Ankle Moment Research Articles

Comparison of lower limb stiffness between male and female dancers and athletes during drop jump landings.

Repetition of jumps in dance and sport training poses a potential injury risk; however, non-contact landing injuries are more common in athletes than dancers. This study aimed to compare the lower limb stiffness characteristics of dancers and athletes during drop landings to investigate possible mechanisms of impact-related injuries. Kinematics and kinetics were recorded as 39 elite modern and ballet dancers (19 men and 20 women) and 40 college-level team sport athletes (20 men and 20 women) performed single-legged drop landings from a 30-cm platform. Vertical leg stiffness and joint stiffness of the hip, knee, and ankle were calculated using a spring-mass model. Stiffness data, joint kinematics, and moments were compared with a group-by-sex 2-way analysis of variance. Multiple linear regression was used to assess the relative contribution of hip and knee and ankle joint stiffness to variance in overall vertical leg stiffness for dancers and athletes. Dancers had lower leg (P<0.001), knee joint (P=0.034), and ankle joint stiffness (P=0.043) than athletes. This was facilitated by lower knee joint moments (P=0.012) and greater knee (P=0.029) and ankle joint (P=0.048) range of motion in dancers. Males had higher leg (P<0.001) and ankle joint stiffness (P<0.001) than females. This occurred through lower ankle range of motion (P<0.001) and greater ankle moment (P=0.022) compared to females. Male and female dancers demonstrated reduced lower limb stiffness compared to athletes, indicating a more pliable landing technique. Dance training techniques could potentially inform approaches to injury prevention in athletes.

Asymmetries in Gait and Balance Control After Ankle Arthrodesis

Previous gait analysis studies of patients with an ankle arthrodesis have reported increased motion in the adjacent joints. However, of similar importance are the forces that act on the ipsi- and contralateral joints and the effect of ankle arthrodesis with regard to balance control. The purpose of the present study was to determine the joint moments and the amount of asymmetrical loading of the ankle and joints adjacent to the ankle in patients after successful ankle arthrodesis. Therefore, 8 patients with a painless ankle fusion were included and assessed using 4 functional tests: preferred and fast speed walking, a sit-to-stand test, and a balance test. The ground reaction force and ankle joint moment were smaller in the fused ankle. During the balance on foam test, the velocity of the center of pressure was significantly larger on the contralateral extremity. In conclusion, ankle arthrodesis leads to small asymmetries in joint moments during gait, indicating greater loading of the contralateral ankle. In addition, the unaffected leg compensates for the operated leg in balance control. Because of the small alterations, overuse of the contralateral ankle is not expected after ankle arthrodesis.

The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments.

BackgroundNormative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects.MethodsA total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW).ResultsHindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW.DiscussionLimited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.

Ankle moment measurement in biomechanics

Biomechanical movement analysis is based on a set of kinematic measurements, generally obtained through video recordings, and kinetic measurements usually through a force platform. In order to obtain more detailed information for example as regards internal joint forces and moments, a biomechanical model is required. Model inputs are kinematic and kinetic measurement data, while internal forces and moments are its outputs. Particularly interesting when dealing with lower limbs models for describing for example walking, jumping or lifting on tiptoes, is the ankle moment. Usually ankle is the first joint in the model and external forces act on it producing moments that foot and ankle have to withstand with muscles acting on it. The measurement of such moment is critical due to several factors primarily the unknown position of centre of rotation for the foot. Several methods are available to indirectly measure ankle moment, we propose here a comparison of different measurement approaches considering their results for different gestures, commenting pros and cons and giving some practical indications.

The Functional Utilization of Propulsive Capacity During Human Walking.

Aging and many gait pathologies are characterized by reduced propulsive forces and ankle moment and power generation during trailing leg push-off in walking. Despite those changes, we posit that many individuals retain an underutilized reserve for enhancing push-off intensity during walking that may be missed using conventional dynamometry. By using a maximum ramped impeding force protocol and maximum speed walking, we gained mechanistic insight into the factors that govern push-off intensity and the available capacity thereof during walking in young subjects. We discovered in part that young subjects walking at their preferred speed retain a reserve capacity for exerting larger propulsive forces of 49%, peak ankle power of 43%, and peak ankle moment of 22% during push-off-the latter overlooked by maximum isometric dynamometry. We also provide evidence that these reserve capacities are governed at least in part by the neuromechanical behavior of the plantarflexor muscles, at least with regard to ankle moment generation. We envision that a similar paradigm used to quantify propulsive reserves in older adults or people with gait pathology would empower the more discriminate and personalized prescription of gait interventions seeking to improve push-off intensity and thus walking performance.

A Pilot Study of Iyengar Yoga for Pediatric Obesity: Effects on Gait and Emotional Functioning.

Obesity negatively impacts the kinematics and kinetics of the lower extremities in children and adolescents. Although yoga has the potential to provide several distinct benefits for children with obesity, this is the first study to examine the benefits of yoga for gait (primary outcome) in youths with obesity. Secondary outcomes included health-related quality of life (HRQoL), physical activity, and pain. Feasibility and acceptability were also assessed. Nine youths (11–17 years) participated in an eight-week Iyengar yoga intervention (bi-weekly 1-h classes). Gait, HRQOL (self and parent-proxy reports), and physical activity were assessed at baseline and post-yoga. Pain was self-reported at the beginning of each class. Significant improvements were found in multiple gait parameters, including hip, knee, and ankle motion and moments. Self-reported and parent-proxy reports of emotional functioning significantly improved. Time spent in physical activity and weight did not change. This study demonstrates that a relatively brief, non-invasive Iyengar yoga intervention can result in improved malalignment of the lower extremities during ambulation, as well as in clinically meaningful improvements in emotional functioning. This study extends current evidence that supports a role for yoga in pediatric obesity.

Relationship between the medial longitudinal arch, foot dorsiflexion range of motion, and dynamic gait parameters

When an evaluation focuses on movement, there is little chance of error by oversight, even by an inexperienced therapist. This study aimed to clarify relationship between the medial longitudinal arch (MLA), foot dorsiflexion range of motion (DF), and the dynamic gait parameters. This study evaluated 20 participants (16 males, 4 females; mean age 21.2 ± 0.4 years). MLA was measured using the navicular drop test (ND) developed by Brody. DF was measured with the knee in extension. Dynamic data were collected with a 9-camera, motion capture system with 3 force plates. The participants performed barefoot gait five times. The gait parameters were navicular height, DF, dynamic navicular drop, ankle moment peak value in stance phase (AMP), and maximum dorsiflexion range of motion, with the ankle moment value and DF measured at 12%, 31%, and 50% of the gait cycle, respectively. These gait parameters were compared using coefficients of correlation for ND and DF. For statistical analysis, we used Pearson's correlation coefficient using the IBM SPSS statistical software (version 21), and P < 0.05 was considered as significant. This study was approved by the Ethics Committees for Human Research of Gunma Paz University. ND did not show a relationship with any gait parameters. However, DF showed a negative correlation with ankle moment at 50% ( P = 0.003, r = −0.623) and AMP ( P = 0.008, r = −0.574) These findings show that DF is more important than ND in gait assessment. In the terminal stance, when DF is limited, the ankle moment shows a higher value. When DF is larger, this is reversed. Eccentric contraction using stretch-reflection was observed in the terminal stance phase. In our opinion, a reflective factor strongly influences gait movement. Thus, evaluation of DF before gait assessment is essential.

Effects of virtual reality with robot training on the gait of subacute stroke patients

Ambulation is always one of the most significant issues for post-stroke patients as well as a formidable challenge. There was few study, to our best knowledge, focusing on the kinetic and kinematic changes resulting from training using robotic devices with virtual reality (VR) for subacute stroke patients. Thus, we analyzed the gait parameters of these patients at 1week and 3 weeks after they suffered the disease. Twenty patients were included in this single blind randomized control study. Patients were randomized to either a VR with robot group ( n = 10) or non-VR group ( n = 10). The training was performed on a robotic gait-training system with situational interaction. Subjects in VR group were trained 5 times a week for two weeks for approximately 30 minutes every time. Others were trained by traditional therapies. After the two-week training, the step time of patients in VR group significantly decreased (from 0.88 ± 0.29 to 0.77 ± 0.16), while the stride length average (from 0.72 ± 0.26 to 0.81 ± 0.25), step length average (from 0.36 ± 0.12 to 0.42 ± 0.10) and walking speed average (from 0.49 ± 0.25 to 0.59 ± 0.23) significantly increased ( P < 0.05). Subjects in VR group demonstrated an obviously larger improvement in the maximum hip moment and minimum ankle moment ( P = 0.028 and P = 0.040, respectively) compared with those in non-VR group. VR training with robot system could also be applied, as traditional therapy, in rehabilitation process of subacute stroke patients, especially in the improvement of step length and walking speed.

Aging effects on the Achilles tendon moment arm during walking

The Achilles tendon (AT) moment arm transforms triceps surae muscle forces into a moment about the ankle which is critical for functional activities like walking. Moreover, the AT moment arm changes continuously during walking, as it depends on both ankle joint rotation and triceps surae muscle loading (presumably due to bulging of the muscle belly). Here, we posit that aging negatively effects the architecturally complex AT moment arm during walking, which thereby contributes to well-documented reductions in ankle moment generation during push-off. We used motion capture-guided ultrasound imaging to quantify instantaneous variations in the AT moment arms of young (23.9 ± 4.3 years) and older (69.9 ± 2.6 years) adults during walking, their dependence on triceps surae muscle loading, and their association with ankle moment generation during push-off. Older adults walked with 11% smaller AT moment arms and 11% smaller peak ankle moments during push-off than young adults. Moreover, as hypothesized, these unfavourable changes were significantly and positively correlated (r2 = 0.38, p < 0.01). More surprisingly, aging attenuated load-dependent increases in the AT moment arm (i.e., those between heel-strike and push-off at the same ankle angle); only young adults exhibited a significant increase in their AT moment arm due to triceps surae muscle-loading. Age-associated reductions in triceps surae volume or activation, and thus muscle bulging during force generation, may compromise the mechanical advantage of the AT during the critical push-off phase of walking in older adults. Thus, strategies to restore and/or improve locomotor performance in our aging population should consider these functionally important changes in musculoskeletal behavior.

Benefits of an increased prosthetic ankle range of motion for individuals with a trans-tibial amputation walking with a new prosthetic foot

BackgroundIndividuals with trans-tibial amputation show a greater peak prosthetic ankle power (push- off) when using energy storing and returning (ESAR) prosthetic feet as compared to solid-ankle cushion-heel feet. ESAR feet further contribute to the users’ body support and thus limit prosthetic ankle motion. To improve ankle motion, articulating prosthetic feet have been introduced. However, articulating feet may diminish push-off. Research questionDoes a novel prosthetic foot, with a serial layout of carbon fibre leaf springs, connected by a multi-centre joint construction, have advantages in kinematics and kinetics over a conventional ESAR prosthetic foot?> MethodsEleven individuals with unilateral trans-tibial amputation were fitted with the novel foot (NF) and a conventional ESAR Foot (CF) and underwent 3D gait analysis. As an additional power estimate of the prosthetic ankle, a unified, deformable, segment model approach was applied. Eleven matched individuals without impairments served as a reference. ResultsThe NF shows an effective prosthetic ankle range of motion that is closer to a physiologic ankle range of motion, at 31.6° as compared to 15.2° with CF (CF vs. NF p = 0.003/NF vs. Reference p = 0.171) without reducing the maximum prosthetic ankle joint moment. Furthermore, the NF showed a great increase in prosthetic ankle power (NF 2.89 W/kg vs. CF 1.48 W/kg CF vs. NF p = <0.001) and a reduction of 19% in the peak knee varus moment and 13% in vertical ground reaction forces on the sound side for NF in comparison to CF. SignificanceThe NF shows that serial carbon fibre leaf springs, connected by a multi-centre joint construction gives a larger ankle joint range of motion and higher ankle power than a conventional carbon fibre structure alone. Consequently load is taken off the contralateral limb, as measured by the decrease in vertical ground reaction forces and peak knee varus moment.

Kinetic Asymmetry during Running at Preferred and Nonpreferred Speeds.

The aim of this study was to investigate the effect of altering preferred running speed by ±20% on kinetic asymmetry. Three-dimensional motion analysis and force data were acquired from 15 healthy males (age, 27 ± 4.6 yr; height, 1.81 ± 0.09 m; mass, 80.4 ± 12.4 kg) during their preferred running speed and at ±20% of this speed. Three-tesla magnetic resonance images were used to measure Achilles tendon cross-sectional area and moment arm, for use in calculation of tendon stress. Kinetic and tendon stress asymmetry were subsequently calculated in each condition using the symmetry index. Across all joints and conditions, the average asymmetry of peak moments was between ±6%, but higher individual values were observed. There was no effect of speed on the magnitude of asymmetry. Ground contact times, vertical ground reaction forces, and support and ankle moments (maximum absolute asymmetry, 9%) were more symmetrical than hip and knee moments (up to 18%). Individual joint contribution to support moment and positive work were similar in both limbs, and ankle and hip compensatory interactions were observed with alterations in running speed. Achilles tendon stress increased with increased running speed, with higher stress in the preferred limb; asymmetry in tendon stress was not related to asymmetry in vertical ground reaction forces. Results show small effects of altering running speed on kinetic asymmetry, but responses are individual specific with interactions occurring between joints to maintain overall movement symmetry. Further research is needed to understand the mechanical and neuromuscular mechanisms underpinning these compensations.

Control of human gait stability through foot placement.

During human walking, the centre of mass (CoM) is outside the base of support for most of the time, which poses a challenge to stabilizing the gait pattern. Nevertheless, most of us are able to walk without substantial problems. In this review, we aim to provide an integrative overview of how humans cope with an underactuated gait pattern. A central idea that emerges from the literature is that foot placement is crucial in maintaining a stable gait pattern. In this review, we explore this idea; we first describe mechanical models and concepts that have been used to predict how foot placement can be used to control gait stability. These concepts, such as for instance the extrapolated CoM concept, the foot placement estimator concept and the capture point concept, provide explicit predictions on where to place the foot relative to the body at each step, such that gait is stabilized. Next, we describe empirical findings on foot placement during human gait in unperturbed and perturbed conditions. We conclude that humans show behaviour that is largely in accordance with the aforementioned concepts, with foot placement being actively coordinated to body CoM kinematics during the preceding step. In this section, we also address the requirements for such control in terms of the sensory information and the motor strategies that can implement such control, as well as the parts of the central nervous system that may be involved. We show that visual, vestibular and proprioceptive information contribute to estimation of the state of the CoM. Foot placement is adjusted to variations in CoM state mainly by modulation of hip abductor muscle activity during the swing phase of gait, and this process appears to be under spinal and supraspinal, including cortical, control. We conclude with a description of how control of foot placement can be impaired in humans, using ageing as a primary example and with some reference to pathology, and we address alternative strategies available to stabilize gait, which include modulation of ankle moments in the stance leg and changes in body angular momentum, such as rapid trunk tilts. Finally, for future research, we believe that especially the integration of consideration of environmental constraints on foot placement with balance control deserves attention.

Differences in lower limb biomechanics between ballet dancers and non-dancers during functional landing tasks

ObjectivesTo determine the differences in the lower limb landing biomechanics of adolescent ballet dancers compared to non-dancers when performing a hop and a stop jump task. DesignCross-sectional. SettingLaboratory. ParticipantsThirteen adolescent female ballet dancers (11.8 ± 1.1 years) and 17 non-dancers (10.9 ± 0.8 years) performed hop and stop jump tasks. Main outcome measuresVertical ground reaction force, and three-dimensional ankle, knee and hip joint angles and moments during the landing phase. ResultsDancers displayed greater sagittal plane joint excursions during the hop and stop jump at the ankle (mean difference = 22.0°, P < 0.001, 14.8°, P < 0.001 respectively), knee (mean difference = 18.1°, P = 0.001, 9.8°, P = 0.002 respectively) and hip (stop jump task; mean difference = 8.3°, P = 0.008). Dancers displayed a larger hip extensor moment compared to non-dancers (P < 0.001) during the stop jump task only. Dancers also took longer to reach peak vGRF and jumped three times higher than non-dancers (P < 0.001) during the stop jump task. No difference in peak vGRF between groups was displayed for either task. ConclusionsAdolescent dancers demonstrate a transfer of landing technique to non-ballet specific tasks, reflective of the greater jump height and sagittal plane joint excursions. This landing strategy may be associated with the low rate of non-contact ACL injuries in female dancers.

Ankle joint function during walking in tophaceous gout: A biomechanical gait analysis study

BackgroundThe foot and ankle are frequently affected in tophaceous gout, yet kinematic and kinetic changes in this region during gait are unknown. The aim of the study was to evaluate ankle biomechanical characteristics in people with tophaceous gout using three-dimensional gait analysis. MethodsTwenty-four participants with tophaceous gout were compared with 24 age-and sex-matched control participants. A 9-camera motion analysis system and two floor-mounted force plates were used to calculate kinematic and kinetic parameters. ResultsPeak ankle joint angular velocity was significantly decreased in participants with gout (P < 0.01). No differences were found for ankle ROM in either the sagittal (P = 0.43) or frontal planes (P = 0.08). No differences were observed between groups for peak ankle joint power (P = 0.41), peak ankle joint force (P = 0.25), peak ankle joint moment (P = 0.16), timing for peak ankle joint force (P = 0.81), or timing for peak ankle joint moment (P = 0.16). ConclusionsThree dimensional gait analysis demonstrated that ankle joint function does not change in people with gout. People with gout demonstrated a reduced peak ankle joint angular velocity which may reflect gait-limiting factors and adaptations from the high levels of foot pain, impairment and disability experienced by this population.

Case Study: A Bio-Inspired Control Algorithm for a Robotic Foot-Ankle Prosthesis Provides Adaptive Control of Level Walking and Stair Ascent.

Powered ankle-foot prostheses assist users through plantarflexion during stance and dorsiflexion during swing. Provision of motor power permits faster preferred walking speeds than passive devices, but use of active motor power raises the issue of control. While several commercially available algorithms provide torque control for many intended activities and variations of terrain, control approaches typically exhibit no inherent adaptation. In contrast, muscles adapt instantaneously to changes in load without sensory feedback due to the intrinsic property that their stiffness changes with length and velocity. We previously developed a “winding filament” hypothesis (WFH) for muscle contraction that accounts for intrinsic muscle properties by incorporating the giant titin protein. The goals of this study were to develop a WFH-based control algorithm for a powered prosthesis and to test its robustness during level walking and stair ascent in a case study of two subjects with 4–5 years of experience using a powered prosthesis. In the WFH algorithm, ankle moments produced by virtual muscles are calculated based on muscle length and activation. Net ankle moment determines the current applied to the motor. Using this algorithm implemented in a BiOM T2 prosthesis, we tested subjects during level walking and stair ascent. During level walking at variable speeds, the WFH algorithm produced plantarflexion angles (range = −8 to −19°) and ankle moments (range = 1 to 1.5 Nm/kg) similar to those produced by the BiOM T2 stock controller and to people with no amputation. During stair ascent, the WFH algorithm produced plantarflexion angles (range −15 to −19°) that were similar to persons with no amputation and were ~5 times larger on average at 80 steps/min than those produced by the stock controller. This case study provides proof-of-concept that, by emulating muscle properties, the WFH algorithm provides robust, adaptive control of level walking at variable speed and stair ascent with minimal sensing and no change in parameters.

Patients with sacroiliac joint dysfunction exhibit altered movement strategies when performing a sit-to-stand task

Summary of Background DataThe ability to rise from a chair is a basic functional task that is frequently compromised in individuals diagnosed with orthopedic disorders in the low back and hip. There is no published literature that describes how this task is altered by sacroiliac joint dysfunction (SIJD). PurposeThe objective of this study was to compare lower extremity biomechanics and the onset of muscle activity when rising from a chair in subjects with SIJD and in healthy persons. Study DesignSix women with unilateral SIJD and six age-matched healthy controls performed a sit-to-stand task while we measured kinematics, kinetics, and muscle activity. Materials and MethodsSubjects stood up at a preferred speed from a seated position on an armless and backless adjustable stool. We measured kinematics with a 10-camera motion capture system, ground reaction forces for each leg with force plates, and muscle activity with surface electromyography. Joint angles and torques were calculated using inverse dynamics. Leg-loading rate was quantified as the average slope of vertical ground reaction (VGRF) force during the 500-millisecond interval preceding maximal knee extension. ResultsBetween-leg differences in loading rates and peak VGRFs were significantly greater for the SIJD group than for the control group. Maximal hip angles were significantly less for the SIJD group (p=.001). Peak hip moment in the SIJD group was significantly greater in the unaffected leg (0.75±0.22 N⋅m/kg) than in the affected leg (0.47±0.29 N⋅m/kg, p=.005). There were no between-leg or between-group differences for peak knee or ankle moments. The onset of activity in the latissimus dorsi muscle on the affected side was delayed and the erector spinae muscles were activated earlier in the SIJD group than in the control group. ConclusionsSubjects with SIJD have a greater VGRF on the unaffected leg, generate a greater peak hip moment in the unaffected leg, use a smaller range of motion at the hip joint of the affected leg, and delay the onset of a key muscle on the affected side when rising from a seated position.

Dynamic Functional Stiffness Index of the Ankle Joint During Daily Living

Exploring ankle joint physiologic functional stiffness is crucial for improving the design of prosthetic feet that aim to mimic normal gait. We hypothesized that ankle joint stiffness would vary among the different activities of daily living and that the magnitude of the stiffness would indicate the degree of energy storage element sufficiency in terms of harvesting and returning energy. We examined sagittal plane ankle moment versus flexion angle curves from 12 healthy subjects during the daily activities. The slopes of these curves were assessed to find the calculated stiffness during the peak energy return and harvest phases. For the energy return and harvest phases, stiffness varied from 0.016 to 0.283 Nm/kg° and 0.025 and 0.858 Nm/kg°, respectively. The optimum stiffness during the energy return phase was 0.111 ± 0.117 Nm/kg° and during the energy harvest phase was 0.234 ± 0.327 Nm/kg°. Ankle joint stiffness varied significantly during the activities of daily living, indicating that an energy storage unit with a constant stiffness would not be sufficient in providing energy regenerative gait during all activities. The present study was directed toward the development of a complete data set to determine the torque-angle properties of the ankle joint to facilitate a better design process.

Multi-plane, multi-joint lower extremity support moments during a rapid deceleration task: Implications for knee loading

The principle of lower limb support, and the contribution of hip, knee and ankle moments to an overall limb support strategy for an impact-like, rapid deceleration movement may help explain individual moment magnitude changes, thereby providing insight into how injury might occur or be avoided. Twenty subjects performed single limb, impact-like, deceleration landings at three different knee flexion angles in the range of 0–25, 25–50 and 50–75°. Kinematic and kinetic measures identified hip, knee and ankle moment contribution to limb support moments (LSMs) in three planes. Repeated measures ANOVA compared LSMs and the contribution of individual joint moments at initial contact (IC) and 50 ms after. There were no significant differences in the overall LSMs at IC in any plane when the deeper knee flexion landings (25–50° and 50–75°) were compared to the 0–25° landing position but there were significant changes in the 50 ms period after IC. There were greater overall extensor LSMs, less resistance to medial opening of the knee and decreased support against internal tibia rotation when landing in greater knee flexion. The role of individual joint moments changed rapidly in the 50 ms period after initial landing; and, the relative contribution of the hip and ankle moments depended on the degree of limb flexion at landing. Analyses of individual joint moments emphasized the critical role that the hip joint moments have in balancing potentially injurious knee moments in all three planes for all three landing conditions.

Effects of bilateral swing-away grab bars on the biomechanics of stand-to-sit and sit-to-stand toilet transfers

Purpose: Kinetic characteristics of transfers to and from a toilet performed using bilateral grab bars are not fully quantified to inform grab bar design and configuration. The purpose of this study was to (1) determine effects of bilateral swing-away grab bars on peaks of ankle, knee and hip joint moments during grab bar assisted stand-to-sit and sit-to-stand transfers; and (2) determine effects of three different heights and widths of swing-away grab bars on the same kinetic characteristics.Methods: Healthy subjects (N = 11, age 25–58 years) performed stand-to-sit and sit-to-stand transfers with and without grab bars. In transfers with grab bars, 9 grab bar configurations were tested by varying their height from the floor (0.787 m, 0.813 m, 0.838 m; 31″–33″) and width, the distance of each grab bar from the toilet’s centerline (0.330 m, 0.356 m, 0.381 m; 13″–15″). Motion capture, force plate and inverse dynamics analysis were used to determine lower limb joint moments.Results: The use of bilateral grab bars generally reduced the peak magnitude of extension moments at lower limb joints during stand-to-sit and sit-to-stand transfers (p < .05), except the ankle joint moments during stand-to-sit transfers. Relatively few differences in peak joint moments were found between studied grab bar widths or heights.Conclusion: The obtained results suggest that the studied ranges of grab bar configurations reduce moment demands on the leg joints and thus decrease difficulty and required lower limb muscle effort to perform the transfers.Implications for RehabilitationMaximizing the benefits of assistive technology in the built environment requires a careful assessment of their spatial and configurational dimensions, especially in respect to the needs and abilities of the intended users.Examining the kinetic characteristics of transfers to and from a toilet using the swing-away grab bars is useful for informing grab bar design and configuration recommendations for assisted living and skilled nursing facilities.Our findings suggest that the swing-away grab bars located at certain ranges are a reasonable alternative to the grab bars mandated by the current Americans with Disabilities Act (ADA) Accessibility Guidelines.Future research investigating the effects of grab bars on transfer performance should consider additional factors, such as a wider range of abilities and transfer methods of the users.

Biomechanical characteristics of lower limb gait waveforms: Associations with body fat in children

BackgroundChildhood obesity is associated with musculoskeletal dysfunction and altered lower limb biomechanics during gait. Few previous studies have explored relationships between childhood obesity measured by body fat and lower limb joint waveform kinematics and kinetics. Research questionWhat is the association between body fat and hip, knee and ankle joint angles and moments during gait and in 7 to 11 year-old boys? MethodsFifty-five boys participated in the study. Body fat was measured by air displacement plethysmography. Hip, knee and ankle 3D waveforms of joint angles and moments were recorded during gait. Principle component analysis was used to reduce the multidimensional nature of the waveform into components representing parts of the gait cycle. Multiple linear regression analysis determined the association between the components with body fat. ResultsHigher body fat predicted greater hip flexion, knee flexion and knee internal rotation during late stance and greater ankle external rotation in late swing/early stance. Greater hip flexion and adduction moments were found in early stance with higher body fat. In mid-stance, greater knee adduction moments were associated with high body fat. Finally, at the ankle, higher body fat was predictive of greater internal rotation moments. SignificanceThe study presents novel information on relationships between body fat and kinematic and kinetic waveform analysis of paediatric gait. The findings suggest altered lower limb joint kinematics and kinetics with high body fat in young boys. The findings may help to inform research in to preventing musculoskeletal comorbidities and promoting weight management.