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Context: Anterior cruciate ligament injuries are directly related to the control of dynamic knee valgus in the landing of a jump, and this is mainly due to the correct activation and neuromuscular function of the lower-extremity muscles. The aim of the study is to assess the relationship between lower limb muscle activity during a single-legged drop jump and knee frontal plane projection angle (FPPA). Design: A correlation study. Methods: Thirty healthy collegiate female athletes were included in the study. Main outcomes measures were peak knee FPPA and muscle activity (% of maximal voluntary isometric contraction). Peak knee FPPA during a single-legged drop jump test was identified using a 2-dimensional motion analysis system. Muscle activity was assessed using a surface electromyograph for gluteus maximus, gluteus medius, biceps femoris, semitendinosus, vastus medialis quadriceps, vastus lateralis quadriceps, medial gastrocnemius, and lateral gastrocnemius. All variables were assessed for both dominant and nondominant limbs. A correlation analysis between peak knee FPPA and muscle activity was performed. Statistical significance was set at P <.05. Results: A mean peak knee FPPA of 14.52° and 13.38° was identified for dominant and nondominant limb single-legged drop jump test, respectively. Muscle activity (% of maximal voluntary isometric contraction) for muscles assessed ranged from 43.97% to 195.71% during the single-legged drop jump test. The correlation analysis found no significant correlation between any of the muscles assessed and peak knee FPPA during the single-legged drop jump test (Pearson coefficient between −.3 and.1). Conclusions: There is no association between muscle activity from the lower limb muscles and the knee FPPA during a single-legged drop jump in female athletes. Thus, different muscle properties should be assessed in order to understand such an important movement as the knee FPPA during a jump. [ABSTRACT FROM AUTHOR]

The present randomized study investigated the effect of acute supplementation of 800 mg/kg of ketone monoester ingestion (KE) or placebo (PL) and 210 mg/kg of NaHCO3 co-ingestion on cycling performance of WorldTour cyclists during a road cycling stage simulation. Twenty-eight cyclists participated in the study (27.46 ± 4.32 years; 1.80 ± 0.06 m; 69.74 ± 6.36 kg). Performance, physiological, biochemical, and metabolism outcomes, gut discomfort, and effort perceived were assessed during a road cycling simulation composed of an 8-min time-trial (TT) performance + 30-s TT + 4.5 hr of outdoor cycling + a second 8-min TT + a second 30-s TT. Greater absolute and relative mean power during the first 8-min TT (F = 5.067, p =.033, η p 2 =.163 , F = 5.339, p =.029, η p 2 =.170 , respectively) was observed after KE than after PL (KE: 389 ± 34, PL: 378 ± 44 W, p =.002, d = 0.294 and KE: 5.60 ± 0.42, PL: 5.41 ± 0.44 W/kg, p =.001, d = 0.442). Additionally, greater concentration of β-hydroxybutyrate blood concentration (F = 42.195, p <.001, η p 2 =.619) was observed after KE than after PL during the first steps of the stage (e.g., after warm-up KE: 1.223 ± 0.642, PL: 0.044 ± 0.058 mM, p <.001, d = 2.589), although the concentrations returned to near baseline after 4.5 hr of outdoor cycling. Moreover, higher values of anion gap were observed (F = 2.333, p =.026, η p 2 =.080) after KE than after PL ingestion, after the warm-up and after the first 8-min and 30-s TT. Additionally, lower concentrations of HCO 3 − were reported in the KE condition after warm-up and after the first 8-min and 30-s TT. During the initial phase of the stage simulation, acute supplementation with KE + NaHCO3 co-ingestion enhanced 8-min TT cycling performance (3.1%) in WorldTour cyclists with a concomitant hyperketonaemia. [ABSTRACT FROM AUTHOR]

Context: Single- and dual-task walking gait assessments have been used to identify persistent movement and cognitive dysfunction among athletes with concussions. However, it is unclear whether previous ankle sprain injuries confound these outcomes during baseline testing. The purpose of this study was to determine the effects of (1) ankle sprain history and (2) time since prior ankle sprain injury on single- and dual-task spatiotemporal gait outcomes and cognitive measures. Design: Cross- sectional study. Methods: We assessed 60 college Division-I athletes (31 with ankle sprain history; 13 females and 18 males, 19.3 [0.8] y; 29 with no ankle sprain history, 14 females and 15 males, 19.7 [0.9] y) who completed injury history forms and underwent concussion baseline testing. Athletes completed single- and dual-task gait assessments by walking back and forth along an 8-m walkway for 40 seconds. Athletes wore a smartphone with an associated mobile application on their lumbar spine to record spatiotemporal gait parameters and dual-task cognitive performance. Separate multivariate analyses of variance were used to assess the effects of ankle sprain injury history on spatiotemporal measures, gait variability, and cognitive performance. We performed a multivariate regression subanalysis on athletes who reported time since injury (n = 23) to assess temporal effects on gait and cognitive performance. Results: Athletes with and without a histoiy of ankle sprains had comparable spatiotemporal and gait variability outcomes during single- (P = .42; P = .13) and dual-task (P = .75; P = .55) conditions. Additionally, ankle sprain injury history did not significantly influence cognitive performance (P = .35). Finally, time since ankle sprain did not significantly affect single- (P = .75) and dual-task gait (P = .69), nor cognitive performance (P = 19). Conclusions: Ankle sprain injury history did not significantly alter spatiotemporal gait outcomes nor cognitive performance during this common clinical assessment. Future studies may consider including athletes with ankle sprain injury history during concussion assessments. [ABSTRACT FROM AUTHOR]

Context: To assess the reliability of a remote 2D markerless motion tracking method (Kinovea) to quantify knee and hip angles during dynamic tasks. Methods: Fourteen healthy adults performed body weight squats and lateral lunges while video recording themselves at home. Knee and hip angles were quantified in the sagittal plane for the squats and in the frontal plane for the lateral lunges. Two students each performed the video analysis procedure twice, 2 weeks apart. Intraclass correlation coefficients were used to calculate the intrarater and interrater reliability for angles at maximum depth. The intrarater and interrater agreement over the joint angle-time signals were quantified using a validation metric; an acceptable agreement threshold was set at a validation metric of 0.803 or higher. Standard error of measurement (SEM) was also calculated. Results: Reliability was good to excellent (intraclass correlation coefficients = .80-.98) for all angle comparisons at maximum depth. The agreement over the entire joint angle-time signal was acceptable for all squat variables except for the interrater hip angle comparison (validation metric = 0.797). None of the lateral lunge variables met the threshold of acceptable agreement. The mean SEM across participants for all joint angle-time signal and for maximum depth was acceptable (<5°) for all measurements (SEM = 1.2°-4.9°). Conclusions: Overall, the reliability, agreement, and SEM quantified in this study support the integration of remote methods to quantify lower-extremity kinematics into research and clinical practice. [ABSTRACT FROM AUTHOR]

Context: Early identification of incoming military personnel at elevated odds for bone stress injury (BSI) is important for the health and readiness of the US military. Design: Prospective cohort study. Methods: Knee kinematic data of the incoming US Military Academy cadets were collected while performing a jump-landing task (The Landing Error Scoring System) using a markerless motion capture system and depth camera. Data on incidence of lower-extremity injury, including BSI, were collected throughout the study period. Results: A total of 1905 participants (452 females, 23.7%) were examined for knee valgus and BSI status. A total of 50 BSI occurred during the study period (incidence proportion = 2.6%). The unadjusted odds ratio for BSI at initial contact was 1.03 (95% confidence interval [CI], 0.94–1.14; P =.49). Adjusted for sex, the odds ratio for BSI at initial contact was 0.97 (95% CI, 0.87–1.06; P =.47). At the instant of maximum knee-flexion angle, the unadjusted odds ratio was 1.06 (95% CI, 1.02–1.10; P =.01), and the odds ratio was 1.02 (95% CI, 0.98–1.07; P =.29) after adjusting for sex. This suggests that there was not a significant enough association for an increase in the odds of BSI based on either degree of knee valgus. Conclusions: Our results did not demonstrate an association between knee valgus angle data during a jump-landing task and future increased odds of BSI in a military training population. Further analysis is warranted, but the results suggests the association between kinematics and BSI cannot be effectively screened by knee valgus angle data in isolation. [ABSTRACT FROM AUTHOR]

Context: Different resistance exercise determinants modulate the musculotendinous adaptations following eccentric hamstring training. The Nordic Hamstring Exercise (NHE) can be performed 2-fold: the movement velocity irreversibly increases toward the end of the range of motion or it is kept constant. Design: This cross-sectional study aimed to investigate if the downward acceleration angle (DWAangle) can be used as a classification parameter to distinguish between increasing and constant velocity NHE execution. Furthermore, the kinetic and kinematic differences of these 2 NHE execution conditions were examined by analyzing the DWAangle in relation to the angle of peak moment. Methods: A total of 613 unassisted NHE repetitions of 12 trained male sprinters (22 y, 181 cm, 76 kg) were analyzed. Results: The majority of analyzed parameters demonstrated large effects. NHEs with constant velocity (n = 285) revealed significantly higher impulses (P <.001; d = 2.34; + 61%) and fractional time under tension (P <.001; d = 1.29; +143%). Although the generated peak moments were significantly higher for constant velocity (P =.003; d = 0.29; +4%), they emerged at similar knee flexion angles (P =.167; d = 0.28) and revealed on average just low relationships to the DWAangle ( R mean 2 = 22.4 %). DWAangle highly correlated with the impulse ( R mean 2 = 60.8 %) and δ (DWAangle–angle of peak moment; R mean 2 = 83.6 %). Conclusions: Relating DWAangle to angle of peak moment assists to distinguish between significantly different NHE execution, which will potentially elicit different musculotendinous adaptations. These insights are essential for coaches and athletes to understand how to manipulate eccentric hamstring training to change its purpose. [ABSTRACT FROM AUTHOR]

A non-slip constraint between a particle and a wall is applied at the microscopic level of collision dynamics using the rough sphere model. We analyze the consequences of the translation–rotation coupling of a rough sphere confined between two parallel planar walls and establish that shearing the walls past each other (i) preferentially deposits energy into the rotational degree of freedom and (ii) results in a bounded oscillation of the energy of the confined particle. [ABSTRACT FROM AUTHOR]

Context: Laboratorial 3-dimensional kinematic analyses have shown changes in the single-leg squat's (SLS) pattern of patients with femoroacetabular impingement syndrome (FAIS). However, it is unknown whether clinicians are able to detect these changes using 2-dimensional kinematics. Objective: To compare the frontal plane 2-dimensional kinematics of patients with FAIS and asymptomatic individuals in the SLS test performed in a clinical setting. Design: Case-control study. Setting: Physical therapy clinic. Participants: Twenty men with bilateral FAIS and 20 asymptomatic men. Main Outcome Measures: Two-dimensional kinematic analysis was collected in the frontal plane during the execution of the SLS test. The outcomes were squat depth, pelvic drop (pelvis angle relative to the horizontal plane), hip adduction (femur angle relative to the pelvis), and knee valgus (femur angle relative to the tibia). Results: Most and least painful limbs of patients with FAIS had squat depth (9.8% [2.9%] and 9.5% [3.1%] of height), pelvic drop (4.2° [3.9°] and 3.7° [4.2°]), hip adduction (74.9° [5.8°] and 75.9° [5.7°]), and knee valgus (4.0° [11.0°] and 5.0° [9.9°]) similar to asymptomatic individuals (9.0% [2.3%], 4.8° [2.6°], 73.7° [4.9°], and −1.7° [8.5°]; P >.05 for all). Conclusion: The frontal plane 2-dimensional kinematic analysis of the SLS test in the clinical setting is not able to distinguish patients with FAIS from asymptomatic individuals. [ABSTRACT FROM AUTHOR]

Objectives: Although nonsurgical and surgical management of knee arthrofibrosis has been reported in the literature, there is little information on the effect of procedural treatment modalities of refractory arthrofibrosis on clinical outcomes. The purpose of this case report is to describe the intervention of refractory knee arthrofibrosis after anterior cruciate ligament reconstruction and investigate long-term clinical outcomes after procedural intervention. Methods: A 27-year-old male presented with decreased range of motion (ROM), patellar mobility, strength, and knee joint function following anterior cruciate ligament reconstruction of his left knee. After failed conservative management, the patient underwent manipulation under anesthesia (MUA) to release scar tissue. Following MUA, the emphasis of comprehensive physiotherapy was on decreasing inflammation, relieving pain, and maintaining patellar mobility while increasing knee joint ROM and strength. Knee ROM, patellofemoral motion, gait, and quadriceps recruitment were measured 3, 6, 12, and 24 months after MUA. Results: At 2-year follow-up after MUA, the patient continued to present with decreased ROM and quadriceps strength compared to the contralateral knee, but had returned to a running program and reported knee joint dysfunction no longer interfered with his daily activities. Conclusions: This case report demonstrates signs and symptoms that could indicate knee arthrofibrosis and introduces procedural intervention for refractory arthrofibrosis after anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

Context: Excessive hip adduction and internal rotation are abnormal movements that may lead to the onset and progression of patellofemoral pain. Previous studies have reported that lower dynamic frontal plane hip joint stiffness in the gait of women is associated with the magnitude of hip adduction and internal rotation angles. However, the factors contributing to the lack of dynamic frontal plane hip joint stiffness in the gait of young women are unclear. This study aims to investigate the factors affecting dynamic frontal plane hip joint stiffness during the weight-acceptance phase of the gait of healthy young women. Design: Cross-sectional study. Methods: This study included 30 healthy women between the ages of 18 and 30 years. The pelvic width/femur length ratio was calculated by dividing the pelvic width by the femur length. Data on hip kinematics and kinetics and activation of the gluteus maximus and medius, tensor fasciae latae, and adductor longus muscles during gait were collected using a motion capture system, force plates, and surface electromyography. Stepwise multiple regression analysis was conducted to determine the extent to which each independent factor affected dynamic frontal plane hip joint stiffness. Results: In healthy young women, decreased dynamic frontal plane hip joint stiffness was associated with decreased muscle activity of the gluteus maximus during the gait, as well as greater pelvic width/femur length ratio. Conclusions: Women with a relatively great pelvic width relative to femur length may have more difficulty in producing dynamic frontal plane hip joint stiffness. However, increasing the muscle activity of the gluteus maximus may contribute to increased dynamic frontal plane hip joint stiffness. [ABSTRACT FROM AUTHOR]

Context: Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration–deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7 d) and when asymptomatic (≤72 h of symptom resolution). Design: Prospective, cohort laboratory study. Methods: Ten concussed (60% male; 19.2 [0.9] y; 178.7 [14.0] cm; 71.3 [18.0] kg) and 10 matched controls (60% male; 19.5 [1.2] y; 176.1 [12.6] cm; 71.0 [17.0] kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6's or 7's) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task. Results: We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03 N·m/body weight; P =.048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09 s; P =.015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥.051). Conclusions: Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research. [ABSTRACT FROM AUTHOR]

Context: Ball velocity for baseball pitchers is influenced by a multitude of factors along the kinetic chain. While a vast amount of data currently exist exploring lower-extremity kinematic and strength factors in baseball pitchers, no previous study has systematically reviewed the available literature. Objective: The aim of this systematic review was to perform a comprehensive assessment of the available literature investigating the association between lower-extremity kinematic and strength parameters and pitch velocity in adult pitchers. Evidence acquisition: Cross-sectional studies that investigated the association between lower-body kinematic and strength factors and ball velocity in adult pitchers were selected. A methodological index for nonrandomized studies checklist was used to evaluate the quality of all included studies. Evidence synthesis: Seventeen studies met the inclusion criteria comprising a total of 909 pitchers (65%, professional, 33% college, and 3% recreational). The most studied elements were hip strength and stride length. The mean methodological index for nonrandomized studies score was 11.75 of 16 (range = 10-14). Pitch velocity was found to be influenced by several lower-body kinematic and strength factors including the following: (1) hip range of motion and strength of muscles around the hip and pelvis, (2) alterations in stride length, (3) alterations in lead knee flexion/extension, and (4) several pelvic and trunk spatial relationships throughout the throwing phase. Conclusions: Based on this review, we conclude that hip strength is a well-established predictor of increased pitch velocity in adult pitchers. Further studies in adult pitchers are needed to elucidate the effect of stride length on pitch velocity given mixed results across multiple studies. This study can provide a basis for trainers and coaches to consider the importance of lower-extremity muscle strengthening as a means by which adult pitchers can improve pitching performance. [ABSTRACT FROM AUTHOR]

OBJECTIVE: There is no consensus on which sit-up strategy to adopt in knee osteoarthritis patients of different ages. Therefore, this study evaluated the biomechanical characteristics of sit-ups in knee osteoarthritis patients of different ages compared with healthy individuals by meta-analysis system and analyzed the sit-up movement patterns of patients of different ages to provide a reference for improving the sit-up function of patients. METHODS: By March 2023, observational studies of biomechanical characteristics of sitting up in patients with knee osteoarthritis and healthy population were retrieved on PubMed, Web of Science and CNKI. Subjects were required to be patients over 50 years of age with knee osteoarthritis who had KellgrenLawrence severity grading ≥I on knee imaging and who had regular knee pain. Subjects were analyzed by age (50-60 years vs. over 60 years) and severity (mild to moderate patients vs. severe patients) subgroups according to inclusion and exclusion criteria. Quality assessment was performed using the modified Down and black scale. Stata 16.0 software was used to perform subgroup analysis to determine the biomechanical characteristics of sitting up in patients with knee osteoarthritis of different ages and severities. RESULTS: A total of 14 randomized controlled trials (824 subjects) were included in the meta-analysis. The mean quality score of all included literature was 76.2, with a range of 66.7 to 86.7, all of which were of medium to high quality and representative. The included studies were of moderate to high quality and representative. Meta-analysis results found that (1) compared to healthy individuals, patients with knee osteoarthritis had longer total sitting up time (SMD=0.92, 95%CI:0.76-1.09), P < 0.001) and longer extension phase time (SMD=0.46, 95%CI:0.18-0.74, P=0.001). Compared to mild to moderate patients, the total duration increased more significantly in severe patients (P < 0.001) and the duration of the extension phase increased more significantly in patients over 60 years of age than in patients 50-60 years of age (P=0.001). (2) Compared to healthy individuals, patients with knee osteoarthritis had greater sitting-up trunk flexion motion range (SMD=0.64, 95%CI:0.37-0.91, P < 0.001); knee flexion motion range (SMD=-0.47, 95%CI: -0.70 to -0.24, P < 0.001) and ankle dorsiflexion motion range (SMD=-0.32, 95%CI:-0.56 to -0.08, P=0.01) were smaller. And knee flexion motion range decreased more significantly in patients over 60 years of age than in patients 50-60 years of age (P < 0.001). (3) The peak hip flexion moment (SMD=-0.57, 95%CI:-0.83 to -0.31, P < 0.001) and peak knee extension moment (SMD=-0.83, 95%CI:-1.08 to -0.59, P < 0.001) were smaller in patients with knee osteoarthritis. CONCLUSION: (1) Patients with knee osteoarthritis over the age of 60 years have a longer sit-up cushion and extension phase than patients aged 50 to 60 years. The increase in total sit-up duration was also more pronounced in patients with higher severity grades. The increased length of sitting up in patients with advanced age and knee osteoarthritis severity may increase the duration of cartilage loading, exacerbate knee pain symptoms, and increase the difficulty of sitting up in this population. (2) Patients with knee osteoarthritis exhibit limited knee and ankle flexion motion range. Knee mobility is more limited in patients over 60 years of age. (3) Patients with knee osteoarthritis have reduced peak hip flexion and knee extension moments, which may be a compensatory strategy for pain relief. [ABSTRACT FROM AUTHOR]

Currently, cranes used at sea are insufficient in efficiency. Accordingly, a floating multi-robot coordinated towing system is proposed to meet offshore towing needs. However, the towing robot is prone to overturning because of the system's utilization of rope-driven robot flexibility and its floating attributes in fluid environments. First, the kinematics and dynamics of the towing system are analyzed through coordinate transformations and hydrodynamic theory. Subsequently, physical modeling of the towing system is conducted, with an emphasis on analyzing the system's fluid-structure coupling properties, supplemented by illustrative examples. Finally, the stability of the floating robot is assessed based on ship stability theory, encompassing analyses of the rope tension effects, size and shape of the floating base, and external environmental factors influencing system stability. Results show that the special shape of the floating base is beneficial in reducing water resistance and improving the stability of the floating robot in the flow field. The results provide a good basis for the system structural design and application. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was fourfold: (1) to quantify acceleration, velocity, and phase overlap for each phase of the stroke cycle (SC) during 200 m front crawl; (2) for each variable, to identify any differences between the four SC phases; (3) to investigate changes in variables during the 200 m; (4) to explore any association between performance and each variable. Methods: Ten swimmers performed a 200 m maximum swim. Four SCs were analyzed, one for each 50 m, using three-dimensional methods. Each SC was split into four phases: entry, pull, push, and recovery. Center of mass (CM) acceleration; maximum, minimum, and average CM velocity; phase duration, and, overlap of a phase of one arm with each phase of the opposite arm were calculated. Results and Conclusion: Phase velocities were positively correlated with performance and decreased during the 200 m. The acceleration data showed high within and between-swimmer variability. When the entry of one arm overlapped with the pull, and sometimes push, phase of the opposite arm, it was propulsive for the whole body. The pull was the slowest phase and overlapped predominantly with the opposite arm's recovery. The push phase was often propulsive for the whole body, regardless of the overlaps with the other arm, and together with the entry were the fastest phases. The recovery of each arm was mostly resistive for the whole body, except the short period of overlap with the opposite arm's push phase. [ABSTRACT FROM AUTHOR]

Background: After posterior cruciate ligament reconstruction (PCLR), functional deficits at the knee can persist. It remains unclear if neighboring joints compensate for the knee during demanding activities of daily living. Purpose: To assess long-term alterations in lower limb mechanics in patients after PCLR. Study Design: Descriptive laboratory study. Methods: A total of 28 patients who had undergone single-bundle unilateral isolated or combined PCLR performed stair navigation, squat, sit-to-stand, and stand-to-sit tasks at 8.2 ± 2.2 years after surgery. Motion capture and force plates were used to collect kinematic and kinetic data. Then, 3-dimensional hip, knee, and ankle kinematic data of the reconstructed limb were compared with those of the contralateral limb using statistical parametric mapping. Results: Side-to-side differences at the knee were primarily found during upward-driven movements at 8 years after surgery. The reconstructed knee exhibited lower internal rotation during the initial loading phase of stair ascent versus the contralateral knee (P =.005). During the sit-to-stand task, higher flexion angles during the midcycle (P =.017) and lower external rotation angles (P =.049) were found in the reconstructed knee; sagittal knee (P =.001) and hip (P =.016) moments were lower in the reconstructed limb than the contralateral limb. In downward-driven movements, side-to-side differences were minimal at the knee but prominent at the ankle and hip: during stair descent, the reconstructed ankle exhibited lower dorsiflexion and lower external rotation during the midcycle versus the contralateral ankle (P =.006 and P =.040, respectively). Frontal hip moments in the reconstructed limb were higher than those in the contralateral limb during the stand-to-sit task (P =.010); during squats, sagittal hip angles in the reconstructed limb were higher than those in the contralateral limb (P <.001). Conclusion: Patients after PCLR exhibited compensations at the hip and ankle during downward-driven movements, such as stair descent, squats, and stand-to-sit. Conversely, residual long-term side-to-side differences at the knee were detected during upward-driven movements such as stair ascent and sit-to-stand. Clinical Relevance: After PCLR, side-to-side differences in biomechanical function were activity-dependent and occurred either at the knee or neighboring joints. When referring to the contralateral limb to assess knee function in the reconstructed limb, concentric, upward-driven movements should be prioritized. Compensations at the hip and ankle during downward-driven movements lead to biases in long-term functional assessments. [ABSTRACT FROM AUTHOR]

Background: The understanding of noncontact anterior cruciate ligament (ACL) injury causation in soccer has improved over the past decades. Bidimensional video analyses have significantly augmented our awareness, representing to date the only practical method to describe injury biomechanics. However, the extent of the problem continues to raise serious concerns. Purpose: To advance our understanding of the causal pathways leading to ACL injury with a large-scale reconstruction of 3-dimensional (3D) whole-body joint kinematics of injuries that occurred to male elite soccer players, as well as to compare the joint angle time course among situational patterns. Study Design: Descriptive laboratory study. Methods: A total of 33 consecutive noncontact and indirect contact ACL injuries that occurred in 6 national and 2 international professional leagues (seasons 2020-2021 to 2022-2023 until December 2022) were analyzed: (1) multiview noncoaxial television images were inspected; (2) multiple camera views were taken from 400 ms before the initial ground contact to 200 ms after the injury frame; (3) a size-matched pitch was modeled and used to calibrate cameras; (4) a 3D skeletal model was adjusted to fit the player's pose in each frame/view; and (5) poses were interpolated, and Euler joint angles were extracted. Results: The authors reconstructed the 3D lower limb joint kinematic curves preceding and during ACL injuries in 33 cases; notably, a sudden external (up to 5°) and then internal knee rotation was observed after the initial contact and before the injury frame. The overall kinematics at injury were knee moderately flexed (45.9°± 21.7°), abducted (4.3°± 5.1°), and externally rotated (3.0°± 6.4°); trunk shallowly flexed (17.4°± 12.5°) and rotated and tilted toward the injured side; and hip flexed (32.0°± 18.7°), abducted (31.1°± 12.0°), and slightly internally rotated (6.6°± 12.2°). Variable behaviors were observed at the ankle level. Conclusion: Via reconstruction of the sequence of whole-body joint motion leading to injury, we confirmed the accepted gross biomechanics (dynamic valgus trend). This study significantly enriches the current knowledge on multiplanar kinematic features (transverse and coronal plane rotations). Furthermore, it was shown that ACL injuries in male professional soccer players manifest through distinct biomechanical footprints related to the concurrent game situation. Clinical Relevance: Interventions aimed at reducing ACL injuries in soccer should consider that environmental features (ie, situational patterns) affect injury mechanics. [ABSTRACT FROM AUTHOR]

Background: Improper sequencing order of maximal joint and segment velocities has been identified as an important predictor for both throwing arm kinetics and ball velocity. Purpose: To investigate the intrapitcher variation of maximal segment velocities and the relationship to throwing arm kinetics and ball velocity in high school (HS) and professional (PRO) pitchers. Study Design: Descriptive laboratory study. Methods: HS (n = 59) and PRO (n = 338) pitchers, instructed to throw 8 to 12 fastball pitches, were evaluated with 3-dimensional motion capture (480 Hz). Maximal joint and segment velocities were calculated for each pitch, and the standard deviation of the maxima was calculated per pitcher. These standard deviations were used to classify pitchers as "low variance" or "high variance" for each segmental velocity subgroup, "overall low variance" or "overall high variance" based on cumulative segment velocity variation, or "population," with any pitcher eligible to be included in multiple subcategories. Maximal velocities and throwing arm kinetics were compared among the various subgroups. Results: The HS low-variance shoulder internal rotation velocity subgroup (4949 ± 642 deg/s) had significantly lower maximal shoulder internal rotation velocity compared with HS population (5774 ± 1057 deg/s) (P <.001); similar findings were observed for PROs (5269 ± 835 vs 5824 ± 1076 deg/s; P <.001), as well as lower shoulder superior force compared with the PRO population (14.8% ± 8.8% vs 17.8% ± 8.8% body weight; P =.001). The PRO low-variance lead knee extension velocity subgroup had significantly lower maximal lead knee extension velocity (216 ± 135 vs 258 ± 125 deg/s; P =.001) and shoulder distractive force (111.5% ± 14.4% vs 115.6% ± 15.9% body weight; P =.003) compared with the PRO population. The PRO overall low-variance subgroup had significantly lower shoulder distractive force (111.8% ± 14.1% vs 119.6% ± 15.5% body weight; P =.008) and elbow anterior force (40.6% ± 5.0% vs 43.6% ± 6.2% body weight; P =.008) compared with the PRO overall high-variance subgroup. Conclusion: HS and PRO pitchers with low variance for joint and segment velocities achieved significantly lower maximal velocities in the subgroup of interest, while preserving ball velocity. PRO pitchers with overall low variance among multiple maximal joint and segment velocities demonstrated decreased shoulder distractive and elbow anterior force. Clinical Relevance: PRO pitchers with low intrapitch variation in maximal joint and segment velocities may be viewed as kinetically conservative throwers. These pitchers with similarly maintained mechanics between pitches may have an increasingly regimented form that preserves kinetic forces about the throwing arm. The opposite may be true for PRO pitchers with increased variability in segmental velocities during their pitching motion, as they showed increased throwing arm kinetics including shoulder distractive and elbow anterior force compared with the overall low-variance group, theoretically increasing their risk of injury. [ABSTRACT FROM AUTHOR]

Background: Historically, it was assumed by some that high leg lift with windup pitching generated more ball velocity whereas pitching from the stretch was quicker to reduce the risk of base stealing but also more stressful on the arm. However, many now believe that velocity and stress do not differ between windup and stretch and always pitching from the stretch is simpler than mastering 2 techniques. Purpose/Hypothesis: The purpose of this study was to compare windup and stretch fastball pitching biomechanics. It was hypothesized that there would be statistically significant and clinically important differences in ball velocity, timing of angular velocities, joint kinetics, and pitching kinematics. Study Design: Controlled laboratory study. Methods: Fastball pitching biomechanics previously captured for 221 healthy baseball pitchers (105 professional, 52 collegiate, and 64 high school level) were analyzed. For each pitcher, data for 3 to 10 windup trials and 3 to 10 stretch trials were available. Ball velocity was recorded using a radar gun. A 12-camera, 240-Hz automated motion capture system was used to track 39 reflective markers attached to the pitcher. A total of 24 kinematic parameters, 4 temporal parameters, and 5 kinetic parameters were calculated. Data for each parameter were compared across the 2 techniques and 3 competition levels using 2-way repeated-measures analysis of variance (P <.01). Based on previous studies and the expertise of the investigators, the minimal clinically important difference (MCID) was set as 2° for angle measurements, 20 deg/s for angular velocities, 0.5 m/s for fastball velocity, and 0.3% body height × weight for normalized joint torque. Results: Fastball velocity was statistically greater from the windup than stretch for the collegiate subgroup but not for the other 2 levels. The collegiate level difference was below the MCID. Pitching from the windup generated greater front knee height and required more time from initiation of leg lift to front foot contact. From foot contact to ball release, there were 11 additional small, statistically significant differences between windup and stretch; however, each of these was well below the MCID. Conclusion: Pitching from the stretch was quicker and should be used with runners on base to prevent stealing. Pitching from the windup and stretch produced similar ball velocity, joint kinetics, and kinematics. Thus, pitchers may choose to use both techniques or stretch only based on comfort and personal preference. Clinical Relevance: The decision to pitch from both the windup and stretch or only from the stretch should not affect a pitcher's performance or joint stress (and injury risk). [ABSTRACT FROM AUTHOR]

Background: Tumor-like distal femoral cortical irregularities (DFCIs) are a frequent incidental finding on knee magnetic resonance imaging (MRI) and are common in young competitive athletes. Purpose: To assess and compare the morphology and prevalence of DFCIs in competitive alpine skiers over 48 months during adolescence. Study Design: Case series; Level of evidence, 4. Methods: Adolescent competitive alpine skiers were prospectively recruited in 2018 and received bilateral 3-T MRI of the knee at baseline and after 48 months. All MRIs were evaluated for the presence and location of DFCIs, which were marked at 1 of 3 anatomic positions: (1) the femoral attachment of the medial head of the gastrocnemius muscle, (2) the lateral head of the gastrocnemius muscle, or (3) the attachment of the adductor magnus aponeurosis. The size of the DFCI was measured by 2 radiologists independently. The measurements were compared using the Wilcoxon signed-rank test, the interclass correlation coefficient (ICC), and Cohen Kappa. Results: A total of 63 athletes (mean age at follow-up, 19.6 ± 1.2 years; n = 25 female) were included in the study. At baseline, DFCIs were detected in 84 out of 126 knees (67%). At the 48-month follow-up, DFCIs were found in 88 out of 126 knees (70%), with multiple DFCIs in 3 knees and no significant difference between male and female patients (n = 24 male, n = 19 female; P =.71). No significant increase was detected for the number (P =.21) and size of the DFCIs between the baseline and the 48-month follow-up (mean size: baseline, 3.7 ± 0.8 mm; 48-month follow-up: 3.6 ± 0.9 mm; P =.66). The interrater agreement for the mean size measurements of DFCIs was good to excellent (ICC 0.88). Conclusion: DFCIs remain a frequent finding on knee MRI in competitive alpine skiers after skeletal maturation and do not disappear during adolescence. The DFCI size was constant in athletes aged between 15 and 19 years. Moreover, DFCIs should not be mistaken for a pathologic finding. [ABSTRACT FROM AUTHOR]

Purpose: The pivot‐shift test is used to clinically assess knee instability in patients with anterior cruciate ligament (ACL) lesions; however, it has low interobserver reliability. Dynamic radiostereometry (dRSA) is a highly precise and noninvasive method for the objective evaluation of joint kinematics. The purpose of this study was to quantify precise knee kinematics during a pivot‐shift test using dRSA imaging. Method: Eight human donor legs, including hemipelvises, were evaluated. Arthroscopic intervention was performed inducing ligament lesions in the ACL, and anterolateral ligament (ALL) section was performed as a capsular incision. The pivot‐shift test was recorded with dRSA on knees with intact ligaments, ACL‐deficient and ACL + ALL‐deficient knees. Results: A pivot‐shift pattern was identifiable after ligament lesion, as a change in tibial posterior drawer velocity from 7.8 mm/s (95% CI: 3.7; 11.9) in ligament intact knees to 30.4 mm/s (95% CI 23.0; 38.8) after ACL lesion to 35.1 mm/s (95% CI 23.4; 46.7) after combined ACL‐ALL lesion. The anterior‐posterior drawer excursion increased from 2.8 mm (95% CI 2.1; 3.4) in ligament intact knees to 7.2 mm (95% CI 5.5; 8.9) after ACL lesion to 7.6 mm (95% CI 5.5; 9.8) after combined lesion. A statistically significant increase in tibial external rotation towards the end of the pivot‐shift motion was observed when progressing from intact to ACL + ALL‐deficient knees (p < 0.023). Conclusion: This experimental study demonstrates the feasibility of dRSA to objectively quantify the kinematic laxity patterns of the knee during the pivot‐shift test. The dynamic parameters obtained through dRSA revealed the kinematic changes from ACL to combined ACL‐ALL ligament lesion. Level of Evidence: Not applicable. [ABSTRACT FROM AUTHOR]

The decline in cognitive function in older adults with mild cognitive impairment (MCI) may contribute to a change in movement pattern during sit-to-stand transitions (STS). However, when comparing older adults with MCI to older adults without MCI, there is a lack of evidence of kinematic and kinetic data during STS. Furthermore, while significant cognitive dual-task interference has been demonstrated in older adults with MCI, studies on the effects of dual motor tasks in MCI, particularly during STS, have not been reported. Are there any differences in the movement time, joint angles, and maximum joint moments while performing STS under single- and dual-task conditions in older adults with and without MCI? In a cross-sectional study, 70 participants were divided into two groups: older adults with MCI and without MCI. Motion analysis and a force plate system were used to collect and analyze the STS movement. All participants were asked to do the STS movement alone and the STS with a dual motor task with the self-selected pattern on an adjustable bench. Older adults with MCI had greater maximum trunk flexion during STS with a dual task than older adults without MCI and greater than STS alone. Furthermore, older adults with MCI had a greater ankle plantar flexion moment during STS with a dual task than during STS alone. Even though the STS task is one of the simplest functional activities, different strategies to achieve the STS action with dual tasks were found among older adults with and without MCI in terms of joint angle and joint moments. • The time used for STS showed no difference between older adults with and without MCI. • STS with dual tasks spent more time to complete than STS alone. • Older adults with MCI perform more trunk flexion during STS with dual tasks. • Older adults with MCI rely on the ankle plantar flexor during STS with dual tasks. [ABSTRACT FROM AUTHOR]

As total ankle arthroplasty (TAA) is an increasingly common surgical intervention for patients with end-stage ankle arthritis, there is a need to better understand the dynamic performance of prosthetic implants during activities of daily living. Our purpose was to quantify and compare relative tibiotalar motion during gait in persons with a fixed-bearing (FB) and mobile-bearing (MB) total ankle arthroplasty. We hypothesized a FB prosthesis would have lower tibiotalar range of motion (ROM). Patients at least 12 months postoperative with either a FB (n=5) or MB (n=3) total ankle arthroplasty were tested. We used high-speed biplanar videoradiography to quantify tibiotalar kinematics during self-selected gait. Angular and linear ROM in three axes were compared between the groups. ROM for dorsiflexion-plantarflexion, internal-external rotation, and inversion-eversion angles in FB subjects averaged 7.47±4.05°, 7.39±3.63°, and 4.51±2.13°, respectively. ROM in MB subjects averaged 6.74±2.04°, 6.28±4.51°, and 5.68±2.81°, respectively. Linear ROM along anteroposterior, mediolateral, and superior-inferior axes in FB subjects averaged 1.47±2.07 mm, 1.13±1.49 mm, and 0.28±0.30 mm, respectively. Linear ROM in MB subjects averaged 0.68±1.44 mm, 0.60±1.41 mm, and 0.20±0.13 mm, respectively. We found no significant difference between the two groups for any of these ROM parameters (p>0.05). Total ankle arthroplasty using either FB or MB design appears to confer similar ankle motion during the gait cycle in this biplanar fluoroscopic model. Level IV, case series. • X-ray motion analysis is a useful tool to compare ankle arthroplasty systems. • No differences in angular motion between MB and FB arthroplasty systems. • No significant difference in linear translation along joint axes in both systems. [ABSTRACT FROM AUTHOR]

Clinical gait analysis (CGA) is a systematic approach to comprehensively evaluate gait patterns, quantify impairments, plan targeted interventions, and evaluate the impact of interventions. However, international standards for CGA are currently lacking, resulting in various national initiatives. Standards are important to ensure safe and effective healthcare practices and to enable evidence-based clinical decision-making, facilitating interoperability, and reimbursement under national healthcare policies. Collaborative clinical and research work between European countries would benefit from common standards. This study aimed to review the current laboratory practices for CGA in Europe. A comprehensive survey was conducted by the European Society for Movement Analysis in Adults and Children (ESMAC), in close collaboration with the European national societies. The survey involved 97 gait laboratories across 16 countries. The survey assessed several aspects related to CGA, including equipment used, data collection, processing, and reporting methods. There was a consensus between laboratories concerning the data collected during CGA. The Conventional Gait Model (CGM) was the most used biomechanical model for calculating kinematics and kinetics. Respondents also reported the use of video recording, 3D motion capture systems, force plates, and surface electromyography. While there was a consensus on the reporting of CGA data, variations were reported in training, documentation, data preprocessing and equipment maintenance practices. The findings of this study will serve as a foundation for the development of standardized guidelines for CGA in Europe. • Survey report on current Clinical Gait Analysis (CGA) practices across Europe. • Good agreement on data included in CGA with video, kinematics, kinetics and EMG. • Training, documentation, maintenance, reliability evaluations vary between laboratories. • New gait analysis tools have limited adoption in CGA. • Results set foundation for a Delphi process to define European CGA standards. [ABSTRACT FROM AUTHOR]

The subtalar joint movement between the talus and calcaneus is restricted in patients with talocalcaneal coalition (TCC). When the motion of the subtalar joint is restricted, shock absorption in the foot decreases, leading to pain during walking. Resection methods to maintain subtalar motion by removing abnormal unions have been proposed. The purpose of this study was to analyze the joint kinematics of patients who underwent TCC resection and to quantitatively evaluate the results of the surgery based on the measured kinematics. Joint kinematics of five patients with TCC were obtained using a biplane fluoroscopic imaging system and an intensity-based two-/three-dimensional registration method. The joint kinematics of the tibiotalar and subtalar joints and the tibiocalcaneal motion during the stance phase of walking were obtained. From the kinematics of the hindfoot joints, the inversion/eversion range of motion (ROM) of the patients before and after resection was statistically analyzed using the Wilcoxon signed-rank test to test whether TCC resection improved the ROM. During the loading response period, the eversion ROM of the subtalar joint and tibiocalcaneal motion significantly increased postoperatively. In addition, a significant postoperative increase was observed in the subtalar and tibiocalcaneal inversion ROM during the pre-swing period. TCC resection surgery increased the ROM of the subtalar joint, which in turn contributed to the increase in tibiocalcaneal ROM. Increased subtalar and tibiocalcaneal ROM could result in increased shock attenuation and may be a contributing factor to pain relief during walking. [ABSTRACT FROM AUTHOR]

Individuals with cerebral palsy (CP) often present with altered motor control. This can be assessed selectively during sitting/lying with the Selective Control Assessment of the Lower Extremity (SCALE), or dynamically with the dynamic motor control index during walking (walk-DMC). Both approaches suggest that altered selective motor control relate to larger gait deviations. Does the walk-DMC provide valuable information in addition to the SCALE for estimating gait deviations in individuals with CP. Retrospective, treadmill-based gait analysis data of 157 children with spastic CP (mean 11.4±3.5 years) and Gross Motor Function Classification System levels I (n=45), II (n=88) or III (n=24) were extracted. Gait kinematic deviations were evaluated using the Gait Profile Score (GPS). The SCALE, walk-DMC and GPS were extracted for the more clinically involved leg (unilateral-analysis), and for both legs together (bilateral-analysis). GPS moderately correlated with both SCALE and walk-DMC scores, unilaterally and bilaterally (r≥0.4; p<0.001). Multivariate linear regression analyses were conducted, taking into account potential confounding factors. In the unilateral analysis, 54% of the GPS variance was explained (p<0.001), with both walk-DMC and SCALE significantly contributing to the GPS variance (p=0.006 and p=0.008, respectively). In the bilateral analysis, 61% of the GPS variance was explained (p<0.001), with both walk-DMC and SCALE significantly contributing to the GPS variance (p=0.006 and p<0.001, respectively). Dimensionless walking speed and use of assistive devices were the only confounding factors included in each analysis. Both SCALE and walk-DMC significantly contribute to GPS variance, suggesting that they likely measure different components of motor control, and both may be useful in understanding the underlying relationship between motor control and deviations in gait kinematics. • Both the SCALE and walk-DMC relate to kinematic gait deviations in CP. • The SCALE and walk-DMC likely measure different components of motor control in CP. • In the absence of EMG, the SCALE can be used to quantify motor control in CP. [ABSTRACT FROM AUTHOR]

Our purpose in this study was to determine the effects of a virtual reality intervention delivering specific motivational motor learning manipulations of either autonomy support (AS) or enhanced expectancies (EE) on frontal plane single-leg squatting kinematics. We allocated 45 participants (21 male, 24 female) demonstrating knee, hip, and trunk frontal plane mechanics associated with elevated anterior cruciate ligament injury risk to one of three groups (control, AS, or EE). Participants mimicked an avatar performing five sets of eight repetitions of exemplary single-leg squats. AS participants were given the added option of choosing the color of their avatar. EE participants received real-time biofeedback in the form of green highlights on the avatar that remained on as long as the participant maintained pre-determined 'safe' frontal plane mechanics. We measured peak frontal plane knee, hip, and trunk angles before (baseline) and immediately following (post) the intervention. The control group demonstrated greater increases in knee abduction angle (Δ = +2.3°) than did the AS (Δ = +0.1°) and EE groups (Δ = −0.4°) (p =.003; η2p =.28). All groups demonstrated increased peak hip adduction (p =.01, ηp2 =.18) (control Δ = +1.5°; AS Δ = +3.2°; EE Δ = +0.7°). Hip adduction worsened in all groups. AS and EE motivation strategies appeared to mitigate maladaptive frontal plane knee mechanics. [ABSTRACT FROM AUTHOR]

Most children with Autism Spectrum Disorder (ASD) have some form of motor deficits. Additionally, based on executive dysfunction, working memory is often atypical in these children. Errorless learning reduces demands on working memory. In this study, we investigated the effectiveness of errorless training on these children's ability to learn golf putting. Participants (N = 20), aged 9–13 years (M = 10.15, SD = 1.4), were randomly assigned to either: (a) an errorless (ER) training group (n = 10) or (b) an explicit instruction (EI) group (n = 10). The ER group practiced putting from different distances without any instruction, while the EI group practiced putting at a particular distance with instruction. We measured motor performance (e.g., putting accuracy) and kinematic variables (e.g., putter face angle). One-way analyses of variance showed that motor performance significantly improved in both groups, but that the ER group showed significantly better accuracy retention (p <.028) and transfer learning (p <.047) than the instructional group. Kinematic variables were also significantly different between the two groups on the transfer test. These findings supported the benefits of errorless training compared to explicit instruction to teach motor skills to children with ASD. [ABSTRACT FROM AUTHOR]

Post-error slowing (PES), the tendency to slow down a behavioral response after a previous error, has typically been investigated during simple cognitive tasks using response time as a measure of PES magnitude. More recently, PES was investigated during a single reach-to-grasp task to determine where post-error adjustments are employed in a more ecological setting. Kinematic analyses in the previous study detected PES during pre-movement planning and within the grasping component of movement execution. In the current study (N = 22), we increased the cognitive demands of a reach-to-grasp task by adding a choice between target and distractor locations to further explore PES, and other post-error adjustments, under different task conditions. We observed a significant main effect of task condition on overall reaction time (RT); however, it did not significantly impact PES or other post-error adjustments. Nonetheless, the results of this study suggest post-error adjustment is a flexible process that can be observed during pre-movement planning and within the onset and magnitude of the reaching component, as well as in the magnitudes of the grasping component. Considering the sum of the results in the context of existing literature, we conclude that the findings add support to a functional account of error reactivity, such that post-error adjustments are implemented intentionally to improve performance. [ABSTRACT FROM AUTHOR]

BACKGROUD: The control of hip and ankle joint movement is important for patients with dynamic knee valgus (DKV), but few studies have used non-elastic taping (NET) to adjust alignment of the hip and ankle joints during overhead squat (OHS) simultaneously in patients with DKV. OBJECTIVE: We investigated changes in lower extremity joint kinematics and dynamic balance after the application of NET to the hip and ankle joints during OHS. METHODS: A total of 30 DKV patients participated in this study. We determined the kinematics of the hip, knee, and ankle joints, and scores on the lower quarter Y-balance test (YBT-LQ) during OHS under three conditions (non-taping, NET on hip and ankle, and sham taping). RESULTS: Hip internal rotation, knee valgus, and the ankle dorsiflexion angle were significantly lower with NET than with non- or sham taping. The hip flexion angle and scores on the YBT-LQ were significantly greater with NET than with non- or sham taping. CONCLUSIONS: The application of NET while performing a OHS is a useful method for correcting lower extremity alignment in patients with DKV, however, application of NET on the ankle should be considered. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the last decades, emerging evidence has shown that muscle growth is not homogeneous along a muscle head. This phenomenon is known as regional muscle hypertrophy and has led to several questions regarding the implications it may have for health and sports performance. OBJECTIVE: The aim of this study was to determine whether regional hypertrophy can be predicted by surface electromyography (sEMG). METHODS: 36 participants performed two arm exercises (preacher curls and inclined curls) in a random order to muscle failure at 70% of the 1 RM of the bicep curl exercise. As every participant performed a different number of repetitions, Peak sEMG and the integral of the sEMG of the last 3 repetitions was analyzed an compared to previously performed maximal voluntary isometric contractions (MVIC). RESULTS: The independent sample t -tests showed no significant differences neither in the peak nor in the integral of the sEMG between exercises for any given region. CONCLUSIONS: sEMG cannot be used to predict regional hypertrophy. [ABSTRACT FROM AUTHOR]

Although it is known that the availability of visual feedback modulates grasping kinematics, it is unclear whether this extends to both the early and late stages of the movement. We tackled this issue by exposing participants to the Uznadze illusion (a medium stimulus appears larger or smaller after exposure to smaller or larger inducers). After seeing smaller or larger discs, participants grasped a medium disc with (closed-loop [CL]) or without (open-loop [OL]) visual feedback. Our main aim was to assess whether the time course of the illusion from the movement onset up to the grasp differed between OL and CL. Moreover, we compared OL and CL illusory effects on maximum grip aperture (MGA) and tested whether preparation time, movement time, and time to MGA predicted illusion magnitude. Results revealed that CL illusory effects decreased over movement time, whereas OL ones remained constant. At the time of MGA, OL, and CL effects were, however, of similar size. Although OL grasps were longer to prepare and showed earlier and larger MGAs, such differences had little impact on modulating the illusion. These results suggest that the early stage of grasping is sensitive to the Uznadze illusion both under CL and OL conditions, whereas the late phase is sensitive to it only under OL conditions. We discuss these findings within the framework of theoretical models on the functional properties of the dorsal stream for visually guided actions. [ABSTRACT FROM AUTHOR]

This paper develops a theoretical basis and a systematic process for resolving all inertia forces along generalized coordinates from the overall energy equation of a dynamical system. The theory is developed for natural systems with scleronomic constraints, where the potential energy is independent of generalized velocities. The process involves expansion of the energy equation, and specifically a special expansion of the kinetic energy term, from which the inertia forces emerge. The expansion uses fundamental kinematic identities of the phase space. It is also guided by insights drawn from the structure of the Hamiltonian function. The resulting equation has the structure of the D'Alembert's equation but involving generalized coordinates, from which the Lagrange's equations of motion are obtained. The expansion process elucidates how certain inertia forces manifest in the energy equation as composite terms that must be accurately resolved along different generalized coordinates. The process uses only the system energy equation, and neither the Hamiltonian nor the Lagrangian function are required. Extension of this theory to non-autonomous and non-holonomic systems is an area of future research. [ABSTRACT FROM AUTHOR]

Propose further indicators for helping to detect hand osteoarthritis (HOA) using either active or functional ranges of motion (AROM or FROM). Hand kinematics data of 16 hand joint angles from previous studies were used, taken from healthy participants and HOA patients with differently affected joints and distinct levels of compromise. Data consisted of: (i) AROM (extreme values and ranges); (ii) FROM while performing the Sollerman Hand Function Test (mean, extreme percentiles and ranges). Two linear discriminant analyses (stepwise method) were conducted, one per dataset (AROM and FROM), with condition (healthy/patient) as the grouping variable. The potential predictors were the data from the joints with significant differences between samples for each analysis (A-predictors and F-predictors). Good sensitivity-specificity values of 85.2–90.9% and 93.8–93.9% for F-predictors and A-predictors, respectively. Sets of predictors corresponded to the joints more commonly affected by HOA. F-predictors: lower maximal flexion of carpometacarpal and interphalangeal thumb joints, higher maximal flexion of thumb metacarpal joint, lower flexion/extension range of ring proximal interphalangeal joint and higher maximal little finger adduction. A-predictors: narrower flexion/extension range of the thumb carpometacarpal joint, lesser extension of the ring metacarpophalangeal joint; lower flexion of the middle finger proximal interphalangeal joint along with a narrower palmar arch range. Both sets of predictors provide discrimination capacity of HOA with good sensitivity-specificity, slightly better for A-predictors. The AROM measurement is technically less demanding and can be clinically applied even with manual goniometry. Range of motion is affected by hand osteoarthritis even before joint deformity is noticeable. Active (AROM) or functional (FROM) ranges of motion can help to identify potential hand osteoarthritis and opening up the possibility of applying rehabilitation treatments to improve quality of life. The AROM measurement is technically less demanding and can be clinically applied even with manual goniometry. [ABSTRACT FROM AUTHOR]

Background: Optimal management and surgical planning of severe bony deformities and muscle tendon unit contractures demands comprehensive evaluation of all structures including the dynamic muscle tendon length of all muscles around the joint during gait. Objectives: Present study aimed to explore dynamic muscle–tendon length for all muscles around the knee joint along with pelvis, hip, and ankle joint kinematics among adolescent children with varying crouch angle. Methods: Muscle–tendon length of 29 adolescent children with cerebral palsy with varying crouch angles was computed using a full-body musculo-skeletal model and expressed as a percentage of muscle–tendon length during walking compared to resting condition. Results: Children with knee flexion angle greater than 25° demonstrated lower anterior pelvic tilt and 11% greater muscle–tendon length of semimembranosus and biceps femoris during stance phase of gait compared to children with knee flexion angle less than 25° and typically developing children (p < 0.01). Conclusions: The findings of present study reported that routine bedside clinical evaluation in adolescent children with knee flexion angle greater than 25° revealed moderate shortening of hamstring muscle in supine position. Whereas instrumented objective evaluation of gait demonstrated lengthened hamstring muscle and reduced hip extension and relatively lower anterior pelvic tilt. Therefore, it may be valuable to add objective assessment of dynamic muscle–tendon length to kinematics of all lower-extremity joint motion during gait, in order to understand the muscle–joint interactions; particularly in children with severe crouch and plan specific, tailor-made surgical and non-surgical interventions. [ABSTRACT FROM AUTHOR]

Study Background: Mechanical alignment has always been considered as the gold standard in total knee arthroplasty (TKA), but various other coronal alignment strategies have been proposed to enhance native knee kinematics and thus elevate patient satisfaction levels. Coronal plane alignment of the knee (CPAK) classification introduced by MacDessi is a simple yet comprehensive system to classify knees based on their coronal plane alignment. It categorizes knees into nine phenotypes based on medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). Materials and Methods: This study investigates the distribution of classification of primary arthritic knees (CPAK) types among arthritic knees in the South Indian population and compares the functional outcomes following total knee arthroplasty (TKA) using traditional mechanical alignment among various CPAK types. The research, spanning from September 2021 to August 2023, encompasses a comprehensive analysis of 324 patients with 352 knees in the first part and 48 patients with 72 knees in the second part of the study who underwent TKA, incorporating demographic data and radiological evaluations. Results: Results indicate a predominant distribution of CPAK type 1, followed by type 2 and type 4 among the South Indian population. In the functional outcomes analysis, regardless of CPAK type, patients exhibited significant improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), and visual analog scale (VAS) scores post-operatively. Conclusion: CPAK distribution among the South Indian population is comparable to other Indian study and studies with an Asian population, but varies with studies among the White population. Significant improvement of functional outcome among all CPAK types signifies the robust nature of conventional mechanical alignment strategy. Thus, our study serves as an initial exploration into the knee phenotype of the South Indian population and findings contribute to ongoing research on optimal alignment strategies in knee arthroplasty, paving the way for future, more extensive studies in this dynamic field. [ABSTRACT FROM AUTHOR]

Purpose: Muscle mechanics is paramount in our understanding of motor performance. However, little is known regarding the sensitivity of fascicle dynamics and connective tissues stiffness to exercise duration and ambient temperature during running, both increasing muscle temperature. This study aimed to determine gastrocnemius medialis (GM) fascicle dynamics in vivo during running in temperate and hot conditions, as well as muscle-tendon unit responses. Methods: Using ultrafast ultrasound, 15 participants (8 men, 7 women; 26 ± 3 yr) were tested before, during (2 and 40 min), and after a running task (40 min at 10 km⋅h-1) in temperate (TEMP; ~23°C) and hot (HOT: ~38°C) conditions. Results: Although core, skin temperatures, and heart rate increased from the beginning to the end of the exercise and in a larger extent in HOT than TEMP (P < 0.001), the physiological stress elicited did not alter running temporal parameters and GM fascicle operating lengths, with similar behavior of the fascicles on their force-length relationship, over time (2 vs 40 min) or across condition (TEMP vs HOT; P ≥ 0.248). Maximal voluntary force production did not reported statistical changes after exercise (P = 0.060), and the connective tissues stiffness measured (i.e., passive muscle and stiffness of the series-elastic elements) did not show neither time (P ≥ 0.281), condition (P ≥ 0.256) nor time-condition interaction (P ≥ 0.465) effect. Conclusions: This study revealed that prolonged running exercise does not alter muscle-tendon unit properties and interplay, which are not influenced by ambient temperature. These findings may rule out potential detrimental effects of heat on muscle properties and encourage further investigations on longer and more intense running exercise. [ABSTRACT FROM AUTHOR]

Purpose: Understanding muscle-tendon forces (e.g., triceps surae and Achilles tendon) during locomotion may aid in the assessment of human performance, injury risk, and rehabilitation progress. Shear wave tensiometry is a noninvasive technique for assessing in vivo tendon forces that has been recently adapted to a wearable technology. However, previous laboratory-based and outdoor tensiometry studies have not evaluated running. This study was undertaken to assess the capacity for shear wave tensiometry to produce valid measures of Achilles tendon loading during running at a range of speeds. Methods: Participants walked (1.34 m⋅s-1) and ran (2.68, 3.35, and 4.47 m⋅s-1) on an instrumented treadmill while shear wave tensiometers recorded Achilles tendon wave speeds simultaneously with whole-body kinematic and ground reaction force data. A simple isometric task allowed for the participant-specific conversion of Achilles tendon wave speeds to forces. Achilles tendon forces were compared with ankle torque measures obtained independently via inverse dynamics analyses. Differences in Achilles tendon wave speed, Achilles tendon force, and ankle torque across walking and running speeds were analyzed with linear mixed-effects models. Results: Achilles tendon wave speed,Achilles tendon force, and ankle torque exhibited similar temporal patterns across the stance phase of walking and running. Significant monotonic increases in peak Achilles tendon wave speed (56.0-83.8 m⋅s-1), Achilles tendon force (44.0-98.7 N⋅kg-1), and ankle torque (1.72-3.68 N⋅m⋅(kg-1)) were observed with increasing locomotion speed (1.34-4.47 m⋅s-1). Tensiometry estimates of peak Achilles tendon force during running (8.2-10.1 body weights) were within the range of those estimated previously via indirect methods. Conclusions: These results set the stage for using tensiometry to evaluate Achilles tendon loading during unobstructed athletic movements, such as running, performed in the field. [ABSTRACT FROM AUTHOR]

Objectives: Despite qualitative observations of wild primates pumping branches before leaping across gaps in the canopy, most studies have suggested that support compliance increases the energetic cost of arboreal leaping, thus limiting leaping performance. In this study, we quantified branch pumping behavior and tree swaying in wild primates to test the hypothesis that these behaviors improve leaping performance. Materials and Methods: We recorded wild colobine monkeys crossing gaps in the canopy and quantitatively tracked the kinematics of both the monkey and the compliant support during behavioral sequences. We also empirically measured the compliance of a sample of locomotor supports in the monkeys' natural habitat, allowing us to quantify the resonant properties of substrates used during leaping. Results: Analyses of three recordings show that adult red colobus monkeys (Piliocolobus tephrosceles) use branch compliance to their advantage by actively pumping branches before leaping, augmenting their vertical velocity at take‐off. Quantitative modeling of branch resonance periods, based on empirical measurements of support compliance, suggests that monkeys specifically employed branch pumping on relatively thin branches with protracted periods of oscillation. Finally, an additional four recordings show that both red colobus and black and white colobus monkeys (Colobus guereza) utilize tree swaying to cross large gaps, augmenting horizontal velocity at take‐off. Discussion: This deliberate branch manipulation to produce a mechanical effect for stronger propulsion is consistent with the framework of instrumental problem‐solving. To our knowledge, this is the first study of wild primates which quantitatively shows how compliant branches can be used advantageously to augment locomotor performance. [ABSTRACT FROM AUTHOR]

Premaxillary protrusion and the performance advantages it confers are implicated in the success of diverse lineages of teleost fishes, such as Cypriniformes and Acanthomorpha. Although premaxillary protrusion has evolved independently at least five times within bony fishes, much of the functional work investigating this kinesis relates to mechanisms found only in these two clades. Few studies have characterized feeding mechanisms in less‐diverse premaxilla‐protruding lineages and fewer yet have investigated the distinctive anatomy underlying jaw kinesis in these lineages. Here, we integrated dissection, clearing and staining, histology, micro‐CT, and high‐speed videography to investigate an isolated and independent origin of jaw protrusion in the hingemouth, Phractolaemus ansorgii, which employs a complex arrangement of bones, musculature, and connective tissues to feed on benthic detritus via a deployable proboscis. Our goals were to provide an integrative account of the underlying architecture of P. ansorgii's feeding apparatus and to assess the functional consequences of this drastic deviation from the more typical teleost condition. Phractolaemus ansorgii's cranial anatomy is distinct from all other fishes in that its adducted lower jaw is caudally oriented, and it possesses a mouth at the terminal end of an elongated, tube‐like proboscis that is unique in its lack of skeletal support from the oral jaws. Instead, its mouth is supported primarily by hyaline‐cell cartilage and other rigid connective tissues, and features highly flexible lips that are covered in rows of keratinous unculi. Concomitant changes to the adductor musculature likely allow for the flexibility to protrude the mouth dorsally and ventrally as observed during different feeding behaviors, while the intrinsic compliance of the lips allows for more effective scraping of irregular surfaces. From our feeding videos, we find that P. ansorgii is capable of modulating the distance of protrusion, with maximum anterior protrusion exceeding 30% of head length. This represents a previously undescribed example of extreme jaw protrusion on par with many acanthomorph species. Protrusion is much slower in P. ansorgii—reaching an average speed of 2.74 cm/s—compared to acanthomorphs feeding on elusive prey or even benthivorous cypriniforms. However, this reorganization of cranial anatomy may reflect a greater need for dexterity to forage more precisely in multiple directions and on a wide variety of surface textures. Although this highly modified mechanism may have limited versatility over evolutionary timescales, it has persisted in solitude within Gonorynchiformes, representing a novel functional solution for benthic feeding in tropical West African rivers. [ABSTRACT FROM AUTHOR]

Previous plasticity models for predicting anchor kinematics under eccentric loading in clay are mostly rigid plastic. They may produce inaccurate outcomes in some conditions. This paper presents an elastoplastic model to address this issue. Closed-form solutions for anchor velocities are derived considering two types of boundary conditions: the padeye (1) fastened to a mooring chain, with the chain behavior modeled; or (2) hinged to a rigid rod. Compared with previous methods, the proposed method more realistically captures the soil behavior while avoiding complicated iterative procedures for solving anchor velocities, thus enabling anchor trajectories to be accurately and efficiently obtained by simple time integration. A series of 3D large deformation finite element analyses are conducted to study the anchor behaviors under different eccentric loading, and the proposed model is used to reproduce these simulations. Their results are compared for validation, with good agreements achieved. These results indicate that anchors under eccentric loading will ultimately translate along a fixed direction with constant soil reaction forces. Analytical solutions for this ultimate state are given based on the proposed method. Particularly, the ultimate resultant soil reaction force is demonstrated always passing through the anchor center. This is an assumption in a previous literature but is found to be a consequence of the proposed anchor constitutive relations. [ABSTRACT FROM AUTHOR]

Background: Mandibular reconstruction patients often suffer abnormalities in the mandibular kinematics. In silico simulations, such as musculoskeletal modelling, can be used to predict post‐operative mandibular kinematics. It is important to validate the mandibular musculoskeletal model and analyse the factors influencing its accuracy. Objectives: To investigate the jaw opening‐closing movements after mandibular reconstruction, as predicted by the subject‐specific musculoskeletal model, and the factors influencing its accuracy. Methods: Ten mandibular reconstruction patients were enrolled in this study. Cone‐beam computed tomography images, mandibular movements, and surface electromyogram signals were recorded preoperatively. A subject‐specific mandibular musculoskeletal model was established to predict surgical outcomes using patient‐averaged muscle parameter changes as model inputs. Jaw bone geometry was replaced by surgical planning results, and the muscle insertion sites were registered based on the non‐rigid iterative closest point method. The predicted jaw kinematic data were validated based on 6‐month post‐operative measurements. Correlations between the prediction accuracy and patient characteristics (age, pathology and surgical scope) were further analysed. Results: The root mean square error (RMSE) for lower incisor displacement was 31.4%, and the error for peak magnitude of jaw opening was 4.9 mm. Age, post‐operative infection and radiotherapy influenced the prediction accuracy. The amount of masseter detachment showed little correlation with jaw opening. Conclusion: The mandibular musculoskeletal model successfully predicted short‐range jaw opening functions after mandibular reconstruction. It provides a novel surgical planning method to predict the risk of developing trismus. [ABSTRACT FROM AUTHOR]

Ascertaining how racket orientation angle differences at ball-impact influence the accuracy of different squash strokes could assist player skill development and possibly reduce the number of unforced errors hit within a match. The purpose of this study was to identify differences in racket orientation angles of accurate and inaccurate forehand and backhand drive, volley and drop shots. A magnetic-inertial measurement unit embedded in a racket output orientation angles of twelve male junior players, with five accurate and five inaccurate shots per player per stroke analysed. Paired samples t-tests revealed that inaccurate backhand drop shots exhibited significantly (p < 0.05) less racket roll angle (racket face less open) at impact than accurate shots, indicating this parameter was a determining factor in the accuracy of this stroke. Racket orientation angle differences between accurate and inaccurate shots of the remaining strokes were too small to be used to distinguish shot accuracy. There was significantly greater variability in racket orientation angles during inaccurate forehand drop and backhand drive shots compared to accurate shots. These findings demonstrate how racket orientation angle differences at ball-impact can influence the accuracy of shots and highlights the need for consistent racket orientations to allow for an accurate shot. [ABSTRACT FROM AUTHOR]

Eccentric quasi-isometric (EQI) contractions (maintaining a yielding contraction for as long as possible, beyond task failure) have gained interest in research and applied settings. However, little is known regarding the biomechanical profile of EQIs. Fourteen well-trained males performed four maximal effort knee-extensor EQIs, separated by 180 seconds. Angular impulse, velocity, and time-under-tension through the 30–100º range of motion (ROM), and in eight ROM brackets were quantified. Statistical parametric mapping, analyses of variance, and standardised effects (Hedges' g (ES), %Δ) detected between-contraction joint-angle-specific differences in time-normalised and absolute variables. Mean velocity was 1.34º·s−1 with most (62.5 ± 4.9%) of the angular impulse imparted between 40–70º. Most between-contraction changes occurred between 30–50º (p≤ 0.067, ES = 0.53 ± 0.31, 60 ± 52%), while measures remained constant between 50–100º (= 0.069–0.83, ES = 0.10 ± 0.26, 14.3 ± 24.6%). EQIs are a time-efficient means to impart high cumulative mechanical tension, especially at short to medium muscle lengths. However, angular impulse distribution shifts towards medium to long muscle lengths with repeat contractions. Practitioners may utilise EQIs to emphasize the initial portion of the ROM, and limit ROM, or apply EQIs in a fatigued state to emphasize longer muscle lengths. [ABSTRACT FROM AUTHOR]

High-level golfers use various warm-up strategies to enhance clubhead and ball speed, including weighted equipment. We investigated the acute effects of the SuperSpeed Golf™ weighted-club warm-up on clubhead, ball, and swing kinematics, and the persistence of any acute effects in subsequent sets. Twelve competitive golfers (handicap < 3.0) completed five sets of five swings using their own drivers under two randomised warm-up conditions (Control and SuperSpeed). We compared swing, peak segment and club angular velocity, and centre of mass (COM) parameters collected using a 3D motion capture system (500 Hz) between conditions. The temporal persistence of any meaningful (Cohen's d ≥ small) and significant (p≤ 0.05) effect detected in the first set was investigated in subsequent sets. SuperSpeed led to small significant changes in clubhead speed (2.6 mph); downswing time; peak angular velocities of the torso, lead arm, and club; and two COM variables in the initial set. There was no significant change in ball speed, resulting in a large negative change in smash factor acutely (d − 0.82, p= 0.009). Nearly all changes observed were no longer meaningful or significant in subsequent sets. Overall, golfers can expect an increase in driving clubhead speed on the first tee using the SuperSpeed Golf™ vs Control warm-up, with trivial effects from the second tee onwards. [ABSTRACT FROM AUTHOR]

Motion capture systems are used in the analysis and interpretation of athlete movement patterns for a variety of reasons, but data integrity remains critical regardless. The extent to which marker location or constraining degrees of freedom (DOF) in the biomechanical model impacts on this integrity lacks consensus. Ten elite academy footballers performed bilateral overhead squats using a marker-based motion capture system. Kinematic data were calculated using four different marker sets with 3DOF and 6DOF configurations for the three joint rotations of the right knee. Root mean squared error differences between marker sets ranged in the sagittal plane between 1.02 and 4.19 degrees to larger values in the frontal (1.30–6.39 degrees) and transverse planes (1.33 and 7.97 degrees). The cross-correlation function of the knee kinematic time series for all eight marker-sets ranged from excellent for sagittal plane motion (>0.99) but reduced for both coronal and transverse planes (<0.9). Two-way ANOVA repeated measures calculated at peak knee flexion revealed significant differences between marker sets for frontal and transverse planes (p < 0.05). Pairwise comparisons showed significant differences between some marker sets. Marker location and constraining DOF while measuring relatively large ranges of motion in this population are important considerations for data integrity. [ABSTRACT FROM AUTHOR]

In swimming, the underwater phase after the start and turn comprises gliding and dolphin kicking, with the latter also known as underwater undulatory swimming (UUS). Swimming performance is highly dependent on the underwater phase; therefore, understanding the training effects in UUS and underwater gliding can be critical for swimmers and coaches. Further, the development of technique in young swimmers can lead to exponential benefits in an athlete's career. This study aimed to evaluate the effects of a training protocol on UUS and underwater gliding performance and kinematics in young swimmers. Seventeen age group swimmers (boys = 10, girls = 7) performed maximal UUS and underwater gliding efforts before and after a seven-week training protocol. Time to reach 10 m; intra-cyclic mean, peak, and minimum velocities; and gliding performance improved significantly after the training protocol. The UUS performance improvement was mostly produced by an improvement of the upbeat execution, together with a likely reduction of swimmers' hydrodynamic drag. Despite the changes in UUS and gliding, performance was also likely influenced by growth. The findings from this study highlight kinematic variables that can be used to understand and quantify changes in UUS and gliding performance. [ABSTRACT FROM AUTHOR]

The Clarke River Shear Zone marks the boundary between the Thomson and Mossman orogens in the northeastern Tasmanides. To better understand the kinematic history of this east-northeast-trending shear zone, and its role during the tectonic history of eastern Gondwana, we investigated rock deformation along a segment of the Clarke River Shear Zone. Based on field observations, interpretation of aeromagnetic data and microstructural analysis, we show that the Clarke River Shear Zone experienced at least three phases of reactivation. Gently plunging stretching lineation and kinematic indicators, such as steeply plunging asymmetric folds and asymmetric porphyroclasts, correspond to an early phase of sinistral strike-slip ductile shearing. Subsequent general dextral shear deformation is suggested based on the presence of S-tectonites, symmetric porphyroclasts and kinematic indicators with dominant dextral and subordinate sinistral shear senses. This phase, which occurred under amphibolite-facies metamorphic conditions, was contemporaneous with the emplacement of the Craigie Tonalite, for which we obtained a new zircon U–Pb crystallisation age of 410.3 ± 1 Ma. A later reactivation phase along the Clarke River Shear Zone, under brittle conditions, is indicated by the presence of cataclasite zones and chlorite–epidote alteration. Based on our findings, and regional information on the tectono-magmatic evolution of northeastern Queensland, we suggest that the Clarke River Shear Zone was possibly a sinistral transform fault during the Silurian. During the Devonian, it is possible that deformation along the Clarke River Shear Zone was related to the transition between the non-retreating subduction zone in the north, and the highly mobile (retreating) plate boundary farther south. However, the dextral kinematic component associated with this deformation is not fully explained. Brittle deformation, likely associated with dextral transpression during the Carboniferous, marked the last stage of activity along the Clarke River Shear Zone. The Clarke River Shear Zone records three phases of reactivation during the Silurian–Carboniferous. Ductile dextral general shear deformation along the Clarke River Shear Zone occurred at ca 410 Ma, based on zircon U–Pb dating of a syn-tectonic intrusion. The Clarke River Shear Zone likely accommodated subduction segmentation during the Silurian–Devonian. [ABSTRACT FROM AUTHOR]