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 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 determine the effect of knee extension constraint training on bilateral knee biomechanics and bilateral symmetry in running after anterior cruciate ligament reconstruction(ACLR).Methods A total of 33 male patients with unilateral ACL injuries were randomly assigned to a BRACE group of 14 wearing a brace with limitation of knee extension,a PLACEBO group of 10 wear-ing a brace without limitation of knee extension,and a CONTROL group of 9,wearing no brace.All groups underwent unilateral hamstring-auto graft ACLR surgery,immediately followed by 12-week rou-tine rehabilitation.Between week 13 and 48,both the BRACE and PLACEBO groups wore braces for one hour on Mondays.Then,running biomechanical tests were performed at the ends of Week 12 and Week 48,and the bilateral knee extension/flexion angle,moment and inter-leg difference(ILD)were calculated.One-dimensional statistical parametric mapping(SPM1d)two-way ANOVA with repeated measures on one factor was used to identify differences in bilateral knee biomechanics and ILD among the three groups before and after the intervention.Results There was no significant interaction effect of group and time on bilateral knee flexion angle,knee extension moment,and ILD in running(P>0.05).Moreover,no significant effect of group was found on the bilateral knee biomechanics and ILD in running(P>0.05).Additionally,significant effects of time were observed on bilateral knee flexion angle and extension moment in running.However,bilateral knee flexion angle decreased during termi-nal stance(ACLR leg:89%～100%,P=0.036;non-ACLR leg:94%～100%,P=0.046),while the bi-lateral knee extension moment increased during mid-stance(ACLR leg:17%～59%,P<0.001;non-ACLR leg:38%～61%,P<0.001)between week 12 and 48.Conclusion In this study,no improvement was found in the abnormal knee biomechanics and symmetry during running in male patients after uni-lateral ACL reconstruction through long-term knee extension constraint training.Moreover,within one year after ACL reconstruction,the knee extension moment of the surgical limb increased gradually over time,with no changes in the knee flexion angle of the surgical limb and bilateral knee symme-try,suggesting that abnormal knee biomechanics and bilateral symmetry should be paid attention to in the post-surgery rehabilitation.

Objective:To explore the advantages of internet-based smart healthcare for full-cycle transcatheter edge-to-edge repair (TEER) management in reducing postoperative adverse events rate, improving cardiac function, and enhancing quality of life.Methods:This retrospective study enrolled patients with mitral regurgitation who underwent transcatheter TEER at Beijing Anzhen Hospital Valve Intervention Center between June 2021 and September 2023. Patients were classified into degeneration mitral regurgitation (DMR) and functional mitral regurgitation (FMR) according to etiology, with further stratification by enrollment period into usual care group (June 2021 to October 2022) and full-cycle management group (November 2022 to September 2023). The 1-year postoperative follow-up data were collected and compared between subgroups with the same etiology. Kaplan-Meier survival curves were plotted, and log-rank tests were used to compare the differences in major endpoint event-free survival rates between the two groups. Univariate and multivariate Cox regression and logistic regression analyses were performed to evaluate the impact of the full-cycle management system on patients′ outcomes.Results:A total of 130 patients were included, aged (72.0±8.6) years, including 82 (63%) males. DMR was identified in 84 cases (40 in the usual care group and 44 in the full-cycle management group), while FMR was observed in 46 cases (27 in the usual care group and 19 in the full-cycle management group). Kaplan-Meier analysis demonstrated higher 1-year major endpoint event-free survival rates in the full-cycle management group compared to the usual care group, though the difference was not statistically significant (log-rank P>0.05). Compared to the usual care group, the full-cycle management group showed significantly higher proportions of New York Heart Association classification Ⅰ-Ⅱ patients (DMR: 67% vs. 52%, P=0.031; FMR: 68% vs. 52%, P=0.021), greater 6-minute walking distances (DMR: (346.39±70.41) m vs. (294.11±60.47) m, P=0.012; FMR: (356.60±54.68) m vs. (318.55±39.02) m, P=0.004), and superior Kansas City Cardiomyopathy Questionnaire scores (DMR: 81.50 (74.50, 85.00) points vs. 71.00 (66.00, 82.25) points, P=0.014; FMR: 83.00 (76.00, 85.00) points vs. 74.00 (70.75, 80.00) points, P=0.030). Multivariate logistic regression confirmed the full-cycle management system as an independent predictor for the above improved outcomes (all P<0.05). Conclusion:Smart healthcare-based full-cycle management improves cardiac function and quality of life in mitral regurgitation patients after TEER, demonstrating lower rates of major endpoint events compared to usual care.

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.

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.