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Context: The best current evidence supports the effectiveness of neuromuscular training in reducing the risk of injury; however, the rate of anterior cruciate ligament (ACL) injuries is still high. Neurocognitive training (NT) has successfully improved biomechanical risk factors, but they have been considered in only a few studies. Objective: To review the literature to determine the effect of NT on biomechanical risk factors related to ACL injury in athletes. Evidence Acquisition: We searched PubMed, Google Scholar, Scopus, Science Direct, and the Physiotherapy Evidence Database from inception to August 2011. We included randomized controlled trials that used motor learning approaches and injury prevention programs to investigate kinematic and kinetic risk factors related to ACL injury. The quality of each clinical trial study was evaluated by the Physiotherapy Evidence Database scale. The eligibility criteria were checked based on the PICOS (population, intervention, comparison, outcome, and study type) framework. Evidence Synthesis: A total of 9 studies were included in the final analysis. Motor learning approaches include internal and external focus of attention, dual tasks, visual motor training, self-control feedback, differential learning, and linear and nonlinear pedagogy, combined with exercise programs. In most of the studies that used NT, a significant decrease in knee valgus; tibial abduction and external rotation; ground reaction force; and an increase in knee-, trunk-, hip-, and knee-flexion moment was observed. Conclusion: In classical NT, deviation from the ideal movement pattern especially emphasizing variability and self-discovery processes is functional in injury prevention and may mitigate biomechanical risk factors of ACL injuries in athletes. Practitioners are advised to use sport-specific cognitive tasks in combination with neuromuscular training to simulate loads of the competitive environment. This may improve ACL injury risk reduction and rehabilitation programs. [ABSTRACT FROM AUTHOR]

Purpose: Performing back squats with elastic bands has been widely used in resistance training. Although research demonstrated greater training effects obtained from adding elastic bands to the back squat, little is known regarding the optimal elastic resistance and how it affects neuromuscular performance. This study aimed to compare the force, velocity, power, and muscle activity during back squats with different contributions of elastic resistance. Methods: Thirteen basketball players performed 3 repetitions of the back squat at 85% of 1-repetition maximum across 4 conditions: (1) total load from free weight and (2) 20%, (3) 30%, and (4) 40% of the total load from elastic band and the remaining load from free weight. The eccentric and concentric phases of the back squat were divided into upper, middle, and bottom phases. Results: In the eccentric phase, mean velocity progressively increased with increasing elastic resistance, and muscle activity of the vastus medialis and rectus femoris significantly increased with the largest elastic resistance in the upper phase (P ≤.036). In the concentric phase, mean power (P ≤.021) and rate of force development (P ≤.002) significantly increased with increasing elastic resistance. Furthermore, muscle activity of the vastus lateralis and vastus medialis significantly improved with the largest elastic resistance in the upper phases (P ≤.021). Conclusion: Velocity, power, rate of force development, and selective muscle activity increased as the elastic resistance increased in different phases during the back-squat exercise. [ABSTRACT FROM AUTHOR]

Purpose: To compare the kinematic profile of 2 underwater pullout breaststroke techniques. Methods: Sixteen swimmers (9 men, 20.67 [2.71] y old; 7 women, 18.86 [0.83] y old) performed 3 × 25-m breaststroke using 2 pullout breaststroke techniques: Fly-Kick first and Combined. A speedometer was used to assess the peak and the mean velocity during the glide, propulsion, and recovery phases of both techniques, as well as for the total underwater sequence. The underwater distance was retrieved from video footage and was considered for each pullout technique. The range of motion of the knee during the fly-kick was also retrieved, and the time to complete the 25 m was considered the performance outcome, accompanied by the mean velocity, stroke rate, stroke length, and stroke index. Results: Velocity–time series showed different profiles between pullout techniques (P ≤.05) mostly in the glide and propulsion phases for males and females, respectively. The mean velocity of 25 m was shown to be greater in females when using the Fly-Kick first technique (P =.05, d = 0.36). Greater values in total underwater distance and knee range of motion were also observed for this technique in both cohorts. Conclusions: Female swimmers presented a higher performance when using the Fly-Kick first technique. Different kinematic profiles arise when swimmers use different underwater pullout techniques where the Fly-Kick first may allow them to reach higher kinematical standard. [ABSTRACT FROM AUTHOR]

This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior–posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints' contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ −.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints' contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints. [ABSTRACT FROM AUTHOR]

Postpartum mothers are susceptible to lumbopelvic pain which may be exacerbated by loading, like carrying their infant in arms and with baby carriers. Nulliparous women carrying infant mannequins may biomechanically mimic mother–infant dyad, but this has not been studied. The purpose of our study was to investigate biomechanical differences of 10 mothers carrying their infants and 10 nulliparous women carrying infant mannequins under 3 gait conditions: carrying nothing, carrying in arms, and carrying in a baby carrier (babywearing). Spatiotemporal gait parameters, peak ground reaction forces and impulses, and lower extremity and trunk kinematics were collected using motion capture and force plates and compared using a mixed 2 × 3 (parity × condition) analysis of variance (α ≤.05). The largest differences occurred between carrying conditions: carrying in arms or babywearing increased vertical and anteroposterior ground reaction forces, trunk extension, ankle dorsiflexion, and hip and knee flexion. Kinematic differences were identified between arms and babywearing conditions. Together this suggests alterations in joint loading for both groups. Our study also contributes a novel understanding of postpartum health by demonstrating alterations in step time, anterior forces, and ankle and knee mechanics, suggesting that during gait, mothers carrying their own infants choose different propulsive strategies than nulliparous women carrying mannequins. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-related groin pain. This is a secondary analysis of data collected during a pilot randomized clinical trial. Thirty patients with hip pain, between the ages of 15 and 40 years, were randomized to MoveTrain or standard. Both groups completed 10 treatment sessions over 12 weeks along with a daily home exercise program. Three-dimensional motion analysis was used to collect kinematic and kinetic data of the pelvis and hip during a single-leg squat task at pretreatment and immediately posttreatment. Compared with the standard group, the MoveTrain group demonstrated smaller hip adduction angles (P =.006) and smaller hip external adduction moments (P =.008) at posttreatment. The desired changes to hip joint biomechanics, as found in this study, may require specificity in training that could allow health care professionals to better customize the rehabilitation of patients with hip pain. These findings can also be applied to the design and implementation of future clinical trials to strengthen our understanding of the long-term implications of different rehabilitation techniques for patients with hip pain. [ABSTRACT FROM AUTHOR]

More than 80% of adult manual wheelchair users with spinal cord injuries will experience shoulder pain. Females and those with decreased shoulder dynamics variability are more likely to experience pain in adulthood. Sex-related differences in shoulder dynamics variability during pediatric manual wheelchair propulsion may influence the lifetime risk of pain. We evaluated the influence of sex on 3-dimensional shoulder complex joint dynamics variability in 25 (12 females and 13 males) pediatric manual wheelchair users with spinal cord injury. Within-subject variability was quantified using the coefficient of variation. Permutation tests evaluated sex-related differences in variability using an adjusted critical alpha of P =.001. No sex-related differences in sternoclavicular or acromioclavicular joint kinematics or glenohumeral joint dynamics variability were observed (all P ≥.042). Variability in motion, forces, and moments are considered important components of healthy joint function, as reduced variability may increase the likelihood of repetitive strain injury and pain. While further work is needed to generalize our results to other manual wheelchair user populations across the life span, our findings suggest that sex does not influence joint dynamics variability in pediatric manual wheelchair users with spinal cord injury. [ABSTRACT FROM AUTHOR]

Purpose: Power output is dependent on the load used during exercise such as bench-press throw (BPT). Attentional focus (external [EXT] vs internal [INT]) during exercise significantly modulates power performance. The purpose of the present study was to examine the effects of load and attentional focus on mechanical parameters during BPT. Methods: In a crossover study, 31 resistance-trained men (mean age 23.5 [3.0] y) performed BPT at 30% (light), 50% (moderate), and 70% (heavy) of 1-repetition maximum (1-RM) using an INT or EXT focus of attention in randomized order. A linear encoder was used to identify barbell vertical displacement, throw time, peak/average velocity, force, and power during the concentric lifting phase. Results: Statistical analysis revealed significant load × focus interaction effects for velocity and vertical displacement (P ≤.045; 0.66 ≤ d ≤ 0.89). Post hoc analyses indicated significantly larger velocities and displacements at 30% and 70% of 1-RM in favor of EXT (P ≤.038; 0.79 ≤ d ≤ 1.13) but similar values at 50% of 1-RM (P >.05). Furthermore, significant main effects of load were found for throw time, force, and power (P <.001; 4.20 ≤ d ≤ 14.0). While time and force gradually increased with higher loads (P <.001; 1.45 ≤ d ≤ 14.0), power output was larger at 50% compared with 30% and 70% 1-RM (P <.001; 3.09 ≤ d ≤ 7.07), irrespective of attentional focus. Conclusions: The present findings indicated that practitioners may use EXT over INT attentional focus to enhance velocity and vertical displacement during BPT at light and heavy loads (ie, 30% and 70% 1-RM). At moderate loads (ie, 50% 1-RM), mechanical bench-press parameters appear to be less affected by attentional focus. [ABSTRACT FROM AUTHOR]

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]

This study aimed to evaluate the effects of a five-week training program on undulatory underwater swimming (UUS) in swimmers and to compare the specific effects prompted by two different training protocols on UUS performance and kinematics. Swimmers (n = 14) were divided into in-water only (WO) (18.61 ± 2.62 years, FINA points: 507 ± 60) and water + dry-land training groups (with conical pulleys) (WD) (18.38 ± 2.67 years, FINA points: 508 ± 83). Three countermovement jumps (CMJ) and three maximal UUS trials were performed before and after a five-week training period. The training program comprised 14 × 30-min sessions. The WO group repeated the same 15-min block twice, while the WD group performed one block of 15 min in the water and the other block on land performing lower limb exercises with conical pulleys. Seven body landmarks were auto-digitalized during UUS by a pre-trained neural network and 21 kinematic variables were calculated. The level of statistical significance was set at p < 0.05. Significant time × group interaction in favour of the WD group was observed for mean vertical toe velocity (p = 0.035, η²p = 0.32). The WD group experienced enhancements in mean and maximum underwater velocity, kick frequency, maximum shoulder angular velocity, as well as mean and maximum vertical toe velocity (p < 0.05). The WO group exhibited an enhancement in CMJ height (p < 0.05). In conclusion, UUS performance was improved in adolescent swimmers after five weeks of specific training, only when combining water and conical pulley exercises. Coaches should include dry-land specific lower limb exercises in addition to in-water training to improve UUS performance. [ABSTRACT FROM AUTHOR]

Background: Motor competence (MC) is a key component reflecting one's ability to execute motor tasks and is an important predictor of physical fitness. For adolescents, understanding the factors affecting MC is pertinent to their development of more sophisticated sporting skills. Previous studies considered the influence of poor proprioceptive ability on MC, however, the relationship between lower limb joint position sense, kinematic control, and MC is not well understood. Therefore, the aim of this study was to determine the relation between joint position sense and kinematic control with MC in adolescents during a lower limb movement reproduction task. Methods: This study was a cross-sectional design. Young people (n = 427, 196 girls and 231 boys) aged 13 to 14 years were recruited. A movement reproduction task was used to assess joint position sense and kinematic control, while the Movement Assessment Battery for Children (mABC-2) was used to assess MC. In this study, participants were categorized into the Typically Developed (TD, n = 231) and Probable Developmental Coordination Disorder (DCD, n = 80) groups for further analysis of joint position sense, kinematic control, and MC between groups. Results: Kinematic data, specifically normalized jerk, showed a significant correlation with MC. There was no correlation between knee joint position sense and MC, and no group differences between DCD and TD were found. Conclusions: Joint position sense should not be used as a measure to distinguish TD and DCD. Rather than joint position sense, control of kinematic movement has a greater influence on the coordination of the lower limbs in adolescents. Movement control training should be implemented in the clinical setting to target kinematic control, rather than focus on joint position sense practice, to improve motor competency. Trial Registration Identifier: NCT03150784. Registered 12 May 2017, https://clinicaltrials.gov/study/NCT03150784. [ABSTRACT FROM AUTHOR]

Background: Biomechanical parameters can distinguish a skilled rower from a less skilled rower and can provide coaches with meaningful feedback and objective evidence to inform coaching practices on rowing technique. Therefore, it is critical to understand which technical characteristics can be related to the fundamental rowing performance indicators. The aim of this systematic scoping review was to describe the current focus and density of rowing biomechanics research specific to on-water rowing and provide a guide for practitioners and researchers on future directions for on-water rowing biomechanics research. Methods: All peer-reviewed publications involving the on-water assessment of rowing biomechanics were reviewed from four databases (SPORTDiscus, PubMed, Sage online journals, and Web of Science). Search results returned 1659 records, of which 27 studies met the inclusion criteria for the review. Results: All reported variables were collated and summarised according to the three main measurements of basic mechanics: time, space and force. Study characteristics were collated to provide a descriptive overview of the literature. The main categorical variables included time, distance, velocity, acceleration, force, power and crew synchrony. Conclusion: Data extraction revealed gate force, horizontal oar angle and boat velocity as the most reported variables with numerous subcategories of metrics within each measure. A framework to help guide and standardise on-water rowing biomechanical assessment and the establishment of standards for environmental data collection could help guide practitioners and researchers in the on-water rowing environment. This scoping review was registered on the Open Science Framework (https://osf.io/8q5vw/). Key Points: While the literature has reported on an extensive range of biomechanical metrics relevant to rowing performance, however, the variability of reported measures across the different boat classes, sex and skill levels makes the collation of data challenging. The rate at which a rower can apply force and the ability to maintain the force into the finish are distinguishing features of elite rowing while prioritizing the measurement and application of power is essential for effectively monitoring and controlling training loads, as well as for refining technique. The development of a standardized framework for on-water rowing biomechanical assessment, coupled with established protocols for environmental data collection, would provide practitioners and researchers with a structured approach for navigating the on-water rowing context. [ABSTRACT FROM AUTHOR]

The effects of occlusal splints on sport performance have already been studied, although their biomechanical impacts are often overlooked. We investigated the kinematical changes during running until exhaustion at severe intensity while wearing a mandibular advancement occlusal splint. Twelve trained runners completed (i) an incremental protocol on a track to determine their velocity corresponding to maximal oxygen uptake and (ii) two trials of square wave transition exercises at their velocity corresponding to maximal oxygen until exhaustion, wearing two occlusal splints (without and with mandibular advancement). Running kinematics were compared within laps performed during the square wave transition exercises and between splint conditions. The mandibular advancement occlusal splint increased the running distance covered (~1663 ± 402 vs. 1540 ± 397 m, p = 0.03), along with a noticeable lap effect in decreasing stride frequency (p = 0.04) and increasing stride length (p = 0.03) and duty factor (p < 0.001). No spatiotemporal differences were observed between splints, except for improved balance foot contact times in the mandibular advancement condition. An increased knee flexion angle at initial contact (p = 0.017) was noted along laps in the non-advancement condition, despite the fact that no differences between splints were found. Running patterns mainly shifted within laps rather than between conditions, indicating that a mandibular advancement occlusal splint had a trivial kinematical effect. [ABSTRACT FROM AUTHOR]

Background: Individual maximum joint and segment angular velocities have shown positive associations with throwing arm kinetics and ball velocity in baseball pitchers. Purpose: To observe how cumulative maximum joint and segment angular velocities, irrespective of sequence, affect ball velocity and throwing arm kinetics in high school pitchers. Study Design: Descriptive laboratory study. Methods: High school (n = 55) pitchers threw 8 to 12 fastball pitches while being evaluated with 3-dimensional motion capture (480 Hz). Maximum joint and segment angular velocities (lead knee extension, pelvis rotation, trunk rotation, shoulder internal rotation, and forearm pronation) were calculated for each pitcher. Pitchers were classified as overall fast, overall slow, or high velocity for each joint or segment velocity subcategory, or as population, with any pitcher eligible to be included in multiple subcategories. Kinematic and kinetic parameters were compared among the various subgroups using t tests with post hoc regressions and multivariable regression models created to predict throwing arm kinetics and ball velocity, respectively. Results: The lead knee extension and pelvis rotation velocity subgroups achieved significantly higher normalized elbow varus torque (P =.016) and elbow flexion torque (P =.018) compared with population, with equivalent ball velocity (P =.118). For every 1-SD increase in maximum pelvis rotation velocity (87 deg/s), the normalized elbow distractive force increased by 4.7% body weight (BW) (B = 0.054; β = 0.290; P =.013). The overall fast group was older (mean ± standard deviation, 16.9 ± 1.4 vs 15.4 ± 0.9 years; P =.007), had 8.9-mph faster ball velocity (32.7 ± 3.1 vs 28.7 ± 2.3 m/s; P =.002), and had significantly higher shoulder internal rotation torque (63.1 ± 17.4 vs 43.6 ± 12.0 Nm; P =.005), elbow varus torque (61.8 ± 16.4 vs 41.6 ± 11.4 Nm; P =.002), and elbow flexion torque (46.4 ± 12.0 vs 29.5 ± 6.8 Nm; P <.001) compared with the overall slow group. A multiregression model for ball velocity based on maximum joint and segment angular velocities and anthropometrics predicted 53.0% of variance. Conclusion: High school pitchers with higher maximum joint and segment velocities, irrespective of sequence, demonstrated older age and faster ball velocity at the cost of increased throwing shoulder and elbow kinetics. Clinical Relevance: Pitchers and coaching staff should consider this trade-off between faster ball velocity and increasing throwing arm kinetics, an established risk factor for elbow injury. [ABSTRACT FROM AUTHOR]

There are different ways to deliver external focus (EF) and internal focus (IF) instruction. Understanding each modality better will help to develop more effective interventions to reduce injury risk. To investigate the difference in landing biomechanics between participants who received EF and IF instruction and control participants. A secondary aim was to evaluate participant perceptions of focus of attention. Randomized controlled trial. Laboratory. Forty-one healthy women (EF: n = 14, 23.0 ± 2.9 years, 1.69 ± 0.07 m, 64.0 ± 6.8 kg; IF: n = 15, 22.9 ± 3.2 years, 1.66 ± 0.08 m, 66.2 ± 12.4 kg; control: n = 12, 21.1 ± 2.9 years, 1.67 ± 0.11 m, 74.3 ± 15.1 kg). Participants scoring greater than or equal to 5 on the Landing Error Scoring System were allocated into the EF, IF, or control group. Knee and hip flexion and abduction were collected pre- and postintervention during 5 drop vertical jumps. For the intervention, each group was provided separate instructions. In between the intervention jumps, participants answered, "What strategy were you focusing on when completing the previous jump-landing trials?" Postintervention minus preintervention change scores were calculated, and separate 1-way analysis of variance assessments were performed to determine differences in the dependent variables. Individuals in the EF group had a greater change in hip and knee flexion angles than individuals in the control group. There was no significant difference between the EF and IF groups for any variables. There were no significant differences in frontal plane variables. In the EF group, 71.4% aligned with the instructions given; in the IF group, 80% aligned; and in the control group, 50% aligned. External focus instruction may not produce immediate changes in movement compared with IF instruction. Hip and knee flexion were greater in the EF group than in the control group but was not better than that in the IF group. Clinicians should provide instructions to patients, but the mode of instruction may not be as critical to see positive biomechanical changes. Patients may not always focus on the instruction being given; therefore, the relationship between instruction and patient experience should be further explored. [ABSTRACT FROM AUTHOR]

We aimed to conduct a biophysical comparison of angular (Biorower) and linear (Concept2) rowing ergometers across a wide spectrum of exercise intensities. Sixteen (eleven male) skilled rowers, aged 29.8 ± 8.6 and 23.6 ± 1.5 years, with international competitive experience, performed 7 × 3 min bouts with 30 W increments and 60 s intervals, plus 1 min of all-out rowing on both machines with 48 h in between. The ventilatory and kinematical variables were measured breath-by-breath using a telemetric portable gas analyzer and determined using a full-body markerless system, respectively. Similar values of oxygen uptake were observed between ergometers across all intensity domains (e.g., 60.36 ± 8.40 vs. 58.14 ± 7.55 mL/min/kg for the Biorower and Concept2 at severe intensity). The rowing rate was higher on the Biorower vs. Concept2 at heavy and severe intensities (27.88 ± 3.22 vs. 25.69 ± 1.99 and 30.63 ± 3.18 vs. 28.94 ± 2.29). Other differences in kinematics were observed across all intensity domains, particularly in the thorax angle at the finish (e.g., 19.44 ± 4.49 vs. 27.51 ± 7.59° for the Biorower compared to Concep2 at heavy intensity), likely due to closer alignment of the Biorower with an on-water rowing technique. The overall perceived effort was lower on the Biorower when compared to the Concept2 (14.38 ± 1.76 vs. 15.88 ± 1.88). Rowers presented similar cardiorespiratory function on both rowing ergometers, while important biomechanical differences were observed, possibly due to the Biorower's closer alignment with an on-water rowing technique. [ABSTRACT FROM AUTHOR]

Multi-segment foot models (MFMs) provide a better understanding of the intricate biomechanics of the foot, yet it is unclear if they accurately differentiate foot type function during locomotion. We employed an MFM to detect subtle kinematic differences between foot types, including: pes cavus, neutrally aligned, and asymptomatic and symptomatic pes planus. The study investigates how variable the results of this MFM are and if it can detect kinematic differences between pathologic and non-pathologic foot types during the stance phase of gait. Independently, three raters instrumented three subjects on three days to assess variability. In a separate cohort, each foot type was statically quantified for ten subjects per group. Each subject walked while instrumented with a four-segment foot model to assess static alignment and foot motion during the stance phase of gait. Statistical analysis performed with a linear mixed effects regression. Model variability was highest for between-day and lowest for between–rater, with all variability measures being within the true sample variance. Almost all static measures (radiographic, digital scan, and kinematic markers) differed significantly by foot type. Sagittal hindfoot to leg and forefoot to leg kinematics differed between foot types during late stance, as well as coronal hallux to forefoot range of motion. The MFM had low between-rater variability and may be suitable for multiple raters to apply to a single study sample without introducing significant error. The model, however, only detected a few dynamic differences, with the most dramatic being the hallux to forefoot coronal plane range of motion. Significance: Results only somewhat aligned with previous work. It remains unclear if the MFM is sensitive enough to accurately detect different motion between foot types (pathologic and non-pathologic). A more accurate method of tracking foot bone motion (e.g., biplane fluoroscopy) may be needed to address this question. • The majority of static measures differed significantly by foot type. • Sagittal hind- and forefoot to leg kinematics differed between groups during stance. • Coronal hallux to forefoot range of motion varied by foot type during gait. • All variability measures were within the true sample variance. [ABSTRACT FROM AUTHOR]

Chronic ankle instability (CAI) has been associated with lower limb deficits that can lead to altered biomechanics during dynamic tasks. There have been contradictory findings in terms of ankle and hip joint biomechanics to date, influenced by the variety of movement tasks and varying definitions of the CAI condition. How do biomechanical variables of the lower extremity differ during walking, running, and jump-landing in individuals with CAI compared with those without CAI? Thirty-two individuals (17 CAI and 15 controls) participated in this retrospective case-control study. Sagittal and frontal plane ankle and hip joint angles and moments, and mediolateral foot balance (MLFB) were calculated during the tasks. Statistical parametric mapping (SPM) was used for the whole trajectory analysis to detect group differences. Discrete variables, including initial contact (IC) and peak angles and moments, were additionally compared. No differences were found between groups during walking. During running, the CAI group exhibited a lower plantar flexor moment (p < 0.001) and more laterally deviated MLFB (p = 0.014) during mid-stance when compared to controls. Additionally, participants with CAI had a significantly greater peak plantar flexion angle in early stance (p = 0.022) and a reduced peak plantar flexor moment (p = 0.002). In the jump-landing, the CAI group demonstrated an increased hip extensor moment (p = 0.008), and a greater peak hip adduction angle (p = 0.039) shortly after ground contact compared to the control group. Differences in ankle and hip biomechanics were observed between groups during running and jump landing, but not during walking. These differences may be indicative of impairments in the sensorimotor system or of learnt strategies adopted to try to minimise instability and injury risk and can help to inform future intervention design. • Individuals with CAI display different ankle joint biomechanics than controls during running. • Individuals with CAI display different hip joint biomechanics than controls during jump-landing. • The level of demand for the task may influence the biomechanical strategy adopted. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament injuries are serious conditions encountered in volleyball players and occur frequently during spike jump landings. During spike jumps, the lower limb kinematics and kinetics during landing may be altered in relation to the ball position. Does the ball position have an effect on lower-limb kinematics and kinetics during spike jumps? We measured the lower limb kinematics and kinetics of 20 healthy female college volleyball athletes during a spike jump using a three-dimensional motion analysis system. The ball positions were set to normal, dominant, and non-dominant positions. A repeated analysis of variance was used to compare the lower limb kinematics and kinetics at the initial contact and the maximum knee flexion during jump landing. Additionally, statistical parametric mapping analysis was used to analyze changes over time during the spike jumps. At the initial contact of the spike jump landing, the knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment when the ball was set at the non-dominant position increased compared to those at the dominant position. Statistical parametric mapping analysis showed no significant change in knee valgus angle and moment of jump landing. Knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment increased with the non-dominant position; furthermore, the risk of ACL injury may also be increased. The posture at ball impact may influence the landing kinematics and kinetics. Therefore, it is necessary to pay close attention to movements during and prior to landing. • Ball positions influenced trunk and lower limb in volleyball. • The knee valgus angle and moment were increased in non-dominant position. • The movement of trunk lateral bend during mid-flight affect the landing movement. [ABSTRACT FROM AUTHOR]

The effects of foot orthoses on lower limb biomechanics during walking have been studied extensively. However, the lack of knowledge regarding the effects of various foot orthoses models for the same population complicates model selection in clinical practice and research. Additionally, there is a critical need to enhance our ability to predict the outcomes of foot orthoses using clinical tests, such as the supination resistance test. What are the effects of two commonly prescribed types of FO (thin-flexible and medially wedged) on lower limb biomechanics during gait? Is there a correlation on these effects with the results of the supination resistance test? Twenty-three participants with flat feet were enrolled in this cross-sectional descriptive study. Participants underwent walking trials under three conditions: shod, thin-flexible FOs and medially wedged FOs. Midfoot, ankle, knee and hip angles, moments were calculated. Repeated measure ANOVAs were employed for within-group comparison across conditions. Correlations between the effects of FOs on foot and ankle angles/moments and supination resistance were determined using regression analyses using a statistical parametric mapping approach. Thin-flexible and medially wedged FOs reduced midfoot dorsiflexion angles and ankle inversion moments. Medially wedged FOs also decreased midfoot and ankle abduction angles, midfoot plantarflexion moments compared to thin-flexible FOs and shoes. Moderate to good correlations between the supination resistance test and the medially wedged FOs were observed for the frontal and transverse ankle angles and moments. Medially wedged FOs are more effective in modifying lower limb biomechanics during walking compared to thin-flexible FOs. Greater supination resistance was associated with more pronounced effects for medially wedged FOs on foot and ankle biomechanics. These findings hold promise for refining orthotic prescription strategies, potentially offering advantages to individuals with musculoskeletal disorders. • Medially wedged foot orthoses generated the greater biomechanical effects. • Foot orthoses primarily impacted the distal segments of the lower limb. • Moderate correlations were observed between SRT and the biomechanical effects. • The supination resistance test will help in the foot orthoses selection process. [ABSTRACT FROM AUTHOR]

Introduction: Maximal acceleration and deceleration tasks are frequently required in team sports, often occurring rapidly in response to external stimuli. Accelerating and decelerating can be associated with lower limb injuries; thus, knowledge of joint mechanics during these tasks can improve the understanding of both human high performance and injury mechanisms. The current study investigated the fundamental differences in lower limb joint mechanics when accelerating and decelerating by directly comparing the hip, knee, and ankle joint moments and work done between the two tasks. Methods: Twenty participants performed maximal effort acceleration and deceleration trials, with three-dimensional marker trajectories and ground reaction forces collected simultaneously. Experimental data were combined with inverse dynamics analysis to compute joint moments and work. Results: Net joint work for all lower limb joints was positive during acceleration and negative during deceleration. This occurred because of significantly greater positive work production from the ankle and hip during acceleration and significantly greater negative work production from all joints during deceleration. The largest contributions to positive work during acceleration came from the ankle, followed by the hip and knee joints, whereas the largest contributions to negative work during deceleration came from the knee and hip joints, followed by the ankle. Peak joint moments were significantly greater when decelerating compared with accelerating, except for the peak ankle plantar flexion and hip flexion moments, which were significantly greater when accelerating. Conclusions: Our findings may help to guide training interventions, which aim to enhance the performance of acceleration and deceleration tasks, while also mitigating the associated injury risk. [ABSTRACT FROM AUTHOR]

Limited research exists on the relationship between aesthetic saut de chat performance and muscle-tendon unit (MTU) characteristics of dancers. We developed a weighted parameter ranking (WPR) tool to incorporate aesthetic leaping aspects (i.e., height, peak split angle, average trunk angle and trunk angle range) for correlation with MTU properties. The purpose was to identify the relationship of saut de chat WPR and leap height with maximal plantarflexion strength, medial gastrocnemius (MG) stiffness, Achilles tendon (AT) stiffness and relative peak power (PP). Dancers (n = 18) performed maximal plantarflexion, short-range stretches and isometric ramping contractions on a dynamometer equipped with ultrasound to determine strength, MG stiffness and AT stiffness, respectively. Subjects then performed saut de chat leaps atop force platforms surrounded by motion capture cameras. A principal component analysis (PCA) was performed to compare WPR variable weightings with PCA results and rankings. Moderate–strong relationships were identified among WPR, maximal plantarflexion strength, MG stiffness and PP. Strong–very strong relationships were also identified between leap height and maximal plantarflexion strength, MG stiffness, AT stiffness, peak split angle and PP. A very strong correlation existed between PCA rankings and WPRs. Practitioners may consider developing strength and power capabilities in dancers to improve leaping. [ABSTRACT FROM AUTHOR]

Background Sidestep cutting technique is highly individual and has been shown to influence knee joint loading. However, studies assessing whether individualized technique feedback improves technique and ACL injury-relevant knee joint loads instantly in a sport-specific task are lacking. Purpose To determine the instant effects of individualized augmented technique feedback and instructions on technique and the peak external knee abduction moment (pKAM) in a handball-specific sidestep cut. Additionally, to determine the effects of technique modifications on the resultant ground reaction force and its frontal plane moment arm to the knee joint center. Study Design Controlled laboratory cohort study Methods Three-dimensional biomechanics of 48 adolescent female handball players were recorded during a handball-specific sidestep cut. Following baseline cuts to each side, leg-specific visual and verbal technique feedback on foot strike angle, knee valgus motion, or vertical impact velocity using a hierarchically organized structure accounting for the variables' association with performance was provided. Subsequently, sidestep cuts were performed again while verbal instructions were provided to guide technique modifications. Combined effects of feedback and instructions on technique and pKAM as well as on the resultant ground reaction force and its frontal plane moment arm to the knee joint center were assessed. Results On average, each targeted technique variable improved following feedback and instructions, leading to instant reductions in pKAM of 13.4% to 17.1%. High inter-individual differences in response to feedback-instruction combinations were observed. These differences were evident in both the adherence to instructions and the impact on pKAM and its components. Conclusion Most players were able to instantly adapt their technique and decrease ACL injury-relevant knee joint loads through individualized augmented technique feedback, thereby potentially reducing the risk of injury. More research is needed to assess the retention of these adaptations and move towards on-field technique assessments using low-cost equipment. Level of Evidence: Level 3 [ABSTRACT FROM AUTHOR]

The objective was to investigate the effects of running shoes with midsole hollow structure span and height on the biomechanics of the lower limbs during running. We collected 21 adults with running habits who wore two pairs of running shoes with different midsole hollow structures and ran at a speed of 3.3m/s on a force-measuring treadmill. The lower limb kinematics, ground reaction force (GRF) and lower limb muscle activation characteristics were simultaneously captured by a motion capture system, a 3D force treadmill, and a surface electromyography (sEMG) system. Paired t-tests were performed on data for the two shoe conditions that fit the normal distribution assumptions; otherwise, Wilcoxon signed-rank tests were used. The statistical parameter mapping (SPM) technology was used for the analysis of 1D parameters of kinematic, dynamic, and sEMG activation characteristics. The result showed that the time to the peak impact force at touchdown of Hollow shoe2 was significantly increased (P<0.01), the maximum loading rate (P<0.01) and average loading rate (P<0.05) were significantly reduced, braking time (P<0.05), push time (P<0.05), contact time (P<0.01) of Hollow shoe2 were significantly increased compared with Hollow shoe1. Hollow shoe2 push phase of the tibialis anterior muscle activation characteristics was significantly lower (SPM, P<0.05) than Hollow shoe1. Our conclusion is that running shoes offer the solution as they have the advantage of the complex structure of the hollow midsole. [ABSTRACT FROM AUTHOR]

Simple Summary: Equestrian sports have evolved beyond traditional disciplines, embracing specialised events that showcase breed-specific abilities. The Criollo horse breed, a product of centuries of genetic refinement, stands out in South America and internationally, particularly in events like the Freio de Ouro. This competition highlights the breed's versatility and skills, emphasising manoeuvres like the esbarrada and volta sobre patas, which demonstrate agility, coordination, and balance. Despite the breed's success, there is a lack of quantitative kinematic studies on these manoeuvres and their relation to horse morphology. Our study aims to fill this gap by using kinematics to analyse the esbarrada and volta sobre patas, exploring any connections between static goniometry and manoeuvre dynamics. Understanding these movements not only enhances our appreciation of equine biomechanics but also informs breeding and training practices, ultimately benefiting both horses and riders in various equestrian disciplines. The esbarrada and volta sobre patas manoeuvres are critical in Criollo horse equestrian activities, yet their kinematics remain largely unexplored. This observational study aimed to kinematically describe the manoeuvres in Criollo breed horses and explore the relationship between static goniometry and dynamics. A 2D kinematic analysis was conducted on 31 Criollo horses performing the manoeuvres using high-speed cameras. Joint angles were measured using static goniometry and analysed in relation to dynamic performance. The esbarrada covered a distance of 4.28 ± 0.99 m in 1.15 ± 0.11 s at a velocity of 3.77 ± 0.55 m/s. Joint angles showed a mean fetlock extension of 75.4° ± 5.3° and hock flexion of 43.2° ± 4.1°. In the volta sobre patas, significant differences were found in turn duration (first: 0.96 ± 0.07 s, second: 1.12 ± 0.09 s, p = 0.03) and thoracic limb suspension (first: 0.23 ± 0.02 s, second: 0.28 ± 0.03 s, p = 0.02). Static goniometry indicated that limb conformation did not significantly correlate with protraction angles during the esbarrada (p = 0.27). The volta sobre patas demonstrated prolonged duration and increased thoracic limb suspension in the second turn. Also, the findings suggest that static conformation does not predict dynamic limb movement during the esbarrada. [ABSTRACT FROM AUTHOR]

The meniscus plays a crucial role in the proper functioning of the knee joint, and when it becomes damaged, partial removal or replacement is necessary to restore proper function. Understanding the stress and deformation of the meniscus during various movements is essential for developing effective materials for meniscus repair. However, accurately estimating the contact mechanics of the knee joint can be challenging due to its complex shape and the dynamic changes it undergoes during movement. To address this issue, the open-source software SCONE can be used to establish a kinematics model that monitors the different states of the knee joint during human motion and obtains relevant gait kinematics data. To evaluate the stress and deformation of the meniscus during normal human movement, values of different states in the movement gait can be selected for finite element analysis (FEA) of the knee joint. This analysis enables researchers to assess changes in the meniscus. To evaluate meniscus damage, it is necessary to obtain changes in its mechanical behavior during abnormal movements. This information can serve as a reference for designing and optimizing the mechanical performance of materials used in meniscus repair and replacement. [ABSTRACT FROM AUTHOR]

This study aimed to assess the validity and reliability of a commercially available inertial measurement unit (Enode) for measuring barbell kinematics and kinetics during a snatch. In order to assess validity and within- and between-session reliability, thirteen competitive weightlifters conducted two snatches on two separate occasions at 85% of their one-repetition maximum. The Enode sensor was attached to the barbell, with each lift recorded via the device's native application concurrently with an 11-camera motion capture system. Passing–Bablok regression indicated fixed and proportional bias in some horizontal measures of barbell mechanics but showed no bias in all but one vertical variable. Collectively, this suggests that the Enode is a valid tool in the measurement of vertically derived, but not horizontally derived, variables from barbell kinematics. Within- and between-session reliability showed moderate to excellent ICCs, with trivial to small differences between repetitions and between sessions. However, between-session reliability showed lower levels of variability and, thus, may help coaches identify changes in technique over time (between sessions) with good accuracy. Overall the Enode offers a practical and affordable option for coaches seeking to monitor weightlifting technique in training environments. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of skill modifications on head motion experienced during women's artistic gymnastics skills. Nine gymnasts (four beginner and five advanced) completed three trials of up to 24 skill progressions, each consisting of a skill and two progressive safety modifications. Gymnasts were instrumented with mouthpiece sensors embedded with an accelerometer and gyroscope collecting motion data at 200, 300, and 500 Hz during each skill performance. Peak-to-peak linear and rotational kinematics during contact phases and peak rotational kinematics during non-contact phases were computed. A mixed-effects model was used to compare differences in modification status nested within skill categories. Timer skills (i.e. drills that simulate performance of a gymnastics skill) resulted in the highest median ΔLA and ΔRA of all skill categories, and 132 skill performances exceeded 10 g ΔLA during a contact phase. Modifications were associated with significant reductions in head kinematics during contact phases of timers, floor skills, bar releases, and vault skills. Gymnasts can be exposed to direct and indirect head accelerations at magnitudes consistent with other youth contact sports, and common safety modifications may be effective at reducing head motion during contact and non-contact phases of gymnastics skills. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine associations between running economy (RE) and running sagittal plane kinematic and kinetic parameters. Method: A total of 30 male recreational runners (age: 21.21 ± 1.22 yr, VO2max: 54.61 ± 5.42 mL·kg-1·min-1) participated in two separate test sessions. In the first session, the participant's body composition and RE at 10 and 12 km·h-1 were measured. In the second session, measurements were taken for the sagittal plane of hip, knee, and ankle angles and range of motion (ROM), as well as ground reaction force. Results:Moderate correlations were found between lower energy costs at 12 km·h-1 and smaller hip flexion at toe-off (r = 0.373) as well as smaller peak hip flexion during stance (r = 0.397). During the swing phase, lower energy costs at 10 km·h-1 were moderately correlated with smaller peak knee flexion and smaller knee flexion and extension ROM (r = 0.366-0.443). Lower energy costs at 12 km·h-1 were moderately correlated with smaller peak hip and knee flexion as well as knee extension ROM(r = 0.369-0.427). In terms of kinetics, there was a moderate correlation between higher energy costs at 10 km·h-1 and larger peak active force, as well as larger peak braking and propulsion force (r = -0.470-0.488). Lower energy costs at 12 km·h-1 were moderately to largely correlated with smaller peak impact and braking force (r = 0.486 and -0.500, respectively). Regarding the statistical parametric mapping analysis, most outcomes showed associations with RE at 10 km·h-1, including knee flexion (42.5%-65.5%of the gait cycle), ankle plantarflexion (32.5%-36%of the gait cycle), active force (30.5%-35%of the stance phase), and propulsion force (68%-72.5% of the stance phase). Lower energy costs at 12 km·h-1 were correlated with smaller hip flexion (5.5%-12% and 66.5%-74%) and smaller knee flexion (57%-57.5%) during the running gait cycle. Conclusions: This study indicates that biomechanical factors are associated with RE in recreational runners. To design effective training methods to improve RE, coaches and runners should focus on the sagittal plane kinematics of the hip, knee, and ankle, as well as lower vertical and horizontal kinetic parameters. [ABSTRACT FROM AUTHOR]

Sports-related concussions are caused by one substantial impact or several smaller-magnitude impacts to the head or body that lead to an acceleration of the head, causing shaking of the brain. Athletes with a history of sports-related concussion demonstrate lower-extremity biomechanics during landing tasks that are conducive to elevated injury risk. However, the effect of head acceleration on lower-extremity biomechanics during landing tasks is unknown. Twenty participants were evenly separated into a vertical hopping group and a lateral hopping group. Participants performed several land-and-cut maneuvers before and after a hopping intervention. Vertical head acceleration (g) was measured via an accelerometer during the hopping interventions. Comparisons in head acceleration during the hopping tasks were made between groups. Additionally, kinematic and kinetic variables were compared pre- and post-intervention within groups as well as post-intervention between groups. The vertical hopping group demonstrated greater vertical head acceleration compared to the lateral hopping group (p = 0.04). Additionally, the vertical hopping group demonstrated greater knee abduction angles during landing post-intervention compared to the lateral hopping group (p < 0.000). Inducing head acceleration via continuous hopping had an influence on lower-extremity biomechanics during a landing task. [ABSTRACT FROM AUTHOR]

We explored the impact of running in the severe intensity domain on running mechanics and muscle oxygenation in competitive runners by investigating the relationship between mechanical deviations from typical stride characteristics and muscle oxygen saturation (SmO2) in the quadriceps muscle. Sixteen youth competitive runners performed an 8‐min exhaustive running test on an outdoor track. Running mechanics were continuously monitored using inertial measurement units. Rectus femoris SmO2 and total hemoglobin (a measure of blood volume) were continuously monitored by near‐infrared spectroscopy. One‐class support vector machine (OCSVM) modeling was employed for subject‐specific analysis of the kinematic data. Statistical analysis included principal component analysis, ANOVA, and correlation analysis. Mechanical deviations from typical stride characteristics increased as the running test progressed. Specifically, the percentage of outliers in the OCSVM model rose gradually from 2.2 ± 0.8% at the start to 43.6 ± 28.2% at the end (p < 0.001, mean ± SD throughout). SmO2 dropped from 74.3 ± 8.4% at baseline to 10.1 ± 6.8% at the end (p < 0.001). A moderate negative correlation (r = −0.61, p = 0.013) was found between the average SmO2 and the percentage of outlier strides during the last 15% of the run. During high‐intensity running, alterations in running biomechanics may occur, linked to decreased quadriceps muscle oxygenation. These parameters highlight the potential of using running kinematics and muscle oxygenation in training to optimize performance and reduce injury risks. Our research contributes to understanding biomechanical and physiological responses to endurance running and emphasizes the importance of individualized monitoring. [ABSTRACT FROM AUTHOR]

This study aimed to compare performance, kinematic, and physiological variables between open water and pool swimming conditions in elite triathletes and to examine the associations between conditions on these variables. Fourteen elite triathletes (10 males and 4 females [23.4 ± 3.8 years]) performed two 1500‐m swimming tests in open water and in a 25‐m pool. Swimming speed, stroke rate (SR), length (SL) and index (SI), heart rate (HR), blood lactate concentrations [La−], and end‐exercise oxygen uptake (EEV̇O2) were assessed in both conditions. Lower SL and SI and higher SR were obtained in open water compared with pool swimming (p < 0.05). Moreover, kinematic variables changed as a function of distance in both conditions (p < 0.05). No differences were found in the main physiological variables (HR, [La−], and EEV̇O2) between conditions. Respiratory exchange ratio presented lower values in open water than in pool conditions (p < 0.05), while time constant was higher in open water (p = 0.032). The fastest triathletes in open water obtained the best performance in the pool (r = 0.958; p < 0.001). All kinematic variables, HR and peak [La−] presented positive associations between conditions (r > 0.6; p < 0.05). Despite physiological invariance, triathletes and coaches should monitor specific open water training to adapt their swimming technique to the competitive environment. [ABSTRACT FROM AUTHOR]

How the neuromechanics of the lower limb functional muscle groups change with running speed remains to be fully elucidated, with implications for our understanding of human locomotion, conditioning, and injury prevention. This study compared the neuromechanics (ground reaction and joint kinetics, kinematics and muscle activity) of middle‐distance athletes running on an instrumented treadmill at six wide‐ranging speeds (2.78–8.33 m·s−1). Ground reaction forces and kinematics were analyzed using inverse dynamics to calculate flexor and extensor joint torques, and positive and negative work done by these torques. Contributions of each functional muscle group to the total positive and negative work done by the limb during stance, swing, and the whole stride were quantified. During stance, the ankle plantar flexors were the major energy generator and absorber (>60%) at all speeds, but their contribution to whole stride energy generation and absorption declined with speed. Positive work by the hip extensors rose superlinearly with speed during stance (3‐fold) and especially during swing (12‐fold), becoming the biggest energy generator across the whole stride at >5 m·s−1. Knee flexor and extensor negative work also rose superlinearly with speed during swing, with the knee flexors becoming the greatest energy absorber over the whole stride at >7.22 m·s−1. Across speeds, plantar flexor peak moment and positive work accounted for 97% and 96% of the variance in step length, and swing hip extension peak moment and positive work accounted for 98% and 99% of the variance in step frequency. There were pronounced speed, phase (stance/swing), and work (positive/negative) dependent contributions of the different functional muscle groups during running, with extensive implications for conditioning and injury prevention. [ABSTRACT FROM AUTHOR]

This study investigated the effects of plyometric training on lower‐limb muscle strength and knee biomechanical characteristics during the landing phase. Twenty‐four male subjects were recruited for this study with a randomised controlled design. They were randomly divided into a plyometric training group and a traditional training group and underwent training for 16 weeks. Each subject was evaluated every 8 weeks for knee and hip isokinetic muscle strength as well as knee kinematics and kinetics during landing. The results indicated significant group and time interaction effects for knee extension strength (F = 74.942 and p = 0.001), hip extension strength (F = 99.763 and p = 0.000) and hip flexion strength (F = 182.922 and p = 0.000). For landing kinematics, there were significant group main effects for knee flexion angle range (F = 4.429 and p = 0.047), significant time main effects for valgus angle (F = 6.502 and p = 0.011) and significant group and time interaction effects for internal rotation angle range (F = 5.475 and p = 0.008). The group main effect for maximum knee flexion angle was significant (F = 7.534 and p = 0.012), and the group and time interaction effect for maximum internal rotation angle was significant (F = 15.737 and p = 0.001). For landing kinetics, the group main effect of the loading rate was significant (F = 4.576 and p = 0.044). Significant group and time interaction effects were observed for knee extension moment at the moment of maximum vertical ground reaction force (F = 5.095 and p = 0.010) and for abduction moment (F = 8.250 and p = 0.001). These findings suggest that plyometric training leads to greater improvements in hip and knee muscle strength and beneficial changes in knee biomechanics during landing compared to traditional training. Highlights: Plyometric training changes landing biomechanics.Changes help to reduce the risk of ACL injury.Changes from long‐term training are more noticeable. [ABSTRACT FROM AUTHOR]

We examined performance across one menstrual cycle (MC) and 3 weeks of hormonal contraceptives (HC) use to identify whether known fluctuations in estrogen and progesterone/progestin are associated with functional performance changes. National Rugby League Indigenous Women's Academy athletes [n = 11 naturally menstruating (NM), n = 13 using HC] completed performance tests [countermovement jump (CMJ), squat jump (SJ), isometric mid‐thigh pull, 20 m sprint, power pass and Stroop test] during three phases of a MC or three weeks of HC usage, confirmed through ovulation tests alongside serum estrogen and progesterone concentrations. MC phase or HC use did not influence jump height, peak force, sprint time, distance thrown or Stroop effect. However, there were small variations in kinetic and kinematic CMJ/SJ outputs. NM athletes produced greater mean concentric power in MC phase four than one [+0.41 W·kg−1 (+16.8%), p = 0.021] during the CMJ, alongside greater impulse at 50 ms at phase one than four [+1.7 N·s (+4.7%), p = 0.031] during the SJ, without differences between tests for HC users. Among NM athletes, estradiol negatively correlated with mean velocity and power (r = −0.44 to −0.50, p < 0.047), progesterone positively correlated with contraction time (r = 0.45, p = 0.045), and both negatively correlated with the rate of force development and impulse (r = −0.45 to −0.64, p < 0.043) during the SJ. During the CMJ, estradiol positively correlated to 200 ms impulse (r = 0.45, p = 0.049) and progesterone to mean power (r = 0.51, p = 0.021). Evidence of changes in testing performance across a MC, or during active HC use, is insufficient to justify "phase‐based testing"; however, kinetic or kinematic outputs may be altered in NM athletes. Highlights: Evidence of changes in testing performance across a menstrual cycle, or during active hormonal contraceptives use, is insufficient to justify "phase‐based testing" at a group or team‐based level among female rugby league athletes.Kinetic or kinematic outputs in jumping movements may be altered in naturally menstruating athletes; however it could not be determined if the observed alterations exceeded between‐day variability. [ABSTRACT FROM AUTHOR]

Background: Advanced osteoarthritis of knees with varus deformity consists of attenuation of lateral structures with contracture of the posteromedial structures and formation of medial osteophytes. The conventional step-wise medial and posteromedial release with measured resection may sometimes hinder achievement of perfectly balanced flexion and extension gaps with maintenance of flexion stability, without the use of a constrained prosthesis. Medial femoral epicondylar sliding osteotomy tailors the balancing to the need of the kinematics of the native knee and precludes the use of a constrained implant. Methods: 15 patients with Ahlbäck Grades III through V osteoarthritic changes at Howrah Orthopaedic Hospital were included in a prospective cohort case series with a minimum period of follow-up being 12 months. Physical examination, clinical questionnaire and radiographic evaluation were done post-operatively for objectification by functional Knee Society and Oxford Knee Scores respectively. Results and Analysis: The mean post-operative femorotibial angulation ameliorated to a value of 3.73 ± 1.58° from 18.67 ± 4.2° in the pre-operative stage. The mean overall Range of Motion of operated knee was 109.87 ± 6.86° with no residual frontal laxity and/or laxity in the coronal plane. The mean amount of resection of tibial plateau in patients with severe varus deformity was kept to a minimum, 6.56 mm from the least deficient portion of the lateral condyle. There were no complications as regards component loosening and/or surgical-site infection. Conclusion: The main objective of balancing a severely varus-afflicted knee is to preserve as much of the Medial Collateral Ligament as possible, to retain its check rein function and not jeopardise the stability. This is ensured by distalisation and posteriorizing the medial epicondyle by an incomplete osteotomy in addition to modest tibial resection fetching a non-isometric point of knee flexion. All osteotomies united by bony union and restoration of kinematic alignment. The limitation of this study however includes the lack of long-term results, such as late instability and polyethylene wear. [ABSTRACT FROM AUTHOR]

Implicit learning has the potential to improve movement execution and reduce injury risk. Previous research showed beneficial effects of short-term interventions with implicit learning in male athletes. However, research on long-term interventions in female athletes is lacking. The aim of this study was to examine the effects of a 4-week intervention with video instruction on movement execution of SSC, a task that is highly related with anterior cruciate ligament (ACL) injury risk, in female athletes. Twenty talented adolescent female soccer players were part of the control (CTRL, n = 10) or video instruction (VIDEO, n = 10) group. All subjects practiced 4 weeks and received general task instructions. In addition, the VIDEO group received expert video instruction during practice. Lower extremity kinematics and kinetics and vertical ground reaction force of SSC were examined during baseline, immediate post, and 1-week retention tests. After nonlinear registration, differences between each subject and the expert she had seen were determined. These differences were analyzed with SPM1D 2-way ANOVA. No interaction effects between time and group were found (p > 0.05). Main effects of time were found in the frontal plane. In particular, smaller deviations of subjects compared with the seen expert of the knee adduction (p = 0.005, 97.9-100% stance phase [SP]) and hip abduction (p = 0.005,11.5-13.8% SP) and adduction (p < 0.001, 33.4-87.7% SP) moments were found in immediate post compared with baseline. These frontal plane short-term improvements, replicating earlier findings in both sexes, may lower ACL injury risk. The large observed interindividual differences overtime may have concealed the long-term effects of video instruction at the group level. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the kinetics and kinematics across incremental loads with the push press (PP), push jerk (PJ), and split jerk (SJ). Eighteen resistance-trained men performed the 1 repetition maximum (1RM) tests (visit 1)3-7 days before an incremental loading protocol (60, 75, and 90% 1RM) of the 3 exercises (visit 2). Kinetics and kinematics were derived from force-time data and compared using a repeated-measures analysis of variance with load and exercise as within-subject factors. Dependent variables for the biomechanics assessment were categorized as output (power and impulse), driver (force and work), and strategy (displacement and duration) metrics. The interrepetition reliability was assessed using the intraclass correlation coefficient and coefficient of variation. The PP, PJ, and SJ 1RM performance were 89.7 ± 15.4, 95.6 ± 14.4, and 103.0 ± 16.9 kg, respectively. Driver, strategy, and outcome metrics displayed moderate-to-excellent (intraclass correlation coefficient: 0.58-0.98) reliability with acceptable variability (% co-efficient of variation: 2.02-10.00). Increased load resulted in significantly large increases in force, work, displacement, duration, power, and impulse (p < 0.001, ηp² = 0.534-0.903). Exercise selection had a significant and large effect on power, impulse, work, and force (p < 0.016, ηp² = 0.387-0.534). There was a significant and large effect of load x exercise interaction on work, displacement, and duration (p < 0.019, ηp² = 0.158-0.220). Practitioners are encouraged to use heavier loads (90 > 75 > 60% 1RM) during the SJ exercise to maximize output, driver, and strategy kinetics and kinematics. [ABSTRACT FROM AUTHOR]

Individuals with chronic ankle instability (CAI) demonstrate altered movement patterns when their vision is disturbed during simple tasks, such as single-legged standing and walking. However, it remains unclear whether visual disruption by stroboscopic glasses alters movement patterns during landing-cutting movements, considered highly demanding sport maneuvers that mimic a typical athletic movement. To identify altered lower extremity kinematics and muscle activation when vision is disrupted by stroboscopic glasses during landing-cutting tasks in individuals with CAI. Case-control study. Laboratory. A total of 18 individuals with CAI (age = 22.3 ± 2.3 years, height = 1.75 ± 0.1 m, mass = 72.5 ± 9.8 kg) and 18 matched healthy controls (age = 21.7 ± 2.3 years, height = 1.75 ± 0.1 m, mass = 71.9 ± 10.3 kg). All participants performed 5 trials of a landing-cutting task with (SV) and without (NSV) stroboscopic glasses. Frontal- and sagittal-plane lower extremity kinematics and 6 lower extremity muscle activations during the stance phase of a landing-cutting task in the SV and NSV conditions. Individuals with CAI demonstrated more ankle-inversion angle from 18% to 22% and from 60% to 100% of the stance phase and more peroneus longus activation from initial contact to 18% of the stance phase under the SV condition than under the NSV condition. We observed no differences in knee- and hip-joint angles between the visual conditions for both groups. When wearing stroboscopic glasses, individuals with CAI showed altered movement patterns, including increased ankle-inversion angle and peroneus longus activation during the stance phase of a landing-cutting task. The results suggest that they may lack the ability to reweight sensory information to adapt their movement to visual disruption. [ABSTRACT FROM AUTHOR]

Clustering algorithms such as k-means and agglomerative hierarchical clustering (HCA) may provide a unique opportunity to analyze time-series kinematic data. Here we present an approach for determining number of clusters and which clustering algorithm to use on time-series lumbar and pelvis kinematic data. Cluster evaluation measures such as silhouette coefficient, elbow method, Dunn Index, and gap statistic were used to evaluate the quality of decision making. The result show that multiple clustering evaluation methods should be used to determine the ideal number of clusters and algorithm suitable for clustering time-series data for each dataset being analyzed. [ABSTRACT FROM AUTHOR]

Objectives. This systematic review and meta-analysis study aimed to evaluate the biomechanical determinants influencing smash performance in racket sports from 2000 to 2024. The study focuses on kinematic, kinetic, and neuromuscular factors that contribute to effective smash execution. Materials and Methods. A comprehensive literature search was conducted across PubMed, Scopus, and Web of Science, yielding 247 articles, of which 9 met the inclusion criteria. The included studies were analyzed for key biomechanical determinants, with a focus on joint angles, limb velocities, trunk rotation, muscle forces, ground reaction forces (GRFs), joint torques, and muscle activation patterns. Meta-analysis was performed to determine pooled effect sizes and assess heterogeneity. Results. The meta-analysis revealed significant positive effects of biomechanical determinants on smash performance. Kinematic factors such as joint angles and trunk rotation (X-Factor) had the highest impact, with a pooled effect size of 1.20. Kinetic determinants, including muscle forces and GRFs, also showed substantial effects (pooled effect size of 1.10). Neuromuscular factors, which are crucial for muscle activation and coordination, had a pooled effect size of 1.15. Fatigue was found to significantly reduce performance metrics, highlighting the need for fatigue management in training programs. The heterogeneity was low to moderate, indicating consistency across studies. Conclusions. The findings underscore the importance of optimizing biomechanical factors to enhance smash performance. Training programs should focus on improving joint angles, limb velocities, trunk rotation, muscle forces, and coordination. Fatigue management strategies are essential to maintain performance levels. These insights provide a foundation for developing targeted training programs to improve athletic outcomes in racket sports.

Abstract Purpose Total joint arthroplasty (TJA) has often been used to treat thumb carpometacarpal (CMC) osteoarthritis (OA). However, guidelines for the CMC prosthesis shape remain unclear. This study aimed to identify the effective shape of a ball-and-socket prosthesis in restoring the range of thumb motion after TJA. Methods The participants were 10 healthy young adult men (22–32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD. Results We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values. Conclusion Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis.

Purpose: Total joint arthroplasty (TJA) has often been used to treat thumb carpometacarpal (CMC) osteoarthritis (OA). However, guidelines for the CMC prosthesis shape remain unclear. This study aimed to identify the effective shape of a ball-and-socket prosthesis in restoring the range of thumb motion after TJA. Methods: The participants were 10 healthy young adult men (22–32 years; 26.8 ± 3.57 [mean ± SD]). CT scans were performed in eight static limb positions during abduction and flexion. We defined three design variables (offset R, height H, and neck rotation angle Φ) as the variables that determine the basic shape of the ball-and-socket prosthesis. The ideal values of these design variables were examined based on the results of a 3D motion analysis, which evaluated the change in the posture of the first metacarpal (r, h, and φ corresponding to R, H, and Φ, respectively) relative to the center of rotation (COR) during abduction and flexion. We also simulated the effect of these design variables on the range of thumb motion after TJA using 3D CAD. Results: We found that the values of r and h averaged over all limb positions were 6.92 ± 1.60 mm and 51.02 ± 1.67 mm, respectively, showing that these values remained constant regardless of limb position. In contrast, φ changed significantly. The simulation results indicated that Φ affected the range of thumb motion after TJA, and Φ = 0° relatively reproduced all limb positions compared to other values. Conclusion: Our results suggested that the desirable values of R and H were the average of r and h over several limb positions and that Φ = 0° was effective in restoring the range of thumb motion after TJA. Our results will provide surgeons with new guidelines for selecting a prosthesis. [ABSTRACT FROM AUTHOR]

Background: This study validated the accuracy of the acromion marker cluster (AMC) and scapula spinal marker cluster (SSMC) methods compared with upright four-dimensional computed tomography (4DCT) analysis. Methods: Sixteen shoulders of eight healthy males underwent AMC and SSMC assessments. Active shoulder elevation was tracked using upright 4DCT and optical motion capture system. The scapulothoracic and glenohumeral rotation angles calculated from AMC and SSMC were compared with 4DCT. Additionally, the motion of these marker clusters on the skin with shoulder elevation was evaluated. Results: The average differences between AMC and 4DCT during 10°−140° of humerothoracic elevation were − 2.2° ± 7.5° in scapulothoracic upward rotation, 14.0° ± 7.4° in internal rotation, 6.5° ± 7.5° in posterior tilting, 3.7° ± 8.1° in glenohumeral elevation, − 8.3° ± 10.7° in external rotation, and − 8.6° ± 8.9° in anterior plane of elevation. The difference between AMC and 4DCT was significant at 120° of humerothoracic elevation in scapulothoracic upward rotation, 50° in internal rotation, 90° in posterior tilting, 120° in glenohumeral elevation, 100° in external rotation, and 100° in anterior plane of elevation. However, the average differences between SSMC and 4DCT were − 7.5 ± 7.7° in scapulothoracic upward rotation, 2.0° ± 7.0° in internal rotation, 2.3° ± 7.2° in posterior tilting, 8.8° ± 7.9° in glenohumeral elevation, 2.0° ± 9.1° in external rotation, and 1.9° ± 10.1° in anterior plane of elevation. The difference between SSMC and 4DCT was significant at 50° of humerothoracic elevation in scapulothoracic upward rotation and 60° in glenohumeral elevation, with no significant differences observed in other rotations. Skin motion was significantly smaller in AMC (28.7 ± 4.0 mm) than SSMC (38.6 ± 5.8 mm). Although there was smaller skin motion in AMC, SSMC exhibited smaller differences in scapulothoracic internal rotation, posterior tilting, glenohumeral external rotation, and anterior plane of elevation compared to 4DCT. Conclusion: This study demonstrates that AMC is more accurate for assessing scapulothoracic upward rotation and glenohumeral elevation, while SSMC is preferable for evaluating scapulothoracic internal rotation, posterior tilting, glenohumeral external rotation, and anterior plane of elevation, with smaller differences compared to 4DCT. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the foot-ankle joint mechanics of running drills and running. Seventeen long-distance runners performed five popular running drills (A-skip, B-skip, Bounding, Heel flicks, Straight leg running) and a run at 3.88 m/s. Kinematics, kinetics and power values were calculated for the ankle, midtarsal (MT) and metatarsophalangeal (MP) joints. Electromyographic activity was recorded for the soleus, gastrocnemius medialis, lateralis and abductor hallucis muscle. The A-skip, the B-skip and the Heel flicks induced a smaller ankle (p < 0.001, ŋ2 = 0.41), MT (p < 0.001, ŋ2 = 0.43) and MP (p < 0.001, ŋ2 = 0.47) dorsiflexion peak than running. No difference was found between the running drills and running for ankle, MT and MP moment. The Bounding induces a higher positive ankle power than running (diff: 5.5 ± 7.5 J/kg, p = 0.014, d = 1.05). The A-skip (diff: 2.8 ± 2.9 J/kg, p < 0.001, d = 1.5) and the B-skip (diff: 2.7 ± 2.1 J/kg, p < 0.001, d = 1.4) induce a smaller MT positive power than running. This study offers an analysis of the mechanical behaviour of the foot-ankle complex to help track and field coaches select their running drills in an evidence-based manner. [ABSTRACT FROM AUTHOR]

Background: Step width is a spatial variable in the frontal plane, defined as the mediolateral distance between the heel (forefoot during sprinting) of bilateral feet at initial contact. Variations in step width may impact the lower limb biomechanics. This systematic review aimed to synthesize the published findings to determine the influence of acute changes in step width on locomotion biomechanics and provide implications for injury prevention and enhanced sports performance. Methods: Literature was identified, selected, and appraised in accordance with the methods of a systematic review. Four electronic databases (Web of Science, MEDLINE via PubMed, Scopus, and ScienceDirect) were searched up until May 2023 with the development of inclusion criteria based on the PICO model. Study quality was assessed using the Downs and Black checklist and the measured parameters were summarized. Results: Twenty-three articles and 399 participants were included in the systematic review. The average quality score of the 23 studies included was 9.39 (out of 14). Step width changed the kinematics and kinetics in the sagittal, frontal, and transverse planes of the lower limb, such as peak rearfoot eversion angle and moment, peak hip adduction angle and moment, knee flexion moment, peak knee internal rotation angle, as well as knee external rotation moment. Alteration of step width has the potential to change the stability and posture during locomotion, and evidence exists for the immediate biomechanical effects of variations in step width to alter proximal kinematics and cues to impact loading variables. Conclusion: Short-term changes in step width during walking, running, and sprinting influenced multiple lower extremity biomechanics. Narrower step width may result in poor balance and higher impact loading on the lower extremities during walking and running and may limit an athlete's sprint performance. Increasing step width may be beneficial for injury rehabilitation, i.e., for patients with patellofemoral pain syndrome, iliotibial band syndrome or tibial bone stress injury. Wider steps increase the supporting base and typically enhance balance control, which in turn could reduce the risks of falling during daily activities. Altering the step width is thus proposed as a simple and non-invasive treatment method in clinical practice. Key Points: Short-term changes in step width during gait could influence multiple lower extremity biomechanics. Increasing step width may be beneficial for specific injury rehabilitation. Wider steps increase the supporting base and typically enhance balance control to reduce the falling risks. [ABSTRACT FROM AUTHOR]

The objective of this systematic review and meta-analysis was to provide an overview of kinematic parameters associated with key points of interest in the tennis serve. The research was conducted according to the PRISMA guideline without date restriction. Google scholar, Science Direct, PubMed/Medline, Mendeley, and Science.gov databases were scanned to find relevant studies. Only English peer-review original article focused on joint body angles at trophy position, racket low point and ball impact were retained. The review, quality appraisal, and data extraction from selected studies were performed independently by two reviewers. A meta-analysis was carried out on the most studied joint parameters. Among the 2,844 records identified, 27 articles were included. The wide variety of methods used required data homogenization for comparison purposes. Trunk inclination (25.0 ± 7.1°) and front knee flexion (64.5 ± 9.7°) were the most studied parameters for trophy position. Shoulder lateral rotation (130.1 ± 26.5°) was systematically evaluated for racket low point. At ball impact, shoulder elevation (110.7 ± 16.9°) and elbow flexion (30.1 ± 15.9°) were the most considered joint angles. The systematic review revealed that many kinematic parameters were not quantified at the various key points of interest. Knowledge of the kinematics is essential for understanding the gesture, implementing training methods, and improving the performance. [ABSTRACT FROM AUTHOR]

Background: Medial patellofemoral ligament (MPFL) reconstruction is considered by many to be the gold standard to treat lateral patellar instability; however, some investigators have reported good clinical results after isolated medial quadriceps tendon–femoral ligament (MQTFL) reconstruction or a combined MPFL/MQTFL reconstruction. A handful of studies have preliminarily investigated the biomechanical consequences of these various medial patellar stabilizing procedures. Despite this, no existing study has included multiple medial patellofemoral complex (MPFC) reconstructions and assessment of lateral patellar translation at distinct flexion angles. Hypothesis: Combined MPFL/MQTFL reconstruction would restore patellofemoral contact areas, forces, and kinematics closest to the native state compared with isolated reconstruction of the MPFL or MQTFL alone. Study Design: Controlled laboratory study. Methods: Ten adult cadaveric knee specimens were prepared and analyzed under 5 different conditions: (1) intact state, (2) transected MPFC, (3) isolated MPFL reconstruction, (4) isolated MQTFL reconstruction, and (5) combined MPFL/MQTFL reconstruction. Patellar tilt, lateral patellar translation, patellofemoral contact forces, and patellofemoral contact areas were measured in each condition from 0° to 80° through simulated knee flexion using a custom servohydraulic load frame with pressure sensor technology and a motion capture system for kinematic data acquisition. Results: The isolated MPFL, isolated MQTFL, and combined MPFL/MQTFL reconstruction conditions produced significantly less lateral patellar tilt compared with the transected MPFC state (P <.05). No statistically significant differences were found when each reconstruction technique was compared with the intact state in patellar tilt, lateral patellar translation, contact forces, and contact areas. Conclusion: All 3 reconstruction techniques (isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction) restored native knee kinematics, contact forces, and contact areas without overconstraint. Clinical Relevance: Isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction all restore patellofemoral stability comparable with the intact MPFC state without the overconstraint that could be concerning for increasing risk of patellofemoral arthritis. [ABSTRACT FROM AUTHOR]

This study aimed (i) to analyze the 1500 m open water swimming performance, (ii) to examine the associations between physiological and biomechanical variables with swimming performance, and (iii) to determine which variables can predict swimming performance in triathletes. Fourteen elite triathletes (23.4±3.8 y) performed a 1500 m test in open water swimming conditions. Swimming performance was assessed using World Aquatics Points Scoring, and data were obtained from the 1500 m open water swimming test. Heart rate, end-exercise oxygen uptake (EE˙VO2) and blood lactate concentrations were measured. The initial 250 m of the 1500 m swimming test presented the highest values of biomechanical variables in males (i. e. swimming speed, stroke rate (SR), length (SL), index (SI)). A decrease in SL was observed in the last 250 m in both sexes. Positive association were found between EE˙VO2 (r=0.513; p =0.030), swimming speed (r=0.873; p <0.001) and SI (r=0.704; p =0.002) with swimming performance. In contrast, time constant of the oxygen uptake (r=−0.500; p =0.034) and buoy-turn times (r=−0.525; p =0.027) were negatively associated with performance. SI was the main predictor (R2 =0.495) of open water swimming performance in triathletes. In conclusion, triathletes and coaches must conduct open water training sessions to maximize SI (i. e. swimming efficiency). [ABSTRACT FROM AUTHOR]