Hip 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 had 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.

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.

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.

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.

Kinematics and joints moments profile during straight arm press to handstand in male gymnasts.

Biomechanical features of the handstand, one of the most fundamental skills required for artistic gymnastics events, have not been well documented. The purpose of this study was to clarify the kinematics and joint moment profiles during straight arm press to handstand in different highly skilled male gymnasts. Fifty-nine male gymnasts performed a straight arm press to handstand on a force platform and were judged on their performance by experienced certified judges. Subjects were divided into two groups (highly-skilled and less-skilled). Kinematic data were obtained using a video camera synchronized with force platform. Joint moments (wrist, shoulder, hip) during each straight arm press to handstand were calculated using the inverse dynamics solution. Larger shoulder flexion moments were observed in less-skilled compared with highly- skilled performers (at 3–59%, p < 0.001) while larger hip flexion moments were observed in highly- skilled performers at 52% (p = 0.045) and 56% (p = 0.048) and normalized time of straight arm press to handstand. Major differences between highly-skilled and less-skilled performers were observed in hip joint moment production as it shifted from extension to flexion from the leg horizontal position to the handstand position in highly-skilled gymnasts. Successful straight arm press to handstand techniques observed in highly-skilled performers were characterized as a more acute pike position at toe-off as well as hip flexor moments at latter phase of the straight arm press to handstand.

Effects of body mass and sex on kinematics and kinetics of the lower extremity during stair ascent and descent in older adults

The effects of body mass and sex on lower limb biomechanics during ascent and descent were examined in participants aged 50 to 75 with normal weight (n ​= ​19), overweight (n ​= ​18), and obese (n ​= ​8). Peak joint angles and joint moment of the lower limb were analyzed with the VICON motion analysis system. Results from multivariate analysis of variance showed that during descent, the overweight participants had significantly higher knee extensor moment (0.98 ​± ​0.30 ​N∙m/kg-1) than the normal-weight participants (0.70 ​± ​0.29 ​N∙m/kg-1). The obese group had significantly higher ankle abductor moment (0.21 ​± ​0.11 ​N∙m/kg-1) than the normal weight (0.12 ​± ​0.08 ​N∙m/kg-1) and overweight groups (0.09 ​± ​0.06 ​N∙m/kg-1). During ascent, the obese participants had significant higher hip flexor moment (0.42 ​± ​0.20 ​N∙m/kg-1) than overweight participants (0.22 ​± ​0.17 ​N∙m/kg-1). Significant sex differences were found in knee extension angles (4.2 ​± ​3.4° vs 7.0 ​± ​3.3°) during descent, plantar flexion angles during ascent (23.7 ​± ​5.3° vs 15.6 ​± ​3.7°) and descent (29.9 ​± ​5.0° vs 22.1 ​± ​7.9°), and ankle adduction angles (6.8 ​± ​4.8° vs 2.5 ​± ​2.5°) during ascent. It is concluded that body mass has significant impact on joint loading of lower limbs during stair walking. Being overweight and obese increased hip joint loading during ascent, and knee and ankle joint loading during descent in older adults. Sex difference in joint kinematics was presented during stair walking regardless of the body mass.

Recovery From a Forward Falling Slip: Measurement of Dynamic Stability and Strength Requirements Using a Split-Belt Instrumented Treadmill

Aim: Falls commonly occur from trips and slips while walking. Recovery strategies from trips and backward falling slips have been extensively studied. However, until recently, forward falling slips (FFSs) have been considered less dangerous and have been understudied. This study aimed first to create an application to realistically simulate FFSs using a split-belt instrumented treadmill and then to understand the biomechanical requirements for young adults to recover from an FFS.Methods: We developed a semi-automatic custom-made application on D-Flow that triggered FFSs by briefly and unexpectedly increasing the speed (a = 5 m·s−2) of the right belt during stance. To validate the protocol, we tested against criteria defined for an ecologically and experimentally valid FFS: unexpected occurrence of the slip, increased foot velocity, forward loss of balance during the slip and consistent perturbation timing. We evaluated the recovery strategies of 17 young adults by measuring dynamic stability, joint moments and ground reaction force (GRF) vector angles before, during and on 15 steps following the FFS.Results: The application successfully triggered FFSs, according to the criteria we defined. Participants' balance returned to normal for a minimum of three consecutive steps in 10.9 (7.0) steps. Recovery from the FFSs was characterised by larger hip flexor and knee extensor moments to support the centre of mass during the slip, and a longer first recovery step with large hip extensor moments to arrest the fall followed by large knee extensor moments to raise and advance the centre of mass into the next step (p < 0.001 compared with normal gait). Subsequent steps progressively returned to normal.Conclusion: This is the first study to experimentally simulate FFSs meeting the aforementioned criteria, and to measure their effects on the dynamic balance and kinetic parameters. The split-belt instrumented treadmill proved a promising tool to better study the mechanisms of falls and recovery. The required large hip and knee joint moments generally agree with findings on trips and backward falling slips and provide an indication of the functional capacities that should be targeted in fall-prevention interventions. These findings should be used to better understand and target the mechanisms of balance loss and falls in older adults following FFSs.

Inter-individual variation in hip flexor length may explain differences in trunk flexion during walking in people with knee osteoarthritis

Purpose: Increasing trunk flexion will shift the position of the centre of mass relative to the hip and knee which may lead to changes in muscle activation patterns during walking. Through previous research, we have demonstrated that people with knee osteoarthritis (OA) walk with an increased flexion of the trunk. Our research has also shown that instructing healthy people to increase trunk flexion during walking, by only 5 degrees, produces a distinct increase in duration and magnitude of both the lateral and medial hamstrings. This may indicate that prolonged/increased hamstring activity in people knee OA may, to some degree, result from increased trunk flexion. Importantly, such muscle patterns are known to increase articular load, accelerate the rate of cartilage loss and to be associated with poor long-term clinical outcomes. It is therefore essential that we understand the underlying drivers of altered trunk flexion in people with knee OA. The hip flexor muscle group comprises iliacus, psoas and rectus femoris. As well as functioning to create a hip flexor moment, the relaxed (resting) length of this muscle group could influence the sagittal plane inclination of the pelvis in standing and during movement. Specifically, if the hip flexor muscles are structurally short, this may lead to a relative anterior tilt of the pelvis on the thigh which could, in turn, lead to an increase in trunk flexion. It is therefore possible that the increase in trunk flexion, observed in people with knee OA, is a consequence of short hip flexor muscles. Therefore, this study had two aims. The first was to compare hip flexor length between people with knee OA and healthy control subjects. The second was to understand the association between hip flexor length and trunk inclination during walking, both in healthy people and those with knee OA. Methods: Data was collected from 20 people with radiographically diagnosed OA of the knee and 20 age/BMI matched healthy participants. For each participant, hip flexor length was measured using the Thomas Test. For this test, subjects lay supine with the non-tested leg held against their chest (knee flexed) while the other leg was extended from a flexed position until muscular restriction prevented any further movement. This tested leg hung freely off the edge of the testing plinth while thigh angle, relative to the horizontal, was measured using an inclinometer. Pelvic position was controlled throughout this testing protocol using a pressure biofeedback cuff. An increase in thigh flexion, in the Thomas test, indicates muscular restriction and therefore shortness of the hip flexor muscles, whereas a more extended thigh position, indicates an increased hip flexor length. Measurements were performed on both left and right sides and the average used for subsequent analysis. Following hip flexor testing, kinematic data were collected at a self-selected walking speed. Trunk flexion angles was then calculated, and an average calculated over the period 15-25% of stance as this corresponds to the period of peak knee loading. Independent t-tests were used to compare trunk flexion and hip flexor length between the two groups. A Pearson’s correlational analysis was then used to understand the association between trunk flexion and hip flexor length in each of the two groups separately. Results: Individuals with knee OA demonstrated a more positive Thomas test (p<0.01), mean (SD) = 6.2 (4.2)° compared to the control subjects, mean (SD) = 1.9 (3.7)°, indicating shorter hip flexor muscles in the group with knee OA. The Individuals with knee OA were also observed to walk with 2.8° more trunk flexion (p<0.05). Interestingly, there was a moderate-strong correlation (r=0.67) between hip flexor muscle length and trunk angle during walking in the group with knee OA and a weak-moderate correlation in the healthy group (r=0.45). Conclusions: These data support the idea that people with knee OA exhibit increased muscular restriction of the hip flexor muscle group in static testing and that they walk with more trunk flexion. These data also support the idea that a reduction in the length of the flexor muscles may be a biomechanical driver of increased trunk inclination in people with the disease. Taken together, these findings motivate future research to understand whether interventions that specifically target hip flexor length could lead to reductions in trunk flexion during walking. Such reductions in trunk flexion may lead to changes in hamstring activation patterns and corresponding reductions in the compressive forces at the knee.

Is There an Optimal Recovery Step Landing Zone Against Slip-Induced Backward Falls During Walking?

Recovery stepping in response to forward slips has the potential to not only rebuild the base of support to prevent backward falling, but also provide extra limb support to prevent downward falling. Hence, recovery stepping is often necessary for fall prevention following an unexpected slip. However, less is known about whether recovery foot placement could affect the likelihood of recovery following a slip. The purpose of this study was to determine whether there is an optimal recovery landing zone within which older adults have a higher likelihood of recovery. 195 participants experienced a novel, unannounced forward slip while walking on a 7-m walkway. The center of mass (COM) stability (computed from its position and velocity), vertical limb support (computed from change in hip kinematics), and recovery limb joint moments (computedfrom joint kinematics and ground reaction force) in the sagittal plane were analyzed. The results showed that a longer distance between recovery foot landing position and the projected COM position at recovery foot touchdown (relative recovery step placement) was conducive to stability improvement but adverse to limb support enhancement, and vice versa for a shorter distance. Relative recovery step placement could predict the recovery likelihood with an accuracy of 67.3%, and the recovery rate was greater than 50% when the distance between recovery foot and COM is less than 0.3 × foot length. This study also found more posterior stepping could be attributed to insufficient ankle plantar flexor and hip flexor moments in the pre-swing phase, while more anterior stepping was induced by insufficient hip and knee extensor moments in the following swing phase.

External loading alters lower extremity kinetics, kinematics, and muscle activity in a distribution-specific manner during the transition from stair descent to level walking

BackgroundExcess body mass is thought to be a major cause of altered biomechanics in obesity, but the effects of body mass distribution in biomechanics during daily living tasks are unknown. The purpose of this study was to determine how increasing body mass centrally and peripherally affects lower extremity kinematics, kinetics, and muscle activation when transitioning from stair descent to level gait. MethodsFifteen normal weight volunteers descended a staircase at a self-selected pace under unloaded, centrally loaded, and peripherally loaded conditions. Spatial-temporal gait characteristics and lower extremity joint kinematics, kinetics, and mean electromyography amplitude were calculated using 3D motion analysis. FindingsBoth central and peripheral loading reduced gait velocity. Peripheral loading increased time spent in stance phase, increased step width, and reduced step length. At the hip joint, peripheral loading reduced peak hip extension and adduction angle. Conversely, central loading reduced peak hip flexor moment. Both central and peripheral loading increased peak knee flexion angle, but only peripheral loading increased peak knee extensor moment. Central and peripheral loading increased mean electromyography amplitude of the medial gastrocnemius, but only peripheral loading increased mean electromyography amplitude of the semitendinosus and the vastus medialis. InterpretationIncreasing mass centrally and peripherally differently affects spatial-temporal gait characteristics and lower extremity joint kinematics, kinetics, and electromyography when transitioning from stair descent to level gait. Body mass distribution may be an important factor for obesity-induced biomechanical alterations and should be considered when developing biomechanical models of obesity.

Biomechanical Associates of Performance and Knee Joint Loads During A 70-90° Cutting Maneuver in Subelite Soccer Players.

McBurnie, AJ, Dos'Santos, T, Jones, PA. Biomechanical associates of performance and knee joint loads during a 70-90° cutting maneuver in subelite soccer players. J Strength Cond Res 35(11): 3190-3198, 2021-The aim of this study was to explore the "performance-injury risk" conflict during cutting, by examining whole-body joint kinematics and kinetics that are responsible for faster change-of-direction (COD) performance of a cutting task in soccer players, and to determine whether these factors relate to peak external multiplanar knee moments. 34 male soccer players (age: 20 ± 3.2 years; body mass: 73.5 ± 9.2 kg; height: 1.77 ± 0.06 m) were recruited to investigate the relationships between COD kinetics and kinematics with performance and multiplanar knee joint moments during cutting. Three-dimensional motion data using 10 Qualisys Oqus 7 infrared cameras (240 Hz) and ground reaction force data from 2 AMTI force platforms (1,200 Hz) were collected to analyze the penultimate foot contact and final foot contact (FFC). Pearson's or Spearman's correlations coefficients revealed performance time (PT), peak external knee abduction moment (KAM), and peak external knee rotation moment (KRM) were all significantly related (p < 0.05) to horizontal approach velocity (PT: ρ = -0.579; peak KAM: ρ = 0.414; peak KRM: R = -0.568) and FFC peak hip flexor moment (PT: ρ = 0.418; peak KAM: ρ = -0.624; peak KRM: ρ = 0.517). Performance time was also significantly (p < 0.01) associated with horizontal exit velocity (ρ = -0.451) and, notably, multiplanar knee joint loading (peak KAM: ρ = -0.590; peak KRM: ρ = 0.525; peak KFM: ρ = -0.509). Cohen's d effect sizes (d) revealed that faster performers demonstrated significantly greater (p < 0.05; d = 1.1-1.7) multiplanar knee joint loading, as well as significantly greater (p < 0.05; d = 0.9-1.2) FFC peak hip flexor moments, PFC average horizontal GRFs, and peak knee adduction angles. To conclude, mechanics associated with faster cutting performance seem to be "at odds" with lower multiplanar knee joint loads. This highlights the potential performance-injury conflict present during cutting.

Effects of anti-pronation shoes on lower limb kinematics and kinetics in female runners with pronated feet: The role of physical fatigue.

Physical fatigue and pronated feet constitute two risk factors for running-related lower limb injuries. Accordingly, different running shoe companies designed anti-pronation shoes with medial support to limit over pronation in runners. However, there is little evidence on the effectiveness and clinical relevance of anti-pronation shoes. This study examined lower limb kinematics and kinetics in young female runners with pronated feet during running with anti-pronation versus regular (neutral) running shoes in unfatigued and fatigued condition. Twenty-six female runners aged 24.1±5.6 years with pronated feet volunteered to participate in this study. Kinetic (3D Kistler force plate) and kinematic analyses (Vicon motion analysis system) were conducted to record participants’ ground reaction forces and joint kinematics when running with anti-pronation compared with neutral running shoes. Physical fatigue was induced through an individualized submaximal running protocol on a motorized treadmill using rate of perceived exertion and heart rate monitoring. The statistical analyses indicated significant main effects of “footwear” for peak ankle inversion, peak ankle eversion, and peak hip internal rotation angles (p<0.03; d = 0.46–0.95). Pair-wise comparisons revealed a significantly greater peak ankle inversion angle (p<0.03; d = 0.95; 2.70°) and smaller peak eversion angle (p<0.03; d = 0.46; 2.53°) when running with anti-pronation shoes compared with neutral shoes. For kinetic data, significant main effects of “footwear” were found for peak ankle dorsiflexor moment, peak knee extensor moment, peak hip flexor moment, peak hip extensor moment, peak hip abductor moment, and peak hip internal rotator moment (p<0.02; d = 1.00–1.79). For peak positive hip power in sagittal and frontal planes and peak negative hip power in horizontal plane, we observed significant main effects of “footwear” (p<0.03; d = 0.92–1.06). Pairwise comparisons revealed that peak positive hip power in sagittal plane (p<0.03; d = 0.98; 2.39 w/kg), peak positive hip power in frontal plane (p = 0.014; d = 1.06; 0.54 w/kg), and peak negative hip power in horizontal plane (p<0.03; d = 0.92; 0.43 w/kg) were greater with anti-pronation shoes. Furthermore, the statistical analyses indicated significant main effects of “Fatigue” for peak ankle inversion, peak ankle eversion, and peak knee external rotation angles. Pair-wise comparisons revealed a fatigue-induced decrease in peak ankle inversion angle (p<0.01; d = 1.23; 2.69°) and a fatigue-induced increase in peak knee external rotation angle (p<0.05; d = 0.83; 5.40°). In addition, a fatigue-related increase was found for peak ankle eversion (p<0.01; d = 1.24; 2.67°). For kinetic data, we observed a significant main effect of “Fatigue” for knee flexor moment, knee internal rotator moment, and hip extensor moment (p<0.05; d = 0.83–1.01). The statistical analyses indicated significant a main effect of “Fatigue” for peak negative ankle power in sagittal plane (p<0.01; d = 1.25). Finally, we could not detect any significant footwear by fatigue interaction effects for all measures of joint kinetics and kinematics. Running in anti-pronation compared with neutral running shoes produced lower peak moments and powers in lower limb joints and better control in rear foot eversion. Physical fatigue increased peak moments and powers in lower limb joints irrespective of the type of footwear.

Passive elastic contribution of hip extensors to joint moments during walking in people with low back pain

BackgroundIt has been found that alterations in passive muscle properties may be associated with low back pain, and these may be responsible for the altered gait parameters often observed in subjects with back pain. The purpose of the present study was to assess total hip and passive hip extensor moments in people with or without low back pain during the hip flexion component of walking. Methods52 subjects volunteered for this study (low back pain group, n = 25 (male n = 13, female n = 12), control group, n = 27 (male n = 15, female n = 12)). Passive hip moments were calculated using an adapted force transducer during supine testing. A biomechanical model and predictive equation were used to calculate passive hip moments during walking. Total hip moments were calculated with the use of a 9 camera, 3-D motion-capture system. FindingsIndependent samples t-tests demonstrated no significant differences between groups for gait parameters or hip or knee angles. Results of the ANOVAs demonstrated significant differences in passive hip flexor moments during the second half of hip flexion (P < 0.05).There were also significant differences in hip power and work done during peaks of power absorption and the second peak of power generation (P < 0.05). InterpretationThe present data demonstrates that subjects with low back pain have altered passive hip extensor and total power and work done during walking compared with healthy controls. Biomechanical models should include individual measurements of passive joint moments.

Average of trial peaks versus peak of average profile: impact on change of direction biomechanics

ABSTRACT The aims of this study were twofold: firstly, to compare lower limb kinematic and kinetic variables during a sprint and 90° cutting task between two averaging methods of obtaining discrete data (peak of average profile vs. average of individual trial peaks); secondly, to determine the effect of averaging methods on participant ranking of each variable within a group. Twenty-two participants, from multiple sports, performed a 90° cut, whereby lower limb kinematics and kinetics were assessed via 3D motion and ground reaction force (GRF) analysis. Six of the eight dependent variables (vertical and horizontal GRF; hip flexor, knee flexor, and knee abduction moments, and knee abduction angle) were significantly greater (p ≤ 0.001, g = 0.10–0.37, 2.74–10.40%) when expressed as an average of trial peaks compared to peak of average profiles. Trivial (g ≤ 0.04) and minimal differences (≤ 0.94%) were observed in peak hip and knee flexion angle between averaging methods. Very strong correlations (ρ ≥ 0.901, p < 0.001) were observed for rankings of participants between averaging methods for all variables. Practitioners and researchers should obtain discrete data based on the average of trial peaks because it is not influenced by misalignments and variations in trial peak locations, in contrast to the peak from average profile.

Alternate stair descent strategies for reducing joint moment demands in older individuals

Descending stairs requires elevated joint moment-generating capability in the lower limbs, making it a challenging daily activity, particularly for older individuals. The aim of the study was to investigate the influence of three different strategies for descending standard and increased height stairs: step-over-step (SoS), step-by-step (SbS) and side-step (SS) on lower limb kinetics in older people. Eleven participants (mean ± SD age: 74.8 ± 3.1 years, height: 1.63 ± 0.07 m, mass: 67.7 ± 9.5 kg) descended a four-step custom built instrumented staircase at a self-selected speed, adopting each of the three strategies, at two configurations: a step-rise height of 170 mm (standard; STD) and a step-rise height of 255 mm (increased; INC). 3D motion capture, synchronised with embedded force plates enabled the calculation of joint kinetics of lead and trail limbs. Data were analysed using a Linear Mixed Model with gait speed selected as a covariate during weight acceptance (WA) and controlled lowering (CL) phases. A large increase in hip extensor moment in both WA and CL in the lead limb was evident during both SoS and SbS at INC step height compared to STD (P < .015 for all), with no such increase in hip flexor moment evident in SS strategy (P = .519). Lead limb knee extensor moment decreased and plantarflexor moment increased in INC SoS compared to STD SoS during CL (P < .001 for both). In the trail limb, increased hip extensor and plantarflexor moments were seen in INC SS compared to STD SS (P < .001 for both). The alternate strategies result in the overall task demand being split between the lead limb (weight acceptance) and trail limb (controlled lowering). Differential demand distribution patterns exist between strategies that imply targeted interventions and/or advice could be provided to older individuals in order to promote safe descent of stairs, particularly for those with specific muscle weaknesses or at high risk of falls.

Gait Deviations in Children With Osteogenesis Imperfecta Type I.

Osteogenesis imperfecta (OI) is a congenital connective tissue disorder often characterized by orthopaedic complications that impact normal gait. As such, mobility is of particular interest in the OI population as it is associated with multiple aspects of participation and quality of life. The purpose of the current study was to identify and describe common gait deviations in a large sample of individuals with type I OI and speculate the etiology with a goal of improving function. Gait analysis was performed on 44 subjects with type I (11.7±3.08 y old) and 30 typically developing controls (9.54±3.1 y old ). Spatial temporal, kinematic, and kinetic gait data were calculated from the Vicon Plug-in-Gait Model. Musculoskeletal modeling of the muscle tendon lengths (MTL) was done in OpenSim 3.3 to evaluate the MTL of the gastrocnemius and gluteus maximus. The gait deviation index, a dimensionless parameter that evaluates the deviation of 9 kinematic gait parameters from a control database, was also calculated. Walking speed, single support time, stride, and step length were lower and double support time was higher in the OI group. The gait deviation index score was lower and external hip rotation angle was higher in the OI group. Peak hip flexor, knee extensor and ankle plantarflexor moments, and power generation at the ankle were lower in the OI group. MTL analysis revealed no significant length discrepancies between the OI group and the typically developing group. Together, these findings provide a comprehensive description of gait characteristics among a group of individuals with type I OI. Such data inform clinicians about specific gait deviations in this population allowing clinicians to recommend more focused interventions. Level III-case-control study.

Isokinetic dynamometry and gait analysis reveal different hip joint status in patients with hip dysplasia.

Objective assessment of hip dysplasia patients' functional hip joint status routinely involves gait analysis or isokinetic dynamometry. However, these methods have shown equivocal results and have not been employed in the same groups of patients and controls. To assess hip flexor and abductor moments by isokinetic dynamometry in the dysplasia patient and controls, for which we previously reported smaller flexor and slightly larger abductor moments during gait in patients compared to controls. The study was designed as a prospective cohort study (Level of Evidence II) and conducted in a biomechanics laboratory at Aarhus University, Denmark, during 2011. Participants comprised 32 dysplasia patients and 32 age and gender matched controls. Outcome measures were static peak hip flexion moment at 15, 45 and 75° hip flexion; dynamic eccentric and concentric peak hip flexion moment at 60° and 120°/second; dynamic eccentric and concentric hip abductor moment at 30° and 60°/second. Hip dysplasia patients had smaller eccentric peak flexion moments and smaller eccentric and concentric peak abduction moments at all tested velocities. Although dysplasia patients have weaker hip flexion and abductor muscles than controls, their abductor muscles are sufficiently strong to ensure normal function during gait. Hence, gait analysis alone might not reveal the true, subnormal hip joint status in dysplasia patients. We suggest that comprehensive assessment of hip joint function in dysplasia patients should include more strenuous activities than gait, particularly in young(er) patients who are likely to prefer a more active lifestyle.

Hip flexor muscle dysfunction during walking at self-selected and fast speed in patients with aortoiliac peripheral arterial disease

ObjectiveIntermittent claudication aggravates physical function and is associated with an increased risk of death in patients with peripheral arterial disease (PAD). Previous studies on kinetic parameters (joint moment and power) of lower limbs in these patients have largely focused on the decline in the ankle plantar flexor moment and power at self-selected (SS) walking speed, which may not be an optimal condition to induce claudication pain. In the present study, we investigated the abnormalities in joint kinetic parameters in patients with PAD at both SS and at fast walking speeds. MethodsWe recruited 16 patients with aortoiliac PAD (4 unilateral and 12 bilateral) and 10 healthy controls. The participants were instructed to walk at SS and fast speeds along a 7-meter walkway embedded with a force plate. Spatiotemporal parameters and joint kinetic parameters of the lower limbs during the stance phase were recorded using a three-dimensional motion analysis device. ResultsCompared with the controls, patients with PAD showed a significant reduction in their walking speed, step length, stride length, and cadence. Further, a reduction in peak hip flexor moment at fast walking speed and in peak hip flexor generation power was observed in both modes of walking. However, no significant between-group differences were observed for the peak ankle plantar flexor moment or power at either walking speed. Multiple regression analysis showed peak hip flexor generation power was a strong contributor to reduction at both SS and fast walking speeds in patients with PAD. ConclusionsPatients with aortoiliac PAD walk slowly and show reduced kinetic parameters of the hip joint at both SS and fast walking speeds. Our results suggest that hip flexor muscles may be a useful target for exercise training in patients with aortoiliac PAD.