Lower Extremity Kinematics Research Articles

Influences of footstrike patterns and overground conditions on lower extremity kinematics and kinetics during running: Statistical parametric mapping analysis

This study investigated lower extremity biomechanics when running on different surfaces among runners with different footstrike patterns. Thirty rearfoot strikers (RFSs) and non-rearfoot strikers (nRFSs) ran at 3.3 m/s on a specially designed indoor track covered with three surfaces: artificial grass, synthetic rubber, and concrete. A motion capture system with ten cameras combined a force plate was used to collect marker trajectory and ground reaction force (GRF) during the running stance phase. A two-way analysis of variance with statistical parametric mapping was employed to evaluate differences in the biomechanics of the lower extremities between footstrike patterns and among running surfaces. The nRFSs exhibited significantly greater ankle inversion angles and increased inversion and internal rotation moments at midstance compared to the RFSs. Conversely, the RFSs demonstrated significantly greater knee abduction moments in late stance. Running on stiffer surfaces was associated with greater vertical GRF in late stance, as well as increased knee and hip extension moments during midstance. Furthermore, running on stiffer surfaces was associated with increased knee abduction moments, hip abduction moments, and hip external rotation moments during late stance. These findings suggested that nRFSs endure more ankle loads, while RFSs face increased knee loads. However, regardless of the footstrike pattern, runners may benefit from selecting softer surfaces to reduce the risk of injury.

Pain-related fear induces aberrant drop jump landing biomechanics in healthy and anterior cruciate ligament reconstructed females.

Rupture of the anterior cruciate ligament (ACL) is a prevalent and debilitating injury typically arising from aberrant biomechanics during landing or deceleration tasks. Pain-related fear, a component of kinesiophobia, has been associated with poor functional outcomes and altered movement patterns in individuals with ACL reconstruction (ACLr), however, the influence of pain-related fear on landing mechanics remains unclear. The purpose of this investigation was to examine the effects of pain-related fear on landing movement patterns in a population of ACLr and healthy females. Thirty-two females (15 recreationally active with a history of ACLr and 17 recreationally active with no history of ACLr) took part. Participants performed five trials of a drop jump (DJ) task (Baseline), underwent a pain stimulus (PS) familiarization task utilizing an electrical stimulus to induce pain-related fear, and performed a subsequent round of DJs while under threat of PS (PS-threat). Lower extremity and trunk kinematics, ground reaction force (GRF) data and muscle activation were analyzed. At baseline, ACLr participants scored higher (21 ± 5.5) on the TSK-11 compared to healthy participants (17 ± 3.4) (p = 0.007). For both groups, the PS intervention significantly increased pain-related fear (ACLr p < 0.001; Healthy p < 0.001). When comparing baseline to PS-threat trials, ACLr participants experienced a significant increase in peak GRF (p = 0.005), decreases in hip (p = 0.003) and knee (p = 0.005) flexion, decreased contact time (p = 0.006) and decreased muscle preactivation for all muscles tested (p < 0.05). Healthy participants experienced significant increases in peak GRF (p = 0.014) and decreased hip (p = 0.005) and trunk peak (p = 0.004) flexion. Pain-related fear alters landing biomechanics in healthy and ACLr females. This may implicate pain-related fear as a contributor to movement alterations commonly associated with ACL injury risk. Level III.

Autologous bone grafting combined with spheroid-based matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee: Good clinical outcomes alongside abnormal postoperative gait patterns.

This study aimed to evaluate the clinical and functional outcomes of autologous bone grafting with spheroid-based matrix-induced autologous chondrocyte implantation (MABCI) for osteochondral defects of the knee by analysing pre- and postoperative patient-reported outcome measures (PROMs). Postoperative gait analysis was conducted and compared with a matched healthy control group to investigate biomechanical deviations. A total of 35 patients (m: 21, f: 14; mean defect size: 4.2 ± 2.4 cm², localisation: femoral condyle: 31, patellofemoral: 5) were analysed. The mean follow-up was 42.6 ± 22.8 months. International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), PROMIS 29 profile, and a questionnaire on patient perception of treatment success were assessed to evaluate PROMs. 3D-instrumented gait analysis (GRAIL, Motek) was used to assess lower extremity kinematics, kinetics and vertical ground reaction forces, compared to sex-, age- and body mass index-matched healthy controls. All clinical scores showed significant improvement compared to the preoperative condition (IKDC: 73.1 ± 10.1 vs. 56.6 ± 17.2, p < 0.01; KOOS subcategories: pain 82.0 [±12.7] vs. 70.7 [±16.7] [p < 0.01], symptoms 79.1 [±20.3] vs. 68.9 [±13.9] [p < 0.01], activities of daily living 90.1 [±11.2] vs. 80.5 [±15.6] [p < 0.01], sport and recreational function: 65.3 [±19.3] vs. 51.3 [±26.29] [p < 0.01], quality of life 52.2 [±18.6] vs. 42.6 [±18.6] [p < 0.01]; numeric pain rating scale: 2.7 ± 2.0 vs. 5.0 ± 2.5, p < 0.01). The analysed patients reported a high satisfaction rate (94.3%). Self-selected walking speed was significantly lower than in healthy controls (1.17 ± 0.17 m/s vs. 0.98 ± 0.18 m/s, p < 0.01). Peak knee flexion angle (PKA) during loading response was significantly smaller (9.6° ± 7.0 vs. 17.7° ± 4.6, p < 0.01), and knee extension moment was significantly reduced (0.1 Nm/kg ± 0.2 vs. 0.4 Nm/kg ± 0.2, p < 0.01). MABCI is an effective treatment for osteochondral knee defects, showing significant improvements in all evaluated PROMs. Postoperative gait analysis revealed abnormal gait patterns, including reduced PKA and lower knee extension moment, suggesting a need for further rehabilitation to optimise functional recovery. Level III.

Relationship of Age and Running Biomechanics in Female Recreational Runners.

Middle-age and older runners demonstrate differences in running biomechanics compared with younger runners. Female runners demonstrate differences in running biomechanics compared with males, and females experience hormonal changes during menopause that may also affect age-related changes in running biomechanics. The purpose of this study was to determine the relationship between age and running biomechanics in healthy female recreational runners. Fifty-two participants (ages 27-65y) ran on an instrumented treadmill at 2 different self-selected speeds: easy pace and 5km race pace. Lower-extremity kinematic and kinetic variables were calculated from 14 consecutive strides. Linear regression was used to determine the relationship between age and lower-extremity running biomechanics, controlling for self-selected running speed. There was a negative relationship between age and easy pace (R = -.49, P < .001) and age and 5km race pace (R = -.43, P = .001). After controlling for self-selected running speed, there were no significant relationships between age and running biomechanics for either running speed. Several biomechanical variables were moderately to strongly correlated with running speed. Running speed should be considered when investigating age-related differences in running biomechanics.

The effect of carbon fiber custom dynamic orthosis type on kinematics and kinetics of lower extremity joints in individuals with lower limb traumatic injuries.

Carbon fiber custom dynamic orthoses have been used to improve gait mechanics after lower limb trauma in military service members, with the goal of restoring function and improving outcomes. However, the effects of commercially available carbon fiber orthoses available to civilians on lower extremity joint kinetics and kinematics are poorly understood. The aim of this study was to examine the effect of two commercially available orthoses on lower extremity kinematics and kinetics in individuals with lower limb trauma. A total of 23 participants with a lower extremity traumatic injury underwent gait analysis while walking without an orthosis, and while wearing a monolithic carbon fiber orthosis or while wearing a modular carbon fiber orthosis, in a randomized order. Study participants accommodated to each orthosis for three months prior to testing. Joint kinematics and kinetics at the ankle, knee, and hip joints, and ground reaction forces were assessed. The two study orthoses significantly reduced ankle motion compared to no orthosis, with large effect sizes observed. Peak plantarflexor moment was greater with the modular orthosis compared to the monolithic orthosis. Ankle push-off power did not differ between orthoses but was significantly reduced relative to no orthosis. Push-off power with the study orthoses was over 25% greater as compared to previous studies with military orthoses. Peak loading response power generation at the knee was greater with the monolithic orthosis as compared to the modular orthosis. The kinematics and kinetics at the hip did not differ between orthoses. Orthoses commonly used in civilian settings to treat limb trauma primarily alter joint kinematics and kinetics at the ankle, in a manner consistent with orthoses used in the military. Additionally, despite the apparent large differences in the designs of the two study orthoses, between-orthosis differences on gait mechanics were limited.

The Relationship Between Foot Anthropometrics, Lower-Extremity Kinematics, and Ground Reaction Force in Elite Female Basketball Players: An Exploratory Study Investigating Arch Height Index and Navicular Drop

Static and dynamic foot function can be evaluated using easy-to-implement, low-cost measurements like arch height index (AHI) and navicular drop (ND). Connections between AHI/ND and lower-extremity kinematics/kinetics have largely focused on gait. Some studies exist evaluating basketball players; however, these predominantly focus on men. To our knowledge, few studies evaluate female athletes, and none have investigated connections between AHI/ND and lower-extremity biomechanics in elite female basketball players. Thus, we conducted an IRB-approved observational investigation of 10 female, National Collegiate Athletic Association (NCAA) Division 1 basketball players, evaluating connections between AHI/ND and lower-extremity biomechanics during basketball activities. Participants completed one visit wherein bilateral AHI/ND measurements and kinematics/kinetics were captured via optical motion capture and force-instrumented treadmill during basketball activities (walking, running, vertical/horizontal jumping, side shuffles, 45° cuts). No connections existed between the AHI and any variable during any task. Contrastingly, ND was statistically significantly correlated with medial/lateral force maximum and range during left cutting. This implies that individuals with stiffer feet produced more side-to-side force than those with more foot mobility during cutting. This is the first report connecting ND to lower-extremity biomechanics in elite, female basketball players. This could inform novel interventions and technologies to improve frontal kinematics/kinetics.

Minimum Normalized Cycling Cadence to Increase Post-Cycling Gait Velocity.

Previous research has shown that increasing cycling cadence can result in improved post-cycling gait velocity. However, the specific threshold of cycling cadence required to bring about clinically meaningful changes in gait velocity remains unknown. This study aimed to determine the minimum increment in cycling cadence that would lead to a significant improvement in post-cycling gait velocity. A total of 42 young adults participated in our study and were randomly assigned to one of three groups: TEN, TWENTY, and THIRTY. Each group was assigned to cycle at a cadence at the corresponding percentage higher than the participant's self-selected gait cadence. Each participant engaged in a 15-min cycling session at their respective assigned cycling cadence. Before and after cycling, participants completed a 10-meter walk test while spatiotemporal parameters of gait, ground reaction forces, lower extremity kinematics, and kinetics were recorded. One-way ANOVA revealed no statistically significant changes in spatiotemporal, ground reaction force, kinematics, and kinetics variables pre- and post-cycling. However, there were both statistically significant (F(2,41) = 3.794, p = 0.031, η2 = 0.604) and clinically meaningful changes (0.07 m/s) in post-cycling gait velocity in the THIRTY group only. This suggests that a cycling cadence of 30% or higher is the minimum requirement to produce a clinically significant improvement in gait velocity.

Effect of foot strike patterns and angles on the biomechanics of side-step cutting.

The study aimed to determine how foot strike patterns and cutting angles affect lower extremity (LE) kinematics, kinetics, and muscle activity during side-step cutting. Twenty male college sport athletes participated in this research. Three-dimensional motion analysis featuring ground reaction force (GRF) and electromyography (EMG) of the dominant leg was used. LE kinematics, kinetics, and EMG data parameters were obtained during a 45° and 90° side-step cutting involving rearfoot strikes (RFS) and forefoot strikes (FFS). The significant foot strike pattern × angle interactions were observed for the ankle eversion range of motion (ROM) at the loading phase. Cutting of 90° had greater knee flexion ROM, knee valgus ROM, and knee varus moment compared to that of 45°. RFS cutting had greater knee flexion, hip flexion, knee valgus, knee varus moment, knee varus moment, and ankle eversion ROM. FFS cutting produced a lower vertical GRF, lateral GRF, and a loading rate. Both vastus medialis and vastus lateralis muscle activities were remarkably greater during cutting of 90° than 45°. At the loading phase, semitendinosus, biceps femoris, and the lateral head of gastrocnemius muscle activities during FFS cutting were considerably greater than those during RFS cutting. The FFS pattern can better protect the anterior cruciate ligament (ACL) and improve the flexibility of athletes by increasing the plantarflexion torque of the ankle. The injury risk also increases with the larger cutting angle. The EMG activities of semitendinosus and biceps femoris are vital for the stability of knee joint during side-step cutting, which helps reduce ACL stress during buffering.

The effect of eight weeks’feedback training program on lower extremity kinematic and performance during jump landing tasks in the men with selected motor control defects

Introduction and objectiveThe present study aims to investigate whether eight weeks’ feedback improves the range of motion in lower extremity joints(in the four phases of eccentric, concentric, maximum knee flexion, and landing moment) and performance in the individuals with motor control defects or not. MethodThe present research is a randomized clinical trial study before and after the intervention. Thirty-four male recreational athletes with movement control defects were selected based on the study criteria and then randomly assigned to a control group and an intervention group. Kinematic and performance data were recorded while the participants performed jump-landing movement tasks in two stages before and after the two-month jump training program. To analyze the data, the two-way analysis of variance and Bonferroni statistical tests were used for each movement task at the significance level of P < 0.05. FindingsThere was a significant difference between the values of Reactive Strength Index (RSI) in the intervention and the control groups in drop vertical jumps and countermovement jumps (p = 0.001). ConclusionThe results of the present study indicated that two months' feedback improved the athletes’ kinematic variables and jumping performance.

Effect of hip abductors training on pelvic drop and knee valgus in runners with medial tibial stress syndrome: a randomized controlled trial

BackgroundMedial tibial stress syndrome (MTSS) is a prevalent running-related injury that could impact athletic performance and quality of life. The purpose of the study was to investigate the effectiveness of functional hip abductor strength training on reducing contralateral pelvic drop angle (hip frontal plane projection angle), and dynamic knee valgus (knee frontal plane projection angle) in runners with medial tibial stress syndrome (MTSS).MethodsForty male and female recreational runners were diagnosed with MTSS for at least one month. The age ranged from 25 to 35 years old, and the body mass index (BMI) ranged between (18.5 and 25 kg/m2) participated in this study. This was a single-blind, randomized controlled trial. Participants were randomized into two groups: a control group (Group A, n = 20) received a selected physical therapy exercise program, and an experimental group (Group B, n = 20) received the same program plus functional hip abductor strength training. Dynamic knee valgus (frontal plane projection angle) and contralateral pelvic drop angle were measured using 2D video and analyzed by Kinovea software at baseline and after 8 weeks. Mixed-effect multifactor analysis of variance (MANOVA) was conducted to compare within and between groups effects on FPPA and pelvic drop angle.ResultsAfter 8 weeks, Group B exhibited a significantly decreased frontal plane projection and pelvic drop angles compared to Group A (p < 0.05). Group A also demonstrated a reduced pelvic drop angle, but to a lesser extent, and their frontal plane projection angle increased.ConclusionsThis study demonstrates that 8 weeks of functional hip abductor strength training, combined with traditional physical therapy, effectively improves lower extremity kinematics in runners with MTSS by reducing dynamic knee valgus and contralateral pelvic drop. This targeted approach likely addresses underlying muscle weakness and movement dysfunction, offering hope for potentially reducing MTSS recurrence.Trial registration: clinicaltrials.gov. NO: NCT05637476. Date: December 1, 2022.

The effect of femoral strapping on hip internal rotation and pain response in females with patellofemoral pain

BackgroundHip internal rotation has been reported to affect patellofemoral joint mechanics and contribute to patellofemoral pain (PFP). The SERF (Stability through External Rotation of the Femur) strap was designed to provide hip stability by pulling the thigh into external rotation during weight-bearing activities. Research questionWhat are the effects of the SERF strap on hip internal rotation and pain response in females with PFP who present with hip internal rotation during weight-bearing activities? MethodsNineteen females between the ages of 18 and 45 with a diagnosis of PFP participated. Lower extremity kinematics were obtained during three tasks (drop-jump, unilateral step-down, over-ground running) under strap and no-strap conditions. A 10-cm visual analog scale (VAS) was used to assess pain response during each task and strap condition. Participants who exhibited at least 5 degrees of hip internal rotation during at least one of the 3 tasks were included in the final analysis. Peak hip internal rotation and mean VAS score were compared separately between strap conditions across tasks using 2 ×3 (strap condition x task) repeated-measures ANOVAs. ResultsEighteen of the 19 females with PFP met the criteria for the presence of hip internal rotation. There was a significant reduction in peak hip internal rotation across tasks when wearing the SERF strap (mean ± sd = 7.4 ± 2.3, p<0.001). Additionally, the change in mean VAS pain score was significantly lower across tasks when wearing the SERF strap (1.0 ± 1.0, p=0.03). SignificanceThe SERF strap was effective in reducing hip internal rotation and PFP during dynamic weight-bearing activities in symptomatic females. The SERF strap may be a useful treatment adjunct for persons with PFP who present with poor transverse plane control of the hip.

Interlaboratory Study Toward Combining Gait Kinematics Data Sets of Long-Distance Runners.

The limited sample size in gait studies has hampered progress in the field. This challenge could be addressed through multicenter studies, thereby leveraging data sets from different laboratories. This study compared 3-dimensional lower-extremity running kinematics between the Biomechanics and Motor Control Laboratory, Federal University of ABC (Brazil), and the Running Injury Clinic, University of Calgary (Canada). Three-dimensional lower-extremity kinematics from 23 male runners were collected from each laboratory using comparable instrumentation and experimental procedures. The 3-dimensional hip, knee, and ankle angles were compared within and between centers using root-mean-square deviation. Two-sample t tests Statistical Parametric Mapping tested the hypothesis that the data from both laboratories were not different. The sagittal plane hip, knee, and ankle angles were similar between laboratories, while notable differences were observed for frontal (hip and ankle) and transverse (hip and knee) plane angles. The average interlaboratory root-mean-square deviation (2.6°) was lower than the intralaboratory root-mean-square deviation (Biomechanics and Motor Control = 4.8°, Running Injury Clinic = 5.6°), with the ankle transverse angle displaying the smallest, and the knee transverse angle displaying the largest variability. This study demonstrates the potential of combining gait kinematics data from different laboratories to increase sample size, but frontal and transverse plane data should be considered with caution.

Analysing lower limb motion and muscle activation in athletes with ankle instability during dual-task drop-jump

ABSTRACT This study investigates the impact of chronic ankle instability (CAI) on athletes’ lower extremity mechanics during bounce drop-jump landings with divided attention. Thirty Division I physical education voluntarily participated in the study. They performed two sets of bounce drop jumps: one set with a divided attention task and the other without. The obtained data were analysed using a paired t-test to compare the outcomes between the divided attention (DA) and non-divided attention (NDA) tasks. Athletes with CAI, during the DA task, displayed higher vertical landing forces, increased ankle inversion velocity, and greater range of motion of the ankle, knee, and hip in the frontal and transverse planes. They also exhibited insufficient neuromuscular preparation of the rectus femoris muscle. Notably, distinct kinematic alterations were observed in the ankle, knee, and hip joints regarding frontal and transverse lower-extremity kinematics. The findings suggest that athletes with CAI experience decreased activation of the rectus femoris muscle, which may impact their dynamic postural stability from pre-landing to ascending phases. Furthermore, the results indicate that individuals with CAI closely replicate the injury mechanisms encountered during a drop-jump landing task with divided attention. These insights offer valuable information about the real-time challenges faced by athletes with CAI.

Neurocognitive demands reducejump distance and coordination variability of the injured leg in athletes after anterior cruciate ligament reconstruction.

The study aimed to evaluate the impact of neurocognitive reliance on jump distance and lower extremity kinematics in individuals who had undergone anterior cruciate ligament reconstruction (ACLR). This was achieved by comparing hop performance under standard and neurocognitive conditions. Thirty-two patients after ACLR and 32 healthy controls (CTRL) participated. Both groups performed a single-leg hop for distance (SLHD) and two neurocognitive hop tests, each designed to evaluate distinct aspects of neurocognition. The neurocognitive tests included the reaction SLHD (R-SLHD), measuring reaction to a central stimulusand working memory SLHD (WM-SLHD) assessing response to a memorized stimulus amidst distractor stimuli. Distances were assessed for the three-hop tests. In addition, joint kinematics were collected to calculate lower extremity coordination of the lower extremity. SLHD performance was defined as the mean hop distance per condition per leg for each participant and was analyzed using a mixed ANOVA with condition and leg as the within-subjects factors and the group (ACLR or CTRL) as the between-subjects factor. Differences in joint coordination variability were analyzed using two-sample t-test statistical parametric mapping (SPM) with linear regression. The WM-SLHD resulted in a significantly decreased jump distance compared with the standard hop test both for ACLR and CTRL. Furthermore, the leg difference within the ACLR group increased under higher cognitive load as tested with the WM-SLHD, indicating leg-specific adaptations in lower extremity coordination. Neurocognitive single-leg hop tests resulted in reduced jump distance in CTRL and ACLR. The neurocognitive hop test revealed changes in coordination variability for the CTRL and the uninjured leg of ACLR individuals, whereas the injured leg's coordination variability remained unaltered, suggesting persistent cognitive control of movements post-ACLR. Level III.

Classification of the foot kinematics during gait and the characteristics of the knee and hip kinematics in individuals with pronated foot

Overuse injuries are often caused by pronated foot and the associated abnormal lower-extremity kinematics during dynamic activities. Various patterns of foot kinematics are observed among individuals with pronated feet during dynamic activities, resulting in different dynamic kinematics of the proximal joint. This study aimed to identify the foot kinematic patterns during gait among individuals with pronated feet and evaluate the relationship between these foot kinematic patterns and the hip and knee kinematics. A three-dimensional motion capture system was used to collect data regarding the foot, knee, and hip kinematics during the stance phase of gait of 42 individuals with pronated feet. A hierarchical cluster analysis method was used to identify the optimal number of clusters based on the foot kinematics, including navicular height (NH) at initial contact and dynamic navicular drop (DND). The differences in the cluster and demographic variables were examined. One-dimensional statistical parametric mapping was used to evaluate the differences in the time histories of the NH, knee, and hip kinematics during the stance phase. Three subgroups were identified on the basis of the NH and DND: Cluster 1, moderate NH at initial contact and larger DND; Cluster 2, highest NH at initial contact and smaller DND; and Cluster 3, lowest NH at initial contact and smaller DND. The hip adduction angle of Cluster 1 was significantly higher than that of Cluster 3 from the 0% to 51% stance phases. Further longitudinal studies are needed to clarify the relationship between identified subgroups and the development of overuse injuries.

Kinematic and Kinetic Differences Between Ball Rotational Exercises and the Throwing Motion in Collegiate Baseball Athletes.

Mylott, JA, Potts, EM, Wolf, JH, Bullock, GS, and Nicholson, KF. Kinematic and kinetic differences between ball rotational exercises and the throwing motion in collegiate baseball athletes. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to observe the associations that medicine ball pushes and chops have on the lower extremities regarding ground reaction forces (GRF) and lead knee flexion angles and to compare these values with a regular baseball overhead throw. Lower extremity kinetics and kinematics were obtained via force plates and marker motion capture. Subjects (n = 35) included baseball players (age 19.7 ± 1.5 years). Five medicine ball movements of each type along with at least 3 pitches or 5 throws off the mound were recorded for data collection. Statistical parametric mapping, including analysis of variance and 2-way t-tests, was used to compare the variables of interest between the movements for continuous time data. All kinematic and kinetic variables were significantly different (p < 0.05) for some time during the motion between the different trial types of medicine ball exercises and throws. A medicine ball chop can increase peak drive leg GRF, whereas a push can help an athlete keep greater driver leg GRF and maintain ground connection into foot plant. A push helps train lead leg deficiencies in the delivery. Both the medicine ball chop and push have benefits for training lead leg stabilization and extension.

The effect of fresh and used ankle taping on lower limb biomechanics in sports specific movements

ObjectivesWe aimed to investigate the effects of ankle taping on lower extremity biomechanics related to injury development and how these effects change after sports-specific use. DesignRandomized, repeated measures design with three conditions: Barefoot, tape applied fresh, and tape after sports-specific use (between-subject factor: sex). MethodsTwenty-five healthy participants (ten female) performed sports-specific movements, including running, drop jumping, and 180° change of direction, under the three conditions. Kinetic and kinematic data were collected using 3D motion capturing and force platforms. ResultsTape applied fresh and tape after sports-specific use significantly reduced peak ankle inversion. Biomechanical risk factors for anterior cruciate ligament or running overuse injuries were either unchanged or decreased with tape applied fresh, except for the peak loading rate of the resultant ground reaction force, which increased between 4% and 18% between movement types. After 15 minutes of sports-specific use of the tape, the alterations induced by tape applied fresh remained for some biomechanical risk factors while they became closer to barefoot again for others, indicating a differential response to prolonged use of taping for different biomechanical variables. ConclusionsAnkle taping protects the ankle joint by reducing biomechanical risk factors associated with ankle sprains, and most biomechanical risk factors for anterior cruciate ligament or running overuse injuries are not increased. Further research is needed to explore the duration of protective effects, variations across sports, and its impact on patients with chronic ankle instability, contributing to a more comprehensive understanding of ankle taping's influence on lower extremity biomechanics.

Kinematics of Hitting in Youth Baseball: Implications for Skill Development.

This study compared lower extremity, trunk, and upper extremity kinematics between tee and front toss hitting in youth baseball athletes. Twenty youth baseball athletes (14.3±2.9 yrs) performed three maximal effort swings off front toss and tee. Kinematic data were collected during the preparatory and acceleration phases. Lower extremity, trunk, and upper extremity kinematics were compared between tee and front toss hitting using 1-dimensional statistical parametric mapping (SPM). There was a significant difference in trunk kinematics between tee and front toss during the preparatory phase (p=.001); the trunk rotated more toward the back side when hitting off a tee compared to front toss (p<0.001). There was also a significant difference in trunk kinematics between tee and front toss for 67% of the acceleration phase; the trunk rotated more towards the back side from 0 to 67% when hitting off the tee (p<0.001). Significant differences were found in trunk kinematics between tee and front toss hitting in youth baseball players, where the trunk is less rotated toward the pitcher in the tee than in the front toss. Coaches utilize various training modalities to enhance hitting performance; however, differences in trunk kinematics should be considered between modalities when developing fundamental hitting techiques in youth baseball athletes.

Changes in Lower-Extremity Gait Biomechanics Following High-Cadence Cycling.

We sought to investigate the lower-extremity biomechanics underlying increased gait velocity following high-cadence cycling. Ground reaction forces (GRF) and lower-extremity kinematics and kinetics were recorded as 15 healthy adults walked at a self-selected pace prior to and immediately following a 15 min bout of cycling at a cadence of 75 rotations per minute. Propulsive GRF and stance-phase peak dorsiflexion and knee extension angles increased, while peak plantarflexion and hip extension angles decreased. Swing-phase peak dorsiflexion, plantarflexion, knee flexion, and hip flexion angles increased, while peak knee extension angle decreased. Peak dorsiflexion, knee extension, and hip extension angular velocity also increased during swing. No changes in peak joint moments were observed; however, peak positive ankle, knee, and hip joint power generation increased following cycling. Completing high-cadence cycling improves gait velocity by increasing propulsive GRF; increasing joint angular velocity during the swing phase of gait for the ankle, knee, and hip; and increasing positive power production by the ankle, knee, and hip during the stance phase. Increased gait velocity post cycling exercise did not increase lower-extremity joint moments. Cycling may be a viable exercise-based modality for increasing gait velocity, especially in populations where gait ability or joint loading is of particular concern.

Validation of OpenCap: A low-cost markerless motion capture system for lower-extremity kinematics during return-to-sport tasks

Low-cost markerless motion capture systems offer the potential for 3D measurement of joint angles during human movement. This study aimed to validate a smartphone-based markerless motion capture system’s (OpenCap) derived lower extremity kinematics during common return-to-sport tasks, comparing it to an established optoelectronic motion capture system. Athletes with prior anterior cruciate ligament reconstruction (12–18 months post-surgery) performed three movements: a jump-landing-rebound, single-leg hop, and lateral-vertical hop. Kinematics were recorded concurrently with two smartphones running OpenCap’s software and with a 10-camera, marker-based motion capture system. Validity of lower extremity joint kinematics was assessed across 437 recorded trials using measures of agreement (coefficient of multiple correlation: CMC) and error (mean absolute error: MAE, root mean squared error: RMSE) across the time series of movement. Agreement was best in the sagittal plane for the knee and hip in all movements (CMC > 0.94), followed by the ankle (CMC = 0.84–0.93). Lower agreement was observed for frontal (CMC = 0.47–0.78) and transverse (CMC = 0.51–0.6) plane motion. OpenCap presented a grand mean error of 3.85° (MAE) and 4.34° (RMSE) across all joint angles and movements. These results were comparable to other available markerless systems. Most notably, OpenCap’s user-friendly interface, free software, and small physical footprint have the potential to extend motion analysis applications beyond conventional biomechanics labs, thus enhancing the accessibility for a diverse range of users.