Search

Ultramarathons are a unique model to study the effects of systemic fatigue in athletes. This investigation applied the spring-mass template to study runners before and 2 days after a road ultramarathon to characterize the effects of fatigue on systemic gait patterns. Overground kinetics were captured 7 days before and 2 days after the event in 14 runners. Traditional kinetic and spring-mass parameters were calculated, along with nonlinear regression-derived parameters and spring-mass model fit metrics. After the ultramarathon, vertical force magnitudes and loading rates were unchanged, but impact peaks increased (1.88 ± 0.08–1.95 ± 0.10 bodyweight). Ground contact times were modestly shorter (−3 ± 1 ms), resulting in increased leg stiffness (10.0 ± 0.5–10.3 ± 0.5 kN/m) with equivocal vertical stiffnesses. The deviation from the modeled spring-mass kinetics also increased (171.3 ± 15.0–181.4 ± 16.5 N). Overall, the systemic mechanical behaviors of the runners persisted despite the fatigue and stress induced by a road ultramarathon. These findings support previous observations that runners maintain gross mechanical behavior when fatigued with small compensatory changes in spatiotemporal and traditional spring-mass characteristics. However, these findings also suggest that the variability within that gross behavior may increase after stress, suggesting new opportunities for quantifying those deviations. [ABSTRACT FROM AUTHOR]

Background: The Sensory Organization Test condition 5 (SOT5) assesses an astronaut's vestibular function pre-/post-spaceflight but has a ceiling effect and mainly evaluates standing balance, neglecting the challenges of walking during space missions. A Locomotor Sensory Organization Test (LSOT) has been developed, mirroring the SOT concept but tailored to assess vestibular function during walking. This study aims to advance current knowledge by examining changes in ground reaction force (GRF) during normal walking (LSOT1) and walking in LSOT5 (vision blocked and treadmill speed varied), both with and without mastoid vibrations. Methods: Sixty healthy adults were recruited and divided into two groups: one with mastoid vibration and one without. GRF peaks and respective variabilities were analyzed in the vertical (V), anterior-posterior (AP), and medial-lateral (ML) directions during stance cycles. The effects of LSOTs and mastoid vibration on each dependent variable were assessed using Friedman's two-way analysis of variance by ranks. Results: The findings revealed that:1) Walking in LSOT5 increased the variabilities of GRFs regardless of the administration of mastoid vibration; 2) the application of mastoid vibration reduced the amplitude of GRF peaks; and 3) walking in LSOT5 while receiving mastoid vibration was the most challenging task compared to all other tasks in this study. Conclusion: The results indicated that analyzing GRF can detect changes in the strategy of balance control across different sensory-conflicted conditions. The findings could be beneficial for assessing the vestibular function pre- and post-space missions and planning for future sensorimotor training programs aimed at enhancing astronauts' abilities to navigate unpredictable sensory-conflicted conditions. [ABSTRACT FROM AUTHOR]

Background: There is little research done on ground reaction forces (GRF) in terms of 3D impulses after total hip replacement (THR). This study aimed to investigate the GRFs and 3D impulses in four sub‐phases of stance during gait in the patients undergoing THR. Methods: A total of 10 pain‐free THR patients and 10 healthy people were recruited. This is an observational and retrospective study. The gait data was collected between 2008 and 2014 and analyzed between 2020 and 2024. All the participants were included in the three‐dimensional gait analysis. Gait parameters, phase durations, GRFs and impulses' key values during gait were calculated in four sub‐phases of stance. Statistical comparisons were performed with generalized linear models including age, gender, body mass index and walking speed as interactive factors. Results: It is found that (1) cadence, walking speed, stride length and step width in THR group were significantly decreased in compared with control group; (2) the THR decreased loading response duration in operative side and pre‐swing duration in non‐operative side compared with the control group, but the THR's two sides have similar duration proportions in sub‐stance phases; (3) the THR group had lower GRFs than the control group in vertical direction but higher in the medial–lateral direction; (4) in operative side, the THR's impulses in loading response phase were lower than the control group in anterior–posterior direction, and (5) in non‐operative side, the THR's impulse in pre‐swing phase in anterior–posterior direction was higher than the control side. Conclusion: The THR group showed slower walking speeds than the control group. The reasons could be from the decreased impulse in loading response phase, the decreased 2nd peak of GRF and the decreased pre‐swing impulse in vertical direction in operative side. Clinicians are suggested to consider the information provided when designing relevant rehabilitation exercises on the related muscles and functions. [ABSTRACT FROM AUTHOR]

The estimation of joint contact forces in musculoskeletal multibody dynamics models typically requires the use of expensive and time-consuming technologies, such as reflective marker-based motion capture (Mocap) system. In this study, we aim to propose a more accessible and cost-effective solution that utilizes the dual smartphone videos (SPV)-driven musculoskeletal multibody dynamics modeling workflow to estimate the lower limb mechanics. Twelve participants were recruited to collect marker trajectory data, force plate data, and motion videos during walking and running. The smartphone videos were initially analyzed using the OpenCap platform to identify key joint points and anatomical markers. The markers were used as inputs for the musculoskeletal multibody dynamics model to calculate the lower limb joint kinematics, joint contact forces, and ground reaction forces, which were then evaluated by the Mocap-based workflow. The root mean square error (RMSE), mean absolute deviation (MAD), and Pearson correlation coefficient (ρ) were adopted to evaluate the results. Excellent or strong Pearson correlations were observed in most lower limb joint angles (ρ = 0.74 ~ 0.94). The averaged MADs and RMSEs for the joint angles were 1.93 ~ 6.56° and 2.14 ~ 7.08°, respectively. Excellent or strong Pearson correlations were observed in most lower limb joint contact forces and ground reaction forces (ρ = 0.78 ~ 0.92). The averaged MADs and RMSEs for the joint lower limb joint contact forces were 0.18 ~ 1.07 bodyweight (BW) and 0.28 ~ 1.32 BW, respectively. Overall, the proposed smartphone video-driven musculoskeletal multibody dynamics simulation workflow demonstrated reliable accuracy in predicting lower limb mechanics and ground reaction forces, which has the potential to expedite gait dynamics analysis in a clinical setting. [ABSTRACT FROM AUTHOR]

Background: Gait can be continuously monitored via vertical ground reaction force (VGRF) and centre of pressure (COP) measurement with pressure-sensing insoles. During daily living, a variety of walking surfaces will be encountered, which could affect the collected data. These effects might need to be taken into account when analysing disease- or injury-related gait characteristics to prevent misinterpretation, especially when drawing conclusions from data obtained in clinical populations. We hypothesized characteristic changes in insole-derived VGRF and COP parameters of healthy participants when walking on different surfaces. Methods: Participants walked on flat indoor surface, flat and inclined outdoor surfaces, as well as on forest, gravel, grass, and sand surfaces while wearing pressure-sensing insoles with 16 pressure sensors each at a recording frequency of 100 Hz. Several gait parameters were extracted from the VGRF and COP data, and were compared between surfaces using repeated measures ANOVA. Results: Thirty participants were included (22 women and 7 men, age 30 ± 12 years, height 172 ± 8 cm, weight 76 ± 23 kg). VGRF and COP data were significantly influenced by the type of surface. The rmANOVA revealed significant within-subject differences between the walking surfaces in all calculated parameters. The largest changes in the VGRF and COP patterns occurred during uphill and downhill walking. Walking on compliant surfaces led to increased gait variability. The highest variability was observed when walking on sand. The change from walking indoors to outdoors, be it on flat, inclined, forest, gravel, grass or sand surfaces, was characterized by a characteristic change in the VGRF stance-phase curve. Based on these characteristic changes, it could be possible to identify whether someone is walking on a slope, as well as on non-compliant or compliant surfaces, while it is difficult to distinguish between different types of compliant surfaces. Conclusion: VGRF data are affected by the type of walking surface in healthy adults. Walking on a slope affects VGRF and COP parameters, and in addition, the compliance of the surface increases their variability. When analysing gait data measured via insoles during daily living, we recommend to correct for the surface type to decrease variability. [ABSTRACT FROM AUTHOR]

In the study of PAM (McKibben-type pneumatic artificial muscle)-driven bipedal robots, it is essential to investigate whether the intrinsic properties of the PAM contribute to achieving stable robot motion. Furthermore, it is crucial to determine if this contribution can be achieved through the interaction between the robot's mechanical structure and the PAM. In previous research, a PAM-driven bipedal musculoskeletal robot was designed based on the principles of the spring-loaded inverted pendulum (SLIP) model. The robot features low leg inertia and concentrated mass near the hip joint. However, it is important to note that for this robot, only the design principles were based on the SLIP model, and no specialized controller was specifically designed based on the model. To address this issue, based on the characteristics of the developed robot, a PAM controller designed also based on the SLIP model is developed in this study. This model-based controller regulates ankle flexion PAM to adjust the direction of the ground reaction force during robot walking motion. The results indicate that the proposed controller effectively directs the leg ground reaction force towards the center of mass during walking. [ABSTRACT FROM AUTHOR]

Accurately predicting physical activity-associated mechanical loading is crucial for developing and monitoring exercise interventions that improve bone health. While accelerometer-based prediction equations offer a promising solution, their external validity across different populations and activity contexts remains unclear. This study aimed to validate existing mechanical loading prediction equations by applying them to a sample and testing conditions distinct from the original validation studies. A convenience sample of 49 adults performed walking, running, and jumping activities on a force plate while wearing accelerometers at their hip, lower back, and ankle. Peak ground reaction force (pGRF) and peak loading rate (pLR) predictions were assessed for accuracy. Substantial variability in prediction accuracy was found, with pLR showing the highest errors. These findings highlight the need to improve prediction models to account for individual biomechanical differences, sensor placement, and high-impact activities. Such refinements are essential for ensuring the models' reliability in real-world applications, particularly in clinical and biomechanical research contexts, where accurate assessments of mechanical loading are critical for designing rehabilitation programs, injury prevention strategies, and optimizing bone health interventions. [ABSTRACT FROM AUTHOR]

This study used a 12-week plyometric and strength training program as an intervention to improve upper- and lower-extremity muscle strength for jumping and landing when climbing high walls. Sixty general non-athlete male college students were openly recruited and divided into an experimental group and a control group. The experimental group underwent a plyometric and strength training program twice a week for 12 weeks (24 sessions). The intervention was divided into three phases, each lasting four weeks, with the training intensity gradually increasing in each phase. A hand grip dynamometer was used to measure grip strength, and a PASCO double-track force plate was used to assess upper-extremity push-up force and lower-extremity take-off and landing strength. The results of the 12-week intervention showed that the experimental group experienced significant increases in grip strength (both hands), hand-ground reaction force, and upper-extremity hang time. Additionally, the time of upper-extremity action on the force plate decreased. Lower-extremity take-off strength improved, as reflected in increased ground reaction force, rate of force development, and passage time. Upon landing, ground reaction force decreased by 3.2%, and cushioning time shortened by 52.7%. This study concludes that plyometric and strength training have promising effects in enhancing upper- and lower-extremity strength, particularly in climbing and landing tasks. [ABSTRACT FROM AUTHOR]

Aging can cause the decline of balance ability, which can lead to increased falls and decreased mobility. This work aimed to discern differences in balance control between healthy older and younger adults. Foot force data of 38 older and 65 younger participants (older and younger than 60 yr, respectively) were analyzed. To first determine whether the two groups exhibited any differences, this study incorporated the orientation of the foot-ground interaction force in addition to its point of application. Specifically, the frequency dependence of the "intersection point" of the lines of actions of the foot-ground interaction forces was evaluated. Results demonstrated that, like the mean center-of-pressure speed, a traditionally employed measure, the intersection-point analysis could distinguish between the two participant groups. Then, to further explore age-specific control strategies, simulations of standing balance were conducted. An optimal controller stabilized a double-inverted-pendulum model with torque-actuated ankle and hip joints corrupted with white noise. The experimental data were compared with the simulation results to identify the controller parameters that best described the human data. Older participants showed significantly more use of the ankle than hip compared with younger participants. Best-fit controller gains suggested increased preference for asymmetric inter-joint neural feedback, possibly to compensate for the effects of aging such as sarcopenia. These results underscore the advantages of the intersection-point analysis to quantify possible shifts in inter-joint control with age, thus highlighting its potential to be used as a balance assessment tool in research and clinical settings. NEW & NOTEWORTHY: Age groups were distinguished by analyzing foot-ground force data during quiet standing in older and younger adults to calculate the foot-force vector intersection point that emerges across frequency bands. Modeling balance and comparing the simulations' outcomes to experimental results suggested that older adults increased reliance on neural feedback, possibly compensating for muscle strength deficiency. This novel analysis also quantified the apparent balance controller for each participant, highlighting its potential as a balance assessment tool. [ABSTRACT FROM AUTHOR]

A recent line of work suggests that the net behavior of the foot-ground interaction force provides insight into quiet-standing-balance dynamics and control. Through human-subject experiments, Boehm et al. found that the relative variations of the center of pressure and force orientation emerge as a distinct pattern in the frequency domain, termed the "intersection-point (IP) height." Subsequent empirical and simulation-based studies showed that different control strategies are reflected in the distribution of intersection-point height across frequency. To facilitate understanding of the strengths and limitations of the intersection-point height in describing the dynamics and control of standing, the present work establishes a spectral-based method that also enables derivation of a closed-form estimate of the intersection-point height from any linear model of quiet stance. This new method explained observations from prior work, including how the measure captures aspects of control and physiological noise. The analysis presented herein highlights the utility of the frequency-dependent foot-force dynamics in probing the balance controller and provides a tool for model development and validation to further our understanding of the neuromotor control of natural upright posture in humans. NEW & NOTEWORTHY: The present work details a closed-form analytical result that reveals a direct link between frequency-domain patterns in the foot-force line-of-action and the closed-loop frequency response function of human upright stance. The analytical method developed herein dramatically simplifies the identification of the intersection-point-height measure of standing balance, and further demonstrates that the net behavior of the foot-ground interaction force quantifies essential characteristics of the underlying neuromotor control of human quiet standing. [ABSTRACT FROM AUTHOR]

In this study, we developed a lightweight shoe sensor system equipped with four high-capacity, compact triaxial force sensors and an inertial measurement unit. Remarkably, this system enabled measurements of localized three-directional ground reaction forces (GRFs) at each sensor position (heel, first and fifth metatarsal heads, and toe) and estimations of stride length and toe clearance during walking. Compared to conventional optical motion analysis systems, the developed sensor system provided relatively accurate results for stride length and minimum toe clearance. To test the performance of the system, 15 older and 8 young adults were instructed to walk along a straight line while wearing the system. The results reveal that compared to the young adults, older adults exhibited lower localized GRF contributions from the heel and greater localized GRF contribution from the toe and fifth metatarsal locations. Furthermore, the older adults exhibited greater variability in their stride length and smaller toe clearance with greater variability compared to the young adults. These results underscore the effectiveness of the proposed gait analysis system in distinguishing the gait characteristics of young and older adults, potentially replacing traditional motion capture systems and force plates in gait analysis. [ABSTRACT FROM AUTHOR]

This research study focused on design, produce, and test an adjustable below-knee prosthetic limb for an 8-year-old with below knee amputation that can be modified to accommodate the child's growth, and to achieve the purpose of the below knee prosthetic limb design in terms of its alterability, also control the length of the shank, with low costs. An adjustable and transtibial prosthetic limb was designed, manufactured, and tested as part of this project. Three steps were taken during the process of designing, creating, and testing the prosthetic limb. The adjustable socket and shank were designed in stages, starting with theoretical and numerical design using 3D CAD software. With an abduction in the upper lateral bone of lower leg, the maximum pressure in the socket was 394 KPa for lateral part, and this is fairly acceptable due to the prominent deformation of the leg bone. According to the numerical findings for the shank, the equivalent stress was 63.303 MPa, and the lowest acceptable stress was 0.040332 MPa. The total deformation of the shank 0.014206 MPa max and zero min. The safety factor for the shank was 5.7122 min, therefore the shank was safe. The readings in this instance for the safety factor and fatigue life were acceptable. The design paves the method for the development of new ways to manufacture lightweight and adjustable limbs. These results are acceptable, the proposed design is aimed at children, and it carries weights exceeding 63 Kg. Socket gives 2 cm for expansion in both sides and allow extra space when the size of the bones in the suspension area grow. [ABSTRACT FROM AUTHOR]

Existing studies on gait phase estimation generally involve walking experiments using inertial measurement units under limited walking conditions (WCs). In this study, a gait phase estimation algorithm is proposed that uses data from force sensing resistors (FSRs) and a Bi-LSTM model. The proposed algorithm estimates gait phases in real time under various WCs, e.g., walking on paved/unpaved roads, ascending and descending stairs, and ascending or descending on ramps. The performance of the proposed algorithm is evaluated by performing walking experiments on ten healthy adult participants. An average gait estimation accuracy exceeding 90% is observed with a small error (root mean square error = 0.794, R2 score = 0.906) across various WCs. These results demonstrate the wide applicability of the proposed gait phase estimation algorithm using various insole devices, e.g., in walking aid control, gait disturbance diagnosis in daily life, and motor ability analysis. [ABSTRACT FROM AUTHOR]

It is accepted that highly skilled golfers are more consistent in their clubhead presentation and shot outcomes than their lesser skilled counterparts. However, the relationships between movement variability, outcome variability and skill in golf are not particularly well understood. This study examined the ground reaction force variability of one-hundred and four amateur golfers for shots with drivers and 5-irons. Principal component analysis was used as a data reduction technique and allowed all three components of ground reaction force to be considered together. There were statistically significant trends for the higher skilled golfers to display lower variability in two of the five principal components (driver) and four of the five principal components (5-iron). A similar trend was also observed in the other principal components, but these trends were not statistically significant. Intra-individual variability was much lower than inter-individual variability across all golfers; the golfers were each relatively consistent in maintaining their own ground reaction force patterns. Lower variability in ground reaction forces may partly explain how highly skilled golfers maintain lower variability in shot outcomes. [ABSTRACT FROM AUTHOR]

Research has documented chronic non-specific low back pain (CNSLBP) as one of the primary causes of absenteeism at work, often accompanied by the use of health insurance and healthcare services. Considering little research on the consequences of open/closed kinetic chain (O/CKC) exercises in water on CNSLBP improvement, the present study is to investigate the effects of such interventions on the electrical activity of selected lumbar muscles, pain, lumbopelvic control (LPC), ground reaction force (GRF), and psychological factors in men with CNSLBP. This is a randomized controlled trial that involves individuals with CNSLBP between the ages of 40 and 60 years. Participants are randomly assigned, using block randomization, to one of the following groups: open kinetic chain (OKC) exercises, closed kinetic chain (CKC) exercises, or controls. The training groups engage in the exercises for eight weeks, with three sessions per week and 60 min each at the University of Bu-Ali Sina pool, following the prescribed workout routine. The primary outcomes of the electrical activity of the multifidus (MF), transversus abdominis (TrA), gluteus medius (GM), and quadratus lumborum (QL) muscles are measured by an electromyography (EMG) device. Additionally, the pressure biofeedback (BFB) device and the visual analog scale (VAS) are utilized to assess LPC and pain intensity, respectively. The secondary outcomes of the GRF, along with foot pressure and kinesiophobia, are subsequently measured by the Tampa Scale of Kinesiophobia (TSK). By comparing the outcomes between the OKC exercise group, CKC exercise group, and control group, this study aims to determine the differential effects of these two water-based exercise interventions on the various physical and psychological parameters in individuals with CNSLBP. The findings provide valuable insights into the most effective approach to water-based rehabilitation for individuals with CNSLBP. By comparing the outcomes of OKC and CKC exercises, healthcare professionals can make informed decisions when designing tailored rehabilitation programs for this patient population. The results also contribute to the development of evidence-based guidelines for the management of CNSLBP using water-based exercises. [ABSTRACT FROM AUTHOR]

ABSTRACT Background There is little research done on ground reaction forces (GRF) in terms of 3D impulses after total hip replacement (THR). This study aimed to investigate the GRFs and 3D impulses in four sub‐phases of stance during gait in the patients undergoing THR. Methods A total of 10 pain‐free THR patients and 10 healthy people were recruited. This is an observational and retrospective study. The gait data was collected between 2008 and 2014 and analyzed between 2020 and 2024. All the participants were included in the three‐dimensional gait analysis. Gait parameters, phase durations, GRFs and impulses' key values during gait were calculated in four sub‐phases of stance. Statistical comparisons were performed with generalized linear models including age, gender, body mass index and walking speed as interactive factors. Results It is found that (1) cadence, walking speed, stride length and step width in THR group were significantly decreased in compared with control group; (2) the THR decreased loading response duration in operative side and pre‐swing duration in non‐operative side compared with the control group, but the THR's two sides have similar duration proportions in sub‐stance phases; (3) the THR group had lower GRFs than the control group in vertical direction but higher in the medial–lateral direction; (4) in operative side, the THR's impulses in loading response phase were lower than the control group in anterior–posterior direction, and (5) in non‐operative side, the THR's impulse in pre‐swing phase in anterior–posterior direction was higher than the control side. Conclusion The THR group showed slower walking speeds than the control group. The reasons could be from the decreased impulse in loading response phase, the decreased 2nd peak of GRF and the decreased pre‐swing impulse in vertical direction in operative side. Clinicians are suggested to consider the information provided when designing relevant rehabilitation exercises on the related muscles and functions.

Sports equipment is widely available in the international market. The market's focus is on the design of sports equipment to prevent injury, and all equipment must be designed to enable performance without causing injury. The purpose of this study is to design and manufacture a new volleyball and comparison of kinetic components with other volleyballs. The present study is applied and developmental type. We used four full-size Federation International Volleyball (FIVB), official volleyballs (V200W MIKASA made in Japan, FOX volleyball, model Spain, made in the United States, BETA, and new volleyballs made in Iran) to determine the biomechanical components, such as stiffness and Ground Reaction Force (GRF) on that ball. Ground reaction force variables and stiffness of all samples were recorded by a force plate device (sampling rate: 1000 Hz) and Shore C (Newton’s per meter N/m), respectively. There was a significant difference in all groups between stiffness (P

Body balancing is a complex task that includes the coordination of muscles, tendons, bones, ears, eyes, and the brain. Imbalance or disequilibrium is the inability to maintain the center of gravity. Perpetuating body balance plays an important role in preventing us from falling or swaying. Biomechanical tests and video analysis can be performed to analyze body imbalance. The musculoskeletal system is one of the fundamental systems by which our balance or equilibrium is sustained and our upright posture is maintained. Electromyogram (EMG) and ground reaction force (GRF) monitoring can be utilized in cases where a rapid response to body imbalance is a necessity. Body balance also depends on visual stimuli that can be either real or virtual. Researchers have used virtual reality (VR) to predict motion sickness and analyze heart rate variability, as well as in rehabilitation. VR can also be used to induce body imbalance in a controlled way. In this research, body imbalance was induced in a controlled way by playing an Oculus game and, simultaneously, EMG and GRF were recorded. Features were extracted from the EMG and were then fed to a machine learning algorithm. Several machine learning algorithms were tested and upon 10-fold cross-validation; a minimum accuracy of 71% and maximum accuracy of 98% were achieved by Gaussian Naïve Bayes and Gradient Boosting classifiers, respectively, in the classification of imbalance and its intensities. This research can be incorporated into various rehabilitative and therapeutic systems. [ABSTRACT FROM AUTHOR]

Low back pain (LBP) is an understudied condition among runners, and it is unclear what biomechanical features could be targeted for gait retraining to mitigate pain. How do running biomechanics differ between healthy individuals and those with running-related LBP? This was a case-controlled, comparative study design of community runners: running-related LBP (n=52) and healthy controls (n=52). All runners completed running history forms and performed a 3-dimensional gait analysis. Kinematic data were collected using a motion capture system and normalized to a gait cycle, while participants ran on a level grade at self-selected speed on an instrumented treadmill. Current running volume, temporal-spatial, kinetic and kinematic features were compared between groups. The LBP group had 39.5 % lower weekly distance and 15.4 % fewer were currently training for a race (all p<.05). Runners with LBP demonstrated lower cadence (166±10 step/min vs. 171±9 step/min; p=.05), greater center of gravity lateral displacement (1.4±0.5 cm vs. 1.2 ±.3 cm; p=.044) and greater stride width variability (1.3±0.4 cm versus 1.0 ± 0.04 cm; p=.008). Runners with LBP had a greater Vertical Average Loading Rate ([VALR] 67.7±22.2 bodyweights [BW]/s vs. 62.2±21.5 BW/s; p=.022), and higher joint moments (N*m/(kg*m)) at the knee in the sagittal plane (2.13±0.50 vs. 1.87±0.56; p <.001), frontal plane (1.44±0.39 vs. 1.29±0.29; p=.013), and at the hip in the frontal plane (2.04±0.51 vs. 1.84±0.41; p=.024). No differences were found between groups in the pelvis, hip, knee, and ankle joint excursions in any plane of motion during a typical gait cycle. These collective motion signature may reflect challenges with control of motion and VALR in the presence of back pain. Cadence training to increase step rate, coupled with core/hip muscle activation, may be an important strategy to reduce motion variability, impact loading rate and pain symptoms while running. • LBP is associated with higher impact loading rates during running. • Cadence and variability of center of mass motion may relate to LBP in runners. • Retraining for LBP may target cadence, impact dampening and core muscle activation. [ABSTRACT FROM AUTHOR]

Sports equipment is widely available in the international market. The market's focus is on the design of sports equipment to prevent injury, and all equipment must be designed to enable performance without causing injury. The purpose of this study is to design and manufacture a new volleyball and comparison of kinetic components with other volleyballs. The present study is applied and developmental type. We used four full-size Federation International Volleyball (FIVB), official volleyballs (V200W MIKASA made in Japan, FOX volleyball, model Spain, made in the United States, BETA, and new volleyballs made in Iran) to determine the biomechanical components, such as stiffness and Ground Reaction Force (GRF) on that ball. Ground reaction force variables and stiffness of all samples were recorded by a force plate device (sampling rate: 1000 Hz) and Shore C (Newton's per meter N/m), respectively. There was a significant difference in all groups between stiffness (P<0.001), vertical ground reaction force (vGRF) (P<0.001), and impulse (P=0.012), also the LSD Post Hoc test showed that stiffness, vGRF, and impulse in new volleyball and MIKASA volleyball were less than BETA and FOX volleyballs. The results indicate that the biomechanical components of the new volleyball with MIKASA were similar. Therefore, the new volleyball design appears to be suitable for an official competition. Nonetheless, more clinical studies are needed to evaluate the kinetic and kinematic parameters of using new volleyball. [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]

This paper proposes a scheme for predicting ground reaction force (GRF) and center of pressure (CoP) using low-cost FSR sensors. GRF and CoP data are commonly collected from smart insoles to analyze the wearer's gait and diagnose balance issues. This approach can be utilized to improve a user's rehabilitation process and enable customized treatment plans for patients with specific diseases, making it a useful technology in many fields. However, the conventional measuring equipment for directly monitoring GRF and CoP values, such as F-Scan, is expensive, posing a challenge to commercialization in the industry. To solve this problem, this paper proposes a technology to predict relevant indicators using only low-cost Force Sensing Resistor (FSR) sensors instead of expensive equipment. In this study, data were collected from subjects simultaneously wearing a low-cost FSR Sensor and an F-Scan device, and the relationship between the collected data sets was analyzed using supervised learning techniques. Using the proposed technique, an artificial neural network was constructed that can derive a predicted value close to the actual F-Scan values using only the data from the FSR Sensor. In this process, GRF and CoP were calculated using six virtual forces instead of the pressure value of the entire sole. It was verified through various simulations that it is possible to achieve an improved prediction accuracy of more than 30% when using the proposed technique compared to conventional prediction techniques. [ABSTRACT FROM AUTHOR]

To evaluate the concurrent validity and test–retest reliability of common movement, strength, and balance tests using portable uniaxial dual force plates. Repeated measures cross-sectional study. Sixteen healthy individuals participated in two testing sessions, where they performed 12 different movement, strength, and balance tests. Vertical ground reaction force and centre of pressure data were collected using the VALD ForceDecks simultaneously with ground-embedded laboratory force plates. Concurrent validity was assessed using root mean square error for raw time-series data and Bland–Altman plots for discrete metrics. Test–retest reliability was assessed using intraclass correlation coefficients and minimal detectable changes. ForceDecks recorded vertical ground reaction forces and center of pressure with high accuracy compared to laboratory force plates. The mean bias between systems was negligible (<2 N or 0.1 mm), with small limits of agreement (<5 N or 1 mm). Overall, 530/674 (79%) showed good or excellent validity (<10% difference) and 611/773 (79%) had good or excellent reliability (intraclass correlation coefficient >0.75). ForceDecks reliability was similar to laboratory force plates (<0.07 intraclass correlation coefficient median difference for all metrics). Portable uniaxial force plates record highly accurate vertical ground reaction forces and center of pressure during a range of movement, strength, and balance tests. The VALD ForcDecks are a valid and reliable alternative to laboratory force plates when strict standardized testing and data analysis procedures are followed. Users should be aware of the validity and reliability characteristics of the tests and metrics they choose. [ABSTRACT FROM AUTHOR]

The purpose was to determine the impact of both cognitive constraint and neuromuscular fatigue on landing biomechanics in healthy and chronic ankle instability (CAI) participants. Twenty-three male volunteers (13 Control and 10 CAI) performed a single-leg landing task before and immediately after a fatiguing exercise with and without cognitive constraints. Ground Reaction Force (GRF) and Time to Stabilization (TTS) were determined at landing in vertical, anteroposterior (ap) and mediolateral (ml) axes using a force plate. Three-dimensional movements of the hip, knee and ankle were recorded during landing using a motion capture system. Exercise-induced fatigue decreased ankle plantar flexion and inversion and increased knee flexion. Neuromuscular fatigue decreased vertical GRF and increased ml GRF and ap TTS. Cognitive constraint decreased ankle internal rotation and increased knee and hip flexion during the flight phase of landing. Cognitive constraint increased ml GRF and TTS in all three axes. No interaction between factors (group, fatigue, cognitive) were observed. Fatigue and cognitive constraint induced greater knee and hip flexion, revealing higher proximal control during landing. Ankle kinematic suggests a protective strategy in response to fatigue and cognitive constraints. Finally, these two constraints impair dynamic stability that could increase the risk of ankle sprain. [ABSTRACT FROM AUTHOR]

Copyright of Ido Movement for Culture. Journal of Martial Arts Anthropology is the property of Idokan Poland Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study is to analyse the kinetic effects of acute fatigue during a 45° change of direction executed with the non-dominant limb, emulating a typical defensive action during pressing in soccer. Seventeen male professional soccer players (age: 21.7 ± 5.4 years) performed a 45° change of direction before and after a fatigue protocol. Participants were instructed to execute an approach run as quickly as possible, to change direction with their non-dominant foot on a force platform, and then continue running with the aim of stopping against an opponent. Times, forces, impulses, and force rates for different subphases during support were compared. Speeds remained consistent across pre-fatigue (4.53 ± 0.55 m s-1) and post-fatigue (4.58 ± 0.70 m s-1) trials. The results indicated a decrease in braking time (p = 0.01), impulse associated with the braking phase (p

BackgroundThe Sensory Organization Test condition 5 (SOT5) assesses an astronaut’s vestibular function pre-/post-spaceflight but has a ceiling effect and mainly evaluates standing balance, neglecting the challenges of walking during space missions. A Locomotor Sensory Organization Test (LSOT) has been developed, mirroring the SOT concept but tailored to assess vestibular function during walking. This study aims to advance current knowledge by examining changes in ground reaction force (GRF) during normal walking (LSOT1) and walking in LSOT5 (vision blocked and treadmill speed varied), both with and without mastoid vibrations.MethodsSixty healthy adults were recruited and divided into two groups: one with mastoid vibration and one without. GRF peaks and respective variabilities were analyzed in the vertical (V), anterior-posterior (AP), and medial-lateral (ML) directions during stance cycles. The effects of LSOTs and mastoid vibration on each dependent variable were assessed using Friedman’s two-way analysis of variance by ranks.ResultsThe findings revealed that:1) Walking in LSOT5 increased the variabilities of GRFs regardless of the administration of mastoid vibration; 2) the application of mastoid vibration reduced the amplitude of GRF peaks; and 3) walking in LSOT5 while receiving mastoid vibration was the most challenging task compared to all other tasks in this study.ConclusionThe results indicated that analyzing GRF can detect changes in the strategy of balance control across different sensory-conflicted conditions. The findings could be beneficial for assessing the vestibular function pre- and post-space missions and planning for future sensorimotor training programs aimed at enhancing astronauts’ abilities to navigate unpredictable sensory-conflicted conditions.

BackgroundGait can be continuously monitored via vertical ground reaction force (VGRF) and centre of pressure (COP) measurement with pressure-sensing insoles. During daily living, a variety of walking surfaces will be encountered, which could affect the collected data. These effects might need to be taken into account when analysing disease- or injury-related gait characteristics to prevent misinterpretation, especially when drawing conclusions from data obtained in clinical populations. We hypothesized characteristic changes in insole-derived VGRF and COP parameters of healthy participants when walking on different surfaces.MethodsParticipants walked on flat indoor surface, flat and inclined outdoor surfaces, as well as on forest, gravel, grass, and sand surfaces while wearing pressure-sensing insoles with 16 pressure sensors each at a recording frequency of 100 Hz. Several gait parameters were extracted from the VGRF and COP data, and were compared between surfaces using repeated measures ANOVA.ResultsThirty participants were included (22 women and 7 men, age 30 ± 12 years, height 172 ± 8 cm, weight 76 ± 23 kg). VGRF and COP data were significantly influenced by the type of surface. The rmANOVA revealed significant within-subject differences between the walking surfaces in all calculated parameters. The largest changes in the VGRF and COP patterns occurred during uphill and downhill walking. Walking on compliant surfaces led to increased gait variability. The highest variability was observed when walking on sand. The change from walking indoors to outdoors, be it on flat, inclined, forest, gravel, grass or sand surfaces, was characterized by a characteristic change in the VGRF stance-phase curve. Based on these characteristic changes, it could be possible to identify whether someone is walking on a slope, as well as on non-compliant or compliant surfaces, while it is difficult to distinguish between different types of compliant surfaces.ConclusionVGRF data are affected by the type of walking surface in healthy adults. Walking on a slope affects VGRF and COP parameters, and in addition, the compliance of the surface increases their variability. When analysing gait data measured via insoles during daily living, we recommend to correct for the surface type to decrease variability.

Background: Osteoarthrosis (OA) is a prevalent disorder among the elderly, causing disability and significant health issues. Knee OA, affecting articular cartilage and subchondral bone, is particularly common in the patellofemoral and tibiofemoral joints. Decreased quadriceps strength is a key factor in OA progression, impacting daily activities. Conservative management includes various modalities such as kinesio-taping (KT) and knee bracing, but their immediate effects on ground reaction forces (GRF) in knee OA patients remain unexplored. Methods: This randomized clinical trial enrolled 42 medically diagnosed grade II knee OA patients. Participants were divided into 2 groups: Group A received patellar KT, and Group B received knee bracing. The immediate effects on GRF during sit-to-stand, stair climbing, and stair descending were measured using a force plate. Data analysis involved Wilcoxon Signed Rank and Mann-Whitney U tests. Results: While both interventions showed low significance, patellar KT demonstrated more notable results. Group A exhibited significant improvement in sit-to-stand GRF (p = 0.006) and stair-descending COP (p = 0.001). Knee bracing in Group B showed significant results only in stair-descending GRF (p = 0.019). No significant differences were observed in baseline and post-intervention COP between groups. Conclusion: This study suggests that patellar KT may have more immediate positive effects on GRF in knee OA patients during specific activities compared to knee bracing. However, the limitations, including a small sample size and short-term analysis, must be considered. Future research with larger, more diverse populations and long-term follow-ups is required to comprehensively understand the effectiveness of such interventions in knee OA management.

This study examines the effects of limb dominance and lead limb in task initiation on the kinetics and kinematics of step-off drop landings. Nineteen male participants performed drop landings led by the dominant and non-dominant limbs at 45-cm and 60-cm drop heights. Ground reaction force (GRF) and lower body kinematic data were collected. Between-limb time differences at the initial ground contact were calculated to indicate temporal asymmetry. Statistical Parametric Mapping (SPM) was applied for waveform analysis while two-way repeated measures ANOVA was used for discrete parameters. SPM results revealed greater GRF and lesser ankle dorsiflexion in the lead limb compared to the trail limb in 3 out of 4 landing conditions. The dominant limb displayed a greater forefoot loading rate (45 cm: p=.009, ηp2 = 0.438; 60 cm: p=.035, ηp2 = 0.225) and greater ankle joint quasi-stiffness (45 cm: p <.001, ηp2 = 0.360; 60 cm: p <.001, ηp2 = 0.597) than the non-dominant limb. Not all 380 trials were lead-limb first landings, with a smaller between-limb time difference (p=.009, d = 0.60) at 60 cm (4.1 ± 2.3 ms) than 45 cm (5.6 ± 2.7 ms). In conclusion, the step-off drop landing is not an ideal protocol for examining bilateral asymmetry in lower limb biomechanics due to potential biases introduced by limb dominance and the step-off limb. [ABSTRACT FROM AUTHOR]

Introduction: The present study findings aimed to investigate the effect of exercises based on the American National Academy of Sports Medicine principles (NASM) on walking kinetics in piriformis syndrome in middle-aged men. Methods: The current research was semi-experimental and laboratory-type. The statistical sample of the present study was 30 men with piriformis syndrome. Subjects were equally and randomly placed in two intervention and control groups. The intervention group performed NASM exercises for eight weeks. Before and after the exercises, the ground reaction force variables were measured using a Bartek force plate device with a sampling rate of 1000 Hz. Kinetic data were smoothed using a fourth-order Butterworth filter with a frequency cutoff of 20 Hz. For statistical analysis, analysis of variance and paired T-test were utilized at the significance level of P < 0.05. Results: The findings of the present study showed that the effect of time on the FxHC and FyHC components at the peak of the forces and the FyHC component at the time of reaching the peak of the ground reaction force increased in the post-test compared to the pre-test. P > 0.025; d = 0.64 - 0.96. The effect of the time factor in the FyPO component at the peak of the ground reaction force in the post-test was less than the pre-test (P < 0.025; d = 1.64-0.96). The interaction effect of the time × group in the FxPO component at the peak of the force and the FzHC component at the time of reaching the peak of the ground reaction force had a significant difference (P < 0.048; d = 0.87-0.83). Conclusions: The NASM exercises used in this research can have a clinical and therapeutic effect that can reduce damage to the lower limbs and improve the quality of walking in people with piriformis syndrome. [ABSTRACT FROM AUTHOR]

Copyright of Revija Šport is the property of Sport: Revija Za Teoreticna in Praticna Vprasanja Sporta and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Increasing step rate has been proposed to reduce overuse injury risk in runners by reducing the magnitude of musculoskeletal loading. Although estimating structure-specific loads is challenging, during level running, changes in a runner's vertical ground reaction force (vGRF) may provide insight to changes in their musculoskeletal loading. Further, vGRF can be approximated using force sensing insoles. Purpose: The primary goal of this study was to examine changes in peak insole force and cumulative weighted peak force (CWPF)/km with increased step rate in collegiate runners. The secondary goal was to determine whether sacral acceleration correlates with insole force when increasing step rate. Methods: Twelve collegiate distance runners ran 1000 m outdoors at 3.83 m⋅s-1 at preferred and 10% increased step rates while insole force and sacral acceleration were recorded. Cumulative weighted peak force/km was calculated from insole force based on cumulative damage models. The effects of step rate on peak insole force and CWPF⋅km-1 were tested using paired t tests or Wilcoxon tests. Correlation coefficients between peak axial (approximately vertical) sacral acceleration times body mass and peak insole force were calculated on cohort and individual levels. Results: Peak insole force and CWPF⋅km-1 decreased (P < 0.001) with increased step rate. Peak axial sacral acceleration did not correlate with peak insole force on the cohort level (r = 0.3 5, P = 0.109) but did within individuals (mean, r = 0.69-0.78; P < 0.05). Conclusions: Increasing step rate may reduce peak vGRF and CWPF⋅km-1 in collegiate runners. Therefore, clinicians should consider step rate interventions to reduce peak and cumulative vGRF in this population. Individual-specific calibrations may be required to assess changes in peak vGRF in response to increasing step rate using wearable accelerometers. [ABSTRACT FROM AUTHOR]

Badminton is the fastest racket sport in the world with smash speeds reaching over 111 m/s (400 kph). This study examined the forehand jump smash in badminton using synchronised force plates and full-body motion capture to quantify relationships to shuttlecock speed through correlations. Nineteen elite male Malaysian badminton players were recorded performing forehand jump smashes with the fastest, most accurate jump smash from each player analysed. The fastest smash by each participant was on average 97 m/s with a peak of 105 m/s. A correlational analysis revealed that a faster smash speed was characterised by a more internally rotated shoulder, a less elevated shoulder, and less extended elbow at contact. The positioning of the arm at contact appears to be critical in developing greater shuttlecock smash speeds. Vertical ground reaction force and rate of force development were not correlated with shuttlecock speed, and further investigation is required as to their importance for performance of the jump smash e.g., greater jump height and shuttle angle. It is recommended that players/coaches focus on not over-extending the elbow or excessively elevating the upper arm at contact when trying to maximise smash speed. [ABSTRACT FROM AUTHOR]

Previous research addressed the spatiotemporal variables of the drop jump (DJ) versus the horizontal drop jump (HDJ). This study compared the kinetic variables of the DJ versus the HDJ in elite jumpers and sprinters. In a single session, sixteen elite jumpers and sprinters performed two DJ attempts with three different fall heights (0.30 m, 0.40 m, and 0.50 m), and after 2 h, performed two HDJ attempts from the same fall heights (0.30 m, 0.40 m, and 0.50 m). Kinetic variables: eccentric ground reaction forces (GRFE) and concentric ground reaction forces; eccentric impulse (PE) and concentric impulse (PC); peak power in the concentric phase; and rate of force decrease (RFDe) were measured using a research-grade force plate. The Wilcoxon test was used to compare the vertical and anteroposterior axes. GRFE was significantly higher (p ≤ 0.05) in the DJ vs the HDJ with large effect sizes. The PE (p ≤ 0.006) and PC (p = 0.002) were significantly lower in the DJ than in the HDJ. The RFDe was also significantly lower in the DJ at 0.30 m vs. the HDJ at 0.30 m (p = 0.002). In summary, elite jumpers and sprinters may benefit from incorporating both the DJ and the HDJ into their training regimens, with the DJ being particularly advantageous for enhancing power metrics and RFDe. [ABSTRACT FROM AUTHOR]

Background and Aims Several treatments have been recommended to enhance the running mechanics of individuals with flat feet. Less emphasis has been paid to the impact of these treatments on the ground reaction forces (GRF) and the center of pressure (COP), while these kinetic effects are essential in identifying possible injuries and the body's compensatory mechanisms in response to any therapeutic approach. The present study aimed to compare the effects of foot orthoses and antipronation taping on COP and GRF on the running of people with flat feet. Methods The present study was quasi-experimental with a randomized cross-over design. The kinematic and kinetic data of 20 young people with flexible flat feet were measured while running under three conditions: athletic shoes, athletic shoes with foot orthoses (FO), and athletic shoes with low-Dye (LD) tape. A one-way repeated measure analysis of variance from the SPM1d package was used to compare differences in GRF and COP time series under different conditions. Results The results showed that foot orthoses reduced the anteroposterior GRF compared to low-Dye tape and increased the lateral GRF compared to athletic shoes alone. However, the conditions did not significantly affect the vertical GRF (P<0.05). Moreover, FO-shoes and LD-shoes caused medial and lateral shifts in COP, respectively (P<0.05). Conclusion This research showed that foot orthoses cause inefficient force transmission in the anterior direction. Furthermore, running with FO-shoes and LD-shoes substantially influences COP displacements towards the end of the stance phase; however, it does not appear to increase running-related injuries since minimal load and forces are applied to the joint at that time. [ABSTRACT FROM AUTHOR]

Being overweight can influence the occurrence of pronated feet (PF). This research aimed to assess the interaction effect of overweight and PF along with sex on the frequency content of ground reaction forces (GRFs). 104 young male and female adults were allocated to four groups: normal body-mass-index/normal feet, normal body-mass-index/PF, excessive weight/normal feet, and excessive weight/PF. Subjects ran at constant speed over the walkway while an embedded force plate was located at the midpoint of the walkway. GRFs were recorded during 20 running trials. Findings demonstrated the significant main effect of "sex" (P<0.001; χ2 = 0.392) and "group" (P<0.001; χ2 = 0.264) and "sex-bygroup interaction" (P<0.001; χ2 = 0.442) for an essential number of harmonic in the vertical direction. Overall, our results showed sex, body mass index, and foot type could possibly affect GRF frequency content while running. The paired-wise comparison demonstrated lower Ne in the vertical direction in the females than in the males. The paired-wise comparison demonstrated the greatest Ne in the vertical direction in the normal weight/normal foot group than the of other groups. These findings could be used for designing rehabilitation protocols (e.g., strength training) for individuals with overweight/obesity or PF and or both of them. [ABSTRACT FROM AUTHOR]

After an ACL injury, rehabilitation consists of multiple phases, and progress between these phases is guided by subjective visual assessments of activities such as running, hopping, jump landing, etc. Estimation of objective kinetic measures like knee joint moments and GRF during assessment can help physiotherapists gain insights on knee loading and tailor rehabilitation protocols. Conventional methods deployed to estimate kinetics require complex, expensive systems and are limited to laboratory settings. Alternatively, multiple algorithms have been proposed in the literature to estimate kinetics from kinematics measured using only IMUs. However, the knowledge about their accuracy and generalizability for patient populations is still limited. Therefore, this article aims to identify the available algorithms for the estimation of kinetic parameters using kinematics measured only from IMUs and to evaluate their applicability in ACL rehabilitation through a comprehensive systematic review. The papers identified through the search were categorized based on the modelling techniques and kinetic parameters of interest, and subsequently compared based on the accuracies achieved and applicability for ACL patients during rehabilitation. IMUs have exhibited potential in estimating kinetic parameters with good accuracy, particularly for sagittal movements in healthy cohorts. However, several shortcomings were identified and future directions for improvement have been proposed, including extension of proposed algorithms to accommodate multiplanar movements and validation of the proposed techniques in diverse patient populations and in particular the ACL population. [ABSTRACT FROM AUTHOR]

Braces are one of the methods for kyphosis treatment, but they can relocate the center of gravity of the trunk, affecting the ground reaction force (GRF) during running. Therefore, this study aimed to investigate the effects of two types of thoracolumbosacral braces on running GRF components in individuals with kyphosis. Participants were 15 males diagnosed with kyphosis who volunteered in this quasi-experimental study. Each subject performed the barefoot running trials on the force plate with one simple brace, with a sensor brace, and without the brace condition. The ground reaction forces components were calculated in the stance phase. Statistical analysis was done with repeated measures test with a significant level of 0.05. Peak medial ground reaction force when running with a sensor brace was lower than running with a simple brace (p = 0.017). Free moments were similar during three running conditions (p > 0.05). Lower maximum medial ground reaction force while using a sensor brace may possibly demonstrate the beneficial effects of a sensor brace in individuals with kyphosis. [ABSTRACT FROM AUTHOR]

Purpose: Comprehensive understanding of force plate parameters distinguishing individuals postprimary anterior cruciate ligament reconstruction (ACLR) from healthy controls during countermovement jumps (CMJ) and/or drop jumps (DJ) is lacking. This review addresses this gap by identifying discriminative force plate parameters and examining changes over time in individuals post‐ACLR during CMJ and/or DJ. Methods: We conducted a systematic review and meta analyses following the Preferred Reporting Items for Systematic Review and Meta‐Analyses (PRISMA) guidelines. Nine databases were searched from inception to March 2022. We included cross‐sectional papers comparing post‐ACLR with healthy controls or longitudinal studies of individuals at least 6 months postprimary ACLR while performing CMJ and/or DJ on force plates. The methodological quality was appraised using the Modified Downs and Black Checklist. Results: Thirty‐three studies including 1185 (50.38%) participants post‐ACLR, and 1167 (49.62%) healthy controls, were included. Data were categorised into single‐leg CMJ, double‐leg CMJ, single‐leg DJ, and double‐leg DJ. Jump height was reduced in both single (mean difference [MD] = −3.13; p < 0.01; 95% confidence interval [CI]: [−4.12, −2.15]) and double‐leg (MD = −4.24; p < 0.01; 95% CI: [−5.14, −3.34]) CMJs amongst individuals with ACLR. Similarly, concentric impulse and eccentric/concentric impulse asymmetry could distinguish between ACLR (MD = 3.42; p < 0.01; 95% CI: [2.19, 4.64]) and non‐ACLR (MD = 5.82; p < 0.01; 95% CI: [4.80, 6.80]) individuals. In double‐leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = −0.10; p = 0.03; 95% CI: [−0.18, −0.01]) but higher in the uninvolved side (MD = 0.15; p < 0.01; 95% CI: [0.10, 0.20]) when compared to controls and demonstrated significant changes between 6 months and 3 years post‐ACLR. Conclusion: This study identified discriminative kinetic parameters when comparing individuals with and without ACLR and also monitored neuromuscular function post‐ACLR. Due to heterogeneity, a combination of parameters may be required to better identify functional deficits post‐ACLR. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

ObjectivesThis study determines gender variation, comparing the significance level between men and women related to functional ambulation characteristics after hip arthroplasty. The study focuses on the broader female pelvis and how it affects the rehabilitation regimen following total hip arthroplasty.Materials and MethodsIn this cross-sectional study, 20 cases of right hip arthroplasty were divided into 10 male and 10 female cases, aged 40–65 years. The functional ambulation parameters (walking cadence, gait speed, stride length, and gait cycle time) were acquired from the GAITRite device, as well as kinematic values for hip frontal plane displacement and kinetic parameters for ground response force in the medial–lateral direction.ResultsAn independent t-test showed a significant difference in the kinematic parameter variables for the anterior superior iliac spine, more significant trochanter displacement, and hip abduction angle between the operated and non-operated limbs for each group separately. Regarding the functional ambulation parameters, there was a significant difference in the walking cadence between the operated and non-operated limbs of both male and female groups. Moreover, the output variables of ground reaction force measures revealed significant differences between their operated and non-operated limbs. The linear regression model used was consistent with the current results, demonstrating a weak negative correlation between the abduction angle of the operated hip and gait speed for both male and female groups.ConclusionBased on the findings, we draw the conclusion that improving a rehabilitated physical therapy program for the abductors of both male and female patients’ operated and non-operated limbs is essential for normalizing the ground reaction force value, avoiding focus on the operated hip, and reducing the amount of time that the operated hip’s abductors must perform. This involves exposing the surgically repaired limb to the risk of post-operative displacement or dislocation, particularly in female patients.

Introduction: The biomechanics associated with human running are affected by gender and speed. Knowledge regarding ground reaction force (GRF) at various running speeds is pivotal for the prevention of injuries related to running. This study aimed to investigate the gait pattern differences between males and females while running at different speeds, and to verify the relationship between GRFs and running speed among both males and females.Methods: GRF data were collected from forty-eight participants (thirty male runners and eighteen female runners) while running on an overground runway at seven discrete speeds: 10, 11, 12, 13, 14, 15 and 16 km/h.Results: The ANOVA results showed that running speed had a significant effect (p < 0.05) on GRFs, propulsive and vertical forces increased with increasing speed. An independent t-test also showed significant differences (p < 0.05) in vertical and anterior-posterior GRFs at all running speeds, specifically, female runners demonstrated higher propulsive and vertical forces than males during the late stance phase of running. Pearson correlation and stepwise multiple linear regression showed significant correlations between running speed and the GRF variables.Discussion: These findings suggest that female runners require more effort to keep the same speed as male runners. This study may provide valuable insights into the underlying biomechanical factors of the movement patterns at GRFs during running.

OBJECTIVE: The study aimed to identify the effects of ground reaction forces (GRF) recorded during landing in typical elements of three dance styles, including classical, modern, and folk dance, on injuries` topography. METHODS: The research involved a survey and measurements of GRF generated during landing after the jump. The survey involved a group of 90 professional dancers. In the questionnaire, the dancers marked areas of the human body that were affected at least once by injuries. Biomechanical tests of the GRF recording were conducted on a group of 15 professional dancers. The analysis focused on the following parameters: a maximum value of the vertical variable of the GRF relative to body weight (maxGRF_z), the time between the moment from first foot contact with the ground to the moment of reaching the maxGRF_z (_tmaxGRFz), and the loading rate of the GRF relative to body weight (LR_GRFz). RESULTS: Regardless of dance style and sex, the lower spine, knee joints, ankle joints and feet were the areas most affected by injuries among professional dancers. The level of maxGRF_z, t_maxGRFz and LR_GRFz during typical jumps in classical, modern, and folk dance was statistically significantly different (P

This study used a 12-week plyometric and strength training program as an intervention to improve upper- and lower-extremity muscle strength for jumping and landing when climbing high walls. Sixty general non-athlete male college students were openly recruited and divided into an experimental group and a control group. The experimental group underwent a plyometric and strength training program twice a week for 12 weeks (24 sessions). The intervention was divided into three phases, each lasting four weeks, with the training intensity gradually increasing in each phase. A hand grip dynamometer was used to measure grip strength, and a PASCO double-track force plate was used to assess upper-extremity push-up force and lower-extremity take-off and landing strength. The results of the 12-week intervention showed that the experimental group experienced significant increases in grip strength (both hands), hand-ground reaction force, and upper-extremity hang time. Additionally, the time of upper-extremity action on the force plate decreased. Lower-extremity take-off strength improved, as reflected in increased ground reaction force, rate of force development, and passage time. Upon landing, ground reaction force decreased by 3.2%, and cushioning time shortened by 52.7%. This study concludes that plyometric and strength training have promising effects in enhancing upper- and lower-extremity strength, particularly in climbing and landing tasks.

Accurately predicting physical activity-associated mechanical loading is crucial for developing and monitoring exercise interventions that improve bone health. While accelerometer-based prediction equations offer a promising solution, their external validity across different populations and activity contexts remains unclear. This study aimed to validate existing mechanical loading prediction equations by applying them to a sample and testing conditions distinct from the original validation studies. A convenience sample of 49 adults performed walking, running, and jumping activities on a force plate while wearing accelerometers at their hip, lower back, and ankle. Peak ground reaction force (pGRF) and peak loading rate (pLR) predictions were assessed for accuracy. Substantial variability in prediction accuracy was found, with pLR showing the highest errors. These findings highlight the need to improve prediction models to account for individual biomechanical differences, sensor placement, and high-impact activities. Such refinements are essential for ensuring the models’ reliability in real-world applications, particularly in clinical and biomechanical research contexts, where accurate assessments of mechanical loading are critical for designing rehabilitation programs, injury prevention strategies, and optimizing bone health interventions.

In this study, we developed a lightweight shoe sensor system equipped with four high-capacity, compact triaxial force sensors and an inertial measurement unit. Remarkably, this system enabled measurements of localized three-directional ground reaction forces (GRFs) at each sensor position (heel, first and fifth metatarsal heads, and toe) and estimations of stride length and toe clearance during walking. Compared to conventional optical motion analysis systems, the developed sensor system provided relatively accurate results for stride length and minimum toe clearance. To test the performance of the system, 15 older and 8 young adults were instructed to walk along a straight line while wearing the system. The results reveal that compared to the young adults, older adults exhibited lower localized GRF contributions from the heel and greater localized GRF contribution from the toe and fifth metatarsal locations. Furthermore, the older adults exhibited greater variability in their stride length and smaller toe clearance with greater variability compared to the young adults. These results underscore the effectiveness of the proposed gait analysis system in distinguishing the gait characteristics of young and older adults, potentially replacing traditional motion capture systems and force plates in gait analysis.