Search Results (33)

Approximately 15% of total knee arthroplasty (TKA) patients remain dissatisfied after surgery, with joint line obliquity (JLO) potentially affecting patient outcomes. This study investigated whether JLO restoration influenced lower extremity frontal plane joint moments during stair negotiation by TKA patients. Thirty unrestored and twenty-two restored JLO patients participated in this study and were asked to perform five trials on each limb for stair negotiation while three-dimensional kinematics and ground reaction forces were recorded. Frontal plane moments at the ankle, knee and hip were calculated using Visual 3D. The restoration of JLO did not alter frontal plane joint moments during stair negotiation. Both groups showed symmetrical moment profiles, indicating no significant biomechanical differences between the restored and unrestored JLO groups. Restoring JLO did not affect frontal plane joint moments during stair negotiation, suggesting it may not contribute to patient satisfaction disparities post-TKA. Further research should explore other factors, such as surgical technique and implant design, that might influence recovery. Full article

Shock attenuation may be a clinically feasible method to assess changes in lower extremity joint loading induced by gait modifications, such as decreasing foot strike angle (forefoot striking). The purpose of this study was to identify changes in lower extremity shock attenuation between habitual and forefoot strike gait conditions. Eighteen participants ran on a treadmill with their habitual gait and an instructed forefoot strike gait. Shock attenuation was measured with inertial measurement units as the ratio of proximal to distal peak resultant/vertical accelerations, with three sensor combinations: ankle to below/above knee (BK/A; AK/A) and AK/BK. Three participants were excluded who were habitual forefoot strikers or failed to decrease their foot strike angle by at least 5° in the forefoot strike condition. The results showed significantly greater resultant shock attenuation in the forefoot strike compared to the habitual condition for BK/A (mean Δ = 0.13, p = 0.004) and AK/A (mean Δ = 0.23, p = 0.007). No significant differences were found for AK/BK or vertical shock attenuation. These results suggest that shock attenuation may not reflect joint-specific loading changes that have been shown for forefoot striking (i.e., increased ankle/shank and decreased knee moments). However, it may capture changes in overall lower extremity loading (i.e., decreased vertical ground reaction forces). Full article

Background: Much of the research conducted on tactical-style boots has evaluated the biomechanical effect of boots in brand-new condition; however, the extent to which changes due to wear influence lower-extremity biomechanics remains uninvestigated. The purpose of this study was to compare lower-extremity biomechanics with worn-in boots and running shoes during both walking and running. Methods: Lower-extremity biomechanical parameters were evaluated during walking and running in 12 individuals with previous tactical experience. Participants were asked to complete one 5 min bout of walking and running at a self-selected pace in both self-selected athletic shoes and their own worn-in standard-issue tactical boots while lower-extremity spatiotemporal, joint kinematic, kinetic, and ground reaction force data were collected. Differences between conditions were evaluated using the Wilcoxon signed-rank test. Results: Spatiotemporal measures of gait, as well as ankle and hip kinematics, were different between shoes and boots during walking. During running, no spatiotemporal differences existed. However, significant differences were found for the ankle, knee, and hip kinematics between shoe and boot conditions during both walking and running. Conclusions: The worn-in boots in our sample performed similarly to running shoes during both walking and running tasks. Though there were several biomechanical differences between boots and shoes during both tasks, small mean differences suggest that these differences may not be large enough to create substantive or relevant changes in performance. This information could aid in developing future tactical boot design strategies to help aid in lower-extremity injury as well as allowing for optimal performance when wearing boots. Full article

Maximal eccentric (MES) and isometric (MIS) muscle strength may enhance vertical jump performance by facilitating preloading and reducing energy loss during the eccentric (ECC) phase of the stretch-shortening cycle (SSC). However, the contributions of ECC and isometric (ISO) strength to the countermovement (CMJ) and depth jump (DJ) remain unclear due to variability in assessment methods (e.g., dynamometry, isometric mid-thigh pull) and the limited range of metrics examined in prior research. The aim of this study was to assess correlations between multi-joint lower extremity MES and MIS, obtained using a seated multi-joint isokinetic dynamometer, and 13 vertical ground reaction force (GRF) measures derived from the performance of three maximal effort DJs and CMJs. Twenty-five healthy young adults participated in this study (age = 21.9 ± 2.9 years). Pearson r correlation coefficients were used to assess the statistical significance (α = 0.05) of the relationships between absolute (N) and body mass normalized (BN) maximal strength measures and vertical jumping metrics. Moderate-to-strong positive correlations were identified between MES and MIS with broad performance metrics in CMJ and DJ, including reactive strength index (r = 0.45–0.53, p < 0.05), modified reactive strength index (r = 0.41–0.62, p < 0.05), and jump height (r = 0.59–0.75, p < 0.05). Moderate-to-strong positive correlations were also observed between MES and MIS with CON work (r = 0.58–0.71, p < 0.05) and CON peak power (r = 0.44–0.71, p < 0.05) for both the CMJ and DJ. In contrast, moderate-to-strong negative correlations were observed between MES and MIS with ECC work (r = 0.42–0.62, p < 0.005) and ECC peak power (r = 0.45–0.60, p < 0.05). These findings suggest that enhanced neuromuscular efficiency and joint stiffness in stronger musculature reduce energy absorption during the eccentric phase, minimizing mechanical deformation and preserving elastic energy for concentric propulsion. Combined, MES and MIS optimize force application, energy utilization, and control, which are crucial for maximizing jump height. These findings underscore the role of MES and MIS in influencing jumping performance across both the ECC and CON phases of the SSC. This insight is valuable for practitioners designing training programs aimed at improving vertical jumping ability. Full article

Background/Objectives: For over 50 years, it has been suggested that the plantar flexors and hip extensors can compensate for weak knee extensors and prevent collapse of the leg during a single-limb stance. However, the effects of these compensations have not been studied thoroughly. The purpose of this computer simulation study was to determine, for a given posture, the hip and ankle net joint torque (NJT) required to prevent leg collapse due to systematic decreases in knee NJT and to determine the effect of these compensations on the horizontal ground reaction force. Methods: Single-limb stance was simulated using a static, multisegmented model in eight different postures. For each posture, the knee NJT was systematically decreased. The ankle and knee NJT necessary to prevent lower extremity collapse, along with any net horizontal ground reaction forces, were then calculated. Results: Decreases in knee NJT required linear increases in ankle and hip NJT to prevent the limb from collapsing. There were greater increases in ankle NJT compared to hip NJT, resulting in posteriorly-directed horizontal ground reaction forces. While the magnitudes were different, these findings applied to all postures simulated. Conclusions: For a given posture, ankle and hip NJTs can compensate for a decrease in knee NJT. However, this resulted in a horizontal ground reaction force, which was in the posterior direction for all the postures examined. This horizontal ground reaction force would induce an acceleration on the body’s center of mass that, if not accounted for, could have deleterious effects on achieving a task objective. Full article

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

Functional ankle instability (FAI), which is characterized by recurrent ankle sprains and perceived joint instability, arises from various factors contributing to compromised biomechanical control during activities, particularly those involving landing tasks. While current research predominantly addresses lower-extremity and core stabilization interventions for FAI, the contribution of upper body control to landing biomechanics in this population remains insufficiently explored. In this study, 42 participants (19 males, 23 females) with FAI were randomly assigned to either the upper-body control training group (UBCTG) or the core muscle stabilization training group (CMSTG). The groups underwent six-week interventions, with the UBCTG receiving a dynamic core exercise program including upper body control and the CMSTG receiving static core muscle training. Pre- and post-intervention assessments encompassed electromyography of the gastrocnemius, tibialis anterior, and peroneus longus, motion analysis of the lower extremities, and ground reaction force (GRF) readings during a single-leg-jump task. Additionally, dynamic balance was assessed using the Y balance test and self-reported measurements of ankle instability were performed. The results showed similar increases in muscle activation, joint movement, and self-reported ankle instability scores within both groups. However, significant between-group differences were observed in terms of knee flexion angle, dynamic balance, and ankle instability scores, favoring the UBCTG. Although the peak vertical GRF significantly decreased and the time to peak vertical GRF increased in both groups, more changes were noted in the UBCTG. Our results demonstrated that dynamic core exercises with additional upper body control training enhance landing biomechanics, dynamic balance, and stability in individuals with FAI. Consequently, we recommend incorporating shoulder girdle exercises, proprioceptive drills, and balance exercises into dynamic core training. Full article

Postural stability may be affected during slope walking, as there are different body kinetics and kinematic responses compared with level walking. Understanding body adaptations toward different inclinations is essential to prevent the risk of injury from falls or slips. This study was conducted to determine the correlations between stability parameters and loading response in terms of joint reaction force at the lower-extremity joints during inclined and declined walking. Twenty male subjects walked in the level, incline, and decline directions on a custom-built platform at three different slope angles (i.e., 5°, 7.5°, and 10°). To determine the ground reaction force (GRF), joint reaction force (JRF), center of pressure (COP), and center of mass (COM), a motion capture system was used to read the data of the ten reflective markers and transfer them to visual three-dimensional (3D) software. Pearson’s correlation test was performed with statistical significance set at p < 0.05 to evaluate the correlation of the required coefficient of friction (RCOF), postural stability index (PSI), and COP-COM distance with the JRF. This study has identified that the JRF changes in opposition to the changes in the RCOF during the initial strike during incline and decline walking, as JRF increases, the RCOF decreases with different strengths of correlation. There is also a strong positive correlation between the PSI and JRF in the proximal–distal direction, where the JRFs change in accordance with the change in the PSI, and the JRF increases with the increment of PSI. In addition, the JRF of the lower extremity also changed in a manner similar to the COP-COM distance in the medial–lateral direction. Overall, each stability parameter was correlated with the JRF of the lower-extremity joints in different directions and strengths. This study demonstrated that slope walking is particularly affected by surface inclination in terms of stability and loading. Therefore, this research can serve as a basis for future studies on slopes, as there is no specific basis for a maximum degree of inclination that is safe and suitable for all applications. Full article

The purpose was to investigate full-body kinematics and vertical ground reaction forces in the lower extremities of the delivery and to determine delivery changes over time after many deliveries in ten-pin bowling. Six male elite ten-pin bowlers completed six bouts of twelve bowling deliveries, all strike attempts, while measuring full-body kinematics and vertical ground reaction forces. Full-body joint angles, peak vertical ground reaction forces in the feet, vertical breaking impulse, centre of mass velocity, bowling score, and ball release velocity (BR_vel) were measured. Results revealed that the BR_vel was significantly decreased over bouts (p < 0.001). Additionally, increased flexion of the dominant wrist (p < 0.001) and elbow (p = 0.004) prior to ball release (BR) and increased pronation of the dominant wrist during BR (p = 0.034) were observed at later bouts. It was concluded that these kinematic changes in the dominant wrist and elbow prior to and during BR were performed to compensate for the change in traction between ball and lane during a bowling match. This, in turn, caused a decrease in BR_vel. A conservation of energy perspective was discussed to highlight training applications and possibilities to enhance elite athletes’ bowling performance. Full article

Purpose: To explore the difference in the biomechanics of the lower extremity during alternating jump rope skipping (AJRS) under barefoot and shod conditions. Methods: Fourteen experienced AJRS participants were randomly assigned to wear jump rope shoes or be barefoot (BF) during the AJRS at a self-selected speed. The Qualisys motion capture system and Kistler force platform were used to synchronously collect the ground reaction forces and trajectory data of the hip, knee, ankle, and metatarsophalangeal (MTP) joints. One-dimensional statistical parameter mapping was used to analyze the kinematics and kinetics of the lower extremity under both conditions using paired t-tests. Results: Wearing shoes resulted in a significant decrease in the ROM (p < 0.001) and peak angular velocity (p < 0.001) of the MTP joint during the landing phase. In addition, the MTP joint power (p < 0.001) was significantly larger under shod condition at 92–100% of the landing phase. Moreover, wearing shoes reduced the peak loading rate (p = 0.002). Conclusion: The findings suggest that wearing shoes during AJRS could provide better propulsion during push-off by increasing the MTP plantarflexion joint power. In addition, our results emphasize the significance of the ankle and MTP joint by controlling the ankle and MTP joint angle. Full article

Badminton is very popular on college campuses. In badminton, the anterior cruciate ligament of the players has a higher risk of injury. There are many studies investigating the impact of fatigue on the injury of professional athletes, but few studies focused on college students. We hypothesized that the knee joint would experience greater ground reaction forces, valgus moments, and flexion moments of lunge contact in amateur after fatigue than those indicators before fatigue. Ten male badminton amateurs were enrolled in this study. They performed a lunge to hit the shuttlecock at the designated position and then quickly returned to the starting position before and after fatigue. Fatigue was induced by repeated isokinetic flexion/extension of the knee. Lower body kinematics and ground reaction force (GRF) were collected and further used to calculate the lower body joint moments from initial contact to maximum knee flexion. Compared to the pre-fatigue condition, the peak flexion moment (p = 0.012) and peak abduction moment of knee joint (p = 0.01), and maximum horizontal ground reaction force (p = 0.027) increased significantly at the initial contact (p = 0.01). After muscle fatigue, the knee buckling moment and valgus moment increased significantly at initial contact, and the horizontal backward maximum GRF also increased significantly. These changes might increase the injury risk of anterior cruciate ligament (ACL). The fatigue of the muscles around the knee joint did not change the maximum GRF in the vertical direction at the moment of contact. Combined with the results of our study, badminton coaches and teachers should increase the training of lower extremity muscle strength and endurance in our daily class and training, and also should pay special attention to the coordinated development of muscles. Full article

Background: By comparatively investigating the joints, muscles and bones of the lower extremity during two progressive motions in Bafa Wubu and normal walking, this paper aims to enrich the diversity of walking exercise and scientifically provide theoretical guidance for primary practitioners. The scientific training methods and technical characteristics of Bafa Wubu, as well as its contribution to comprehensive exercise of the lower extremities, are further explored. Methods: A total of eight professional athletes of Tai Chi at the national level were recruited. The kinetic parameters of the lower extremity were calculated using AnyBody 7.2 musculoskeletal modeling. Stress analysis of the iliac bone was performed using an ANSYS 19.2 workbench. Results: In Bafa Wubu, the ground reaction force during two progressive motions was significantly smaller than that noted during normal walking. During warding off with steps forward and laying with steps forward, the load at the three joints of the lower extremity was significantly smaller than that during normal walking in the frontal plane, but significantly greater than that noted during normal walking in the vertical axis. In addition, the lower limb joint torque was higher than that of normal walking in both progressive movements, and lower limb muscle activation was higher. The iliac bone loads during the two progressive motions were larger than those during normal walking, and the maximum loading point differed. Conclusions: This is the first study to demonstrate the biomechanical performance of Bafa Wubu in professional athletes of Tai Chi. Two progressive motions of Bafa Wubu require the lower extremity to be slowly controlled, thereby resulting in a smaller ground reaction force. In addition, the loads of the three joints at the lower extremity all increase in the vertical direction and decrease in the lateral direction, reducing the possibility of lateral injury to the joints. In addition, the two progressive motions significantly enhance the muscle strength of the plantar flexion muscles, dorsiflexor, and muscles around the thigh, and effectively stimulate the bones of the lower extremity. Therefore, progressive motion training contributes to improving the controlling and supporting capabilities of the lower extremities during normal walking. Full article

Background: The role of multifidus in the biomechanics of lumbar spine remained unclear. Purpose: This study aimed to investigate the role of multifidus in the modeling of lumbar spine and the influence of asymmetric multifidus atrophy on the biomechanics of lumbar spine. Methods: This study considered five different multifidus conditions in the trunk musculoskeletal models: group 1 (with entire multifidus), group 2 (without multifidus), group 3 (multifidus with half of maximum isometric force), group 4 (asymmetric multifidus atrophy on L5/S1 level), and group 5 (asymmetric multifidus atrophy on L4/L5 level). In order to test how different multifidus situations would affect the lumbar spine, four trunk flexional angles (0°, 30°, 60°, and 90°) were simulated. The calculation of muscle activation and muscle force was done using static optimization function in OpenSim. Then, joint reaction forces of L5/S1 and L4/L5 levels were calculated and compared among the groups. Results: The models without multifidus had the highest normalized compressive forces on the L4/L5 level in trunk flexion tasks. In extreme cases produced by group 2 models, the normalized compressive forces on L4/L5 level were 444% (30° flexion), 568% (60° flexion), and 576% (90° flexion) of upper body weight, which were 1.82 times, 1.63 times, and 1.13 times as large as the values computed by the corresponding models in group 1. In 90° flexion, the success rate of simulation in group 2 was 49.6%, followed by group 3 (84.4%), group 4 (89.6%), group 5 (92.8%), and group 1 (92.8%). Conclusions: The results demonstrate that incorporating multifidus in the musculoskeletal model is important for increasing the success rate of simulation and decreasing the incidence of overestimation of compressive load on the lumbar spine. Asymmetric multifidus atrophy has negligible effect on the lower lumbar spine in the trunk flexion posture. The results highlighted the fine-tuning ability of multifidus in equilibrating the loads on the lower back and the necessity of incorporating multifidus in trunk musculoskeletal modeling. Full article

Spinal orthoses are an effective option for restoring the spine to its original position and controlling poor posture. However, the effects of poor posture and spinal orthoses on the kinematics and kinetics of trunk and lower extremity joints remain unclear. A six-camera Vicon motion capture system and two AMTI force plates were employed to collect gait parameters, including joint angle (spine, thorax, hip, knee, and ankle), range of motion (ROM), and ground reaction forces (GRFs). Furthermore, joint moments and joint reaction forces (JRFs) were calculated using a full-body musculoskeletal model in OpenSim. One-way repeated-measures ANOVA (p < 0.05) was used to compare significant differences among three trial conditions. These three conditions were walking in a normal posture, poor posture, and spinal orthosis. The results showed that spine ROM in the coronal and transverse plane was significantly lower when walking with a spinal orthosis compared to walking in normal and poor posture (p < 0.05). Compared to normal posture, the lumbar moments and back compressive forces were significantly increased when walking in poor posture (p < 0.05). However, when walking with a spinal orthosis, there was a significant decrease in trunk moments and reaction forces compared to walking in poor posture (p < 0.05). Individuals with poor posture could potentially induce instability and disorders, as evidenced by an increase in trunk moments and JRF compared to the normal posture. Spinal orthosis not only restricts spine ROM but also reduces the load on the spine and thus increases balance and stability. Full article

With the progress and innovation of table tennis technology, individualized training programs may deserve special attention. This study aimed to analyze elite table tennis athletes in chasse-step, with a particular focus on sex-based biomechanical differences. A total of 36 (18 males and 18 females) elite table tennis athletes performed topspin forehand of chasse-step. Angles and moments of hip, knee, and ankle joints were calculated using OpenSim (v4.2) with marker trajectories and ground reaction forces were measured via Vicon motion capture system and AMTI in-ground force platform. Males had greater hip and knee flexion angles during the entire motion phase and greater internal rotation angles of the hip during the forward swing phase. The joint stiffness of knee in males was greater than females in the frontal plane. Females in the forward swing phase showed greater hip flexion, adduction, and internal rotation moments than males. It was suggested that the difference may be due to the limitation of anatomical structures in sexes. Male table tennis athletes should strengthen lower extremity muscle groups to improve performance, while female table tennis athletes should focus on hip joint groups to avoid injury. The sex differences presented in this study could help coaches and athletes to develop individualized training programs for table tennis. Full article