Ankle Power Research Articles

Body Tempering and its Effect on Ankle Dorsiflexion and Power

Body Tempering and its Effect on Ankle Dorsiflexion and Power

Bilateral vs. Paretic-Limb-Only Ankle Exoskeleton Assistance for Improving Hemiparetic Gait: A Case Series.

People with lower-limb hemiparesis have impaired function on one side of the body that affects their walking ability. Wearable robotic assistance has been investigated to treat hemiparetic gait by applying assistance to the paretic limb. In this exploratory case series, we sought to compare the effects of bilateral vs. paretic-limb-only ankle exoskeleton assistance on walking performance in a case series of three heterogeneous presentations of lower-limb hemiparesis. A secondary goal was to validate the use of a real-time ankle-moment-adaptive exoskeleton control system for effectively assisting hemiparetic gait; the ankle moment controller accuracy ranged from 72 - 90% across all conditions and participants. Compared to walking without the device, both paretic-limb-only and bilateral assistance resulted in greater average total ankle power (up to 72%), improved treadmill walking efficiency (up to 28%), and increased over-ground walking distance (up to 41%). All participants achieved a more symmetrical, efficient gait pattern with bilateral assistance, indicating that assisting both limbs may be more beneficial than assisting only the paretic side in people with hemiparetic gait. The results of this case series are intended to inform future clinical studies and exoskeleton designs in a wide range of patient populations.

How does ankle power on the prosthetic side influence loading parameters on the sound side during level walking of persons with transfemoral amputation?

Background:Increased ankle power on the prosthetic side seems to decrease biomechanical loading parameters on the sound side. This assumption is based on biomechanical comparisons of different foot constructions. However, such study designs could not show whether the amount of ankle power solely influences the sound side.Objective:To analyze the influence of divergent ankle power, resulting from different foot constructions and from different ankle power settings, on the sound side loading parameters.Study design:Interventional cross sectional study.Methods:Level walking of transfemoral amputees with a microprocessor knee joint and Solid Ankle Cushioned Heel (SACH), energy storing and returning (ESR) and powered foot (PF) was analyzed. The PF was adapted in three configurations: without power (np), low power (lp), and optimal power (op). An optoelectronic camera system with 12 cameras and two force plates were used.Results:The ankle power on the prosthetic side shows significant differences about foot types and different settings of the PF. The knee adduction moment, the knee flexion moment, and the vertical ground reaction forces on the sound side were significantly reduced with PF_op and ESR in comparison to SACH. When analyzing these parameters for the different PF configurations, only some show significant results at normal velocity.Conclusions:The additional positive mechanical work for an active push off in the PF tends to have a relieving effect. The biomechanical sound side loading parameters are reduced with PF_op in comparison to SACH and ESR, resulting in a relief of the sound side of lower limb amputees.

The relationship between quantitative magnetic resonance imaging of the ankle plantar flexors, muscle function during walking and maximal strength in people with neuromuscular diseases

BackgroundProgression of plantar flexor weakness in neuromuscular diseases is usually monitored by muscle strength measurements, although they poorly relate to muscle function during walking. Pathophysiological changes such as intramuscular adipose tissue affect dynamic muscle function independent from isometric strength. Diffusion tensor imaging and T2 imaging are quantitative MRI measures reflecting muscular pathophysiological changes, and are therefore potential biomarkers to monitor plantar flexor functioning during walking in people with neuromuscular diseases. MethodsIn fourteen individuals with plantar flexor weakness diffusion tensor imaging and T2 scans of the plantar flexors were obtained, and the diffusion indices fractional anisotropy and mean diffusivity calculated. With a dynamometer, maximal isometric plantar flexor strength was measured. 3D gait analysis was used to assess maximal ankle moment and power during walking. FindingsFractional anisotropy, mean diffusivity and T2 relaxation time all moderately correlated with maximal plantar flexor strength (r > 0.512). Fractional anisotropy and mean diffusivity were not related with ankle moment or power (r < 0.288). T2 relaxation time was strongly related to ankle moment (r = −0.789) and ankle power (r = −0.798), and moderately related to maximal plantar flexor strength (r < 0.600). InterpretationIn conclusion, T2 relaxation time, indicative of multiple pathophysiological changes, was strongly related to plantar flexor function during walking, while fractional anisotropy and mean diffusivity, indicative of fiber size, only related to maximal plantar flexor strength. This indicates that these measures may be suitable to monitor muscle function and gain insights into the pathophysiological changes underlying a poor plantar flexor functioning during gait in people with neuromuscular diseases.

Surgical treatment of chronic Achilles tendon rupture results in improved gait biomechanics

BackgroundChronic Achilles tendon rupture is associated with persistent weakness at push-off with the affected foot and poor balance, resulting in significant alterations to normal gait. Surgical repair is the most common treatment for improving gait in patients with a Chronic Achilles tendon rupture, but, to date, the outcomes have not been quantified in the literature.MethodsA total of 23 patients with a Chronic Achilles tendon rupture (mean age 61 ± 15 years) underwent three-dimensional gait analysis according to a standardized protocol using an optical tracking system. Data of spatiotemporal, kinematic and kinetic variables were collected preoperatively and one year postoperatively. In addition, the postoperative gait biomechanics were compared with the gait biomechanics of a control group consisting of 70 healthy individuals (mean age 49 ± 20 years). The prospectively collected data were analyzed by an independent t test.ResultsPostoperatively, increments were found in gait speed (mean difference − 0.12 m/s), stride length (− 0.12 m), peak ankle moment (− 0.64 Nm/kg), peak ankle power (− 1.38 W/kg), peak knee power (− 0.36 m) and reduced step width (0.01 m), compared with preoperative gait biomechanics (p < 0.014). Compared with the control group, patients with a Chronic Achilles tendon rupture exhibited slower postoperative gait speed (mean difference 0.24 m/s), wider step width (− 0.02 m), shorter stride length (0.16 m), longer relative stance phase (− 2.15%), lower peak knee flexion (17.03 degrees), greater peak knee extension (2.58 degrees), lower peak ankle moment (0.35 Nm/kg), peak ankle power (1.22 W/kg) and peak knee power (1.62 W/kg), (p < 0.010).ConclusionSurgical intervention and postoperative rehabilitation can be an effective treatment for alterations in gait after a Chronic rupture of the Achilles tendon. However, at one year postoperatively, patients still exhibit impairments in spatiotemporal variables and knee and ankle power compared with healthy controls.

Influence of metatarsophalangeal joint stiffness on take-off performances and lower-limb biomechanics in jump manoeuvres

ABSTRACT Forefoot and toes are prominent regions for locomotion and individual metatarsophalangeal joint (MTPJ) stiffness may be linked to jump take-off mechanics and performances. However, little is known about the relationships between MTPJ stiffness and take-off related variables. This study examined the relationship between individual MTPJ stiffness and biomechanical variables under various vertical countermovement jumps (CMJ) conditions. We measured MTPJ stiffness on 21 male university basketball players and then asked them to perform jumps under single, consecutive and running CMJ conditions. Pearson’s correlation coefficient was employed to examine the relationships between MTP passive stiffness and each jumping performance, ground reaction force (GRF) and joint kinematic and kinetic variables. The results indicated that MTPJ stiffness significantly correlated with maximum jump height (r = 0.49, moderate), peak take-off velocity (r = 0.47, moderate), peak take-off ankle plantarflexion moment (r = 0.68, strong), peak dorsiflexion moment (r = 0.60, strong) and peak take-off ankle power (r = 0.44, moderate) in consecutive CMJ. Only a moderate correlation between MTPJ stiffness and peak MTPJ extension take-off velocity (r = −0.46, moderate) was determined in a single CMJ. There were no significant correlations found in running CMJ conditions. These findings imply that higher MTPJ stiffness of participants was related to improved jump performances in consecutive jumps.

Muscle-tendon properties and functional gait outcomes in clubfoot patients with and without a relapse compared to typically developing children

BackgroundAltered muscle-tendon properties in clubfoot patients could play a role in the occurrence of a relapse and negatively affect physical functioning. However, there is a lack of literature about muscle-tendon properties of clubfoot relapse patients. Research questionThe aim of this study was to determine whether the muscle architecture of the medial gastrocnemius and the morphology of the Achilles tendon differ between typically developing children (TDC) and clubfoot patients with and without a relapse clubfoot and to determine the relationships between morphological and functional gait outcomes. MethodsA cross-sectional study was carried out in clubfoot patients treated according to the Ponseti method and TDC aged 4–8 years. A division between clubfoot patients with and without a relapse was made. Fifteen clubfoot patients, 10 clubfoot relapse patients and 19 TDC were included in the study. Morphologic properties of the medial head of the Gastrocnemius muscle and Achilles tendon were assessed by ultrasonography. Functional gait outcomes were assessed using three-dimensional gait analysis. Mean group differences were analysed with ANOVA and non-parametric alternatives. Relationships between functional and morphologic parameters were determined for all clubfoot patients together and for TDC with Spearman’s rank correlation. ResultsMorphological and functional gait parameters did not differ between clubfoot patients with and without a relapse, with exception of lower maximal dorsiflexor moment in clubfoot relapse patients. Compared to TDC, clubfoot and relapse patients did show lower functional gait outcomes, as well as shorter and more pennate muscles with a longer Achilles tendon. In all clubfoot patients, this longer relative tendon was related to higher ankle power and plantarflexor moment. SignificanceIn clubfoot and relapse patients, abnormalities in morphology did not always relate to worse functional gait outcomes. Understanding these relationships in all clubfoot patients may improve the knowledge about clubfoot and aid future treatment planning.

Ankle plantar flexor muscle performance and patient reported outcomes in people following total ankle arthroplasty

BackgroundThe purpose of this study was to prospectively evaluate ankle power generation during gait in people with total ankle arthroplasty, and examine the relationships between postoperative plantar flexor strength, ankle power, and patient outcomes. MethodsNineteen people with end-stage ankle arthritis who received a total ankle arthroplasty and 19 healthy matched controls participated in this case-control study. Patient reported outcomes included a region specific measure of foot function and a generic measure of physical function. Gait speed was recorded with the 6-min walk test. Isokinetic plantar flexor strength was measured with an instrumented dynamometer. Motion capture and force plate data were used to calculate peak ankle power generation during walking. Paired or independent t-tests were used to compare ankle power across time and between groups, respectively. Bivariate correlations were performed to examine the interplay of postoperative strength, ankle power, gait speed, and patient reported outcomes. FindingsAnkle power was not different between the preoperative and 6-month postoperative time points (d = 0.20). Six-month postoperative ankle power was less than controls (d = 1.32). Strength, ankle power, and gait speed were directly correlated in the patient group 6-months postoperatively (r or ρ ≥ 0.47). Six-month postoperative strength and ankle power were directly correlated to select 2-year patient reported outcomes (both ρ = 0.54). InterpretationLower than normal 6-month postoperative ankle power, which was correlated to strength, gait speed, and longer-term patient reported outcomes, suggests efforts toward improving ankle plantar flexor muscle performance may improve patient outcomes.

Effects of Forefoot Shoe on Knee and Ankle Loading during Running in Male Recreational Runners

Objectives: Although overuse running injury risks for the ankle and knee are high, the effect of different shoe designs on Achilles tendon force (ATF) and Patellofemoral joint contact force (PTF) loading rates are unclear. Therefore, the primary objective of this study was to compare the ATF at the ankle and the PTF and Patellofemoral joint stress force (PP) at the knee using different running shoe designs (forefoot shoes vs. normal shoes). Methods: Fourteen healthy recreational male runners were recruited to run over a force plate under two shoe conditions (forefoot shoes vs. normal shoes). Sagittal plane ankle and knee kinematics and ground reaction forces were simultaneously recorded. Ankle joint mechanics (ankle joint angle, velocity, moment and power) and the ATF were calculated. Knee joint mechanics (knee joint angle velocity, moment and power) and the PTF and PP were also calculated. Results: No significant differences were observed in the PTF, ankle plantarflexion angle, ankle dorsiflexion power, peak vertical active force, contact time and PTF between the two shoe conditions. Compared to wearing normal shoes, wearing the forefoot shoes demonstrated that the ankle dorsiflexion angle, knee flexion velocity, ankle dorsiflexion moment extension, knee extension moment, knee extension power, knee flexion power and the peak patellofemoral contact stress were significantly reduced. However, the ankle dorsiflexion velocity, ankle plantarflexion velocity, ankle plantarflexion moment and Achilles tendons force increased significantly. Conclusions: These findings suggest that wearing forefoot shoes significantly decreases the patellofemoral joint stress by reducing the moment of knee extension, however the shoes increased the ankle plantarflexion moment and ATF force. The forefoot shoes effectively reduced the load on the patellofemoral joint during the stance phase of running. However, it is not recommended for new and novice runners and patients with Achilles tendon injuries to wear forefoot shoes.

Study on Lifting Up and Unloading Work Support with Ankle Foot Orthotics Using Carbon Fiber Composite Material

To prevent back pain during load lifting, assist suits have been developed to reduce physical load by assisting human motion. There are two methods of lifting heavy objects: the stoop method and the squat method. Assistive suits to facilitate the squat method, which reduces the burden on the lower back, have not yet been put to practical use. Therefore, there is a need to develop assistive suits that are lightweight and do not require power. In this study, we developed a short leg orthosis using a leaf spring made of carbon fiber reinforced plastic (CFRP), and conducted lifting and unloading experiments of heavy objects while wearing the orthosis. We then investigated the work support effects of wearing the orthosis based on measurements of lower limb joint power using a three-dimensional motion analysis system and surface electromyography measurements. The results showed that joint angles and power at the ankle and knee joints during lifting was reduced, and joint angles at the ankle and knee joints and power at the knee joint during unloading was reduced by using the orthosis. In both lifting up and unloading, muscle use of the rectus femoris and gastrocnemius muscles decreased, while spinal muscles showed an increasing trend. In addition, muscle synergy analysis revealed two muscle synergies in both lifting up and unloading, indicating that wearing the orthosis reduced lower limb strain during lifting up, and reduced lower back and lower limb strain during unloading and standing up.

Feasibility evaluation of a dual-mode ankle exoskeleton to assist and restore community ambulation in older adults.

Age-related deficits in plantar flexor muscle function during the push-off phase of walking likely contribute to the decline in mobility that affects many older adults. Isolated strengthening of the plantar flexor muscles has failed to improve push-off power or walking economy in this population. New mobility aids and/or functional training interventions may help slow or prevent ambulatory decline in the elderly. The overarching objective of this study was to explore the feasibility of using an untethered, dual-mode ankle exoskeleton for treating walking disability in the elderly; testing the device in assistance mode as a mobility aid to reduce energy consumption, and as a resistive gait training tool to facilitate functional recruitment of the plantar flexor muscles. We recruited 6 older adults between the ages of 68 to 83 years to evaluate the feasibility of the dual-mode exoskeleton across two visits. On the first visit, we quantified acute metabolic and neuromuscular adaption to ankle exoskeleton assistance during walking in older adults, and subsequently determined if higher baseline energy cost was related to an individual's potential to benefit from untethered assistance. On the second visit, we validated the potential for push-off phase ankle resistance combined with plantar pressure biofeedback to facilitate functional utilization of the ankle plantar flexors during walking. We also conducted a twelve-session ankle resistance training protocol with one pilot participant to explore the effects of gait training with wearable ankle resistance on mobility and plantar flexor strength. Participants reached the lowest net metabolic power, soleus variance ratio, and soleus iEMG at 6.6 ± 1.6, 19.8 ± 1.6, and 5.8 ± 4.9 minutes, respectively, during the 30-minute exoskeleton assistance adaptation trial. Four of five participants exhibited a reduction (up to 19%) in metabolic power during walking with assistance relative to baseline, but there was no group-level change. Participants who had greater baseline metabolic power exhibited a greater reduction during walking with assistance. Walking with resistance increased stance-phase soleus iEMG by 18 - 186% and stance-phase average positive ankle power by 9 - 88% compared to baseline. Following ankle resistance gait training, the participant exhibited a 5% increase in self-selected walking speed, a 15% increase in fast walking speed, a 36% increase in 6-min-walk-test distance, and a 31% increase in plantar flexor strength compared to pre-intervention measurements. Our results suggest that dual-mode ankle exoskeletons appear highly applicable to treating plantar flexor dysfunction in the elderly, with assistance holding potential as a mobility aid and resistance holding potential as a functional gait training tool. We used an untethered design to maximize the relevance of this for informing the design of intervention studies that may take place at home and in the community to improve mobility and quality of life in older adults. Future studies with larger sample sizes are recommended to expand on the results of this feasibility investigation.

The effects of ankle-foot orthoses with plantar flexion stop and plantar flexion resistance using rocker-sole shoes on stroke gait: A randomized-controlled trial.

Objectives This study aims to evaluate the effect of two ankle-foot orthoses (AFOs), AFO with plantar flexion stop (AFO-PlfS), and AFO with plantar flexion resistance (AFO-PlfR), while wearing standard shoes and rocker-sole shoes. Patients and methods Between November 2017 and July 2018, in this randomized-controlled study, a total of 20 stroke patients (8 males, 12 females; mean age: 48.1 years; range, 33 to 65 years) in chronic phase were randomized to AFO groups (AFO-PlfS group, n=10 and AFO-PlfR group, n=10). Each group received the allocated AFO along with two kinds of shoes (standard shoe and rocker shoe) for a two-week adaptation. Two effects were separately evaluated: The orthotic effect and rocker shoe effect were defined as the evaluation of using an AFO wearing standard shoe compared to only standard shoe, and evaluation of using an AFO wearing rocker shoe compared to an AFO wearing standard shoe, respectively. The gait of each group was measured by three-dimensional motion analysis. Results A significant orthotic effect was found in both AFO groups in spatiotemporal parameters and maximum ankle dorsiflexion in the single-support phase. Additionally, the AFO-PlfR group showed a significant improvement in the parameters related to the first rocker of gait, but not for AFO-PlfS group concerning the orthotic effect. The rocker shoe effect was found in significant reduction of peak ankle plantar flexor moment and power ankle generation during preswing for both AFO groups. Conclusion According to the orthotic effect, an AFO-PlfR can create better function in the improvement of parameters related to the first rocker. Although a rocker shoe can facilitate rollover for weight progression in the third rocker of gait, it cannot make a strong push-off function in stroke survivors.

BLDC 모터 및 유압식 브레이커 기반의 하이브리드 동력의지 개발

The purpose of this study was to develop a hybrid-powered prosthetic knee and ankle (power leg) using the brushless DC (BLDC) modules and hydraulic breakers of stance and swing phase control. The system comprised BLDC motors for the swing phase control unit and hydraulic cylinders for the stance phase control unit. An individual could walk using a low-power battery for a longer time than with a fully active or powered prosthetic leg. Moreover, the individual could walk by applying less kicking force. More stable lateral symmetry was exhibited than a prosthesis of stance phase control type. The gait algorithm is classified into five gait events using the inertial and load sensors: heel contact, heel rise, toe-off, swing flexion, and swing extension. We controlled the hydraulic breaker’s resistance force at each gait event and generated gait motion using the BLDC motors. The reliability of the system was evaluated by a transfemoral amputee subject. By comparing the gait character between the power leg and the stance phase control type prosthesis, we confirmed that the power leg improved the center of pressure (COP) of the lateral symmetry by about 71% from the center.

No effects of early functional mobilization on gait patterns after acute Achilles tendon rupture repair.

This study aimed to compare recovery of gait patterns in patients treated with early functional mobilization (EFM) or standard treatment (ST) after Achilles tendon rupture repair. Second, this study aimed to explore associations between gait patterns and tendon elongation and calf muscle atrophy, respectively. Forty-seven patients (12 females), mean age 38.7 (7.3) years, were included. Patients were postoperatively randomized to EFM (n = 29), including immediate weightbearing and ankle motion for 6 weeks, or ST (n = 18), with 2 weeks of unloading in a plaster cast followed by 4 weeks of weightbearing in an orthosis. Three-dimensional gait analyses were performed at 8 weeks and 6 months postoperatively to evaluate ankle and knee kinematics and kinetics. Ultrasound imaging was performed to assess tendon length and calf muscle atrophy. At 8 weeks, there were no significant group differences in ankle and knee kinematics and kinetics, while side-to-side differences between injured and uninjured side were present within both groups. At 6 months, the ST group exhibited higher generating ankle power and greater peak moments in ankle and knee compared to the EFM group. In both groups, peak ankle dorsiflexion angle was greater on the injured side compared to the uninjured side. No correlations were found between ankle joint gait deviations and degree of tendon elongation or muscle atrophy. Clinical significance: The accelerated rehabilitation regimen with EFM did not result in a more symmetrical gait pattern. The gait pattern deviations in the ankle joint were not related to the degree of muscle atrophy or tendon elongation.

Effect of Obesity on Knee and Ankle Biomechanics during Walking.

The purpose of this retrospective study was to quantify the three-dimensional knee and ankle joint kinematics and kinetics during walking in young participants with different degrees of obesity and to identify the associated effects by stratifying the obese participants according to their BMI. Thirty-two young obese individuals (mean age 30.32 years) and 16 normal-weight age-matched individuals were tested using 3D gait analysis. Analysis of kinematic and kinetic data revealed significant differences in mechanics at knee and ankle joints in all the evaluated planes of movement. Compared to the healthy-weight participants, obese adults demonstrated less knee flexion, greater knee ab-adduction angle during the entire gait cycle and abnormalities at the knee flex-extension moment. At the ankle joint, reduced range of motion was observed together with a lower peak of ankle plantarflexor moment and power during terminal stance. These results provide insight into a potential pathway by which obesity predisposes a healthy adult for increased risk of osteoarthritis.

Preoperative Gait Analysis of Peroneal Tendon Tears.

Little is known regarding the impact of peroneal tendon tears on function. This study quantifies gait changes associated with operatively-confirmed peroneal tendon tears. Sixty-five patients with unilateral peroneal tendon tears were prospectively evaluated using preoperative 3D multisegment gait analysis of both limbs. Data were analyzed according to pattern/severity of tears, as confirmed surgically: peroneus brevis tears, reparable (PBR); peroneus brevis tears, irreparable (PBI); peroneus longus tears, irreparable (PLI); and concomitant irreparable tears of both tendons (PBI+PLI). The following parameters were analyzed: ankle sagittal motion, coronal motion, axial rotation, foot progression angle, sagittal power, sagittal moment. Twelve patients (18.5%) had the PBR pattern, 37 (56.9%) PBI, 10 (15.4%) PLI, and 6 (9.2%) PBI+PLI. Compared with the contralateral, nonpathologic extremities, limbs with peroneal tears had diminished ankle sagittal motion (mean 23.14 vs 24.30 degrees, P = .012), ankle/hindfoot axial rotation (6.26 vs 7.23 degrees, P = .001), sagittal moment (1.16 vs 1.29 Nm/kg, P < .001), and sagittal power (1.24 vs 1.47 W/kg, P < .001). The most severe tear patterns had the greatest derangements in multiple parameters of gait (PBI+PLI > PBI or PLI > PBR). For example, all groups except PBR had loss of ankle sagittal moment and/or power in the affected limb, and the greatest losses in moment and power were in the PBI+PLI group (1.22 vs 0.91 Nm/kg, P = .003 for moment; 0.73 vs 1.31 W/kg, P < .001 for power). The PBI+PLI group had a >10-degree varus shift in coronal motion on the affected side (P = .002). This is the first study to demonstrate diminished biomechanical function in patients with peroneal tendon tears. In vivo 3-dimensional gait analysis found significant changes in hindfoot motion, ankle motion, and ankle power. Impairments were related to the pattern and severity of the tears, and demonstrated a strong association of peroneal tendon tears with diminished ankle plantarflexion strength. Level III, retrospective cohort study.

Effects of Longitudinal Bending Stiffness of forefoot rocker profile shoes on ankle kinematics and kinetics.

Rocker profile shoes with a proximally placed apex are currently one of the most prescribed shoe modifications for treatment and prevention of lower leg deficits. Three geometrical rocker design parameters apex position (AP), apex angle (AA) and rocker radius (RR) influence both plantar pressure redistribution and kinetic and kinematic alterations of the lower leg. In addition, longitudinal bending stiffness (LBS) of the outsole influences these parameters as well. This study aims to investigate the effects of the LBS in combination with different forefoot radii of rocker shoes on kinematics and kinetics of the lower limb. 10 participants walked in standard shoes and six experimental shoe conditions with high and low LBS and three different forefoot rocker radii with the same (proximal) AP and AA. Lower extremity kinematics and kinetics were collected while walking on an instrumented treadmill at preferred walking speed and analysed with a repeated measures ANOVA and Statistical Parametric Mapping (SPM) (α = .05; post hoc α = .05/6). SPM analyses revealed no significant differences for LBS and interaction LBS*RR for most research variables in terminal stance (ankle angle, ankle moment, ankle power, foot-to-horizontal angle, shank-to-vertical angle, external ankle moment, ground reaction force angle). A significant LBS effect was found for anterior-posterior position of the centre of pressure during pre-swing and peak ankle dorsiflexion angle. No relevant significant differences were found in spatio-temporal parameters and total work at the ankle between low and high LBS. This study showed that longitudinal bending stiffness does not affect the biomechanical working mechanism of rocker profile shoes as long as toe plantarflexion is restricted. Providing that the forefoot rocker radius supports at least a normal foot-to-horizontal angle at toe-off, there is no reason to increase sole stiffness to change ankle kinematics and kinetics.

Effects of Fatigue Running on Joint Mechanics in Female Runners: A Prediction Study Based on a Partial Least Squares Algorithm

Background: Joint mechanics are permanently changed using different intensities and running durations. These variations in intensity and duration also influence fatigue during prolonged running. Little is known about the potential interactions between fatigue and joint mechanics in female recreational runners. Thus, the purpose of this study was to describe and examine kinematic and joint mechanical parameters when female recreational runners are subject to fatigue as a result of running. Method: Fifty female recreational runners maintained running on a treadmill to induce fatigue conditions. Joint mechanics, sagittal joint angle, moment, and power were recorded pre- and immediately post fatigue treadmill running. Result: Moderate reductions in absolute positive ankle power, total ankle energy dissipation, dorsiflexion at initial contact, max dorsiflexion angle, and range of motion of the joint ankle were collected after fatigue following prolonged fatigue running. Knee joint mechanics, joint angle, and joint power remained unchanged after prolonged fatigue running. Nevertheless, with the decreased ankle joint work, negative knee power increased. At the hip joint, the extension angle was significantly decreased. The range motion of the hip joint, hip positive work and hip positive power were increased during the post-prolonged fatigue running. Conclusion: This study found no proximal shift in knee joint mechanics in amateur female runners following prolonged fatigue running. The joint work redistribution was associated with running fatigue changes. As for long-distance running, runners should include muscle strength training to avoid the occurrence of running-related injuries.

The influence of step-down technique on lower extremity mechanics during curb descent

When stepping down from a curb, individuals typically make initial ground contact with either their rearfoot or forefoot. The purpose of this study was to compare vertical ground reaction forces, lower extremity mechanics, and intra-limb work distribution when individuals adopt a rearfoot technique vs. a forefoot technique, during simulated curb descent. Sixteen subjects stepped down from a platform with both a rearfoot and a forefoot technique. Vertical ground reaction forces and sagittal plane joint kinematics and kinetics were examined for the lead limb during the step-down task. Paired t-tests were used for comparison. Subjects demonstrated greater ankle joint power and negative work, and less hip joint power and negative work, with the forefoot technique vs. the rearfoot technique. Total lower extremity negative work was greater for the forefoot technique vs. the rearfoot technique. The percent contribution to the total negative work was greater for the ankle joint, and less for the hip and knee joints, with the forefoot technique vs. the rearfoot technique. The results of this study may provide insight into how curb descent technique can be modified to alter lower extremity loading.

Foot and ankle biomechanics during walking in older adults: A systematic review and meta-analysis of observational studies.

The foot and ankle complex undergoes significant structural and functional changes with advancing age. The objective of this systematic review and meta-analysis was to synthesize and critique the research literature pertaining to foot and ankle biomechanics while walking in young and older adults. Electronic databases (Web of Science, PubMed, Scopus and Embase) were searched from inception to April 2019 for cross-sectional studies which compared kinematics, kinetics and plantar pressure differences between young and older adults. Screening and data extraction were performed by two independent assessors, with disagreements resolved by consensus. A total of 39 articles underwent full-text screening, and 19 articles met the inclusion criteria and were included. Meta-analysis showed that older adults had less ankle joint plantar flexion (5 studies; weighted mean difference [WMD]: -5.15; 95 %CI: -6.47 to -3.83; P < 0.001) and less ankle joint power generation (6 studies; standardized mean difference [SMD]: -0.62; 95 %CI: -0.82 to -0.41; P < 0.001) during propulsion compared to young adults. These differences persisted in subgroup analyses comparing different walking speeds. Plantar pressure findings were highly variable due to differences in data collection protocols and meta-analysis was not possible. Older adults have unique foot and ankle kinematics and kinetics during walking characterized by reduced ankle joint plantarflexion and power generation during propulsion.