Ageing alters ankle mechanics and muscle co-contraction patterns across the gait cycle.

Muscle force contributions to ankle joint contact forces during an unanticipated cutting task in people with chronic ankle instability

Propulsive and braking mechanisms during acceleration and deceleration in human gait.

Biomechanical analysis of gait waveform data: exploring differences between shod and barefoot running in habitually shod runners

Pattern of anterior cruciate ligament force in normal walking

No studies have reported ground reaction force (GRF) profiles of the repeated depth jump (DJ) protocols commonly used to study exercise-induced muscle damage. Furthermore, while compression garments (CG) may accelerate recovery from exercise-induced muscle damage, any effects on the repeated bout effect are unknown. Therefore, we investigated the GRF profiles of 2 repeated bouts of damage-inducing DJs and the effects of wearing CG for recovery. Nonresistance-trained males randomly received CG (n = 9) or placebo (n = 8) for 72hours recovery, following 20 × 20m sprints and 10 × 10 DJs from 0.6m. Exercise was repeated after 14days. Using a 3-way (set × bout × group) design, changes in GRF were assessed with analysis of variance and statistical parametric mapping. Jump height, reactive strength, peak, and mean propulsive forces declined between sets (P < .001). Vertical stiffness, contact time, force at zero velocity, and propulsive duration increased (P < .05). According to statistical parametric mapping, braking (17%-25% of the movement) and propulsive forces (58%-81%) declined (P < .05). During the repeated bout, peak propulsive force and duration increased (P < .05), while mean propulsive force (P < .05) and GRF from 59% to 73% declined (P < .001). A repeated bout of DJs differed in propulsive GRF, without changes to the eccentric phase, or effects from CG.

A characterisation of established unilateral transfemoral amputee gait using 3D kinematics, kinetics and oxygen consumption measures

The modulation of forward propulsion, vertical support, and center of pressure by the plantarflexors during human walking

Lower-limb joint quasi-stiffness in the frontal and sagittal planes during walking at different step widths

IntroductionStudies of intermittent claudication gait report inconsistent outcomes. Changes in gait are often attributed to degradation of calf muscles, but causation has not been proven through real-time electromyographic data. Neither have effects of walking speed been fully considered. This study aimed to investigate the effect of intermittent claudication on kinematics, kinetics and muscle activity during pain-free gait. Methods18 able bodied individuals and 18 with intermittent claudication walked at their preferred speed while lower limb kinematic, kinetic and electromyography data were collected. FindingsPeople with intermittent claudication walk slower and with reduced step length. Internal ankle plantarflexion moment (P = 0.004, effect size = 0.96) and ankle power generation (P < 0.001, effect size = 1.36) in late stance were significantly reduced for individuals with intermittent claudication. Significant moment and power reductions at the knee and power reduction at hip occurred in early stance, with similar reductions in early and late stance for ground reaction forces. Peak electromyography of soleus activity was significantly reduced in late stance (P = 0.01, effect size = 1.1, n = 13). Effects were independent of walking speed. InterpretationReductions in ankle plantarflexion moments and power generation were consistent with reduced soleus electromyography activity and reduced peak vertical ground reaction forces during late stance. These effects are not due to a reduced walking speed. Changes in knee and hip function are also unrelated to walking speed. These outcomes provide a platform for the design and evaluation of interventions that seek to restore normal walking and improve pain-free walking distances for people with intermittent claudication.

Stroke has emerged as a leading health threat, characterized by its rapid onset, high mortality rate, and significant disability. One of the primary effects of stroke is the abnormality in gait, particularly the asymmetry observed in patients, which severely impacts daily activities and mobility. This study aims to compare the symmetry of lower limb muscle activity during gait in individuals who have suffered a stroke. Method: Nine stroke patients were recruited from the Rehabilitation Hospital. A motion-capture system equipped with ten cameras (VICON Motion Systems Ltd, UK) and a split-belt treadmill (Motek, Amsterdam, NL) was synchronized to collect marker trajectories and ground reaction forces at sampling frequencies of 200 Hz and 1000 Hz, respectively. We collected the kinematic and kinetic parameters of the participants' walking gait cycles. Subsequently, a paired sample T-test was conducted using SPSS to compare these parameters, with a significance level set at P &lt; 0.05. The force exerted by the soleus muscle in the paretic leg was significantly lower than that in the non-paretic leg during the 7-15% (p &lt; 0.001, t = 3.235) and 19-51% (p &lt; 0.001, t = 3.235) phases of the gait cycle. Additionally, the force of the medial gastrocnemius was significantly greater in the paretic leg compared to the non-paretic leg during the 0-58% phase (p &lt; 0.001, t = 3.286). Conversely, the force of the lateral gastrocnemius was significantly lower during the 0-15% (p &lt; 0.001, t = 3.255) and 25-47% (p &lt; 0.001, t = 3.255) phases. These results indicate that the lengths of the soleus, medial gastrocnemius, lateral gastrocnemius, and tibialis posterior muscles were significantly shorter in the paretic leg compared to the non-paretic leg throughout the walking gait cycle. Stroke patients exhibit asymmetric lower limb dynamics, characterized by diminished soleus and lateral gastrocnemius forces, accompanied by compensatory overactivity of the medial gastrocnemius in paretic limbs. The paretic muscles demonstrate reduced lengths throughout the gait cycle, suggesting that neuromuscular compensation and structural adaptations contribute to post-stroke gait asymmetry. These findings underscore the importance of rehabilitation strategies that target force deficits and enhance muscular adaptability to improve gait symmetry.

Contributions of muscles to mediolateral ground reaction force over a range of walking speeds

Hip osteoarthritis (OA) is an increasingly significant public health concern, contributing to substantial economic and societal burden worldwide. Emerging evidence suggests that running may promote cartilage health through optimal joint loading. However, it remains unclear how modifications to running posture, such as altering footstrike patterns or adjusting foot progression angles, affect hip contact forces (HCF). This study investigated HCF differences across three running conditions: natural running, forefoot strike (FFS) modification, and toe-out modification. FFS may enhance shock attenuation through increased lower limb flexion and altered ankle mechanics, while toe-out running laterally shifts the center of pressure, reducing the lever arm. Ten healthy participants ran along a 20-meter walkway under the three running conditions in a randomized order. Running biomechanics were recorded using an 8-camera motion capture system synchronized with four force plates. Kinematic and kinetic data were used to calculate right-limb HCF during early and late stance using a musculoskeletal model and the software OpenSim. Within-subject differences in HCF across the three running conditions were analyzed with one-way repeated measures ANOVA. FFS running resulted in a significantly lower vertical HCF during early stance and a significantly higher vertical HCF during late stance compared to both natural running (early stance: p=0.011; late stance: p=0.004) and toe-out running (early stance: p=0.028; late stance: p=0.013). No statistically significant differences were observed in medial-lateral HCF during either early stance or late stance (p>0.220) across the three conditions. No significant differences in vertical or medial-lateral HCF were found between toe-out and natural running during either early or late stance (p>0.366). Footstrike modification appears to be a viable strategy to alter vertical HCF compared to natural and toe-out running. However, none of the selected strategies effectively modified HCF in the frontal plane. These findings have implications for developing targeted interventions to manage hip OA.

The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds

A comparison of centre of pressure behaviour and ground reaction force magnitudes when individuals walk overground and on an instrumented treadmill

Objectives:Clinical outcome measures suggest the unloader brace provides small-to-moderate improvements in pain and function in varus knee osteoarthritis (OA) patients. However, controversy still exists as to whether the brace has the real effect of increasing tibiofemoral joint space in the medial compartment during functional activity. As a limitation, the previous studies did not report ground reaction forces (GRF) with and without the brace, which could be a confounding factor affecting joint space. Therefore, the purpose of the present study was to investigate the effect of an unloader brace on dynamic joint space in medial compartment in OA patients while simultaneously recording GRF during gait. The hypotheses were (1) dynamic joint space in the medial compartment would be greater with the unloader brace than without the brace during gait, and (2) GRF during gait would be smaller with the brace than without the brace.Methods:Ten varus knee OA patients were enrolled (Age: 52±8 years). After minimum 2-week daily use of the unloader brace, subjects walked (1.0 m/s) on an instrumented treadmill while biplane radiographs of the OA knees were acquired at 100 Hz. Tibiofemoral motion was determined from the biplane radiographs from initial contact to terminal stance phase (gait cycle: 0-40%) using a previously validated model-based tracking process. Dynamic joint space measurement in the medial compartment was performed using previously reported method. Briefly, the medial tibial plateau was divided into 9 sub-regions (Figure 1A) and the average minimum distance between femur and tibia subchondral bone was calculated in each region. The region with the smallest joint space over the three walking trials was selected for the analysis. GRF during gait were collected at 1000 Hz and normalized by each subject’s body weight. Output parameters were averaged over 10% intervals of the gait cycle. Two-way repeated measures ANOVA (gait cycle x brace condition) was used to explore differences in medial compartment dynamic joint space and GRF between the 2 conditions (unbraced and braced). Post-hoc paired t-tests identified the differences between the 2 conditions during the same gait cycle period. Significance level was set as P < 0.05. A subjective questionnaire for the brace usage was collected at the time of the test.Results:The dynamic joint space in the medial compartment was significantly greater with the unloader brace than without the brace during gait (P = 0.004) (Table 1, Figure 1B). The average difference between the 2 conditions was 0.27 mm (95% confidential interval: 0.12-0.43). No significant difference was observed in terms of GRF between unbraced and braced conditions. The questionnaire showed participants felt reduced pain (4.1±0.7 out of 5 scale) and were comfortable (3.8±0.8 out of 5) when wearing the brace.Conclusion:The unloader knee brace induced a small but significant increase in medial dynamic joint space during gait. Furthermore, no differences in GRF during gait were found between unbraced and braced conditions, indicating that the increase of medial joint space with bracing was not due to decreased limb-loading during gait, but instead due to the brace use itself. These results suggest that the OA unloader brace may reduce medial compartment joint loading during dynamic loading activities.Figure 1.(A) Medial compartment regions used to calculate dynamic joint space. The medial tibial plateau was divided into 9 sub-regions, and the average joint space in each region was obtained over every 10% of gait cycle. The regions with the smallest joint space (region 5 in 9/10 subjects) was selected for the analysis. (B) The instantaneous dynamic joint space during gait at 15% of the gait cycle for one subject, demonstrating increased medial compartment joint space in the braced condition.Table 1.Results of medial compartment dynamic joint space and ground reaction forces during gait. *Statistically significant difference (vs unbraced condition)Gait cycleMedial compartment dynamic Joint space (mm)Ground reaction forces / Body weightUnbracedBracedP-valueUnbracedBracedP-value0-10%2.8 ± 0.93.2 ± 1.0*0.0070.55 ± 0.11*0.56 ± 0.12*N/A10-20%2.4 ± 0.82.6 ±0.8*0.0010.94± 0.11*0.94 ± 0.08*20-30%2.4 ± 0.82.6 ±0.7*0.0280.87 ± 0.09*0.92 ± 0.08*30-40%2.3± 0.72.6 ±0.6*0.0170.90 ± 0.08*0.91 ± 0.09*Overall2.5 ± 0.82.8 ±0.7*0.0040.81 ± 0.04*0.83 ± 0.04*0.15