The Effects of Fatigue on Biomechanics of Heading Performance in Soccer

Soccer is one of the high intermittent sports, in which the athletes perform various activities of different intensities over a prolonged period. One of the most important and potentially dangerous skills in soccer is heading because it can potentially cause concussion if it is not executed correctly. Even though coaches and practitioners recognize that heading the ball is one of the factors to cause concussion, there are few studies that have examined the kinematics of head and neck motion while performing heading skill. Therefore, the purpose of this study was to examine the effects of short period fatigue on the biomechanical performance of soccer heading skill. Six competitive college male soccer players (age, 21.5 ± 3.15 years; height, 1.76 ± 0.06 m; mass, 71.38 ± 9.55 kg) participated in this study. A standard two-dimensional kinematic analysis was conducted using a high-speed video camera operated at 120 Hz during heading performance. A 90-second fatigue protocol soccer course was set up to mimic a real soccer game situation. All soccer players completed fatigue protocol five sets to induce fatigue. The mechanics of heading skills were recorded prior to the fatigue protocol and then after each fatigue protocol. Six joint reflective markers were placed on the right side of each participant’s body. The statistical analysis between the baseline and after each fatigue protocol data was conducted using one-way repeated measure ANOVA at α = 0.05 and followed up by t-test with Bonferroni adjustment if a significant difference was found. The result showed that there were no statistically significant differences in the heading ball velocity and acceleration, cervical spine and hip joint angle, velocity and acceleration at the time of ball contact. The results of this study suggest that heading ball velocity and acceleration, biomechanics of cervical spine and hip joint may not indicate fatigue even if athletes were fatigued during practices or games. Moreover, recreationally active male individuals may require more than five sets of 90-second fatigue protocol soccer course to induce fatigue if research or training personnel intend to use this protocol to study changes in heading ball velocity and acceleration and cervical spine and hip joint angle, velocity, and acceleration at the time of ball contact

Chronic Ankle Instability Subjects Demonstrate Lower Rate of Torque Development in Ankle Eversion, Hip Abduction Muscles Compared to Healthy, Coper Groups

Chronic ankle instability (CAI) is a pathological condition characterized by repeated lateral ankle sprains. Many ankle sprains are not a singular occurrence and can lead to perpetual disability, with some patients reporting repeated episodes of the ankle “giving way” during activity. CAI is multifactorial in nature, with contributors such as ligamentous laxity, strength deficit, and proprioceptive impairment (1). Each of these contributors negatively affects the muscles of the ankle complex. Rate of torque development (RTD) is a metric demonstrating explosive muscle capability, and is related to measurement of maximal voluntary isometric contraction (MVIC). RTD is a more accurate reflection of functional strength than MVIC because peak torque generally occurs 300ms or more after the onset of torque generation (2) while the time available for torque production in a functional daily movement context is generally between 50-250ms (3). RTD is generally measured within the first 200ms of the trial and therefore better captures the muscle’s ability to generate strength for daily activities. Understanding the relationship between RTD of the ankle evertor/invertor muscles and hip abductor muscles in individuals with CAI against healthy controls will better inform rehabilitation strategies and provide a benchmark of improvement for individuals recovering from CAI. PURPOSE: The purpose of this study was to better understand how CAI affects the force production capabilities of the ankle evertors/invertors, as well as the hip abductors. We hypothesized that individuals with CAI would demonstrate lower RTD in all three muscle groups in comparison to healthy and coper controls. METHODS: A total of 58 males and females participated in this study, and participants were divided into three cohorts. The first was a CAI patient group, a “coper” group, defined as individuals who can return to pre-injury levels of performance after LAS, and a healthy control group. CAI individuals and LAS copers were identified using the guidelines provided by the International Ankle Consortium (4). Subject exclusion criteria included previous history of lower extremity surgery, fracture, neurological disease affecting the lower extremity, or any injury to the lower extremity in the 3 months leading up to the study. Before data was obtained participants were familiarized with experimental procedures and protocols. Signed consent was obtained from each subject prior to data collection. The study was approved by the university institutional review board (Approval number: F2019-338). The study design required two visits from the subjects. The first visit was to familiarize subjects with the ankle eversion, inversion, and hip abduction movements they would be required to perform. On this day patients were also made familiar with the Biodex dynamometer (System Pro 4, Biodex Medical Systems, Inc., Shirley, NY; sampling rate: 100 Hz). On the second day subjects were seated on the dynamometer and performed 3 maximal voluntary isometric contractions (MVIC) of each movement. Patients were instructed to perform the movements as quickly as possible and to hold each trial for 5 seconds. Three trials were collected for each movement, with a minute separating each trial. Subjects were encouraged to give maximal effort through verbal cues. RTD and MVIC were calculated from each torque-time curve using custom code written in MatLab (MathWorks 2021a, Natick, MA). RTD was defined as the rate of change of the first 200ms of each trial; MVIC was defined as the peak value of each trial. RTD and MVIC values were averaged for each subject. RESULTS: No statistically significant differences in sex, age, height, or mass were detected among subjects (Table 1). Table 2 shows mean RTD for each group for the ankle eversion, inversion, and hip abduction movements. Notable results from Table 2 include the finding that CAI patients demonstrated significantly lower RTD than healthy controls (p = .02) and lower RTD than LAS copers (p = .03). Furthermore, CAI patients showed lower hip abductor RTD than healthy controls (p = .04). Table 3 shows MVIC data for each group for each movement and demonstrates that CAI patients showed significantly lower MVIC of the ankle eversion muscles than healthy controls (p = .02). No statistically significant differences in any strength metrics were detected between LAS copers and healthy controls, nor were there differences detected between groups in the ankle inversion movement. DISCUSSION: The primary finding from this study was that CAI ankle eversion RTD was significantly lower than RTD in healthy controls. This is significant because it provides insight on the adverse effects of repeated LAS on the muscles of the ankle complex. One of the factors determining RTD is the force transmission capabilities of the tendinous structures (10), and it is possible that the stretching of the ankle ligaments during LAS negatively affects its ability to efficiently transmit force generated from the muscle. Given the correlation between CAI patients and decreased RTD of ankle eversion muscles, it is possible that focusing on improvement in RTD of this muscle group could improve CAI symptoms. Numerous studies have focused on modalities targeted at improving RTD of the leg extensors muscle groups with generally positive results (5, 9), the majority of which include protocols that would be easily modifiable to the ankle eversion muscle group. Another notable finding from this study was that RTD of the hip abductors in the CAI group was significantly less than that of the healthy group. Although studies exist that have measured maximal hip abduction isometric strength in CAI groups, to our knowledge this is the first study analyzing the RTD of hip abduction. Our findings of deficits in hip abduction strength coincide with those of previous studies (6-8). Whether deficits in hip abduction strength increase potential for LAS or arise as a result of CAI is unclear, but it is becoming evident that the two factors are related. This is a promising area of CAI research and further study is required to fully elucidate the relationship between CAI and hip abductor strength. CONCLUSION: RTD of the ankle evertors in individuals with CAI is significantly lower than in LAS copers and healthy controls. Additionally, CAI patients demonstrated significantly lower RTD in hip abduction than healthy controls. While the need for exploring muscle force production capabilities in individuals with CAI persists, we suggest exploring modalities targeted at improving ankle eversion and hip abduction strength in patients with CAI. It is possible that improving strength in these areas will help return CAI patients to pre-injury levels of function and further our understanding of CAI

Submaximal Force Steadiness and Accuracy in Patients With Chronic Ankle Instability

Context: Patients with chronic ankle instability (CAI) have demonstrated sensorimotor impairments. Submaximal force steadiness and accuracy measure sensory, motor, and visual function via a feedback mechanism, which helps researchers and clinicians comprehend the sensorimotor deficits associated with CAI. Objective: To determine if participants with CAI experienced deficits in hip and ankle submaximal force steadiness and accuracy compared with healthy control participants. Design: Case-control study. Setting: Research laboratory. Patients or Other Participants: Twenty-one patients with CAI and 21 uninjured individuals. Main Outcome Measure(s): Maximal voluntary isometric contraction (MVIC) and force steadiness and accuracy (10% and 30% of MVIC) of the ankle evertors and invertors and hip abductors were assessed using the central 10 seconds (20%– 87% of the total time) of the 3 trials. Results: Relative to the control group, the CAI group demonstrated less accuracy of the invertors (P , .001). Across all motions, the CAI group showed less steadiness (P , .001) and less accuracy (P , .01) than the control group at 10% of MVIC. For MVIC, the CAI group displayed less force output in hip abduction than the uninjured group (P , .0001). Conclusions: Patients with CAI were unable to control ongoing fine force (10% and 30% of MVIC) through a feedback mechanism during an active test. These findings suggested that deficits in sensorimotor control predisposed patients with CAI to injury positions because they had difficulty integrating the peripheral information and correcting their movements in relation to visual information

Effects of Running on Femoral Articular Cartilage Thickness for Anterior Cruciate Ligament Reconstruction Patients and Non-ACLR Control Subjects

Anterior cruciate ligament reconstruction (ACLR) patients are more likely to develop posttraumatic knee osteoarthritis than non-ACLR counterparts. The effect of running on femoral articular cartilage thickness is unclear. PURPOSE: The purpose of this study was to compare how 30 minutes of running influences femoral articular cartilage thickness for ACLR patients and non-ACLR control subjects. We hypothesized that running would deform the femoral articular cartilage more for the ACLR patients than for the control subjects. METHODS: We recruited 20 individuals with primary unilateral ACLR and 20 matched non-ACLR controls. ACLR patients and control subjects were matched based upon age, gender, BMI, and weekly running mileage. The present procedures were approved by the appropriate institutional board and all subjects provided informed consent before data collection. We used ultrasound imaging to measure femoral articular cartilage thickness before and after 30 minutes of running. The ultrasound images were manually analyzed using ImageJ software by the same investigator. Total femoral articular cartilage cross-sectional area of each image was segmented into three regions: medial, lateral, and intercondylar. Deformation due to the run was compared between the ACLR patients and control subjects for each region using independent t tests (P \u3c 0.05, adjusted for multiple comparisons). RESULTS: The 30-minute run resulted in more deformation for the ACLR patients (0.03 ± 0.01 cm) than the matched controls (0.01 ± 0.01 cm) for the medial region (p \u3c 0.01) of the femoral articular cartilage. Identically, the 30-minute run resulted in more deformation for the ACLR patients (0.03 ± 0.01 cm) than the matched controls (0.01 ± 0.01 cm; p \u3c 0.01) for an average of the entire articular cartilage area (medial, lateral, and intercondylar). No significant differences existed between groups for the lateral or intercondylar regions. CONCLUSION: Thirty minutes of running deformed medial and overall femoral articular cartilage more for ACLR patients than non-ACLR control subjects

Running Biomechanics and Knee Cartilage Health in ACLR Patients

Anterior cruciate ligament reconstruction (ACLR) patients are more likely to subsequently suffer from knee osteoarthritis than non-ACLR counterparts. Exercise is thought to influence articular cartilage, however, it is unclear how running biomechanics are associated with femoral cartilage thickness and composition in ACLR patients. PURPOSE: The purpose of this study was to investigate relationships between running biomechanics and measures of femoral articular cartilage condition (thickness and composition) in ACLR patients and control subjects. METHODS: We used ultrasound and MRI (T2 mapping sequence) to measure articular cartilage thickness and composition, respectively, for 20 ACLR patients (age: 23 ± 3 yrs; mass: 70 ± 10 kg; time post-ACLR: 14.6 ± 6.1 months) and 20 matched controls (age: 22 ± 2 yrs; mass: 67 ± 11 kg). After these measures, all participants completed a 30-minute run on a force-instrumented treadmill. Correlational analyses were used to explore relationships between running biomechanics (vertical ground reaction force (vGRF)) and femoral cartilage thickness and composition (T2 relaxation time). The present procedures were approved by the appropriate institutional board and all subjects provided informed consent before data collection was performed. RESULTS: Significant positive correlations existed for the control subjects only between peak vGRF and overall (r = 0.34; p \u3c 0.01), medial (r = 0.23; p \u3c 0.01), lateral (r = 0.39; p = 0.02), and intercondylar (r = 0.31; p \u3c 0.01) femoral thickness. The ACLR patients showed significant negative correlations between T2 relaxation time for the central-medial region of the femoral condyle, and peak vGRF (r = −0.53; p = 0.01) and vertical impulse due to the vGRF (r = −0.46; p = 0.04). CONCLUSION: These findings offer some limited support for the idea that femoral articular cartilage benefits from increase vGRF during running. This is evidenced by the increased thickness for the control subjects and decreased T2 relaxation time (indicative of increased free-flowing water in the cartilage) for the ACLR patients, as running vGRF increased

Femoral Articular Cartilage Quality, but Not Thickness, Is Decreased for Anterior Cruciate Ligament Reconstruction Patients Relative to Control

Anterior cruciate ligament reconstruction (ACLR) patients are at risk of developing posttraumatic knee osteoarthritis (OA). The etiology of posttraumatic knee OA is complex, potentially involving biomechanical and biochemical factors. Changes in femoral cartilage thickness and composition are associated with knee OA, while current research is ambiguous on cartilage in ACLR patients. PURPOSE: This study aimed to compare femoral cartilage thickness and T2 relaxation time (a compositional measure) between ACLR patients and healthy controls in a resting state. We hypothesized that ACLR patients would exhibit thinner femoral cartilage and increased T2 relaxation times. METHODS: Twenty ACLR patients (6-24 months post-surgery) and 20 matched healthy controls were recruited following institutional board approval. Ultrasound and magnetic resonance imaging data were collected on two separate days, allowing cartilage thickness and composition measurements to be made, respectively. Statistical analyses, including independent t-tests and Holm-Bonferroni corrections, were performed on selected regions of interest. RESULTS: The ACLR group showed increased T2 relaxation times in four of eight femoral regions compared to controls. No significant differences in femoral cartilage thickness were observed between the groups. The primary finding from this study is that ACLR patients did not show differences in femoral cartilage thickness (a morphological measure), but displayed prolonged T2 relaxation times (a compositional measure) compared to controls, at rest. This finding suggests that compositional changes precede morphological shifts in femoral cartilage in early post-ACLR periods (6-24 months). CONCLUSION: These early compositional changes may indicate articular cartilage that is more compressible and subject to increased strain on the solid components of the joint. While ultrasound is a more accessible imaging method, magnetic resonance imaging may provide a more accurate and early evaluation of cartilage quality. Further research is needed to develop practical tools for early detection and monitoring of cartilage degradation in ACLR patients before progression into knee osteoarthritis

Air-stable van der Waals PtTe2 conductors with high current-carrying capacity and strong spin- orbit interaction

High-performance van der Waals (vdW) integrated electronics and spintronics require reliable current-carrying capacity. However, it is challenging to achieve high current density and air-stable performance using vdW metals owing to the fast electrical breakdown triggered by defects or oxidation. Here, we report that spin-orbit interacted synthetic PtTe2 layers exhibit significant electrical reliability and robustness in ambient air. The 4-nm-thick PtTe2 synthesized at a low temperature (similar to 400 degrees C) shows intrinsic metallic transport behavior and a weak antilocalization effect attributed to the strong spin-orbit scattering. Remarkably, PtTe2 sustains a high current density approaching approximate to 31.5 MA cm(-2), which is the highest value among electrical interconnect candidates under oxygen exposure. Electrical failure is caused by the Joule heating of PtTe2 rather than defect-induced electromigration, which was achievable by the native TeOx passivation. The high-quality growth of PtTe2 and the investigation of its transport behaviors lay out essential foundations for the development of emerging vdW spin-orbitronics

Dichotomizing Level of Pial Collaterals on Multiphase CT Angiography for Endovascular Treatment in Acute Ischemic Stroke: Should It Be Refined for 6-Hour Time Window?

Purpose Although endovascular treatment is currently thought to only be suitable for patients who have pial arterial filling scores >3 as determined by multiphase computed tomography angiography (mpCTA), a cut-off score of 3 was determined by a study, including patients within 12 hours after symptom onset. We aimed to investigate whether a cut-off score of 3 for endovascular treatment within 6 hours of symptom onset is an appropriate predictor of good functional outcome at 3 months. Materials and Methods From April 2015 to January 2016, acute ischemic stroke patients treated with mechanical thrombectomy within 6 hours of symptom onset were enrolled into this study. Pial arterial filling scores were semi-quantitatively assessed using mpCTA, and clinical and radiological parameters were compared between patients with favorable and unfavorable outcomes. Multivariate logistic regression analysis was then performed to investigate the independent association between clinical outcome and pial collateral score, with the predictive power of the latter assessed using C-statistics. Results Of the 38 patients enrolled, 20 (52.6%) had a favorable outcome and 18 had an unfavorable outcome, with the latter group showing a lower mean pial arterial filling score (3.6±0.8 vs. 2.4±1.2, P=0.002). After adjusting for variables with a P-value of 2 vs. ≤2. Conclusion A pial arterial filling cut-off score of 2 as determined by mpCTA appears to be more suitable for predicting clinical outcomes following endovascular treatment within 6 hours of symptom onset than the cut-off of 3 that had been previously suggested

Altered Visual Reliance Induced by Stroboscopic Glasses during Postural Control

Little is known about how disrupted vision affects visual reliance during postural control. postural control. Twenty-four physically active adults volunteered to participate in the study. Static postural control was quantified with center of pressure measures during a one-legged balance test with four different visual inputs (eyes-open (EO), high frequency of strobe vision (HSV), low frequency of strobe vision (LSV), and eyes-closed (EC)) and on two different surfaces (firm and foam). Dynamic postural control was calculated by the dynamic postural stability index and the Y-Balance test for three different visual inputs (EO, HSV, and LSV) and the two different surfaces. Romberg ratios (HSV/EO, LSV/EO, and EC/EO) were then calculated and used for statistical analysis to assess visual contribution during postural control. In the results, Romberg ratios were higher when people were on the foam surface than the firm surface in center of pressure total path in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Similarly, Romberg ratios were higher on the foam surface than the firm surface in dynamic stability index in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Stroboscopic glasses could alter visual reliance when the somatosensory system is disturbed by a foam pad during both static and dynamic postural control. Clinicians could use the glasses to manipulate visual reliance during dynamic balance training for patients with musculoskeletal injuries

Construction Waste Reduction through Application of Different Structural Systems for the Slab in a Commercial Building: A South Korean Case

Construction waste generation along with the extensive consumption of natural resources has propelled researchers to investigate effective measures for minimising the waste. While several studies have shown that the structural design would be an influencing factor on the carbon dioxide emissions of a building, there is a lack of studies to corroborate the effect of different structural systems to generate waste during the construction stage. This article seeks to bridge some of the knowledge gaps regarding the waste generation from different structural systems during the construction phase in a building project in South Korea and demonstrate its potential for waste reduction. In this study, the amount of waste generation during the construction phase was calculated based on the quantities and the material loss rate of each building material to estimate the quantity of construction waste by the changes in the application of different structural systems for the slab of the studied model. The total waste generation during the construction phase of the different slab systems shows that the solid slab system produces the largest amount of construction waste, which is 101,361.385 kg. On the other hand, the void slab system generates 87,603.958 kg of the construction waste, which is the lowest amount among the four variables of this study. The additional purchasing costs due to the loss of construction materials indicate that the solid slab system would require 80,709.76 USD, which is the highest value of the four variables in this study. The void slab system would cost USD 50,054.12 for additional materials purchasing costs, which is approximately 38% lower than the solid slab system