Joint Position Research Articles

The influence of different intensity of Tan Tui exercises on the posture control of students in the Tai Chi Elective Course: protocol for a randomized controlled trial

BackgroundTai Chi (TC) holds a unique and valued place in promoting the physical and mental health of college students. Its significance is underscored by its incorporation as a compulsory physical education course in every university in China. TC, with its rich tradition, places a strong emphasis on posture control as a core sports ability. However, the students in Tai Chi Elective Course (TCEC) have very poor posture control ability. This study protocol investigates the potential of Tan Tui (TT) to address these issues, as TT is a fundamental skill for beginners of traditional Chinese martial arts and has a track record of enhancing lower limb strength and balance, making it a promising choice for improving posture control in TCEC.Methods/designTo investigate the impact of different intensities of TT exercises on posture control in TCEC students, we have designed a randomized, double-blind, parallel-controlled trial. Seventy-six students in the TCEC will be randomly divided into low-intensity Tan Tui (LTT), medium-intensity Tan Tui (MTT), and high-intensity Tan Tui exercises group (HTT) and control group (CON), each with 19 people. The LTT group, MTT group, and HTT group will be given different intensity of TT exercises, and the CON group will be given regular TCEC. The intervention period will be 6 weeks (2 times a week, 20 min each time). At baseline (before), 4 weeks of intervention (middle), and 6 weeks of intervention (after), the Unipedal Stance Test (UST), the Star Excursion Balance Test (SEBT), 60°/s angular velocity knee joint flexion and extension relative peak torque (RPT), and knee joint position perception (KJPP) will be evaluated.DiscussionThis is the first randomized controlled trial protocol from the perspective of training intensity to evaluate the effect of different intensity of TT exercises on posture control of students in TCEC. Should our research reveal a significant intervention effect, the results will offer preliminary, higher-quality evidence supporting the positive impact of varying intensities of Tan Tui exercises on posture control in TCEC students.Trial registrationChinese Clinical Trial Registry ChiCTR2000039109. Registered on October 17, 2020.

Cervical Sensorimotor Function Tests Using a VR Headset-An Evaluation of Concurrent Validity.

Sensorimotor disturbances such as disturbed cervical joint position sense (JPS) and reduced reaction time and velocity in fast cervical movements have been demonstrated in people with neck pain. While these sensorimotor functions have been assessed mainly in movement science laboratories, new sensor technology enables objective assessments in the clinic. The aim was to investigate concurrent validity of a VR-based JPS test and a new cervical reaction acuity (CRA) test. Twenty participants, thirteen asymptomatic and seven with neck pain, participated in this cross-sectional study. The JPS test, including outcome measures of absolute error (AE), constant error (CE), and variable error (VE), and the CRA test, including outcome measures of reaction time and maximum velocity, were performed using a VR headset and compared to a gold standard optical motion capture system. The mean bias (assessed with the Bland-Altman method) between VR and the gold standard system ranged from 0.0° to 2.4° for the JPS test variables. For the CRA test, reaction times demonstrated a mean bias of -19.9 milliseconds (ms), and maximum velocity a mean bias of -6.5 degrees per seconds (°/s). The intraclass correlation coefficients (ICCs) between VR and gold standard were good to excellent (ICC 0.835-0.998) for the JPS test, and excellent (ICC 0.931-0.954) for reaction time and maximum velocity for the CRA test. The results show acceptable concurrent validity for the VR technology for assessment of JPS and CRA. A slightly larger bias was observed in JPS left rotation which should be considered in future research.

Correlations of temporomandibular joint morphology and position using cone-beam computed tomography and dynamic functional analysis in orthodontic patients: A cross-sectional study.

To correlate temporomandibular joint (TMJ) morphology and position with cone-beam computed tomography (CBCT) images, Joint Vibration Analysis (JVA), and Jaw Tracker (JT) to develop a radiation-free, dynamic method for screening and monitoring the TMJ in orthodontic patients. A total of 236 orthodontic patients without symptoms of TMJ disorders who had undergone CBCT were selected for the JVA and JT tests in this cross-sectional study. TMJ position and morphology were measured using a three-dimensional analysis software. JT measurements involved six opening-closing cycles, and JVA measurements were performed using a metronome to guide the mouth opening-closing movements of the patients. The correlations among the three measuring devices were evaluated. Abnormalities in condylar surface morphology affected the mandibular range of motion. The cut-off value results show that when various measurement groups are within a certain range, abnormalities may be observed in morphology (area under the curve, 0.81; P < 0.001). A 300/< 300 Hz ratio ≥ 0.09 suggested abnormal morphology (P < 0.05). Correlations were observed among the maximum opening velocity, maximum vertical opening position, and joint spaces in the JT measurements. Correlations were also observed between the > 300/< 300 Hz ratio, median frequency, total integral, integral < 300 Hz, and peak frequency with joint spaces in the JVA measurements. JT and JVA may serve as rapid, non-invasive, and radiation-free dynamic diagnostic tools for monitoring and screening TMJ abnormalities before and during orthodontic treatment.

Longitudinal assessment of knee joint proprioception using weight-bearing and non-weight-bearing tests throughout rehabilitation after anterior cruciate ligament reconstruction

ObjectiveEvaluate active knee joint position sense (JPS) throughout rehabilitation after anterior cruciate ligament reconstruction (ACLR). DesignLongitudinal. SettingMotion laboratory. ParticipantsTwenty-two individuals post-ACLR and 22 activity-matched non-injured controls performed weight-bearing and non-weight-bearing knee JPS tests. The ACLR participants performed at three functional timepoints: T1, able to perform single-leg sit-to-stand; T2, able to hop maximally; T3, cleared for return to sports. Controls performed on one occasion. Main outcome measuresConstant, absolute, variable errors (CE, AE, VE) and interlimb symmetry estimates (100% signifying perfect symmetry), for 40° and 65° knee flexion target angles. ResultsFor the weight-bearing 40° condition, CE and AE of the ACLR knee significantly increased from T1 to T2 (P = 0.010) and T1 to T3 (P = 0.002). Consequently, interlimb asymmetry for AE significantly increased from T1 (AEsym% = 101.2% ± 55.4%) to T3 (AEsym% = 139.7% ± 54.8%). Compared to controls, AE for the ACLR knee was significantly smaller at T1 (P = 0.016). No other significant differences were observed. ConclusionsSmaller JPS errors at early rehabilitation while weight-bearing may have been due to heightened quadriceps activation and increased γ motor neuron sensitivity, compensating for deficient ACL mechanoreceptors. In contrast, non-weight-bearing testing did not reveal changes over time. Clinicians are advised to consider these distinctions when assessing proprioception at different rehabilitation stages.

Comparative Impact of Core Stabilization vs Proprioceptive Neuromuscular Facilitation Exercises on Muscle Activation, Endurance, and Balance in Obese Children: A Randomized Controlled Trial.

BACKGROUND The purpose of the study was to compare the effects of core stabilization exercise (CSE) and proprioceptive neuromuscular facilitation (PNF) exercise on core muscle activation, core muscle endurance, proprioception, and balance in 80 obese children. MATERIAL AND METHODS In this single-blind, randomized controlled study, 80 obese children aged 10-13 years were randomly divided into 3 groups. The first group received CSE (n=27) and the second group received PNF exercises (n=27) 3 days a week for 8 weeks. The third group, which was the control group (n=26), received no treatment. Participants were evaluated before treatment (BT) and after treatment (AT) and at follow-up (3 months after treatment). Core muscle activation level was evaluated by Sahrmann Core Stability test (SCST), lumbar core muscle endurance was evaluated by McGill core endurance tests, and lumbar joint position sense (JPS) was evaluated by laser cursor. The single-leg standing balance test (SLSBT) and Y balance test (YBT) were used for static and dynamic balance, respectively. RESULTS AT and at follow-up, core activation, core endurance, JPS, and static balance were significantly different between the groups (P<0.05). There was no significant difference between the groups in YBT dominant and non-dominant side mixed reach distances (P>0.05). Clinical effect sizes were higher in the CSE group for all outcome measures. CONCLUSIONS CSE and PNF exercises improve the level of core muscle activation, lumbar core muscle endurance, lumbar JPS, and balance in obese children. However, the results of this study show that CSE are more clinically effective in obese children. The effects decline in the medium term.

Unity and ROS as a Digital and Communication Layer for Digital Twin Application: Case Study of Robotic Arm in a Smart Manufacturing Cell.

A digital twin (DT) is a virtual/digital model of any physical object (physical twin), interconnected through data exchange. In the context of Industry 4.0, DTs are integral to intelligent automation driving innovation at scale by providing significant improvements in precision, flexibility, and real-time responsiveness. A critical challenge in developing DTs is achieving a model that reflects real-time conditions with precision and flexibility. This paper focuses on evaluating latency and accuracy, key metrics for assessing the efficacy of a DT, which often hinder scalability and adaptability in robotic applications. This article presents a comprehensive framework for developing DTs using Unity and Robot Operating System (ROS) as the main layers of digitalization and communication. The MoveIt package was used for motion planning and execution for the robotic arm, showcasing the framework's versatility independent of proprietary constraints. Leveraging the versatility and open-source nature of these tools, the framework ensures interoperability, adaptability, and scalability, crucial for modern smart manufacturing applications. Our approach was validated by conducting extensive accuracy and latency tests. We measured latency by timestamping messages exchanged between the physical and digital twin, achieving a latency of 77.67 ms. Accuracy was assessed by comparing the joint positions of the DT and the physical robotic arm over multiple cycles, resulting in an accuracy rate of 99.99%. The results highlight the potential of DTs in enhancing operational efficiency and decision-making in manufacturing environments.

Analysis of Polynomial Interpolation Characteristics Based on 6DOF Manipulator Trajectory Planning

Aiming at the problems of choosing and using polynomials of different times and mixed polynomials in the process of manipulator trajectory planning, such as difficulty, wide range of light and low accuracy, in this paper, the application of different polynomials in manipulator trajectory planning is systematically analyzed by using MATLAB Robot Toolbox simulation platform and Polynomial interpolation algorithm. Using a 6-dof robotic arm Puma560 as a simulation object, the effects of three-, five-, and seven-Polynomial interpolation on joint position and pose in joint space trajectory planning were analyzed, a preliminary understanding of the application of different polynomials, and secondly, the more complex application of the fifth and seventh degree polynomials in Descartes space for the trajectory planning of the manipulator, the influence of trajectory planning with different degree polynomials on the position and pose of manipulator joint is clarified. The results show that the higher the number of polynomials, the smoother the transition of the joint at the critical path points, but the greater the maximum angular velocity and angular acceleration of the joint, the Polynomial interpolation of joint space and Descartes space trajectory planning are 14% and 23% lower than the average of absolute maximum angular velocity and absolute maximum angular acceleration of the Polynomial interpolation, respectively. Based on the analysis of the research results, this paper presents the applicable conditions and applications of Polynomial interpolation method in trajectory planning, and further summarizes the application conditions and methods of mixed polynomials.

Influence of texting while walking on lower extremity gait function in young adults

Texting while walking (TWW) is a dual-task activity that young adults perform in their everyday lives. TWW has been reported to affect gait characteristics such as gait speed, stride length, and cadence. However, the influence of TWW on lower extremity gait function has not been investigated. Therefore, the purpose of this study was to quantify gait function by examining gait symmetry and using a time series analysis. Twenty-eight young adults (14 males, 14 females) walked at their preferred speed for 10 m as a baseline condition and a 10 m TWW task. Three-dimensional segment tracking was achieved utilizing a lower extremity and trunk marker set and the Model Statistic was used to test for statistical differences between the hip, knee, and ankle angular joint positions. The hip yielded the most asymmetries (25 out of 101 points) throughout the gait cycle, while asymmetries for the knee and ankle joints yielded 16 out of 101 points and 11 out of 101 points, respectively. The outcomes of this study suggest there are differences between baseline and TWW gait symmetry, however, the percentage of the gait cycle affected was less than 25 % - indicating gait function is not strongly influenced by texting while walking in young adults.

THE EFFECT OF TRUNK STABILITY TRAINING ON UPPER EXTREMITY ENDURANCE, STABILITY AND SHOULDER JOINT PROPRIOCEPTION IN POSTMENOPAUSAL WOMEN

Purpose: The incidence of shoulder pathologies is increasing in postmenopausal women. In this period, there is a need for protective approaches to be applied to prevent shoulder injuries. The aim of this study is to investigate the effects of clinical pilates exercises on upper extremity stability, endurance, function and shoulder joint proprioception in postmenopausal women. Methods: 30 postmenopausal women between the ages of 40-60 were included in our study. Participants were given clinical pilates training for 6 weeks, 3 days a week, 60 minutes by a physiotherapist. Before and after pilates training, dynamic stability of the shoulder was evaluated with Closed Kinetic Chain Upper Extremity Stability Test (CKCUES Test) and Upper Quarter Y Balance Test (UQYBT). Upper extremity muscle endurance was evaluated with the modified push up test. Laser Pointer-Assisted Angle Reproduction Test (LP-ART) was used to evaluate shoulder joint position sense. Results: A statistically significant difference was found in CKCUES Test (p=0.000, r=0.594), UQYBT (p=0.000, r=0.537), modified push up (p=0.000, r=0.594), LP-ART abduction (p=0.000, r= 0.491) and LP-ART flexion (p=0.000, r=0.484) at end of the training compared to the pre-training. The exercise program was found to be highly effective on all parameters. Conclusion: It was concluded that clinical pilates training applied in postmenopausal women increased the dynamic stability of the shoulder, endurance and position sense. Trunk stabilization exercises may be beneficial as a preventive approach in the prevention of shoulder pathologies in postmenopausal women.

Study on Stress Characteristics Response of Submarine Shield Segment Under Ultra-high Water Pressure

In the construction and operation stage of shield tunnel, mastering and clarifying the mechanical characteristics of the overall structure is essential for ensuring shield tunnel safety. In this paper, the shell-spring model is established by ABAQUS finite element software for the ultra-high water pressure submarine shield tunnel. The mechanical behavior of shield segment structure under varying water pressure, different key block position and different strata is studied and analyzed. The results show that at the same segment assembly position, the axial force of the segment increases greatly with the increase of water pressure, and the growth rate is as high as 150 %. The internal force of the segment is mainly axial force. Under the ultra-high water pressure, the corresponding position of the maximum deformation of the segment is related to the position of the segment joint at the arch bottom. In the staggered assembly, the axial force fluctuation near the arch bottom is larger than that of the straight assembly, and the peak bending moment and the maximum axial force are near the invert. In addition, near the 120 degree of the vault, the bending moment oscillates obviously near the joint in the stratum with small coefficient of soil reaction. The larger the coefficient of soil reaction is, the more uniform the axial force of the whole segment is. The research results provide a theoretical insights for the optimization design of shield tunnel segments.

Effect of the Material Properties and Knee Position to the Bone Bruise Pattern in Skeletally Mature and Immature Subjects.

A bone bruise is generated by a bony collision that could occur when the ACL is injured, and its pattern supposedly depends on the injury mechanism and level of skeletal maturity. The objective of this study was to determine the effect of material properties and knee position on the bone bruise pattern in skeletally mature and immature subjects using finite element analysis. Finite element models were created from an MR image in the sagittal plane of a skeletally mature and immature male subject. The femur and tibia were collided at 2 m/s to simulate the impact and determine the maximum principal stress. The analysis was performed at 15, 30 and 45 degrees of knee flexion, and neutral, 10 mm anterior and posterior translated position at each flexion angle. Although high stress was distributed toward the metaphysis area in the mature model, the stress did not cross the growth plate in the immature model. The size of the stress area was larger in the mature model than those in the immature model. The location of the stress area was dependent on the joint position as well as Young's modulus of cartilage and trabecular bone. Thus, the bone bruise pattern was affected by the knee position and tissue quality. In conclusion, although the bone bruise distribution was generally called footprint of the injury, the combined evaluation of the quality of the structure and the bone bruise distribution is necessary for properly diagnosing tissue injury based on the MR imaging.

Human movement monitoring system for classification of strength exercises and verification of their execution technique

Human movement analysis is critical to optimizing sports training and influencing exercise intensity and effectiveness. In the age of modern technology, more and more advanced systems are emerging to support coaches and expand the range of analysis performed. This article aims to verify that artificial intelligence, together with machine learning algorithms, can accurately classify exercises in a dynamic gym environment and effectively assess the correctness of their performance. For the initial analysis of movement, the Google MediaPipe Pose model was used, which was responsible for detecting the human silhouette and determining the coordinates of the position of critical joints. Based on these coordinates, the angles between each joint were calculated, and then their sequences were further analyzed. The sequences were analyzed using the following three algorithms: support vector machine (SVM), dense neural network, and LSTM recurrent network. As a result, the system based on recurrent LSTM networks achieved the best prediction efficiency of approximately 98%, enabling accurate exercise classification. Subsequently, verification of the activities' correctness was also carried out, and the system, based on recursive LSTM networks, again achieved the best efficiency, this time equal to 96% on average for all exercises. On this basis, it was concluded that the discussed approach enables practical analysis of human movement, which can significantly improve training methods and facilitate coaching work.

Wushu Movement Recognition System Based on DTW Attitude Matching Algorithm

Motion recognition technology is widely used in intelligent video surveillance, human-computer interaction and other fields. With the development of computer vision technology, improving the accuracy and efficiency of motion recognition has become the focus of research. The purpose of this study is to improve the performance of Wushu movement recognition through improved dynamic time warping algorithm and hierarchical model. Firstly, a high-dimensional feature vector is constructed by using the position, velocity and Angle changes of human bone joints. The actions are subdivided by the hierarchical model, and matched and recognized by the max-minimum dynamic time regularization model. Meanwhile, the K-class mean algorithm is combined to optimize the type of tree core, improve the performance of the model, reduce the interference of noise nodes, and effectively classify Wushu actions. Experimental verification was carried out on four public data sets of KTH, Olympic Sports, Hollywood2 and HMDB51. The experimental results showed that the recognition rate of the proposed model in KTH data set was 95.2%, and that in Olympic Sports data set was 91.4%. The Hollywood2 dataset was 66.7%, and the HMDB51 dataset was 61.2%. Comparing the results of different algorithms, the proposed method improved the recognition performance by 10% compared with long short-term memory network and gated cycle unit. Compared with one-dimensional convolutional neural network, the time of the proposed method was 15s longer, but the recognition rate was 1.6% higher. The results showed that the proposed method had significant performance advantages in diverse and complex action recognition tasks. Meanwhile, the results emphasized the factors to be considered in the design of the model, demonstrating its effectiveness in the application of Wushu movement recognition.

Assessing the contribution of different upper limb degrees of freedom to an unconstrained shoulder proprioception task

For the purpose of testing shoulder joint proprioception while controlling for axioscapular muscle recruitment, a novel shoulder thoracohumeral (TH) rotation joint position sense (JPS) measurement device was designed. This device was intended to measure shoulder TH rotation, while also implicitly constraining other upper limb degrees of freedom (DOF) and minimizing cutaneous sensation. The purpose of this study was to determine whether joint motion aside from shoulder TH rotation is being captured by the shoulder JPS measurement device. Upper limb kinematics were collected from 32 participants during joint angle matching trials using the shoulder JPS measurement device. Step wise multiple regression revealed that shoulder TH rotation (β-Humeral Rotation = 0.409, p < 0.001), and wrist deviation (β-Wrist Deviation = 0.104, p = 0.008) both contributed a significant unique variance in the prediction of shoulder JPS measurement device rotation. Findings suggest that seated, unconstrained shoulder TH rotation JPS testing protocols in literature may be confounded by contributions from joints both proximal and distal to the shoulder. Researchers should be aware of the limitations of both constrained and unconstrained shoulder TH rotation JPS testing protocols.

EFFECTS OF BALANCE TRAINING WITH STROBOSCOPIC GLASSES ON JOINT POSITION SENSE, POSTURAL STABILITY, AND FUNCTIONAL PERFORMANCE TESTING IN CHRONIC ANKLE INSTABILITY NATIONAL ATHLETES: A SINGLE-BLINDED RANDOMIZED CONTROLLED TRIAL

Chronic Ankle Instability (CAI) significantly affects athletic performance and increases the risk of recurrent ankle sprains. Stroboscopic Glasses (SG) may enhance proprioceptive feedback and postural control. We aimed to evaluate the augmented effects of Proprioceptive Feedback Training (PFT) combined with SG in athletes with CAI. We conducted a single-blinded randomized controlled trial with participants assigned to the PFT+SG or PFT alone groups. The interventions were administered over an eight-week period. Improvements in the Foot and Ankle Ability Measure Sport subscale (FAAM-S), Identification of Functional Ankle Instability (IdFAI) Questionnaire, Joint Position Sense (JPS) error value, postural stability via the Balance Velocity Test (BVT), Functional Performance Tests (FPTs), and giving-way episodes were assessed pre- and post-intervention. Substantial improvements in FAAM-S and IdFAI scores were observed in the PFT+SG group compared to those in the PFT group. JPS and BVT were significantly higher in the PFT+SG group than in the PFT group. FPTs and giving-way episodes were significantly higher in the PFT+SG group than in the PFT group. The inclusion of SG in PFT significantly enhanced rehabilitation outcomes in athletes with CAI. SG combined with PFT may address proprioceptive deficits and improve functional performance in patients with CAI.

Joints mechanical characteristics of prefabricated subway station considering bending stiffness difference

In prefabricated subway stations, the presence of joints leads to an uneven circumferential distribution of structural stiffness. However, there has been limited research focusing on the variability in bending stiffness of joints so far. Therefore, this paper proposes a theoretical framework to study deformation characteristics considering the differences in bending stiffness. This study aim to analyze the deformation characteristics of prefabricated structures, with a specific focus on the impact of variations in bending stiffness on the overall structural behavior. The research scope includes the calculation methods for the bending stiffness of joints, predicting maximum settlement of the top plate, and analyzing the influence of key parameters such as joint positions, geometric shapes, and dimensions, overburden density γ, lateral earth pressure coefficient λ, overburden thickness hf, and concrete density ρ on the joint bending stiffness. Results validate the reliability of the proposed method for calculating joint bending stiffness and demonstrate the key factors contributing to differences in bending stiffness.

Effect of Foot Posture on Limits of Stability in Children With Spastic Diplegic Cerebral Palsy.

Cerebral palsy (CP) is a neurological condition that affects musculoskeletal system causing altered balance control, which is governed by constant adjustments by muscular activity and joint positioning. Since the foot is the platform upon which we stand and balance, it is important to study and characterize foot posture abnormalities in CP to better understand their possible effect on multidirectional limits of stability (MDLS) in standing. Our aim was to find relation between foot posture and MDLS in diplegic children. Thirty diplegics (13 pes-planus and 17 pes-cavus) between the age of 6 to 14, gross motor function classification system (GMFCS) levels I and II, whose parents consented were included in this study. Diplegics unable to stand unsupported for < 2 minutes, undergone lower-limb surgeries in 6 months, having visual impairments were excluded. Foot posture was assessed with arch index, MDLS were measured by GEAMASTER stabilometer. There was significant positive correlation between foot posture and limits of stability. Diplegic children having pes-planus have better MDLS as compared with pes-cavus.

EFFECT OF TIME ELAPSED BETWEEN SUCCESSIVE CONCRETE POURINGS AND LOCATION OF THE COLD JOINTS ON THE FLEXURAL CAPACITY OF RC BEAMS

This research investigates the effect of the time interval between successive concrete pouring and the position of cold joints on properties and bending strength capacity in reinforced beams. Two horizontal cold joints were examined: another positioned in the zone of compressions (h=110 mm) and one situated in the beam's tension area ( h = 50mm). In both cold joint elevations, the time interval between two mert patches was varied as 1.5 hrs.,3 hr and 4 hrs. Furthermore, six nominally standardized RC beams were tested and analyzed with a reference beam devoid of cold joints. The obtained outcomes revealed the decrease of beams' ultimate flexural capacity with an increase in time elapsed between periods of pouring from 1.5 to 4.5 hours. The reduction in flexural strength was more evident when a cold joint went through the compression fibre of a beam. Additionally, the hardness and rigidity of the tested beams roughly inversely correlated with time intervals between consecutive pourings. More specifically, the percentage reduction in ultimate load, stiffness and toughness of cold joints for tension fibres at 1.5 hours was (4.36% ,9.7% and 9.3%) while that of compression fibre was (5.36%),(34.2%)and ( 34.5% ) % respectively when compared with control beam.

Manual Inter-Structural Release Procedure Can Alter Muscle Shear Modulus.

Inter-structural release (ISR) procedure to skeletal muscles is believed to attenuate adhesion between neighboring muscles and alleviate subjective symptoms, including perceived stiffness and associated pain. However, objective evidence about the effect of ISR on the mechanical properties of the muscles is limited. The purpose of this study was to test the acute effect of ISR on the shear modulus of adjacent muscles. It was hypothesized that ISR applied to the border between synergistic muscles would acutely reduce the resting shear modulus of the involved muscle. To assess the effect of ISR, the shear modulus of the resting peroneus longus (PL) and soleus (SOL) muscles was measured at various ankle joint positions (inversion/eversion) before and after interventions in nine non-symptomatic male individuals (age: 21.9 ± 1.4 years, height: 170 ± 6.6 cm, body mass: 64.3 ± 4.0 kg). Potential muscle activity during the measurement was assessed by recording surface electromyogram from these muscles. The interventions were ISR to the lower leg between the deep fascia of the PL and SOL and sham (massage). As the ankle joint position was passively varied toward inversion, the shear modulus increased substantially in PL and decreased moderately in SOL. Shear modulus of the proximal PL in the most inverted position increased acutely after ISR (by 11.4 ± 5.8%, P < 0.001), but not after the sham, without any change in the amplitude of electromyogram. These results provide objective evidence that the ISR procedure can acutely alter shear modulus, at least in a specific site in a resting muscle.

Effects of slow dynamic, fast dynamic, and static stretching on recovery of performance, range of motion, balance, and joint position sense in healthy adults

IntroductionConsidering the effects of fatigue on athletic performance and the subsequent increase in the probability of injury, the purpose of this study was to compare the effects of slow dynamic, fast dynamic, and static stretching on the recovery of performance, range of motion (ROM), balance, and joint position sense.MethodsFifteen collegiate healthy females were involved in four separate sessions of slow dynamic stretching (SDS), fast dynamic stretching (FDS), static stretching (SS), and control condition (CC; without stretching), in a random order with at least 48 h of rest between sessions. After warming up, the individuals performed ROM, balance, joint position sense (JPS) maximum voluntary isometric contraction (MVIC) force as well as countermovement (CMJ) and squat jump (SJ) as pre-tests. After performing the knee fatigue protocol of 4 sets of knee extension and flexion at 60% of 1 repetition maximum (RM) to exhaustion (CC; without stretching) or stretching programs (SDS or FDS or SS), the subjects repeated all the tests at post-test 1 (after 5 min) and post-test 2 (after 60 min).ResultsA significantly lower JPS error was detected with SDS while JPS error increased in the SS and control conditions (p < 0.0001). MVIC force significantly increased with SDS and FDS but decreased in control and SS conditions (p < 0.0001). Moreover, a significant decrease in CMJ and SJ height in SS and control conditions was revealed (p < 0.0001). Also, a significant decrease in balance with the control condition was revealed. But only SDS minimized fatigue-induced balance decrements (p < 0.0001). Additionally, the control condition experienced a significant decrease in knee extensor ROM, which contrasted with the significant increase in the quadriceps flexibility with the stretching conditions.ConclusionsThe present results support the idea that SDS may increase quadriceps MVIC force, knee extensor ROM and knee JPS. So according to the present results, it is suggested that the SDS could be implemented and incorporated into a regular recovery program.