty 3-week-old Sprague-Dawley rats were fed a high-fat diet for 16 weeks to establish an obesity model.Fifty obese rats that met the criteria were then selected and randomly assigned according to their body weight into five groups of normoxia-sedentary(NC),normoxia-exercise(NE),hypoxia-sedentary(HC),high-liv-ing high-training(HH),and low-living high-training(LH),each of 10.The hypoxic environment was set at 13.6%O2(simulating 3,500 m altitude).Then the NE,HH and LH groups performed daily one-hour treadmill training(NE:20 m/min;HH and LH:16 m/min),5 days/week for 4 weeks.After the intervention,the body composition was measured using dual-energy X-ray absorptiometry(DEXA),while Irisin concentrations in cell culture media and rat serum were determined by using the enzyme-linked immunosorbent assay.Moreover,fibronectin type Ⅲ domain-containing 5(FNDC5)mRNA expression in L6 cells and rat skeletal muscle was measured by quantitative polymerase chain reaction(qPCR),while FNDC5 and silent information regulator 1-peroxisome proliferators-activated re-ceptor γ coactivator lalpha(SIRT1-PGC-1α)pathway proteins were analyzed using Western blotting.Results(1)Cell experiments:①Compared with the N group,there were significantly higher Irisin lev-els in the culture medium of the E,H,and HE groups(P<0.01,P<0.05),as well as elevated FNDC5 mRNA and protein expression in the E and HE groups(P<0.05,P<0.01).Moreover,the Iri-sin concentration and FNDC5 protein levels of group HE were significantly higher than group E(P<0.05).②Compared with group N,significantly increased SIRT1 and PGC-1α protein expression was observed in groups E and HE(P<0.05,P<0.01).(2)Animal experiments:①Compared with the NC group,body weight and fat mass were significantly lower in the NE,LH,and HH groups(P<0.01),with further reductions observed in the HH group compared with the NE group(P<0.05).② Com-pared with group NC,groups NE,LH,and HH exhibited higher serum Irisin levels and increased FNDC5 mRNA and protein expression in skeletal muscle(P<0.05,P<0.01).Furthermore,FNDC5 pro-tein expression of the HH group was significantly higher than the NE group(P<0.05).③ Compared with the NC group,SIRT1 and PGC-1α protein levels were significantly upregulated in the NE,LH,and HH groups(P<0.05,P<0.01).Conclusion Hypoxic exercise effectively alleviates obesity,reduces body weight and fat accumulation in high-fat diet-induced obese rats,and enhances FNDC5 expres-sion and Irisin secretion,which may be mediated through activation of the SIRT1-PGC-1α signaling pathway.Moreover,among the different hypoxic exercise modalities,the"high-living high-training"protocol appears to have greater benefits in promoting FNDC5/Irisin expression and facilitating weight and fat reduction in obese rats.

BACKGROUND:The stiffness of muscle fibers and tendons within skeletal muscles is regulated by the neuromuscular system and remains variable.However,observing the mechanical properties of muscle fibers and tendons during complex multi-joint movements is challenging,and the real-time variation patterns of their stiffness are not yet clear.OBJECTIVE:Taking the open-access simulation data of triceps surae at different running speeds and gait phases as an example,to explore the real-time stiffness change rules of muscle fiber stiffness and tendon stiffness.METHODS:OpenSim simulation results of muscle fiber activation,length,velocity parameters,and tendon length parameters of the triceps surae in five long-distance runners at different running speeds were collected from the Website of Stanford University.The instantaneous slope of the force-length relationship curve of muscle fibers and tendons in the Hill-Zajac muscle model used in the simulation was extracted as the real-time stiffness of the triceps surae muscle fibers and tendons.The temporal changes of stiffness indicators of muscle fibers and tendons during gait were analyzed.RESULTS AND CONCLUSION:The regulation of muscle fiber activation-length-velocity status and tendon strain resulted in the stiffness of muscle fibers and tendons changing in the same trend as the applied force.Compared with lower running speeds,the stiffness of the gastrocnemius muscle fibers was higher in the early support phase at higher running speeds(P ≤ 0.01),and the tendon stiffness of the medial head of the gastrocnemius was higher in the early support phase(P≤ 0.02).The stiffness of the gastrocnemius muscle fibers and tendons was lower from the mid-support to the mid-swing phase(P≤ 0.03),and the stiffness of the soleus muscle fibers was higher during the support phase(P ≤ 0.02).Under all running speeds,the stiffness of the triceps surae muscle fibers and tendons showed a trend of being higher during the support phase than during the pre-swing phase(P ≤ 0.03),and the stiffness of the gastrocnemius muscle fibers and tendons increased again in the late swing phase(P ≤ 0.05).These findings indicate that increasing running speed can increase the stiffness of triceps surae muscle fibers and tendons during the stance phase;when running speed and gait phase change,gastrocnemius and soleus muscles have different patterns of muscle fiber and tendon stiffness changes,whereas gastrocnemius can increase its muscle fiber stiffness and tendon stiffness in the late swing phase through pre-activation phenomenon.

Objective To investigate the dynamic features of patients with patellofemoral pain(PFP)during running by using support vector machine(SVM)classifier and feature selection method,so as to provide a theoretical support for the prevention and rehabilitation of PFP.Methods An SVM classification model was used to classify healthy individuals(n=13),PFP patients with long-term disease course(n=13),and PFP patients with short-term disease course(n=10)based on their dynamic features during running.The most effective minimum feature set was selected through feature selection method.Results The accuracy rate of the constructed classification model was 83.3%.The minimum feature set selected contained 3 key features.PFP patients with short-term disease course showed a delay in the appearance of impact valleys and active peaks,while PFP patients with long-term disease course showed a lower impact peak-valley slope.Conclusions PFP patients with short-term disease course mainly showed a prolonged shock absorption process and a delayed propulsion action,while PFP patients with long-term disease course showed the most significant feature of having a lower vertical reaction force impact peak-valley slope.These features revealed the specific characteristics of PFP at different stages of the disease,providing a basis for developing individualized rehabilitation programs.

Objective By applying the long short-term memory(LSTM)neural network model and using lower body landmark coordinates obtained from a markerless motion capture system as inputs,to estimate ground reaction force(GRF)curves during running.Methods The video images and GRF data of 59 amateur runners during running were collected by the markerless motion capture system and three-dimensional(3D)force plates.The LSTM model was established,and the 3D coordinates of 11 lower body landmarks,obtained via the Theia3D markerless system,were used as inputs to estimate the 3D GRF curves during the stance of running.The estimation performance was evaluated using correlation coefficients r,root mean square error(RMSE),and normalized root mean square error(nRMSE)by comparing LSTM model estimation and force plate measurement.Statistical parametric mapping was used to analyze differences in GRF curves estimated by the LSTM model and measured by the force plate,while paired t-tests were used to assess differences in GRF characteristics between model estimation and actual measurement.Results A strong correlation(r＞0.85,P＜0.001)and lower error(RMSE＜0.3 body weight,nRMSE＜15％)was found between the LSTM model estimation and actual measurements.No significant difference was found in GRF curve intervals between LSTM model estimation and actual measurements.There was no significant difference in GRF characteristics between LSTM model estimation and actual measurements(P＞0.05).Conclusions Based on the LSTM model,the 3D GRF curves can be effectively estimated by lower body landmark coordinates obtained from the makerless motion capture system,thereby acquiring the highly accurate GRF characteristics.The LSTM model developed in this study can be used to monitor injury risks during running in outdoor environments.