Flexor Moment Research Articles

Should individuals with unilateral transtibial amputation carry a load on their intact or prosthetic side?

Carrying side loads often occurs during activities of daily living. As walking is most unstable mediolaterally, side load carriage may further compromise gait biomechanics, especially for transtibial amputees (TTAs). This study investigated the effects of side load carriage on gait kinetics during steady-state walking to determine which side, intact or prosthetic, TTAs should carry a load. Twelve unilateral TTAs wore a passive-elastic foot and carried a side load of 13.6 kg while walking at their self-selected speed. Kinetic metrics, including ground reaction force peaks and impulses, loading and unloading rates, and joint moments and powers, were analyzed. TTAs had smaller propulsive forces on their intact limb during the prosthetic side load condition. During the intact side load condition, they exhibited smaller hip flexor moment in late stance and smaller knee flexor moment at the end of swing on their intact limb. They had higher hip and knee abductor moments on their intact limb and prosthetic limb in early and late stance during the contralateral side load condition. TTAs generated higher hip extensor power at weight acceptance during the ipsilateral side load. Significant interactions were observed in hip extensor power and abductor moment, suggesting strong associations between hip extensor power generation and the ipsilateral side load and between hip abductor moment and the contralateral side load. These mixed results demonstrate some kinetic changes due to side load carriage and suggest that the side TTAs should carry a load depends on the desired effects, primarily on their intact limb.

Muscle recruitment during gait in individuals with unilateral transfemoral amputation due to trauma compared to able-bodied controls.

Individuals with transfemoral lower limb amputations walk with adapted gait. These kinetic and kinematic compensatory strategies will manifest as differences in muscle recruitment patterns. It is important to characterize these differences to understand the reduced endurance, reduced functionality, and progression of co-morbidities in this population. This study aims to characterize muscle recruitment during gait of highly functional individuals with traumatic transfemoral amputations donning state-of-the-art prosthetics compared to able-bodied controls. Inverse dynamic and static optimisation methods of musculoskeletal modelling were used to quantify muscle forces of the residual and intact limb over a gait cycle for 11 individuals with traumatic transfemoral amputation and for 11 able-bodied controls. Estimates of peak muscle activation and impulse were calculated to assess contraction intensity and energy expenditure. The generalized estimation equation method was used to compare the maximum values of force, peak activation, and impulse of the major muscles. The force exhibited by the residual limb's iliacus, psoas major, adductor longus, tensor fasciae latae and pectineus is significantly higher than the forces in these muscles of the intact contralateral limb group and the able-bodied control group (p < 0.001). These muscles appear to be recruited for their flexor moment arm, indicative of the increased demand due to the loss of the plantar flexors. The major hip extensors are recruited to a lesser degree in the residual limb group compared to the intact limb group (p < 0.001). The plantar flexors of the intact limb appear to compensate for the amputated limb with significantly higher forces compared to the able-bodied controls (p = 0.01). Significant differences found in impulse and peak activation consisted of higher values for the limbs (residual and/or intact) of individuals with transfemoral lower limb amputations compared to the able-bodied controls, demonstrating an elevated cost of gait. This study highlights asymmetry in hip muscle recruitment between the residual and the intact limb of individuals with transfemoral lower limb amputations. Overall elevated impulse and peak activation in the limbs of individuals with transfemoral amputation, compared to able-bodied controls, may manifest in the reduced walking endurance of this population. This demand should be minimised in rehabilitation protocols.

Task-specific differences in lower limb biomechanics during dynamic movements in individuals with chronic ankle instability compared with controls

BackgroundChronic ankle instability (CAI) has been associated with lower limb deficits that can lead to altered biomechanics during dynamic tasks. There have been contradictory findings in terms of ankle and hip joint biomechanics to date, influenced by the variety of movement tasks and varying definitions of the CAI condition. Research QuestionHow do biomechanical variables of the lower extremity differ during walking, running, and jump-landing in individuals with CAI compared with those without CAI? MethodsThirty-two individuals (17 CAI and 15 controls) participated in this retrospective case-control study. Sagittal and frontal plane ankle and hip joint angles and moments, and mediolateral foot balance (MLFB) were calculated during the tasks. Statistical parametric mapping (SPM) was used for the whole trajectory analysis to detect group differences. Discrete variables, including initial contact (IC) and peak angles and moments, were additionally compared. ResultsNo differences were found between groups during walking. During running, the CAI group exhibited a lower plantar flexor moment (p < 0.001) and more laterally deviated MLFB (p = 0.014) during mid-stance when compared to controls. Additionally, participants with CAI had a significantly greater peak plantar flexion angle in early stance (p = 0.022) and a reduced peak plantar flexor moment (p = 0.002). In the jump-landing, the CAI group demonstrated an increased hip extensor moment (p = 0.008), and a greater peak hip adduction angle (p = 0.039) shortly after ground contact compared to the control group. SignificanceDifferences in ankle and hip biomechanics were observed between groups during running and jump landing, but not during walking. These differences may be indicative of impairments in the sensorimotor system or of learnt strategies adopted to try to minimise instability and injury risk and can help to inform future intervention design.

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

BackgroundObesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds. MethodsFull gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping. FindingsCompared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed. InterpretationWhile few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

The association between obesity, knee pain, and gait during stair descent in older adults with knee osteoarthritis

BackgroundObesity and knee osteoarthritis adversely affect activities of daily living in older adults. Together, the complexities of their interaction on mobility, including stair negotiation, are unresolved. The purpose of this study was to determine the relationship between obesity, pain, and stair negotiation in older adults with knee osteoarthritis. MethodsOlder adults with symptomatic knee osteoarthritis and overweight or obesity participated in the study (n = 28; age range = 57.0–78.0 yrs.; body mass index range = 26.6–42.8 kg•m−2). The Western Ontario and McMaster Universities Osteoarthritis Index pain subscale was used to measure knee pain. Measurements included a three-dimensional biomechanical analysis during descent on a set of force plate-instrumented stairs and a timed stair descent test. Pearson's r was used to determine associations between body mass index and pain, stair descent weight-acceptance phase vertical ground reaction force (vGRF) variables and lower extremity joint kinematics and kinetics, and timed stair descent performance. FindingsSignificant correlations existed between body mass index and pain (r = 0.41; p = 0.03), peak vGRF (r = 0.39; p = 0.04), vertical impulse (r = 0.49; p = 0.008), and peak ankle plantar flexor moments (r = 0.50; p = 0.007) in older adults with knee osteoarthritis. InterpretationGreater obesity in older adults with knee osteoarthritis was associated with greater knee pain and higher ankle joint loads during stair descent. These results support the recommendations of osteoarthritis treatment guidelines for weight-loss as a first-line of treatment for older adults with obesity and knee osteoarthritis.

Moment arm and torque generating capacity of semitendinosus following tendon harvesting for anterior cruciate ligament reconstruction: A simulation study.

Altered semitendinosus (ST) morphology and distal tendon insertion following anterior cruciate ligament reconstruction (ACLR) may reduce knee flexion torque generating capacity of the hamstrings via impaired ST force generation and/or moment arm. This study used a computational musculoskeletal model to simulate mechanical consequences of tendon harvest for ACLR on ST function by modeling changes in ST muscle tendon insertion point, moment arm, and torque generating capacity across a physiological range of motion. Simulated ST function was then compared between ACLR and uninjured contralateral limbs. Magnetic resonance imaging from 18 individuals with unilateral history of ACLR involving a hamstring autograft was used to analyse bilateral hamstring muscle (ST, semimembranosus, bicep femoris long head and short head) morphology and distal ST tendon insertion. The ACLR cohort was sub-grouped into those with and without ST regeneration. For each participant with ST regeneration (n = 7), a personalized musculoskeletal model was created including postoperative remodeling of ST using OpenSim 4.1. Knee flexion and internal rotation moment arms and torque generating capacities of hamstrings were evaluated. Bilateral differences were calculated with an asymmetry index (%) ([unaffected limb-affected limb]/[unaffected limb + affected limb]*100%). Smaller moment arms or knee torques within injured compared to uninjured contralateral limbs were considered a deficit. Compared to uninjured contralateral limbs, ACLR limbs with tendon regeneration (n = 7) had minor reductions in knee flexion (5.80% [95% confidence interval (CI) = 3.97-7.62]) and internal rotation (4.92% [95% CI = 2.77-7.07]) moment arms. Decoupled from muscle morphology, altered ST moment arms in ACLR limbs with tendon regeneration resulted in negligible deficits in knee flexion (1.20% [95% CI = 0.34-2.06]) and internal rotation (0.24% [95% CI = 0.22-0.26]) torque generating capacity compared to uninjured contralateral limbs. Coupled with muscle morphology, ACLR limbs with tendon regeneration had substantial deficits in knee flexion (19.32% [95% CI = 18.35-20.28]) and internal rotation (15.49% [95% CI = 14.56-16.41]) torques compared to uninjured contralateral limbs. Personalized musculoskeletal models with measures of ST distal insertion and muscle morphology provided unique insights into post-ACLR ST and hamstring function. Deficits in knee flexor and internal rotation moment arms and torque generating capacities were evident in those with ACLR even when tendon regeneration occurred. Future studies may wish to implement this framework in personalized musculoskeletal models following ACLR to better understand individual muscle function for injury prevention and treatment evaluation.

A simulation framework to determine optimal strength training and musculoskeletal geometry for sprinting and distance running.

Musculoskeletal geometry and muscle volumes vary widely in the population and are intricately linked to the performance of tasks ranging from walking and running to jumping and sprinting. As an alternative to experimental approaches, where it is difficult to isolate factors and establish causal relationships, simulations can be used to independently vary musculoskeletal geometry and muscle volumes, and develop a fundamental understanding. However, our ability to understand how these parameters affect task performance has been limited due to the high computational cost of modelling the necessary complexity of the musculoskeletal system and solving the requisite multi-dimensional optimization problem. For example, sprinting and running are fundamental to many forms of sport, but past research on the relationships between musculoskeletal geometry, muscle volumes, and running performance has been limited to observational studies, which have not established cause-effect relationships, and simulation studies with simplified representations of musculoskeletal geometry. In this study, we developed a novel musculoskeletal simulator that is differentiable with respect to musculoskeletal geometry and muscle volumes. This simulator enabled us to find the optimal body segment dimensions and optimal distribution of added muscle volume for sprinting and marathon running. Our simulation results replicate experimental observations, such as increased muscle mass in sprinters, as well as a mass in the lower end of the healthy BMI range and a higher leg-length-to-height ratio in marathon runners. The simulations also reveal new relationships, for example showing that hip musculature is vital to both sprinting and marathon running. We found hip flexor and extensor moment arms were maximized to optimize sprint and marathon running performance, and hip muscles the main target when we simulated strength training for sprinters. Our simulation results provide insight to inspire future studies to examine optimal strength training. Our simulator can be extended to other athletic tasks, such as jumping, or to non-athletic applications, such as designing interventions to improve mobility in older adults or individuals with movement disorders.

Lower limb strength and training experience in elite and sub-elite female footballers

BACKGROUND: Strength differences between performance levels remain unclear in female football. Furthermore, the relationship between fulltime training and strength has been unexplored despite increased professionalisation in the sport. OBJECTIVE: The aims of this research were to examine knee flexor/extensor and hip adductor/abductor strength differences between elite and sub-elite female footballers, and then determine the relationship of strength performance to age, years of football experience (FE), and years of fulltime training (FTT). METHODS: 15 elite and 15 sub-elite professional female footballers were tested. The main outcomes were concentric isokinetic knee flexor and extensor peak moment at 60, 180, and 300∘/s, and isometric hip adductor (ADD) and abductor (ABD) force. RESULTS: The elite team had higher absolute (300∘/s: 47.13–49.33 Nm vs 37.33–38.93 Nm, p&lt; 0.05) and normalised (300∘/s: 0.76–0.80 Nm/kg vs 0.59–0.62 Nm/kg, p&lt; 0.05) knee flexor values, and higher normalised ADD (5.64–5.66 N/kg vs 4.98–5.05 N/kg, p&lt; 0.05) and ABD force (5.80–6.00 N/kg vs 5.26–5.39 N/kg, p&lt; 0.05), compared to the sub-elite team. Age, FE, and FTT were correlated to knee flexor values (r= 0.381–0.559, p&lt; 0.05). Additionally, FTT was correlated with normalised ADD and ABD force (r= 0.362–0.546, p&lt; 0.05). CONCLUSION: Sub-elite female footballers may require additional knee flexor and hip strengthening in order to make the step up to the elite level. Those who are younger or have low FTT may also be recommended additional lower limb strengthening ahead of joining a fulltime training environment.

Gait and strength assessment following surgical repair by intramedullary nailing of isolated tibial shaft fracture.

The objective of the study was to evaluate the long-term strength and gait outcomes after intramedullary nailing of isolated tibial diaphyseal fractures. This retrospective cohort study was conducted at an academic Level I trauma center. Fifteen participants with isolated tibial diaphyseal fractures (OTA/AO 42) at least 2 years postoperative from intramedullary nailing (IMN) provided informed consent. The average age was 40 ± 14 (range, 24-69); there were nine men and six women. Knee flexion-extension strength data were collected. Temporal-spatial, kinematic, and kinetic gait parameters were measured and compared to historic control data. Participants completed the SF-36 and shortened musculoskeletal function assessment questionnaires. The mean length of follow-up between surgery and gait analysis was 6 ± 2 years. The fractured limb demonstrated deficits in quadriceps strength between 9.8% and 23.4% compared to the unaffected limb. Temporal-spatial parameters revealed slower walking speed, shorter stride length, decreased cadence, and shorter single-limb support time in the fractured limb. Altered kinematic and kinetic findings included a knee extension shift during stance, with an increased knee flexor moment demand and decreased total knee power during loading and midstance. These findings represent deficits in concentric and eccentric knee extensor activity. Additionally, the fractured limb demonstrated decreased ankle dorsiflexion during stance and diminished ankle push-off power. Long-term outcomes after IMN of tibial diaphyseal fractures demonstrate decreased quadriceps strength and altered gait parameters that may have implications to the high incidence of knee and ankle pain in the fractured limb.

Injury and performance related biomechanical differences between recreational and collegiate runners.

Running related injuries (RRI) are common, but factors contributing to running performance and RRIs are not commonly compared between different types of runners. We compared running biomechanics previously linked to RRIs and performance between 27 recreational and 35 collegiate runners. Participants completed 5 overground running trials with their dominant limb striking a force plate, while outfitted with standardised footwear and 3-dimensional motion capture markers. Post hoc comparisons revealed recreational runners had a larger vertical loading rate (194.5 vs. 111.5 BW/s, p < 0.001) and shank angle (6.80 vs. 2.09, p < 0.001) compared with the collegiate runners who demonstrated greater vertical impulse (0.349 vs. 0.233 BWs, p < 0.001), negative impulse (-0.022 vs. -0.013 BWs, p < 0.001), positive impulse (0.024 vs. 0.014 BWs, p < 0.001), and propulsive force (0.390 vs. 0.333 BW, p = 0.002). Adjusted for speed, collegiate runners demonstrated greater total support moment (TSM), plantar flexor moment, knee extensor moment, hip extensor moment, and had greater proportional plantar flexor moment contribution and less knee extensor moment contribution to the TSM compared with recreational runners. Unadjusted for speed, collegiate runners compared with recreational had greater TSM and plantar flexor moment but similar joint contributions to the TSM. Greater ankle joint contribution may be more efficient and allow for greater capacity to increase speed. Improving plantarflexor function during running provides a strategy to improve running speed among recreational runners. Moreover, differences in joint kinetics and ground reaction force characteristics suggests that recreational and collegiate runners may experience different types of RRI.

Functional mobility and lumbopelvic rhythm in women with and without stress urinary incontinence: An observational pilot study

ObjectiveTo examine the functional mobility and lumbopelvic rhythm of the continent and incontinent women. DesignAn observational pilot study was performed with two groups of women, who never experienced falls. MethodsParticipants were 27 women with urinary incontinence and 27 matched controls. The incontinent group had urinary incontinence assessed by the International Consultation on Incontinence Questionnaire Short Form (ICIQ-SF) (score ≥1); and the continent group had an ICIQ-SF score equal to 0. The functional mobility and lumbopelvic rhythm were assessed using G-Sensor® gadget wireless system. With the G-sensor® at the second lumbar vertebra, the participants performed the Walk-Test (functional mobility), Time Up and Go (TUG) (functional mobility), and lumbopelvic rhythm. Student T test, Chi-Square, and Mann-Whitney test were applied to compare continuous variables between groups. p < 0.05 for significance level. Hegdes'g statistic and R2 [Z2/(total n)] were used to effect size. ResultsWalk-test was not different between groups. TUG was different between groups: the continent group (11.0 ± 2.1s) was faster than the incontinent group (12.5 ± 3.3s) (p = 0.03). The sitting-to-standing position knee flexion angle was larger in the continent group (45.0 ± 17.2°) than in the incontinent (34.1 ± 18.8°) (p = 0.03). ConclusionThe incontinent group showed a decrease in functional mobility according to the TUG test. Limiar differences in the flexion angle from sitting to standing suggest incontinent women might have a lower potential for hip flexor moment during hip lifting.

A numerical study towards shape memory alloys application in orthotic management of pediatric knee lateral deviations

Exerting a constant load would likely improve orthosis effectiveness in treating knee lateral deviations during childhood and early adolescence. Shape memory alloys are potential candidates for such applications due to their so called pseudoelastic effect. The present study aims to quantitatively define the applicable mechanical loads, in order to reduce treatment duration while avoiding tissular damage and patient discomfort. This is essential for performing a more efficient design of correction devices. We use a patient-specific finite elements model of a pediatric knee to determine safe loading levels. The achievable correction rates are estimated using a stochastic three-dimensional growth model. Results are compared against those obtained for a mechanical stimulus decreasing in proportion to the achieved correction, emulating the behavior of conventional orthoses. A constant flexor moment of 1.1 Nm is estimated to change femorotibial angle at a rate of (7.4 ± 4.6) deg/year (mean ± std). This rate is similar to the achieved by more invasive growth modulation methods, and represents an improvement in the order of 25% in the necessary time for reducing deformities of (10 ± 5) deg by half, as compared with conventional orthoses.

Mechanical adaptations in walking using carbon fiber ankle foot orthoses for patients with peripheral artery disease

BackgroundThe effectiveness of community-based walking programs for patients with peripheral artery disease (PAD) can be limited by calf claudication during exercise. Recent evidence finds adding carbon fiber ankle foot orthoses (AFO) to a walking program can result in improvements in patient mobility and delay claudication onset when walking. Research questionHow may carbon fiber AFO alter ankle walking mechanics and corresponding triceps surae muscle recruitment in a manner that could improve patient mobility? MethodsIn this repeated measures cohort study, fifteen patients with PAD were fit with bilateral AFO before completing self-paced gait analysis including electromyography. Patients were then given standard advice to walk at home using the devices for 12 weeks. Twelve patients completed follow-up testing. ResultsThere were no significant interactions between main effects for any variable of interest (p ≥ 0.189). Further, there were no within-subjects main effects for testing time for self-selected gait speed or any of the kinetic or kinematic variables (p ≥ 0.435). There were significant main effects for AFO use with reductions in dorsi flexion (p < 0.001), plantar flexion at toe off (p < 0.001), ankle plantar flexor moment (p = 0.037), and ankle plantar flexor power (p < 0.001). Triceps surae recruitment did not change between AFO conditions (p > 0.05). SignificanceAdding carbon fiber AFO limits peak ankle motion and joint power during self-paced walking for people with PAD while maintaining their walking speed. These gait adaptions were maintained over our 12 weeks of walking practice time. A resulting decrease in plantar flexor power while maintaining gait speed may provide the mechanism by which AFO can delay claudication onset which are major barrier to PAD walking programs. Calf muscle recruitment was maintained when adding the AFO which suggests sufficient muscle exertion could exist to maintain muscle integrity with sustained AFO use.

Acute Effects of Combination Therapy by Triceps Surae Stretching and Electrical Stimulation to the Tibialis Anterior on Medial Forefoot Plantar Pressure During Gait in Patients With Diabetes Mellitus.

High plantar flexor moment and limited ankle mobility are known to cause high plantar pressure under the forefoot. Stretching is an effective physical therapy for the limited ankle range of motion (ROM), and electrical stimulation is used to regulate the activity of antagonistic muscle via the action of reciprocal inhibition. Additionally, stretching paired with electrical stimulation has been reported to improve the limited ROM significantly. This study aims to investigate the influences of stretching on triceps surae (STR), electrical stimulation to tibialis anterior (ES), and the combination (ES+STR) on the ROM, kinematic parameters, and plantar pressure distribution during gait in patients with diabetes mellitus. Planter pressure and other parameters were measured before and after the intervention of ES, STR, ES+STR, or the rest sitting on the bed (CON) for 10 min. Pressure time integral under the medial forefoot decreased in the ES+STR compared to CON (P< .05). Interestingly, ES+STR increased passive and dynamic ROM on ankle dorsiflexion during gait and increased the lateral center of pressure excursion (P < .05). Furthermore, these changes were followed by decreased contact duration under the medial forefoot (P < .05). The combined therapy improves ankle mobility during gait and reduces the contact duration and the plantar pressure under the medial forefoot in patients with diabetes mellitus.

EFEITOS DO TREINAMENTO CÍCLICO DE RESISTÊNCIA SOBRE FORÇA E EQUILÍBRIO DOS MEMBROS INFERIORES EM ATLETAS DE BASQUETEBOL

ABSTRACT Introduction: Cyclic resistance training allows that at the end of each movement cycle, all parts of the athlete’s body return to the initial position, allowing the constant repeatability of the exercise. It is believed that this activity can significantly influence the physical capacity of the lower limbs of basketball athletes. Objective: Study the effects of cyclic resistance training on basketball players’ lower limb strength and balance ability. Methods: 36 basketball players were selected and randomly divided into experimental and control groups. The experimental group received training for eight weeks combining routine training with cyclic resistance training, while the control group remained with routine training only. Relevant performance, strength, and balance data were analyzed before and after the procedure, undergoing statistical analysis and confrontation with current literature. Results: The peak flexor moment in the experimental group increased from 94.42 ± 28.20 Nm to 101.85 ± 23.30 Nm; the peak torque of the extensor muscle increased from 161.88 ± 39.16 Nm to 186.19 ± 40.29 Nm. In the balance ability test, the left lateral test increased from 68.78 ± 4.65 cm to 74.35 ± 3.29 cm, the left increased from 109.33 ± 7.22 cm to 114.65 ± 7.54 cm. The increase in the control group was small. Conclusion: Cyclic resistance training demonstrated a beneficial effect on both lower limb strength and balance in basketball athletes, and was effective in improving the physical capacity of basketball players.Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Sensitivity of lower-limb joint mechanics to prosthetic forefoot stiffness with a variable stiffness foot in level-ground walking

This paper presents the effectsof the Variable Stiffness Foot (VSF) on lower-limb joint mechanics in level-ground walking. Persons with transtibial amputations use lower-limb prostheses to restore level-ground walking, and foot stiffness and geometry have been shown to be the main factors for evaluating foot prostheses. Previous studies have validated the semi-active and stiffness modulation capabilities of the VSF. The core aim of this study is to investigate the mechanical effects of adjusting stiffness on knee and ankle mechanics for prosthetic users wearing the VSF. For this study, seven human participants walked with three different stiffnesses (compliant, medium, stiff) of the VSF across two force plates in a motion capture lab. Linear mixed models were utilized to estimate the significance and coefficients of determinations for the regression of stiffness on several biomechanical metrics. A stiffer VSF led to decreased ankle dorsiflexion angle (p < 0.0001, r2 = 0.90), increased ankle plantarflexor moment (p = 0.016, r2 = 0.40), increased knee extension (p = 0.021, r2 = 0.37), increased knee flexor moment (p = 0.0007, r2 = 0.63), and decreased magnitudes of prosthetic energy storage (p < 0.0001, r2 = 0.90), energy return (p = 0.0003, r2 = 0.67), and power (p < 0.0001, r2 = 0.74). These results imply lower ankle, knee, and hip moments, and more ankle angle range of motion using a less stiff VSF, which may be advantageous to persons walking with lower-limb prostheses. Responsive modulation of the VSF stiffness, according to these findings, could help overcome gait deviations associated with different slopes, terrain characteristics, or footwear.

Modifications to the net knee moments lead to the greatest improvements in accelerative sprinting performance: a predictive simulation study

The current body of sprinting biomechanics literature together with the front-side mechanics coaching framework provide various technique recommendations for improving performance. However, few studies have attempted to systematically explore technique modifications from a performance enhancement perspective. The aims of this investigation were therefore to explore how hypothetical technique modifications affect accelerative sprinting performance and assess whether the hypothetical modifications support the front-side mechanics coaching framework. A three-dimensional musculoskeletal model scaled to an international male sprinter was used in combination with direct collocation optimal control to perform (data-tracking and predictive) simulations of the preliminary steps of accelerative sprinting. The predictive simulations differed in the net joint moments that were left ‘free’ to change. It was found that the ‘knee-free’ and ‘knee-hip-free’ simulations resulted in the greatest performance improvements (13.8% and 21.9%, respectively), due to a greater knee flexor moment around touchdown (e.g., 141.2 vs. 70.5 Nm) and a delayed and greater knee extensor moment during stance (e.g., 188.5 vs. 137.5 Nm). Lastly, the predictive simulations which led to the greatest improvements were also found to not exhibit clear and noticeable front-side mechanics technique, thus the underpinning principles of the coaching framework may not be the only key aspect governing accelerative sprinting.

35. Effect of surgical intervention on gait function in patients with symptomatic lumbar canal stenosis

<h3>BACKGROUND CONTEXT</h3> Gait impairment is one of the primary symptoms of degenerative lumbar canal stenosis (LCS), yet it is poorly understood due to a lack of quantitative data on kinematics and kinetics during the gait. Gait analysis is a well-established tool for the quantitative assessment of gait disturbances, providing a functional diagnosis, assessing treatment plan and monitoring of disease progress. <h3>PURPOSE</h3> To analyze the effect of decompression surgery on gait characteristics in patients with LCS. <h3>STUDY DESIGN/SETTING</h3> Prospective non-randomized comparative study at a teaching hospital. <h3>PATIENT SAMPLE</h3> Eighteen patients with symptomatic LCS and 18 healthy volunteers. <h3>OUTCOME MEASURES</h3> Gait quality: spatiotemporal, kinetic and kinematic parameters functional outcome: ODI, VAS. <h3>METHODS</h3> Eighteen patients with single-level LCS and 18 healthy volunteers were prospectively recruited. All the patients with symptomatic LCS underwent TLIF (transforaminal lumbar interbody fusion) surgery. Gait analysis was perfomed preoperatively and six months postoperatively as per standard protocol. The spatiotemporal, kinematic and kinetic parameters were analyzed. The Kolmogorov-Smirnov test and coefficient of skewness and kurtosis was used to assess the normality of distribution. Pre- and postoperative clinical outcomes, spatial-temporal, kinetic and kinematic data were compared with the paired t-test or Wilcoxon signed-rank test according to the normality of the distribution. Unpaired t-test was used to compare the two groups. Stepwise linear regression models were used to detect significant relationships between changes in ODI and VAS score, and parameters describing gait function. <h3>RESULTS</h3> Significant improvement was noted in ODI (p < 0.05) and VAS scores (p < 0.05) six months post-surgery. Spatiotemporal (Stride time [p=0.01], Swing phase % [p=0.01], Double support phase % [p=0.02], Mean velocity [p < 0.01], Cadence [p < 0.01], Stride length [p < 0.01], Step length [p < 0.01] and step width [p < 0.01])and kinetic parameters (peak hip [p < 0.01], knee [p < 0.01] and ankle power [p < 0.01], vertical GRF [p=0.01]) were significantly better following surgery, reaching normal levels when compared to healthy individuals. The kinematic parameters (trunk tilt [p=0.02], peak hip extension [p < 0.01], peak knee flexion in stance [p=0.01] and swing phase [p < 0.01], peak ankle dorsiflexion in stance [p < 0.01] and swing phase [p=0.04], GPS [p < 0.01] and GDI [p < 0.01]) were significantly improved following surgery but did not reach normal levels when compared to controls. A significant correlation was found between change in ODI and VAS score with change in certain kinematic parameters (knee power, stance time, ankle plantarflexion, peak ankle dorsiflexion moment, GDI, swing time, peak ankle dorsiflexion in swing, peak hip and knee flexor moment). <h3>CONCLUSIONS</h3> Decompression surgery in LCS produces improvement in gait parameters, pain scores, and functional outcome that significantly improves walking tolerance and speed. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Biomechanics of running: A special reference to the comparisons of wearing boots and running shoes.

Boots are often used in sports, occupations, and rehabilitation. However, there are few studies on the biomechanical alterations after wearing boots. The current study aimed to compare the effects of running shoes and boots on running biomechanics. Kinematics and ground reaction forces were recorded from 17 healthy males during running at 3.3 m/s with shoe and boot conditions. Temporal distance gait variables, ground reaction force components as well as lower limb joints angle, moment, and power were compared using Paired t-test and Statistical Parametric Mapping package for time-series analysis. Running with boots was associated with greater stride, step, flight, and swing times, greater flight length, and smaller cadence (p<0.05). The only effect of boots on lower limb joints kinematics during running was a reduction in ankle range of motion (p<0.05). Significantly greater hip flexor, abductor, and internal rotator moments, greater knee extensor and abductor moments, and ankle plantar flexor moments were observed at push-off phase of running as well as greater ankle dorsiflexor moment at early-stance in boot condition (p<0.05). Also, knee joint positive power was greater with a significant temporal shift in boot condition, suggesting a compensatory mechanism in response to limited ankle range of motion and the inability of the ankle joint to generate the required power. Our findings showed that running with boots is physically more demanding and is associated with a greater net contribution of muscles spanning hip and knee joints in order to generate more power and compensate for the ankle joint limitations, consequently, may increase the risk of both musculoskeletal injuries and degenerative joint diseases.

An exploratory analysis of gait biomechanics and muscle activation in pregnant females with high and low scores for low back or pelvic girdle pain during and after pregnancy

BackgroundThe purpose of this study was to compare gait kinematics, kinetics, and muscle activation between pregnant females with high and low scores for low back and/or pelvic girdle pain during and after pregnancy. MethodsTwenty participants tested during second trimester, third trimester, and again post-partum. At each session, motion capture, force plates, and surface electromyography data were captured during self-selected velocity over-ground walking. Participants completed the Quebec Back Pain Disability Scale (QBPDS) and were assigned to high (QBPDS ≥15) or low pain groups (QBPDS <15) based on third trimester scores. Two-way mixed model ANOVAs were used to compare high and low pain groups over time. FindingsNine participants met the high pain group criteria and 11 were low pain. During second trimester the high pain group compared to the low pain group demonstrated smaller peak hip flexor moments, total hip work, percent hip contribution to work, and larger percent ankle contribution to work. Pregnant females demonstrated greater hip, knee, and ankle moments, ankle work, and gluteus maximus muscle activation third trimester than second trimester. InterpretationReduced hip and greater ankle contribution to work in the high pain group during second trimester could indicate decreased hip utilization early in pregnancy and may contribute to disability as pregnancy progresses. It is also possible kinetic differences during second trimester reflect an early strategy to reduce pain by avoiding hip joint loading. Increased moments and work during third trimester indicate a clinical imperative to better prepare pregnant females to accommodate increased joint loading and muscular demand.