Joint synergy and muscle activity in the motion of the ankle-foot complex.

The movement of the ankle-foot complex joints is coupled as a result of various physiological and physical constraints. This study introduces a novel approach to the analysis of joint synergies and their physiological basis by focusing on joint rotational directions and the types of muscle contractions. We developed a biomimetic model of the ankle-foot complex with seven degrees of freedom, considering the skeletal configuration and physiological axis directions. Motion capture experiments were conducted with eight participants performing dorsiflexion and plantarflexion in open-chain states, as well as various walking tasks in closed-chain states, across different ground inclinations (±10, ±5, 0 deg) and walking speeds (3 and 4 km h-1). Hierarchical cluster analysis identified joint synergy clusters and motion primitives, revealing that in open-chain movements, plantarflexion of the ankle, tarsometatarsal and metatarsophalangeal joints exhibited synergy with the inversion of the remaining joints in the complex; meanwhile, dorsiflexion was aligned with eversion. During closed-chain movements, the synergies grouping was exchanged in the subtalar, talonavicular and metatarsophalangeal joints. Further analysis showed that in open-chain movements, synergy patterns influenced by multi-joint muscles crossing oblique joint axes contribute to foot motion. In closed-chain movements, these changes in synergistic patterns enhance the propulsion of the center of mass towards the contralateral leg and improve foot arch compliance, facilitating human motion. Our work enhances the understanding of the physiological mechanisms underlying synergistic motion within the ankle-foot complex.

Reliability and validity of the medial standing overhead arm reach (SOAR) test as a measure of functional hip adduction motion.

OBJECTIVE: The Posterior Standing Overhead Arm Reach (SOAR) test has been previously reported as a reliable clinical measure of closed chain hip extension motion. The proposed Medial SOAR test expands on that testing approach to provide a similar measure of functional hip adduction motion. This was a preliminary intrarater and interrater reliability and validity study of the Medial SOAR test as a measure of functional hip adduction. DESIGN: Cross-sectional. SETTING: University motion analysis laboratory. PARTICIPANTS: Fifty hips were assessed in 25 (22 female) asymptomatic participants (mean age = 23.4 years, SD = 0.8). MAIN MEASURES: Maximum hip adduction during the Medial SOAR test was measured with a standard goniometer independently by two examiners. The test was also performed using three-dimensional motion capture. The intrarater and interrater reliability of the goniometric measure was determined using intraclass correlation coefficients, and the relationship between measures obtained via goniometry and three-dimensional motion capture was assessed with Pearson correlations and Bland-Altman analysis. RESULTS: Intrarater reliability (ICC2,3) was 0.88 (95% CI = 0.80-0.92) for Examiner 1 and 0.87 (95% CI = 0.79-0.92) for Examiner 2. The standard error of measurement and minimal detectable change were less than 3.0°. Interrater reliability demonstrated an intraclass correlation coefficient = 0.62 (95% CI = 0.28-0.79). Pearson correlations were significant with low-to-moderate associations (r = 0.49, P < 0.001; r = 0.24, P = 0.045). CONCLUSIONS: Similar to the previously reported Posterior SOAR test, the Medial SOAR test demonstrated acceptable intrarater and interrater reliability, along with low-to-moderate associations with three-dimensional motion capture. The Medial SOAR test has the potential to provide a reliable and accurate assessment of closed chain hip adduction.

Difference in Functional Performance on the Upper-Quarter Y-Balance Test Between High School Baseball Players and Wrestlers.

CONTEXT: The Upper Quarter Y-Balance Test (YBT-UQ) is a unique movement test where individuals perform at the limits of their stability, requiring the coordination of balance, proprioception, range of motion, and stabilization. It is not yet clear if performance on the YBT-UQ differs between sports with dissimilar emphasis on upper-extremity performance. OBJECTIVE: To compare performance on the YBT-UQ between wrestlers, whose sport requires some degree of closed-chain activity, and baseball players, whose sport is primarily open kinetic chain in nature. DESIGN: Cross-sectional. SETTING: High school preparticipation physical assessment. PARTICIPANTS: 24 healthy high school male wrestlers (mean age 16.12 ± 1.24 y) and 24 healthy high school male baseball players (mean age 15.79 ± 1.25 y). INTERVENTIONS: All subjects performed the YBT-UQ, which requires reaching in 3 directions while maintaining a push-up position. MAIN OUTCOME MEASURES: The variables of interest include the maximum reach in each direction, as well as the composite score. In addition, asymmetries between limbs for each reach direction were compared. RESULTS: Wrestlers performed significantly better than baseball players in the medial direction, inferolateral direction, and in composite scores. In the medial direction, wrestlers exhibited greater scores (P < .01) on both left and right limbs, 10.5 ± 10.2%LL and 9.95 ± 10.2%LL, respectively. Significant differences (P < .01) were also observed in the inferolateral direction, with a difference of 11.3 ± 12.0%LL on the left and 8.7 ± 11.0%LL on the right. Composite scores were higher (P < .01) for the wrestlers, with a difference of 7.0% on the left and 7.1% on the right. CONCLUSIONS: This study suggests that wrestlers perform better on the YBT-UQ than baseball players. The findings may suggest sport-specific normative data for the YBT-UQ in high school athletes.

Reliability and Validity of a Novel Approach to Measure Hip Rotation.

CONTEXT: Currently, hip-rotation range of motion (ROM) is clinically measured in an open kinetic chain in either seated or prone position using passive or active ROM. However, during activities of daily living and during sports participation the hip must be able to rotate in a loaded position, and there is no standard measurement for this. OBJECTIVE: To determine if a novel method for measuring hip rotation in weight bearing will result in good to very good reliability as demonstrated by an intraclass correlation coefficient (ICC) of >.80 and to investigate if weight-bearing hip measurements will result in significantly reduced hip ROM compared with non-weight-bearing methods. DESIGN: Repeated measures. SETTING: Outpatient sports physical therapy clinic. PARTICIPANTS: 20 healthy participants (10 men, 10 women) recruited for hip-rotation measurements. METHODS: Three trials of both internal and external rotation were measured in sitting, prone, and weight bearing. Two therapists independently measured each participant on the same day. The participants returned the following day to repeat the same measurements with the same 2 therapists. MAIN OUTCOME MEASURES: Degrees of hip internal and external rotation measured in prone, sitting, and loaded positions. RESULTS: In general, the measurement of hip ROM across the different conditions was reliable. The intrarater reliability was .67-.95, while interrater reliability was .59-.96. Interrater reliability was improved when values were averaged across the measures (.75-.97). ICCs for active loaded ROM were .67-.81, while interrater ICCs were .53-.87. In general, prone hip ROM was greater than supine and supine was greater than loaded. CONCLUSIONS: Loaded hip rotation can be measured in a clinical setting with moderate to good reliability. The rotation ROM of a loaded hip can be significantly decreased compared with unloaded motion.

Effects of closed chain exercises for the lumbar region performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis.

[Purpose] This study examined the effects of closed chain exercises performed with local vibration applied to an unstable support surface on the thickness and length of the transverse abdominis. [Subjects] The subjects were 64 healthy university students who were randomly assigned to a bridge exercise with sling and vibration group (BESVG, n=30) and a bridge exercise with sling group (BESG, n=34). [Methods] The bridge exercise was repeated four times per set and a total of 18 sets were performed: 9 sets in a supine position and 9 sets in a prone position. In both the BESVG and the BESG groups, the thickness and length of the transverse abdominis (TrA) were measured using ultrasonography with the abdomen "drawn-in" and the pressure of a biofeedback unit maintained at 40 mmHg, both before and after the intervention. [Results] In intra-group comparisons, the BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA. The BESG showed significant increases in the thickness of the TrA. The BESVG showed significant increases in the thickness of the TrA and significant decreases in the length of the TrA compared to BESG. [Conclusion] Closed chain exercises for the lumbar region performed with local vibration applied to slings, which are unstable support surfaces, are an effective intervention for altering the thickness and length of the TrA.

Comparison of the clinical effects of open and closed chain exercises after medial patellofemoral ligament reconstruction.

[Purpose] To compare the effects of open-chain exercise (OCE) and closed-chain exercise (CCE) for patients after medial patellofemoral ligament (MPFL) reconstruction. [Subjects and Methods] Forty patients after MPFL reconstruction were randomly divided into an OCE group and a CCE group. All the patients were evaluated at four different time points. [Results] The mean change of thigh circumference decrease in the CCE group was lower than that in the OCE group at both the 3rd and 6th month after surgery. The Lysholm score of the CCE group was higher than that of the OCE group at both the 3rd and 6th month. At the 3rd month after surgery, the visual analog scale score of the CCE group was lower than that of the OCE group. [Conclusion] CCE is better than OCE for both short and long term outcomes of patients after MPFL reconstruction.

Cannabis policy in The Netherlands: Rationale and design of an experiment with a controlled legal ('closed') cannabis supply chain.

Since the Dutch tolerance policy, allowing the purchase of cannabis in 'coffeeshops', is associated with problems of public order and safety as well as health risks, there has been a long debate about legalisation of cannabis production and supply. It was therefore decided to conduct an experiment with a controlled legal ('closed') cannabis supply chain for recreational use. This is of international relevance in view of the current illegal cannabis exports from the Netherlands, the importance of sharing knowledge about the effectiveness of cannabis policies, and the accumulation of evidence needed to evaluate and update international treaties. Here we describe and discuss the background, general approach and design of the experiment. An independent expert committee elaborated how the closed chain will operate and be evaluated, based on the experience with the medicinal cannabis chain, and round table discussions with stakeholders (mayors, coffeeshop owners, cannabis consumers, growers, regulators, scientists, and addiction experts). Ten trusted cannabis growers are contracted to produce and supply cannabis to the coffeeshops in intervention municipalities, with product quality control, law enforcement against criminal interference, and preventive efforts to reduce health risks being implemented. No changes will be made in the cannabis supply to the coffeeshops in participating control municipalities. A process evaluation will assess whether the chain from production to sale in the intervention municipalities was really closed. In a quasi-experimental study comparing intervention and control municipalities, the chain's effects on public health, cannabis-related crime, safety and public nuisance will be estimated. The fieldwork period is expected to start early 2024 and will take four years, including reporting to the government and parliament. These will then decide whether and what further steps towards legalisation of the production and supply of cannabis will be taken.

Differences in strength and fatigue resistance of scapular protractors and retractors between symptomatic and asymptomatic dyskinesis.

CONTEXT: Scapular dyskinesis is a shoulder dysfunction that can be asymptomatic or associated with pain or weakness. Reduced strength and fatigue resistance of the scapular protractor and retractors muscles that stabilize the scapula might contribute to dyskinesis. OBJECTIVE: To determine the strength and fatigue resistance profiles of subjects with symptomatic and asymptomatic scapular dyskinesis, and to compare them to healthy controls using isokinetic assessment. DESIGN: Cross-sectional study. SETTING: University Hospital. PARTICIPANTS: Twenty healthy controls and 21 overhead athletes with symptomatic (n=10) and asymptomatic (n=11) scapular dyskinesis. MAIN OUTCOME MEASURES: Strength (peak torque, maximum work), fatigue resistance (total work) and protraction/retraction ratios measured during a closed-chain isokinetic protocol (40 repetitions in concentric mode at 24.4 cm/s). RESULTS: The scapular protractors' strength and fatigue resistance were significantly higher (p<0.01) in healthy controls (peak torque: 5.0±0.9 N/Kg; maximum work: 2.4±0.5 J/Kg; total work: 72.4±0.6 J/Kg) than in asymptomatic (peak torque: 3.4±0.7 N/Kg; maximum work: 1.7±0.4 J/Kg; total work: 50.0±13.7 J/Kg) and symptomatic (peak torque: 3.8±0.6 N/Kg; maximum work: 1.8±0.3 J/Kg; total work: 58.1±12.9 J/Kg) dyskinetic participants. The dyskinetic symptomatic group presented the highest retractors' strength and fatigue resistance (p<0.01) values (peak torque: 5.2±0.6 N/Kg; maximum work: 2.9±0.8 J/Kg; total work: 87.7±22.7 J/Kg) followed by the healthy controls (peak torque: 4.7±1.0 N/Kg; maximum work: 2.1±0.5 J/Kg; total work: 65.3±17.9 J/Kg) and the asymptomatic dyskinetic participants (peak torque: 3.9±1.0 N/Kg; maximum work: 1.9±0.6 J/Kg; total work: 58.6±18.5 J/Kg). The protraction / retraction ratios showed a gradual decrease (p<0.001) from healthy controls (1.1) to asymptomatic (0.9) and symptomatic (0.7) dyskinetic subjects. CONCLUSIONS: Scapular dyskinesis is characterized by weaker scapular protractors and reduced agonist/antagonist ratios, especially when symptomatic. Targeting the scapular protractors for a better balance of scapular musculature in rehabilitation and strengthening programs may improve shoulder symptoms and function, but more interventional studies are required.

A preliminary study of the reliability and validity of the Posterior Standing Overhead Arm Reach (SOAR) test as a measure of functional hip extension motion.

BACKGROUND: Current clinical tests do not provide a method to reliably measure closed chain hip extension. We developed the Posterior Standing Overhead Arm Reach (SOAR) test for this purpose. OBJECTIVES: This was a preliminary intrarater and interrater reliability and validity study of the Posterior SOAR test as a measure of functional hip extension. DESIGN: Cross-sectional. METHOD: Hip extension on the Posterior SOAR test was measured with a standard goniometer independently by two examiners. The test was then repeated using three-dimensional (3D) motion capture. Intraclass correlation coefficients (ICC) were used to determine the intrarater and interrater reliability of the goniometric measure and Pearson correlations were used to assess the relationship between measures obtained via goniometry and 3D motion capture. RESULTS: Fifty hips were assessed in 25 (14 female, 11 male) asymptomatic participants (mean age = 24.0 years, SD = 1.1). Intrarater reliability (ICC2,3) was 0.80 (95% CI = 0.68-0.88) for Examiner 1 and 0.77 (95% CI = 0.64-0.86) for Examiner 2, indicating excellent reliability. The standard error of the measure (SEM90) ranged from 2.5° to 3.0° with a minimal detectable change (MDC90) of 3.5° to 4.2°. Interrater reliability was good with ICC = 0.65 (95% CI = 0.36-0.80). Pearson correlations were significant with low to moderate associations (r = 0.36, P = 0.009; r = 0.51, P < 0.001). CONCLUSIONS: The Posterior SOAR test demonstrated excellent intrarater reliability, good interrater reliability, and low to moderate associations with 3D motion capture. The Posterior SOAR test has the potential to provide a reliable and accurate assessment of closed chain hip extension.

Characterizing healthy knee symmetry using the finite helical axis and muscle power during open and closed chain tasks.

Understanding healthy joint movement and muscle control, and injurious alterations, is important to determine musculoskeletal contributions to post-injury joint instabilities or altered dynamic joint function. The contralateral limb is often used as a point of reference to determine the effects of knee joint injury. However, it is currently difficult to interpret within subject variability between limbs as this is not well established in the healthy population. There is a continuing need to characterize healthy knee joint mechanics and neuromuscular control to determine the degree of symmetry within healthy individuals. The current study quantified limb symmetry in healthy individuals using the finite helical axis with a unique reference position (rFHA) and electromyography (EMG) approaches, for a closed-chain single leg squat (SLS) and an open-chain seated leg swing. Muscle power and FHA translation, orientation and dispersion were similar between limbs. However, the FHA was located significantly more anterior in the dominant limb relative to the contralateral during both tasks. These between-limb differences in FHA location could be attributed to differences in joint geometry and strength between limbs. This finding provides evidence that healthy knees have asymmetries which have implications for selection of control limbs in studies comparing conditions within and between individuals. Differences identified in dynamic joint function between tasks suggest that the SLS is useful for revealing joint asymmetries due to altered muscular control strategies, while the swing task is expected to highlight asymmetries in joint motion due to altered knee structures following injury.

The effect of functional bracing on the arthrokinematics of anterior cruciate ligament injured knees during lunge exercise.

BACKGROUND: Functional knee braces are extensively used for partially and completely torn anterior cruciate ligament (ACL) patients and those who have undergone ACL graft reconstruction, in order to support the healing ACL, improve the joint's functional stability, and restore the normal joint kinematics. RESEARCH QUESTION: Does wearing braces alter the arthrokinematics of the ACL deficient knees during lung exercise? METHODS: For ten male unilateral ACL deficient subjects, 3D knee models were reconstructed from CT images, acquired in rest position. Sagittal plane fluoroscopy was then performed throughout a complete cycle of lunge in braced and non-braced conditions. The 3D kinematics of the knees were obtained using a 2D-3D registration method in which six anatomical bony landmarks on the fluoroscopic images were matched with those on the 3D models. RESULTS: No significant difference was found between the tibial anterior-posterior translations and abduction-adduction motions of the braced and non-braced knees. A significant decrease, however, was observed after bracing in the tibial internal rotation at 45° flexion during eccentric (non-braced: 5.9° (±6.7°) vs. braced: 2.4° (±7.0°); p = 0.045), and at 30° flexion during concentric (non-braced: 2.3° (±6.9°) vs. braced: -1.6° (±8.1°); p = 0.001) phases of the lunge cycle. SIGNIFICANCE: The immediate effect of knee bracing is limited to controlling the tibial rotation of the ACL deficient individuals during the lunge exercise. Hence, care should be taken in prescribing the lunge exercise for rehabilitation of ACL injured patients with high anterior-posterior knee instability, even when wearing knee braces.

The significance of closed kinematic chains to biological movement and dynamic stability.

Closed kinematic chains (CKCs) are widely used in mechanical engineering because they provide a simple and efficient mechanism with multiple applications, but they are much less appreciated in living tissues. Biomechanical research has been dominated by the use of lever models and their kinematic analysis, which has largely ignored the geometric organization of these ubiquitous and evolutionary-conserved systems, yet CKCs contribute substantially to our understanding of biological motion. Closed-chain kinematics couple multiple parts into continuous mechanical loops that allow the structure itself to regulate complex movements, and are described in a wide variety of different organisms, including humans. In a biological context, CKCs are modular units nested within others at multiple size scales as part of an integrated movement system that extends throughout the organism and can act in synergy with the nervous system, where present. They provide an energy-efficient mechanism that enables multiple mechanical functions to be optimized during embryological development and increases evolutionary diversity.

Comparison of unilateral squat strength between the dominant and non-dominant leg in men and women.

The purpose of this study was to compare unilateral squat strength of the dominant and non-dominant leg in young adult men and women. Seventeen apparently healthy men (mean mass 90.5 ± 20.9 kg and age 21.7 ± 1.8 yrs) and 25 women (mean mass 62.2 ± 14.5 kg and age 21.9 ± 1.3 yrs) completed the study. To determine unilateral strength, the subjects completed a one repetition maximum (1RM) modified unilateral squat (MUS) on the dominant and non-dominant leg. The subjects completed the squat to a depth that attained a 90° angle at the knee. This exercise was executed by placing the top of the metatarsophalangeal area of the foot of the uninvolved leg on a support bar behind the subject to isolate the use of the lead leg. Paired samples t-test revealed no significant difference between the men's 1RM mean strength on the dominant (107.0 ± 21.4 kg) and non-dominant (106.0 ± 21.4 kg) leg with a mean side-to-side difference (comparing the stronger to the weaker leg) of 2.8 %. Leg strength symmetry was also found between the women's 1RM mean strength on the dominant (45.3 ± 12.5 kg) and non-dominant (45.0 ± 12.4 kg) leg with a mean side-to-side difference of 5.0 %. The data indicate that unilateral squat strength, measured in a weight bearing stance, is similar in the dominant and non-dominant leg in apparently healthy young adult men and women. Key PointsMUS strength was similar between the dominant and non-dominant leg in young adult men and women.Mean side-to-side differences (comparing the stronger to the weaker leg) resulted from higher dominant and non-dominant scores for the men and womenThe range of side-to-side differences warrants the practice of weight bearing strength assessment to identify those at risk for injury.

Functional progression and return to sport criteria for a high school football player following surgery for a lisfranc injury.

UNLABELLED: Lisfranc injuries are a challenging diagnosis for the sports physical therapist because of the lack of data on how to rehabilitate them properly. To date, the available rehabilitation literature has focused on the mechanism of injury and the conservative management of this injury. Furthermore, there is a lack of consensus on the appropriate testing and return to play criteria for an athlete recovering from this perplexing injury. This case describes a high school athlete whose primary sport was football, but was injured during wrestling. He suffered a Lisfranc injury and subsequently underwent surgical fixation. The purpose of this case report is to focus on the exercise, functional progression, and return to sport criteria utilized after operative treatment of a Lisfranc ligament injury. LEVEL OF EVIDENCE: V.

Comparison of kinematics of ACL-deficient and healthy knees during passive flexion and isometric leg press.

BACKGROUND: Studying the kinematics of the ACL deficient (ACLD) knees, during different physiological activities and muscle contraction patterns, can improve our understanding of the joint's altered biomechanics due to ACL deficiency as well as the efficacy and safety of the rehabilitations exercises. METHODS: Twenty-five male volunteers, including 11 normal and 14 unilateral ACLD subjects, participated in this study. The kinematics of the injured knees of the ACLD subjects was compared with their intact knees and the healthy group during passive flexion and isometric leg press with the knees flexed from full extension to 45° flexion, with 15° intervals. An accurate registration algorithm was used to obtain the three dimensional kinematical parameters, from magnetic resonance images. RESULTS: The ACL deficiency mainly altered the tibial anterior translation, and to some extent its internal rotation, with the change in other parameters not significant. During leg press, the anterior translation of the ACLD knees was significantly larger than that of the normal knees at 30° flexion, but not at 45°. Comparison of the anterior translations of the ACLD knees during leg press with that of the passive flexion revealed improved consistency (CVs changed from 1.2 and 4.0 to 0.6 and 0.6, at 30° and 45° flexion, respectively), but considerable larger translations (means increased by 6.2 and 4.9mm, at 30° and 45° flexion, respectively). CONCLUSION: The simultaneous contraction of the quadriceps and hamstrings during leg press, although reduces the knee laxity, cannot compensate for the loss of the ACL to restore the normal kinematics of the joint, at least during early flexion.

Tibial displacement and rotation during seated knee extension and wall squatting: a comparative study of tibiofemoral kinematics between chronic unilateral anterior cruciate ligament deficient and healthy knees.

BACKGROUND: Following anterior cruciate ligament (ACL) rupture, the knee becomes unstable with alterations in joint kinematics including anterior tibial displacement (ATD), and internal tibial rotation. Therapeutic exercises that promote faulty kinematics should be discouraged, especially early post-reconstruction, to avoid graft stretching and possibly longer-term osteoarthritis. Our study aimed to compare ATD and tibial rotation during two commonly prescribed exercises, namely: open kinetic chain (OKC) seated extension and closed kinetic chain (CKC) single leg wall squatting in ACL-deficient and healthy knees. METHODS: Eight ACL-deficient patients and eight healthy subjects matched for age, gender and sports history were assessed using Qualisys 3D-Motion Analysis System to track 17 infrared markers while performing a seated knee extension with 3kg weight and a unilateral wall squat. We developed a model to measure joint kinematics through 70° of knee flexion and extension. ANOVA and paired t-tests compared relative ATD and tibial rotation between exercises and groups at 10° increments of flexion and extension. RESULTS: We found increased ATD in the wall squat compared to the seated extension (p=0.049). There was no difference in ATD between the healthy and ACL-deficient knees but overall the tibia was significantly more internally rotated (p=0.003) in ACL-deficient knees, irrespective of the exercise, possibly interfering with the screw-home mechanism. CONCLUSIONS: CKC exercises, in particular wall squats, are not necessarily safer for patients with ACL-deficiency and possibly ACL-reconstruction; although generalization should only be made with appropriate caution. Clinicians require a detailed knowledge of the effect of exercise on knee joint kinematics.

The Study of Isokinetic Concentric Contraction of Low Limbs with Closed Chain / 中国康复理论与实践

@#normal males were tested by BIODEX isokinetic test and rehabilitation system and its closed chain attachment.The results show that Peak Torque,Peak Torque/Body Weight,Time to PT,Total Work,Total Work/Body Weight and Average Power were higher when extention than flexion.There were no significant influence on D1/D2 ratio.And the results with closed chain are the same with non closed chain test.