Objective To investigate the factors influencing international normalized ratio (INR)>3.0 in patients undergoing warfarin anticoagulation therapy after mechanical heart valve replacement. Methods A retrospective analysis was performed on the clinical data of patients who underwent mechanical heart valve replacement surgery and received warfarin anticoagulation therapy at West China Hospital of Sichuan University from January 1, 2011 to June 30, 2022. Based on the discharge INR values, patients were divided into two groups: an INR≤3.0 group and an INR>3.0 group. The factors associated with INR>3.0 at the time of discharge were analyzed. Results A total of 8901 patients were enrolled, including 3409 males and 5492 females, with a median age of 49.3 (43.5, 55.6) years. The gender, body mass index (BMI), New York Heart Association (NYHA) cardiac function grading, INR, glutamic oxaloacetic transaminase, and preoperative prothrombin time (PT) were statistically different between the two groups (P<0.05). Multivariate logistic regression analysis revealed that lower BMI, preoperative PT>15 s, and mitral valve replacement were independent risk factors for INR>3.0 at discharge (P<0.05). Conclusion BMI, preoperative PT, and surgical site are factors influencing INR>3.0 at discharge in patients undergoing warfarin anticoagulation therapy after mechanical heart valve replacement. Special attention should be given to patients with lower BMI, longer preoperative PT, and mitral valve replacement to avoid excessive anticoagulation therapy.

Objective To investigate the effects of different foot strike patterns during running on Achilles tendon(AT)morphology and mechanical loading.Methods Fourteen habitual rearfoot strike runners and 14 habitual forefoot strike runners were recruited.Morphological characteristics(tendon length,cross-sectional area,and thickness)of the AT were collected using ultrasound imaging.The AT loading characteristics(plantar flexion moment,tendon force,load rate,impulse,and stress)of subjects wearing cushioned running shoes while running at a speed of 10 km/h were collected and calculated using a three-dimensional force measurement treadmill.Results Compared to habitual rearfoot strike runners,habitual forefoot strike runners showed a significant increase in peak plantar flexion moment of ankle joint,AT peak force,average loading rate,and peak loading rate(P<0.05).However,the differences in AT length,cross-sectional area,and thickness between the two groups were not statistically significant(P>0.05).Conclusions Long-term forefoot strike patterns can adaptively enhance the mechanical loading characteristics of the AT during repetitive stretch-shortening cycles.

Objective To investigate the effects of high-definition transcranial direct current stimulation(HD-tDCS)on the modulation of the H-reflex and M-wave during ankle dorsiflexion-plantar flexion fatigue tasks to provide direction for the application of HD-tDCS in mitigating neuromuscular fatigue.Methods Twenty healthy young male participants were recruited and randomly assigned to either the real stimulation or sham stimulation group,with 10 participants in each group.The intervention consisted of a 5-day single-blind HD-tDCS application(duration:20 min;intensity:2 mA;target:Cz).Baseline measurements of the H-reflex and M-wave under resting conditions,M-wave during maximal voluntary isometric contraction(MVIC)of the dorsiflexor muscle,and MVIC torque of the dorsiflexor and plantar flexor muscles were obtained.An ankle dorsiflexion fatigue task was performed to determine the time to achieve fatigue for the task.The same fatigue task was repeated and evaluated one day after the intervention.A repeated-measures two-factor(stimulation condition x pre/post fatigue)analysis of variance(ANOVA)was used to analyze the effects of independent variables on the mechanical properties of the muscles and α-motoneuron conduction characteristics.Results After fatigue,voluntary activation(VA),maximal H-reflex(Hmax),maximal M-wave(Mmax),and dorsiflexor and plantar flexor MVIC torques in both groups were significantly reduced compared with pre-fatigue levels(P＜0.05).However,compared to the real stimulation group,the sham stimulation group showed a more significant decline in VA and plantar flexor MVIC torque(P＜0.05).Conclusions A continuous 5-day HD-tDCS intervention can effectively increase α-motoneuron activity at the spinal segment.It can also exert an inhibitory effect on reducing information transmission capacity at the peripheral neuromuscular junction under the ankle dorsi-plantarflexion fatigue task.

Humans ; Female ; Mastectomy, Segmental ; Margins of Excision ; Reoperation ; Breast Neoplasms/surgery* ; Retrospective Studies ; Carcinoma, Ductal, Breast/surgery* ; Neoplasm Recurrence, Local

Sports fatigue of the lower limbs is one of the important factors affecting sports performance. How to improve the anti-fatigue ability of the lower limbs during endurance exercise is the focus of the research field of human sports biomechanics. This study systematically reviewed the relevant literature on transcranial direct current stimulation (tDCS) intervention on lower limb endurance performance, summarized the effect of tDCS on lower limb endurance performance, and analyzed the influencing factors and potential mechanisms. The results showed that: tDCS intervention has a significant effect on the endurance performance of the whole lower limbs, but there is no unified conclusion on the effect on the endurance performance of the knee joint. The researchers deem that tDCS can increase the excitability of the primary motor cortex and reduce the activation of the supplementary motor area and the premotor area to producing a lower rating of perceived exertion, but cannot affect the perception of exercise-induced pain, and stimulation protocols varied across studies, which may be partly responsible. This study can provide a theoretical basis for exploring the central mechanism of tDCS to improve endurance performance, formulating rehabilitation and sports training programsfor different groups of people, and developing new stimulation equipment to enhance the human body’s anti fatigue ability.

Objective To explore the correlation between foot morphology and toe/metatarsophalangeal joint muscle strength. Methods Twenty-six male recreational runners were recruited. Foot length, truncated foot length, foot width, navicular height, dorsum height at 50% of the foot length, metatarsophalangeal joint strength, tensile force of the first and remaining four toes were measured by using digital caliper, metatarsophalangeal joint strength tester and dynameter, respectively. Partial correlations were used to analyze the correlation between foot morphology and foot muscle strength. ResultsWith adjusted age and body mass index (BMI), the foot width in standing position and truncated foot length in sitting and standing position were positively correlated to tensile force of the first toe; the foot length, foot width and truncated foot length were positively correlated to tensile force of the remaining four toes in both positions, and the arch height index in sitting position was negatively associated with tensile force of the remaining four toes; the foot width was positively correlated to metatarsophalangeal joint strength in both positions. Conclusions The longer foot length, foot width, truncated foot length, and the lower arch height in normal range might be related to the larger foot muscle strength. The consideration of the differences in foot morphological characteristics in different positions during the measurement of foot morphology can provide references for predicting foot muscle strength and preventing foot injury.

Objective To investigate the mechanical properties of Achilles tendon (AT) during running under different shoe conditions (minimalist vs conventional shoes). MethodsSixteen healthy male runners with habitual rearfoot strike patterns were recruited to complete the running trials at the speed of 3.16~3.50 m/s under two shoe conditions. The cross-sectional area of the AT was obtained by ultrasound imaging. Sagittal plane ankle kinematics and ground reaction forces were recorded by motion capture system and three-dimensional force platform simultaneously. Mechanical properties of the ankle and AT were calculated. Paired t test was used to compare the effects of two shoe conditions on various parameters (ankle angle, strike angle, AT force, stress, strain, etc). ResultsCompared with conventional shoes, foot inclination angle was significantly reduced by 39.9% with minimalist shoes. Obvious increase in ankle moment, peak AT force, peak AT loading rate, average loading rate, and obvious decrease in time to peak AT force were observed with minimalist shoes. Peak AT stress, peak AT strain and corresponding stress rate, peak strain rate also increased significantly with minimalist shoes. ConclusionsGreater AT loading was observed when runners with habitual rearfoot strike pattern in conventional shoes begin to wear minimalist shoes. Therefore, a gradual transition to minimalist shoes was recommended for them so as to improve the ability to load adaptively.

The technical deficiencies in traditional medical imagining methods limit the study of
Ankle ; Ankle Joint ; Biomechanical Phenomena ; Range of Motion, Articular ; Technology

The research progress in fatigue protocols and biomechanics of lower extremity and its relationship with injury induced by exercise-induced fatigue was reviewed in this paper. At present, fatigue protocols can be divided into the traditional fatigue-induced protocol and the functional fatigue-induced protocol under laboratory condition. The former mainly includes power-cycling model, treadmill run model and step-ups model, while the latter is closer to what is experienced during competition, which is usually shown as multidirectional movements. In addition, the biomechanical measures of exercise-induced fatigue mainly include kinematics, ground reaction force, joint mechanics and electromyography. Different fatigue protocols do not uniformly produce alterations in lower limb biomechanical factors. The refinement of fatigue protocols and specific indicators should be considered in future studies, in order to compare the induced effects of fatigue protocols and provide references for the selection of fatigue protocols in laboratory tests. Meanwhile, the relationship between the response of brain-nerve system and the activation of musculoskeletal system for specific athletic task should be focused, so as to understand the difference of biomechanical mechanisms between fatigue protocols and further explore the effect of exercise-induced fatigue on sports injuries.

In recent years, the effects of the neuro-biomechanical ergogenic technology on improving and enhancing human function and physical movement performance have widely attracted certain attentions. This review summarized the recent achievements in the effects of non-invasive brain stimulation (NIBS) and biomechanical ergogenic technology based on sports equipment on human physical performance, and further explored the possible mechanisms for improving and promoting human physical performance. The obtained preliminary evidence based on animal experiments and biomechanical researches on neuromotor control under multi-joint movement were also summarized, so as to explain the coordinated development of human function enhancement at cerebral cortex regulation and neuromuscular coordinated control levels, and interpret its integration with sports equipment. This review ultimately provided certain references for the future frontier development and research position of neuro-biomechanics and human sports biomechanics.