Gait

Quantifying stair gait stability and plantar pressure in an aging community, with modifications to insoles and lighting

Introduction: Stair gait is an activity performed daily. Inherently falls during stair gait continue to be a concern especially for older adults 65 years +. Recently falls have become the most common cause of injury-related deaths in individuals over the age of 75 y.o. Stair descent falls account for 75% of stair falls and also present a greater injury severity. Poor shoes or insoles and lighting condition can contribute to an increased risk of falls during stair locomotion. Stability can be measured using the COM-BOS ‘stability margin’ relationship. Center of pressure (COP), another stability measure,can be calculated from a multi-axis force-plate system. As well, plantar pressure is an important indicator of gait pattern efficiency. Aim: To identify aspects of stair gait that increase the risk of falls. By measuring the COM-BOS ‘stability margin’, the COP and plantar pressure patterns of individuals during stair gait, while modifying insoles and lighting. Methods: Young and older adults will ascend and descend a 4 level staircase, with two imbedded AMTI-force platforms in varying lighting condition (low, normal). Participants will be fitted with standardized footwear with Medi-logic insoles placed under varying hardnesses of insoles. An Optotrak motion capture system will record 12 IRED markers placed on the individual to determine the COM trajectory and BOS of location. Hypothesis: Partipants should demonstrate a greater lateral displacement in the single support phase during dim lighting as opposed to normal lighting. The stability of older adults will be compromised with alteration to the insoles (soft and hard).


Listed In: Biomechanics, Gait, Other


Kinetics and kinematics of the lower extremity during performance of two typical Tai Chi movements by the elders

Tai Chi (TC) has the rehabilitative potential to prevent falls in the elderly, however it is unclear how TC training improves postural control capacity. Fifteen male participants with more than 4 years of TC experience were asked to perform two TC movements, the “Repulse Monkey (RM)” and “Wave-hands in clouds (WHIC).” Three-dimensional (3-D) temporospatial, kinematic and kinetic data was collected using VICON motion analysis system with 10 infrared cameras and 4 force plates. Stride width, step length, step width, single- and double-support times, center of mass (COM) displacement, peak joint angles, range of motion, peak joint moments, time to peak moment, and ground reaction force (GRF) were analyzed. The differences in the measurements of the two TC movements were compared with walking using two-way ANOVA analysis. Compared with walking kinematics, both TC movements spent less time in single-support; RM and WHIC had larger mediolateral and vertical displacement of the COM. Compared with walking kinetics, both TC movements generated significantly smaller peak ground reaction forces in all directions, except the anterior; larger hip extension, adduction and internal rotational moments, knee adduction/abduction and internal rotation moments and eversion/inversion and external/internal moments of ankle–foot; and longer peak moment generation time for hip extension, adduction and internal rotation, knee extension and ankle dorsiflexion and inversion. The slow, gentle stepping-action and loading patterns that are consistent with the mechanical behavior of biological tissues. These two TC movements would be suitable training to help strengthen the lower extremities and prevent falls in the elderly.
Listed In: Biomechanics, Gait, Sports Science


Gait variability in patients with COPD during a self-paced 6-minute walk test

Patients with chronic obstructive pulmonary disease (COPD) have an increased fall risk [1] and demonstrate gait deficits [2,3]. Gait variability has been associated with increased fall risk in the aging population [4]. However, studies reporting gait variability in COPD are scarce. Therefore, we aim to assess gait variability in patients with COPD during the 6-minute walk test (6MWT). Eighty patients with COPD (62±7yrs; FEV1:56±19%pred.) and 39 healthy subjects (62±6yrs; FEV1:119±17%pred.) performed two self-paced 6MWTs while kinematic parameters were recorded (100Hz, Vicon). The amount (coefficient of variation; CoV) and structure (sample entropy; SE) of variability of stride time, stride length and step width, and local divergence exponent (LDE) of the centre of mass velocity (CoMv) in three directions were computed. The sub-analysis accounted for gait speed influences on gait variability between groups. Stride time was longer (MD:0.13s, p<0.001) and stride length was smaller (MD:-0.30 m, p<0.001) in COPD. CoV for stride length was increased (MD:1.8%, p<0.001) and stride length SE was lower in COPD (MD:0.21, p<0.001). LDE for CoMv differed in vertical (MD: -0.12, p=0.001) and anteroposterior direction (MD: 0.10, p=0.017). The CoV for stride length remained higher in COPD (MD:1.0%, p=0.003) and stride length SE remained lower in COPD (MD:-0.12, p=0.011), after the sub-analysis of 14 patients with COPD and 14 healthy subjects with comparable walking speeds (MD:-0.02m/s, p=0.588). Patients with COPD demonstrate alterations in the amount and structure of variability in stride length, indicating alterations in the control of stride length variability patterns.
Listed In: Biomechanics, Gait


INFLUENCE OF AGE AND GENDER ON INTERLIMB ASYMMETRY IN RECREATIONAL RUNNERS

INTRODUCTION:Previous studies have reported that men and women demonstrate distinctly different biomechanics during running and that older runners use a variety of biomechanical adaptations compared with younger runners. It is hypothesized that excessive asymmetry due to biomechanical and anatomical abnormalities contributes to increased risk of injuries, however it is still unclear how age and gender might impact this.METHODS: A cross sectional study was employed and healthy recreational runners were categorized into four groups based on age and gender.Two-way multivariate analysis of variance was performed with age and gender as factors and Symmetry Angle values for peak hip adduction angle (HA), peak knee adduction moment (KAM), peak knee flexion angle (KF), and peak vertical ground reaction force (VGRF) were used as the dependent variables. RESULTS: Overall, gender had a significant effect on HA asymmetry (p=0.02) and both gender and age showed a significant interaction effect on KAM asymmetry (p=0.04).CONCLUSIONS:This study suggests that interlimb asymmetry in running gait for KAM and HA also differs with aging and gender.Understanding age and gender related adaptations in interlimb asymmetry will help improve running performance and develop programs aimed at reducing injury rates.
Listed In: Biomechanics, Gait, Orthopedic Research


Association of isometric hip and ankle strength with frontal plane kinetics in females during running

Frontal plane mechanics have been associated with running-related injuries such as patellofemoral pain. Strengthening and gait retraining programs aimed at reducing hip adduction during running have been shown to be effective at alleviating symptoms, however evidence of their effect on running kinematics is equivocal. It is possible that such programs exert their benefits through altering kinetics rather than kinematics in the frontal plane during running. Further, the contributions of the ankle to frontal plane mechanics have not been well studied. PURPOSE: To determine if hip and ankle strength are associated with frontal plane kinetics in female runners. METHODS: 64 healthy women running at least 16km per week participated in this study. Isometric hip abduction and ankle inversion strength were measured using a handheld dynamometer. 3D gait analysis was conducted as participants ran on an instrumented treadmill at 2.7 m/s. Participants were ranked in order of isometric strength of both the hip and ankle, and divided into tertiles of high, medium and low strength. 2-way MANOVA was used to determine the relationship between strength and peak moment, positive work and negative work in the frontal plane of the hip and the ankle. Tukey post-hoc tests were conducted where applicable (α=0.05). RESULTS: There was no significant interaction effect, or main effect of hip strength. There was a significant main effect of ankle strength on frontal plane kinetics (p=0.024). Specifically, the strong ankle group compared to the weak ankle group had significantly greater magnitude of peak ankle inversion moment (0.95(0.32) vs 0.68(0.22) Nm/kg, p=0.033), hip abduction moment (-2.78(1.02) vs -1.88(0.24) Nm/kg, p=0.002) and hip frontal plane positive work (0.27(0.19) vs. 0.13(0.03) W/kg, p=0.006). CONCLUSION: Isometric ankle but not hip strength is associated with kinetics in the frontal plane during running in females. Thus ankle strength should not be overlooked in clinical evaluation and treatment of runners.
Listed In: Biomechanics, Gait, Physical Therapy, Sports Science


QUADRICEPS IMPAIRMENT IS ASSOCIATED WITH KNEE MECHANICS DURING GAIT IN OBESE YOUNG ADULTS

Background: Approximately 33% of the adult population in the United States is considered obese (28), which increases the risk of comorbidities such as osteoarthritis (OA) (34). The most notable feature of OA is the loss of articular cartilage within a joint, resulting in pain and physical disability (3). The association between obesity and OA is due to a combination of mechanical and metabolic factors (3). Greater weight from obesity adds stress to articular cartilage in weight-bearing joints, and contributes to cartilage breakdown (21). Previous studies have demonstrated an association between gait biomechanics and OA in older populations (15, 25), but data are lacking in young obese individuals without OA. Young obese compared to normal weight adults have lesser knee flexion excursion (KFE) (31), and greater vertical loading rates (vLR) during gait (30, 31). However, the source of aberrant gait mechanics in obese adults is unclear, and could be related to impaired shock attenuation from weakened musculature in the lower extremity. Obese young adults have deficits in quadriceps function after normalizing to fat-free mass, and walk slower compared to normal weight young adults. RTD was moderately associated with KEM at habitual gait speed, and KEM was also lesser in obese compared to normal weight adults. The lesser KEM in the obese group suggests that obese young adults walk with a quadriceps avoidance gait, which may contribute to knee OA development. Exercise interventions targeting RTD may be useful for improving walking mechanics in obese adults.
Listed In: Biomechanics, Gait, Orthopedic Research


More Push from your Push-Off: Joint-Level Modifications to Modulate Propulsive Forces in Old Age

Even prior to walking slower, older adults walk with a diminished push-off – decreased propulsive forces (FP) accompanied by reduced ankle moment and power generation. The purpose of this study was to identify age-related differences in the joint-level modifications used to modulate FP generation during walking. We posit that there are two possibilities for older adults to enhance FP generation. First, older adults may increase ankle power generation and thereby alleviate compensatory demands at the hip. Alternatively, older adults may opt to exacerbate their distal to proximal redistribution by relying even more on the hip musculature. 10 healthy young adults and 16 healthy older adults participated in this study. Subjects walked at their preferred speed while watching a video monitor displaying their instantaneous FP while instructed to modify their FP to match target values representing normal and ±10% and ±20% of normal. For all trials, we estimated lower extremity joint kinematics and kinetics. During normal walking, older adults exerted smaller FP and ankle power than young adults. Enhancing FP via biofeedback alleviated mechanical power demands at the hip, without changes in ankle power. Further, older adults walked with increased FP without increasing their total positive joint work. Thus, given the same total requisite power generation, older adults got ‘more bang for their ankle power buck’ using biofeedback.
Listed In: Biomechanical Engineering, Biomechanics, Gait


VERTICAL GROUND REACTION FORCES DURING UNEXPECTED HUMAN SLIPS

Falls due to slippery conditions are among the primary causes of disabling workplace injuries. Despite the extensive amount of human slip studies in the literature, only a handful of studies have reported ground reaction forces at the instant of slip initiation. The purpose of this study was to quantify the vertical ground reaction forces (VGRF) at slip initiation during unexpected human slips across different footwear-contaminant conditions. Forty-seven healthy subjects were unexpectedly exposed to a liquid–contaminant, while the vertical force was measured at the moment that the foot began to start slipping. The average VGRF were between 100 and 300 N and varied significantly across the footwear. These forces were significantly less than the typical forces (400-700 N) applied during slip-resistance measurements. This finding may suggest that available coefficient of friction (ACOF) measurements should use lower force levels in order to achieve higher relevance to the onset of slipping.
Listed In: Biomechanics, Gait


EFFECTS OF STRENGTH AND PROPRIOCEPTIVE EXERCISES ON WALKING ENERGETIC PATTERNS IN CHRONIC ANKLE INSTABILITY

Chronic ankle instability (CAI) patients often exhibit altered walking mechanics, due to strength and proprioceptive deficits associated with CAI. Reduced strength and proprioception function may alter walking energetic patterns, by reducing energy absorption and generation capability. It is unclear whether strength and proprioceptive training can affect walking energetics for CAI patients. PURPOSE: To examine the effect of a 6-week ankle and hip rehab program on ankle, knee, and hip joint energetic patterns during walking in CAI patients. METHODS: 15 CAI patients (23 ± 2 yrs, 178 ± 8 cm, 76 ± 9 kg, 83 ± 7% FAAM ADL, 56 ± 10% FAAM Sports, 3.6 ± 1.1 MAII, 4.7 ± 2.0 ankle sprains) performed ankle and hip strength and proprioceptive exercises (i.e., theraband, wobble board, etc.) 3 times per week, for 6 weeks (rehab group). 14 CAI patients (22 ± 2 yrs, 177 ± 9 cm, 75 ± 12 kg, 81 ± 9% FAAM ADL, 56 ± 12% FAAM Sports, 3.4 ± 1.2 MAII, 5.9 ± 3.3 sprains) performed no rehab exercises (control group). We measured ankle, knee, and hip joint power during walking for all patients before and after 6 week duration. Functional statistics (α = 0.05) were used to evaluate the influence of the rehab exercises on joint power for both groups across the entire stance phase of walking. RESULTS: The rehab intervention resulted in up to 0.07 W/kg more positive ankle power (concentric) between 19 and 26% of stance and up to 0.06 W/kg more positive knee power (concentric) between 40 and 48% of stance. No changes were detected in hip joint power during the stance phase of walking. CONCLUSION: Strength and proprioceptive training resulted in an improved gait energetic efficiency via increased ankle and knee power generation during mid-stance. As greater muscular strength can lead to an increase in power absorption and generation, the intervention focusing on strength could be beneficial in improving walking energetics in a CAI population.
Listed In: Biomechanics, Gait


Characterising gait over different walking speeds in patients with bilateral vestibular loss: preliminary results

Bilateral vestibular hypofunction (BVH) is a bilateral reduction or loss of vestibular function resulting in balance deficits and an increased falls risk. As part of a larger study, this experiment aimed to assess how spatiotemporal gait characteristics and their variability change across different walking speeds in patients with BVH. Nine patients (55±15y) with BVH have participated thus far. Experiments were conducted on the CAREN Extended system (Motekforce Link, Amsterdam, The Netherlands). Following multiple familiarisation trials, the participants completed five recorded two minute walking bouts at different speeds (0.6m/s, 0.8m/s, 1.0m/s, 1.2m/s and 1.4m/s). 60 strides per speed were analysed and the means, standard deviations and coefficients of variation (CV) of stride length and time, step length and width, double support time and swing phase toe clearance were calculated. Stride length, step length and toe clearance all increased with increases in walking speed (P<0.001). Stride and double support time decreased with increased walking speed (P<0.0001). No walking speed effect was found for step width (P=0.25). Significant reductions in variability with increases in walking speed were found for stride length, stride time, step length, toe clearance (P<0.01) and double support time (P<0.05). A significant increase in step width variability was observed with increases in walking speed (P=0.0033). These preliminary data suggest that while anteroposterior gait characteristics may improve in terms or variability with increases in walking speed in these patients, mediolateral motions may become more variable, which may have implications for mediolateral stability and falls risk in patients with BVH.
Listed In: Biomechanics, Gait, Neuroscience