Peak Vertical Force Research Articles

Acute Effects of Unplanned and Planned Hop-Landing Training on Neurocognitive Function and Knee Biomechanics.

Athletes with decreased baseline neurocognitive function may experience noncontact anterior cruciate ligament (ACL) injury in unanticipated athletic situations. Many ACL injury prevention programs (IPPs) focus on improving closed-skill movements (eg, planned landing). However, the more open-skill movements (eg, unplanned reactive movements) required in unpredictable sports scenarios are commonly absent from ACL IPPs, and the acute effects of open-skill training on neurocognitive function remain unclear. To investigate the acute effects of unplanned versus planned training on neurocognitive function and knee biomechanics associated with ACL injury risk during the side-step cutting motion. Controlled laboratory study. A total of 32 adult recreational athletes (16 female, 16 male) were randomly assigned to either an unplanned training (UT) group or a control (CON) group. The UT group performed unplanned hop-landing training while the CON group performed planned hop-landing training. Both before and after the training, neurocognitive function was evaluated using the Trail Making Test-part B and Stroop Color and Word Test. Additionally, unanticipated and anticipated side-step cutting tasks were performed while 3-dimensional kinematic and kinetic data for the dominant leg were collected. Neurocognitive test scores and biomechanical variables relevant to ACL injury were analyzed using 2-way repeated-measures analysis of variance to determine the main effects of training, group, and training × group interaction. Trail Making Test-part B and Stroop Color and Word Test scores significantly improved from pre- to posttraining in both groups (P < .001 for both). There was a significant training × group interaction for peak knee abduction angle during the unanticipated side-step cutting task (pre- vs posttraining: -8.81°± 7.23° vs -7.40°± 7.24° [UT group]; -8.23°± 9.40° vs -9.99°± 9.83° [CON group]; P = .02) and for peak vertical ground-reaction force during the anticipated side-step cutting task (pre- vs posttraining: 3.86 ± 0.59 vs 4.08 ± 0.74 percentage body weight [%BW] [UT group]; 3.70 ± 0.62 vs 3.34 ± 0.62 %BW [CON group]; P = .04). Study findings showed a significant training × group interaction for knee abduction angle during the unanticipated side-step cutting task with unplanned training and for vertical ground-reaction force during the anticipated side-step cutting task with planned training. Designing ACL IPPs based on the sport type (ie, open skill or closed skill) may contribute to better preparation.

Measurement of ground reaction forces in cats after total hip replacement.

The aim of this study was to evaluate ground reaction forces (GRFs) in cats after unilateral total hip replacement (THR) and compare them with cats after femoral head and neck ostectomy (FHO). The databases of the Small Animal Clinic of the Veterinary University in Vienna and three referral clinics were searched for cats that had undergone unilateral THR with the BioMedtrix Micro total hip system or FHO more than 6 months previously. Owners were invited to complete a survey and bring their cats for re-examination, inlcuding clinical and orthopaedic examinations, hip radiography and a gait analysis using a pressure-sensitive plate. Nine cats were included in each group. Cats after THR showed larger GRF values (peak vertical force [PFz] and vertical impulse [IFz] normalised to total force [%TF]) on the operated limb. The resulting symmetry indices (SIs) were lower in terms of vertical force in 7/9 (78%) cats and vertical impulse in 6/9 (67%) cats between the hindlimbs in cats after THR compared with FHO - SI (PFz) = 3.31% ± 2.19% (THR) vs 4.84% ± 2.99% (FHO) and SI (IFz) = 5.17% ± 3.66% (THR) vs 8.27% ± 3.12% (FHO). Cats after FHO showed significantly lower muscle circumference and range of motion (ROM) at the operated hindlimb compared with the contralateral side, whereas cats after THR showed no statistically significant differences between their hindlimbs. Owner surveys revealed significant differences in their subjective assessment of activity and change in gait between the two groups, with better values for cats after THR. This was the first study that measured GRFs in cats after THR. PFz (%TF) and IFz (%TF) values were higher in the operated limb of the THR group than in those of the FHO group, resulting in lower symmetry indices (indicating better symmetry) and better loading of the corresponding hindlimb. This finding is clinically relevant and can help in making decisions regarding the treatment of hip joint pathologies in cats.

Do bilateral deficits in hop for distance performance occur concomitantly with bilateral movement differences in people with patellofemoral pain? A cross-sectional investigation with between-group and -limb comparisons.

People with patellofemoral pain (PFP) may have bilateral deficits in hop for distance test (SLHD) performance, whereas the worsening performance of the pain-free or less painful limbs suggests that bilateral movement differences may occur. While clinicians may not be aware of bilateral movement differences that may be employed during the clinical assessment of SLHD performance (e.g., excessive trunk flexion, lower knee, hip and ankle angles), their suboptimal investigation may overestimate function and favor long-term sequelae. Do people with PFP exhibit bilateral differences in trunk and lower limb movements as well as bilateral deficits in SLHD performance compared to pain-free controls? We captured three-dimensional motion of 26 adults with PFP and 22 controls during testing and calculated trunk and lower limb sagittal plane kinematics, total concentric and eccentric work, and hip, knee, and ankle work contributions during the jumping and landing phases of the SLHD. We also calculated vertical ground reaction forces during the landing phase and compared between-group and -limb differences using independent and paired t-tests. People with PFP demonstrated bilateral deficits in SLHD performance (medium effects; p = .028-.050) and lower peak vertical ground reaction force values (medium-to-large effects; p = .006-.012) as compared to controls. No other between-group or -limb differences were identified. Bilateral deficits in SLHD performance seem to occur independently of movement differences in people with PFP, as they presented shorter distance but no differences in sagittal plane biomechanical patterns.

Inertial One-Leg Squat Training and Drop Jump Biomechanics in Athletes With Anterior Cruciate Ligament Reconstruction After Return to Sport.

Henderson, FJ and Shimokochi, Y. Inertial one-leg squat training and drop jump biomechanics in athletes with anterior cruciate ligament reconstruction after return to sport. J Strength Cond Res XX(X): 000-000, 2024-Athletes with anterior cruciate ligament reconstruction (ACLR) display altered jumping mechanics persisting long after returning to sport (RTS). We investigated the effects of flywheel rear leg elevated (Bulgarian) split squat (RLESS) training on single-leg drop jump (SLDJ) biomechanics in athletes with ACLR after RTS. Eleven competitive athletes with unilateral ACLR (546 ± 270 days postsurgery) performed 16 sessions of 1 set of deep knee flexion RLESS until failure in the reconstructed leg (REC) using a flywheel. Using motion capture and force plates, jump height and leg joint contribution were calculated during a 30-cm SLDJ, alongside peak vertical ground reaction force (vGRF), lower extremity joint peak angle, displacement, work, peak internal moment, and peak power. After training, the jump height increased in REC (p < 0.05) but not the intact leg (INT), although the jump height in REC remained lower than that in INT. Reconstructed leg knee contribution increased, whereas REC hip contribution decreased, so no bilateral difference remained after training. Although jump height remained unchanged in INT, several kinematic and kinetic variables changed significantly. Vertical ground reaction force showed no significant difference while asymmetry in internal knee varus moment disappeared, suggesting that some risk factors of ACL injury were reduced. Therefore, athletes with ACLR show persistent deficits in jumping performance, but adding 8 weeks of flywheel RLESS in REC can safely improve performance and restore normal joint contribution. Besides, coaches should be aware of possible changes in jumping mechanics in INT despite unchanged jumping performance when monitoring athletes with ACLR.

Limb Underloading in Walking Transmits Less Dynamic Knee Joint Contact Forces after Anterior Cruciate Ligament Reconstruction.

Individuals with anterior cruciate ligament reconstruction (ACLR) often walk with a less dynamic vertical ground reaction force (vGRF), exemplified by a reduced first peak vGRF and elevated midstance vGRF compared to uninjured controls. However, the mechanism by which altered limb loading affects actual tibial plateau contact forces during walking remains unclear. Our purpose was to use musculoskeletal simulation to evaluate the effects of first peak vertical ground reaction force (vGRF) biofeedback on bilateral tibiofemoral contact forces relevant to the development of post-traumatic osteoarthritis (OA) in 20 individuals with ACLR. We hypothesized that reduced first peak vGRF would produce less dynamic tibial plateau contact forces during walking in individuals with ACLR. As the pivotal outcome from this study, and in support of our hypothesis, we found that less dynamic vGRF profiles in individuals with ACLR - observations that have associated in prior studies with more cartilage breakdown serum biomarkers and reduced proteoglycan density - are accompanied by less dynamic tibiofemoral joint contact forces during walking. We conclude that more sustained limb-level loading, a phenotype that associates with worse knee joint health outcomes following ACLR and was prescribed herein using biofeedback, alters the loading profile and magnitude of force applied to tibiofemoral cartilage.

Efficacy and Safety of a Diet Enriched with EPA and DHA, Turmeric Extract and Hydrolysed Collagen in Management of Naturally Occurring Osteoarthritis in Cats: A Prospective, Randomised, Blinded, Placebo- and Time-Controlled Study.

This study evaluated a therapeutic diet high in eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) of marine source (EPA:DHA ratio 0.69:1), turmeric extract, and hydrolysed collagen in cats (N = 30) with naturally occurring osteoarthritis (OA) over a 13-week (W) period, followed by a 4-W washout, using four previously validated pain/functional outcomes. Compared to the placebo diet, the therapeutic diet significantly improved peak vertical force (p = 0.017; W16, 64% responders), correlating to enhanced weight bearing; stair assay compliance (p < 0.001; W16, 87% responders), reflecting reduced fatigue related to OA pain; night-time actimetry (cohort effect; p = 0.05, 67% responders), suggesting greater spontaneous mobility and comfort; and MI-CAT(V) score (cohort effect; p < 0.001, 80% responders), indicating reduced functional impairments. The earliest therapeutic response was observed at W06, marked by an inflection point between actimetric linear regressions of both cohorts, confirmed by significant MI-CAT(V) differences (p < 0.007; W08; W12; W16). The MI-CAT(V) clinical metrology instrument was validated for inter-rater reliability, minimal placebo effect (<15% responders), and OA severity clustering. Despite baseline differences in biomechanical assessments (p < 0.05), both moderate and severe OA clusters responded equally positively to the therapeutic diet. Based on all outcomes, the therapeutic diet showed promise for the long-term management of feline OA, with no observed side effects.

Impact of Cognitive Tasks on Biomechanical Adjustments During Single-Leg Drop Landings in Individuals with Functional Ankle Instability

This study aimed to evaluate the biomechanics of single-leg drop landing in individuals with functional ankle instability (FAI) during cognitive tasks, contrasting these findings with those of healthy controls to provide insights for evidence-based rehabilitation strategies. Fifteen FAI participants, identified using clinical tools, were age- and activity-matched with controls. They performed drop landings with and without a cognitive task, and the data were analyzed using a 2 × 2 mixed ANOVA. At the initial ground contact (IC), the FAI group’s affected side showed a significantly smaller plantarflexion angle than the control group (p = 0.008). With cognitive tasks, this angle increased in the FAI group (p = 0.005). The FAI group also had larger knee flexion at contact (p = 0.002) and greater knee valgus at peak vertical ground reaction force (vGRF) (p = 0.027). They exhibited a higher peak vGRF, shorter time to peak vGRF (T-vGRF), and higher loading rate (LR) (all p &lt; 0.05). No differences were found in other variables (p &gt; 0.05). This study shows that FAI individuals make specific biomechanical adjustments under cognitive tasks, notably increased plantarflexion at IC, suggesting reactive compensations. Despite similar motor control to controls, this may reflect long-term adaptations rather than equal proficiency.

Robustness analysis of dynamic progressive collapse of precast concrete beam–column assemblies using dry connections under uniformly distributed load

A series of dynamic progressive collapse tests using the uniformly distributed load (UDL) was conducted, to analyze the robustness of three precast concrete (PC) beam–column assemblies using dry connections of top-and-seat angles (TSA-D), strengthened top-and-seat angles (STSA-D), and high-ductility reinforcement (DSTSA-D), under a middle column removal scenario. Finite element (FE) models were also developed to accurately simulate the collapse process. Based on the tests and FE models, comparative studies were conducted on dynamic and static collapse responses of the PC assemblies with identical configuration, loading regime, and boundary conditions. The results showed that: the horizontal reaction force developments were similar under dynamic and static collapse scenarios; under dynamic collapse scenarios, the initial stiffness of the PC assemblies increased due to the strain rate effect, while the peak vertical reaction forces under the compressive arch action (CAA) were smaller than those under static collapse scenarios, attributed to dynamic damage; under both dynamic and static collapse scenarios under UDL, the beam deformed in a downward convex curved shape, with local material deformation becoming more concentrated under dynamic collapse scenarios. An energy-based method for calculating dynamic collapse resistance was evaluated and revised: 1) the traditional method, which converts static responses from static analysis into dynamic responses was found to underestimate the resistance under small deformations due to neglecting the strain rate effect, and to overestimate ultimate resistance by ignoring dynamic damage; 2) by using dynamic vertical reaction forces instead, a more accurate prediction of the dynamic collapse resistance was achieved with a single dynamic collapse analysis. Additionally, dynamic amplification factors for the PC assemblies were calculated based on FE models and static test results providing basic knowledge in whole PC structural level research.

Is biomechanical loading reduced in individuals with unilateral transtibial amputation during fast-paced walking when using different ankle/foot prostheses? A pragmatic randomized controlled trial.

Sound side loading is a risk factor for osteoarthritis development, which has been noted to reduce when using advanced prostheses during normal-paced walking in individuals with unilateral transtibial amputation (UTTA). However, descriptions of loading during fast-paced walking remain relatively unreported. Therefore, the aim of this study was to describe the biomechanical loading of individuals with UTTA while using different ankle/foot prostheses during fast-paced walking. A blinded, randomized control trial was conducted in a group of K3-K4 ambulators, who used 3 different prosthetic feet (1. a solid ankle cushioned heel foot prosthesis [SACH], 2. a standard energy storage and return foot prosthesis [ESAR], and 3. a novel ESAR foot prosthesis [N-ESAR]) in a 2-week randomized crossover design. The spatiotemporal and kinetic data of the participants' fast walking pace were collected. Data were analyzed using a mixed model and one-way analysis of variances (p < 0.05) and Cohen d. Twenty individuals with UTTA (age: 40 ± 16 years; height: 1.76 ± 0.09 m; and BMI: 24.72 ± 3.63 kg/m2) participated in this study. There were minimal changes in the spatiotemporal data between the different prosthetic feet. When the participants used the N-ESAR feet, they had a lower peak vertical ground reaction force (p = 0.02) and external knee adduction moment (p = 0.02) on the sound side, as well as a higher distal shank power on the prosthetic side (p < 0.01). Overall fast-paced walking resulted in higher sound side loading forces compared with normal-paced walking. However, use of the N-ESAR prosthesis reduced the biomechanical loading on the sound side in individuals with UTTA while walking at a fast pace compared with the ESAR and SACH prostheses. The percentage change in the biomechanical loading from normal- to fast-paced walking of the N-ESAR foot was also larger compared with the other prostheses, perhaps because of the individuals' ability to achieve a faster walking pace when using the N-ESAR prosthesis. Longitudinal intervention studies should be performed to further investigate the possible benefits of using advanced prostheses.

Effectiveness of Injury Prevention Program Using a Global Systems Approach on High-Risk Movement Mechanics for Noncontact ACL Injury.

Injury prevention training using a global systems approach was designed to develop integrated trunk-lower extremity neuromuscular control using whole-body, rotational forces about the vertical Z-axis during simulated sports movements. Compared with traditional hip-focused exercises, injury prevention training using a global systems approach could improve kinetic and kinematic measures related to anterior cruciate ligament injury. Controlled laboratory study. Level 3. A total of 39 male and female athletes received 6 weeks of either global systems approach (n = 20), or hip-focused strengthening, balance, and plyometrics training (n = 19) exercises. Before and after the training program, participants performed a single-leg vertical drop jump task on their dominant leg. Peak vertical ground-reaction forces (GRFs), peak knee abduction, internal rotation moments, peak hip flexion, hip adduction, knee flexion, knee abduction, contralateral pelvic drop, and lateral trunk flexion angles were assessed. Biomechanical data were compared between the 2 groups using a random-intercept linear mixed-models analysis. A significant group × time interaction effect was found for vertical GRFs (P = 0.01; change difference relative to baseline: 4.5%), knee abduction moment (P = 0.01; 14.8%), hip adduction (P < 0.01; 16.7%), knee abduction (P < 0.01; 13.8%), contralateral pelvic drop (P < 0.01; change difference: 26.6%), and lateral trunk flexion (P = 0.04; 20.37%) angles, favoring the global systems approach group after 6 weeks of training. Participants who trained using the global systems approach had significantly decreased lateral trunk flexion, hip adduction, knee abduction and contralateral pelvic drop angles, peak vertical GRFs, and peak knee abduction moment during a single-leg vertical drop jump compared with participants who trained with hip-focused exercises. Incorporating additional external resistance at the proximal trunk results in improved biomechanics compared with conventional hip-focused exercises.

How does prolonged tennis playing affect lower limb muscles' activity during first and second tennis serves?

We examined the effect of prolonged tennis playing on lower limb muscles' activity during the execution of first and second tennis serves. Ten male competitive tennis players executed five first and second serves before (pretest) and after (posttest) a 3-h tennis match. Surface electromyographic (EMG) activity of four lower limb muscles (vastus lateralis, rectus femoris, gastrocnemius lateralis, and soleus muscles) on each leg was recorded along with maximum ball velocity measured by a radar gun and peak vertical forces recorded by a force platform. For the vastus lateralis, gastrocnemius lateralis, and soleus muscles of the left leg as well as the vastus lateralis muscle of the right leg, EMG amplitude decreased from pre- to posttests (p≤0.033). These reductions in the EMG signal were generally more pronounced in the first serve (i.e., ranging from -10% to -40%) compared to the second serve (0% to -25%). Maximum ball velocity for both first (159±12 vs. 154±12km/h) and second (126±20 vs. 125±15km/h) serves remained unchanged from pre- to posttests (p=0.638) Similarly, peak vertical forces did not differ between pretest and posttest for both first (1.78±0.30 vs. 1.72±0.29 body weight) and second (1.62±0.25 vs. 1.75±0.23 body weight) serves (p=0.730). In conclusion, a 3-h tennis match led to decreased activation levels in various leg muscles during serves, particularly in first serves compared to second serves. Despite consistent maximum ball velocity and peak vertical forces, these reductions in EMG signals suggest that skilled tennis players may adopt compensatory strategies after prolonged play.

Relationship between Peak Eccentric Force during the Nordic Hamstring Exercise and One Repetition Maximum Deadlift Performance.

The Nordic hamstring exercise (NHE) is useful for preventing hamstring strain injuries. However, its adoption rates in the sports field are currently low, necessitating a safe and efficient introduction. The purpose was to examine the relationship between the eccentric force during the NHE and the one repetition maximum of deadlift. It was hypothesized that the eccentric force during the NHE would be correlated with the one repetition maximum (1RM) of the deadlift. Cross-sectional study. Healthy student rugby players with no history of hamstring tears were recruited to participate. The peak eccentric forces during the NHE, which is the vertical peak force on the part holding the leg, were measured in both legs, while gradually leaning forward to a prone position over three seconds. The 1RM of deadlift was calculated from the weight that could be raised three times during a deadlift (x kg) using the estimated formula (x kg / 0.93). The correlation between the left and right peak eccentric forces during the NHE, the total left and right forces, and the 1RM of the deadlift was examined using Spearman's rank correlation coefficient, with all values corrected for body mass. During the NHE, the peak eccentric force of the right and left legs and the total peak eccentric force of both legs were 3.8 ± 1.1 N/BM, 3.8 ± 1.2 N/BM, and 7.6 ± 2.1 N/BM, respectively. The 1RM of deadlift was 1.9 ± 0.3 kg/BM. Weak correlations (r = 0.34-0.37) were found between the 1RM of the deadlift and the peak eccentric force in the right and left legs and the total peak eccentric force of both legs. The present study revealed a weak correlation between the peak eccentric force during the NHE and 1RM of deadlift. 2c.

6-week Gait Retraining Elicits An Increase In Peak Vertical Ground Reaction Forces In Acl-reconstructed Individuals

6-week Gait Retraining Elicits An Increase In Peak Vertical Ground Reaction Forces In Acl-reconstructed Individuals

Efficacy of a Single Injection of Stromal Vascular Fraction in Dogs with Elbow Osteoarthritis: A Clinical Prospective Study

This study aimed to assess the efficacy of a single intra-articular injection of autologous stromal vascular fraction (SVF) in dogs with chronic lameness due to advanced elbow osteoarthritis (OA) that were unresponsive to conventional drug therapy. In this clinical, prospective, non-blinded, single-center study, twenty-three dogs received autologous SVF derived from falciform adipose tissue. Primary outcome measures over the six-month study period included clinical-orthopedic and radiographic examinations, objective gait analysis and validated owner questionnaires. In 19 of 23 joints, no progression of OA was visible radiographically. Peak vertical force improved significantly at three months and vertical impulse at six months after the injection compared to baseline. Over 33% of dogs demonstrated treatment-related improvements in lameness based on objective gait analysis. Owner questionnaires indicated significant improvement in clinical signs throughout the study period and 26% of dogs showed treatment-related improvements in pain scores according to the Canine Brief Pain Inventory. No side effects were reported. These findings suggest that autologous regenerative cell therapy may provide a promising treatment option for dogs with advanced OA that do not respond to conventional drug therapy. However, the treatment did not improve the clinical symptoms in all dogs, so it cannot be recommended for all patients.

A Kinetic Enhanced Tuck Jump Assessment Exposes Residual Biomechanical Deficits in Female Athletes 9 Months Post Anterior Cruciate Ligament Reconstruction.

Kember, LS, Riehm, CD, Schille, A, Slaton, JA, Myer, GD, and Lloyd, RS. Residual biomechanical deficits identified with the tuck jump assessment in female athletes 9 months after ACLR surgery. J Strength Cond Res XX(X): 000-000, 2024-Addressing biomechanical deficits in female athletes after anterior cruciate ligament reconstruction (ACLR) is crucial for safe return-to-play. The tuck jump assessment (TJA) is used to identify risks associated with ACL injury, yet its fundamental analyses lack the ability to explore landing forces. Kinetic asymmetries during the TJA were assessed in athletes with ACLR (n = 38) and matched healthy controls (n = 21) using discrete time-point analysis and statistical parametric mapping (p < 0.05). The ACLR group performed fewer jumping cycles with distinct kinetic differences, including longer ground contact time (g = 1.45), larger peak center of mass displacement (g = 1.29), and lower peak vertical ground reaction force (VGRF) (g = -2.05) and relative leg stiffness (g = -1.51). Greater interlimb kinetic asymmetries were evident in the ACLR group for VGRF (g = 0.84), relative leg stiffness (g = 0.85), average loading rate (g = 0.84), peak braking force (g = 0.85), and time of braking (g = 0.80) and propulsive peaks (g = 1.04). Moderate differences in VGRF favored the uninvolved limb of the ACLR group for the majority (2-100%) of the stance phase of TJA (d = -0.52). Distinct jump-landing strategies between ACLR athletes and healthy controls were revealed during the TJA, which may indicate compromised stretch-shortening cycle function. Findings highlight the need for targeted rehabilitation to foster greater kinetic symmetry in jump-landing performance and underscore the importance of longitudinal and progressive monitoring for optimized return-to-play outcomes in athletes after ACLR.

Characterization of spatiotemporal and kinetic gait variables in dogs with hindlimb ataxia and bilateral hindlimb lameness

BackgroundDiscriminating the underlying cause of gait abnormalities can be challenging in a clinical setting, especially in the presence of bilateral disease. Pressure-sensitive walkways (PSWs) have been utilized to characterize the gait of dogs with various neurologic or orthopaedic conditions. The potential use of the PSW includes the discrimination of conditions that can be similar in clinical presentation, such as bilateral hindlimb lameness and hindlimb ataxia. The primary aim of this study was to describe the spatial, temporal, and kinetic gait parameters of dogs with hindlimb ataxia or bilateral hindlimb lameness and compare them to those of normal dogs. Forty-six dogs were prospectively recruited. The normal group included 20 dogs with normal neurologic and orthopaedic exams. The orthopaedic group included 15 dogs with bilateral hindlimb orthopaedic diseases with weight-bearing hindlimb lameness and normal neurologic exams. The neurologic group included 11 dogs with ambulatory paraparesis and normal orthopaedic exams. Each dog was walked across the PSW, and at least 3 valid trials were collected. The stride time, stance time, swing time, stride length, gait velocity, peak vertical force (PVF), vertical impulse (VI), and limb symmetry were recorded. The mean values of all parameters from the valid trials were calculated and used for data analysis. The outcomes were compared among all groups.ResultsCompared with the normal group, the orthopaedic group had a significantly greater percent body weight distribution (%BWD) and vertical impulse distribution (VID) in the forelimbs. When comparing the spatiotemporal parameters, the neurologic group showed an increase in forelimb stance time compared to that of the normal group. Compared with that in the normal group, the stride velocity in the forelimbs in the orthopaedic group was greater. There were no significant differences in the kinetic parameters between the neurologic group and the normal group, nor in stride time or stride length among the groups.ConclusionThe gait parameters obtained by PSW demonstrated that the orthopaedic and neurologic groups may have different compensatory mechanisms for their gait deficiencies. These parameters can potentially be used to construct a predictive model to evaluate PSW as a diagnostic tool in future studies.

Association Between Longitudinal Changes in Patellar Tendon Abnormality and Land-Jump Biomechanics in Male Collegiate Basketball Players.

The relationship between self-reported symptoms and the severity of patellar tendon abnormality (PTA) as seen on magnetic resonance imaging and ultrasound is unclear, but biomechanical testing may resolve this. To (1) compare land-jump limb biomechanics between pre- and postseason timepoints, (2) assess whether seasonal changes in biomechanics are associated with seasonal changes in PTA and symptom severity, and (3) explore models that identify seasonal changes in PTA and symptoms with seasonal changes in biomechanics in collegiate basketball players. Cohort study; Level of evidence, 2. Victorian Institute of Sport Assessment Scale - Patellar Tendon (VISA-P) scores and bilateral measurements from 18 National Collegiate Athletic Association Division I and II male basketball players (n = 36 limbs) at the preseason (visit 1) and postseason (visit 2) timepoints were collected. PTA was graded with ultrasound and magnetic resonance imaging morphology measurements proximally and distally, and 3-dimensional lower extremity sagittal kinematics and kinetics were measured during a land-jump test. Multivariate and chi-square analyses assessed timepoint differences. The association of seasonal (Δ = visit 2 - visit 1) biomechanics with seasonal morphology (ΔPTA: no change/worsened) and symptoms (ΔVISA-P: improved/no change/worsened) was tested with multivariate models. Logistic regressions modeled the accuracy of seasonal biomechanics to classify seasonal PTA and symptoms. Three athletes (6 limbs) at visit 1 and 2 athletes (4 limbs) at visit 2 were symptomatic. VISA-P scores were not significantly different between preseason and postseason. Regarding PTA, multivariate analyses found differences among grouped ground-reaction force variables (P < .05); univariate analyses found that worsened PTA was associated with seasonal decreases in peak vertical jumping force and with seasonal increases in knee flexion velocity at contact and maximum knee flexion velocity (P < .05 for all). Regarding VISA-P scores, multivariate analyses found differences among grouped hip (P < .01) and ankle (P < .05) kinematic variables; univariate analyses found that worsened VISA-P was associated with seasonal increases in hip (P < .01) and knee (P < .01) flexion velocity at contact and seasonal increases in ankle range of motion (P < .05). The findings demonstrated an association between seasonal changes in dynamic lower extremity biomechanics and seasonal changes in patellar tendon imaging signals as well as self-reported symptoms.

Identifying the Problem Side with Single-Leg Squat and Hamstrings Flexibility for Non-Specific Chronic Low Back Pain.

Background and Objectives: In patients with non-specific chronic low back pain (LBP), their pain and problem sides can differ. Clinical Pilates assessment provides an approach to identify the problem side, but this approach requires experience and can be subjective. This study aimed to investigate if objective measures of single-leg squat postural control and hamstrings flexibility could identify the problem side in adults with non-specific chronic LBP. Materials and Methods: Forty adults with non-specific chronic LBP were tested on single-leg squat postural control and hamstrings flexibility. The problem side of participants was assessed with the Clinical Pilates method. Paired t-tests were used to compare the postural sway parameters of the single-leg squat and hamstrings flexibility between the problem and non-problem sides. Cohen's kappa was then used to assess the agreement of postural sway and flexibility measures with the Clinical Pilates method. Results: The problem side showed smaller vertical force variance, larger sway path distances, lower peak vertical force, smaller terminal knee flexion angle, longer time to complete the five single-leg squats, and tighter hamstrings as compared to the non-problem side. However, only the overall and anteroposterior sway path distances, terminal knee flexion angle, total squat duration, and hamstrings flexibility yielded moderate to strong agreement with the Clinical Pilates method. Conclusions: Single-leg squat postural sway parameters and hamstrings flexibility can objectively identify the problem side in adults with non-specific chronic LBP.

External Focus of Attention Reduces Cartilage Load During Drop Landings.

The aim of the present study was to examine the effects of attentional focus instructions on acute changes in the transverse relaxation time (T2) of the femorotibial cartilage and in cartilage volume during repeated drop-jump landings. Ten healthy females (Mage = 20.4 ± 0.8 years) performed a drop landing task from a 50 cm high box over the course of 3 days (50 repetitions each day) across three attentional focus conditions: external focus (EF: focus on landing as soft as possible), internal focus (IF: focus on bending your knees when you land), and control (CON: no-focus instruction), which was counterbalanced across focus conditions. T2 mapping and the volume of femorotibial cartilage were determined from magnetic resonance imaging scans at 1.5 T for the dominant knee before and after completing the drop landings in each attentional focus condition per day. Results indicated a smaller change in cartilage T2 relaxation time and volumetry in the central load-bearing lateral cartilage under the EF, compared to IF and CON. Moreover, the change in T2 and cartilage volume was greater for lateral tibial cartilage as compared to femoral cartilage and was independent of attentional focus instructions. No significant acute quantitative changes were observed in the medial compartment. The peak vertical ground reaction force was found to be the lowest under the EF, compared to IF and CON. These findings suggest that external focus of attention may reduce cartilage load, potentially aiding in the control or management of cartilage injuries during landing in female athletes.

Does chronic ankle instability patients lead to changes in biomechanical parameters associated with anterior cruciate ligament injury during landing? A systematic review and meta-analysis.

This study aimed to determine if patients with chronic ankle instability (CAI) exhibit biomechanical changes associated with the increased risk of anterior cruciate ligament (ACL) injury during landing tasks. This study was conducted through systematic review and meta-analysis. Searches were conducted in May 2024 across five electronic databases, including Web of Science, Scopus, PubMed, SPORTDiscus, and Cochrane Library. Studies were included if they (1) involved subjects with CAI and healthy controls and (2) assessed biomechanical variables such as ground reaction forces, joint angles, and joint torques. Of the 675 identified studies, 171 were included in the review, and 13 were eligible for meta-analysis. The reviewed studies clearly defined research objectives, study populations, consistent participant recruitment, and exposures, and they used valid and reliable measures for outcomes. However, areas such as sample size calculation, study sample justification, blinding in assessments, and addressing confounders were not robust. This meta-analysis involved 542 participants (healthy group: n = 251; CAI group: n = 291). Compared with healthy individuals, patients with CAI exhibited a greater peak vertical ground reaction force (peak VGRF; SMD = 0.30, 95% CI: 0.07-0.53, p = 0.009), reduced hip flexion angles (SMD = -0.30, 95% CI: -0.51 to -0.17, p < 0.0001), increased trunk lateral flexion (SMD = 0.47, 95% CI: 0.05 to 0.9, p = 0.03), greater hip extension moments (SMD = 0.47, 95% CI: 0.09-0.84, p = 0.02), and increased knee extension moments (SMD = 0.39, 95% CI: 0.02-0.77, p = 0.04). During landing tasks, patients with CAI demonstrate increased hip extension moments and knee extension moments, decreased hip flexion angles, increased peak VGRF, and increased trunk lateral flexion angles. These biomechanical variables are associated with an elevated risk of ACL injuries.