Virtual Poster Session

Welcome to the Virtual Poster Session, a new and powerful tool for networking and information exchange. Here you can share your work, search though the poster library, and start a dialogue with others in your field. Each uploaded poster that pertains to force measurement and testing can currently be used to apply for an academic travel scholarship; please see the Scholarships page for application details and deadlines.

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Name: empliner

MOTIVATION: Ladder fall injury rates are highest among older adults. While standing stability has been quantified using center of pressure (COP) to classify general fall risk of older adults, it has not been applied to older adults’ balance and performance on ladders. This study investigates the standing stability of older adults while performing a task on a ladder.

METHODS: One-hundred four older adults completed the Physiological Profile Assessment (PPA) to classify fall risk and climbed to the second step of a household step ladder to change a light bulb. Force plates under the step ladder were used to calculate the COP. COP parameters were extracted to assess stability on the step ladder including path length (time-normalized), RMS and elliptical area.

Task time and COP parameters were compared between 10 participants with the highest fall risk and 10 participants with the lowest fall risk based on the PPA.

RESULTS: Task time was 8.4 seconds (63.9%) longer for the high fall risk group. Time-normalized path lengths were similar between the two groups. The high fall risk group showed an increase in RMS by 18.1% and elliptical area by 44.6%.

CONCLUSIONS: Differences in tasks time, RMS and elliptical area were observed between low and high fall risk groups. Larger RMS values and elliptical area indicate more movement away from the average COP location. This suggests high fall risk older adults to be more variable than low fall risk older adults in their standing stability when completing a task on a step ladder.

Name: priya28dharshini

Gait is influenced by peripheral circulation and neuro musculoskeletal system which can be affected by diabetes. Gait variations play an important role in increasing the peak plantar pressure in persons with diabetes. Biomechanical alterations in diabetic neuropathy could facilitate foot injuries, thus contributing to foot ulceration [1]. Understanding the gait characteristics in different category of diabetic population during walking can reveal the biomechanical factors which may collectively lead to foot pathology.
3-Dimensional (3D) Gait analysis was performed on 28 subjects with similar age, height, weight and Body Mass Index (BMI) (p > 0.05) with diabetes and without neuropathy (D), persons with diabetic neuropathy (DN) and persons who had a history of foot ulcer (DHU). Spatial and Temporal gait parameters along with kinematics and kinetics were compared between the three groups.
The lower extremity gait data shows that DHU subjects show increased hip flexion throughout the gait cycle with delay in peak extension and DN subjects showing a slight delay in achieving peak hip extension. DHU show a significant deviation in hip, knee and ankle mechanics when compared to other two groups. There is a slight increase in dorsiflexion among diabetic subjects during the mid - stance phase. The ground reaction force (GRF) graphs shows that the breaking force and propelling force is less in magnitude for all the three groups when compared to normal. The vertical GRF data reveals there is no significant difference among the three groups but the graph shows delayed heel rocker during the gait.
The compensation gait observed in DHU group may be due to the muscle weakness acquired in the past when there was active foot ulcer. This altered compensatory gait observed in DHU participants need to be addressed using proper corrective footwear and gait training sessions for preventing recurrence of ulcer.
[1] Katoulis EC, Ebdon-Parry M, Lanshammar H, Vileikyte L, Kulkarni J, Boulton AJM. Gait Abnormalities in Diabetic Neuropathy. Diabetes Care. 1997 Dec; 20(12): 1904-1907.
1. M. V. Hospital for Diabetes, Royapuram, Chennai
2. CSIR – Central Leather Research Institute and Department of Science and Technology, India

Listed In: Gait
Name: Nicholas_Romanchuk

ACL injury mechanisms are commonly determined from evidence gathered during highly controlled lab-based activities. However, many non-contact ACL ruptures occur following a reaction to an external stimulus, when athletes are unable to pre-plan their movement strategy1. The purpose of this study was to determine if unanticipated drop-jump landing altered lower-limb biomechanics.

Ten participants performed two counter-balanced single-leg drop-jump landing conditions (anticipated and unanticipated). Unanticipated landings were conducted by randomly displaying either a left or right arrow immediately following jump takeoff. The visual cue was triggered by the participant making contact with a force platform, set at a threshold of 10N. Three-dimensional kinematic and kinetic data for the ankle, knee and hip were time-normalized over the jumping and landing phase and with-in participant averaged over the successful trials. Paired sample t-tests, using Statistical Parametric Mapping, evaluated between condition differences over the jumping and landing phases (α = 0.05).
Participants landed with significantly greater hip abduction (p=0.004) during the unanticipated condition over the entire landing phase (0-100%). Participants also landed with significantly less hip external rotation (p=0.048) over the final 17% of the landing phase.

Although no differences were identified at the knee joint, participants landed with greater hip abduction and less external rotation when the movement was unaticipated. Given that proximal factors play a contributing role towards controling knee mechanics, the altered hip position could be a compensatory strategy to limit knee abduction and reduce ACL injury risk during unanticipated tasks2.

1. Olsen et al. AJSM 2004;32(4):1002-1012
2. Powers JOSPT 2010;40(2):42-51

Listed In: Biomechanics
Name: WYL

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
Name: geokrik

Accurate measurements of tendon mechanics are necessary for biomechanists when trying to identify injury risk factors, optimise athletic performance and develop musculoskeletal models. Measuring Achilles tendon (AT) mechanics dynamically is now possible by combining motion capture and ultrasound (US). The aim of this study was to quantify sources of error when measuring AT length using motion capture and US, and establish their effect on calculated strain values. Errors in AT insertion tracking and data synchronisation caused differences in AT length and moment arm of 5.3 ± 1.1 mm and 11.2 ± 0.9 mm, respectively; this decreased calculated AT peak strain from 11.6 ± 3.5% to 5.4 ± 2.5%. These differences could significantly impact a researcher‘s interpretation of the effects of footwear, technique, and specific kinematics on AT loading.

Name: noelletuttle

Generalized joint laxity (GJL) is a condition in which most joints of the body move beyond the accepted normal range of motion. It allows for greater flexibility, which is beneficial to sports such as dance, but can lead to musculoskeletal injuries and decreases in strength. The ability to control landings with strength and stability is key to high level dance performance. Therefore, the purpose of this study was to evaluate differences in peak ground reaction force (GRF; vertical, medial-lateral, and anterior-posterior), during landing between dancers with and without GJL. Twenty healthy female volunteers with experience in ballet or modern dance were screened for GJL using the Beighton Scale. 10 subjects with GJL (score of 6 or higher) and 10 without GJL (score of 3 or below) were selected for testing. Subjects performed three forward, unshod, single-leg drop landings from a height of 40 cm onto a portable force plate (Bertec Corporation, OH, USA). Peak GRF for each landing was found and averaged for each subject, and for each group. No significant differences were found in peak GRF in any direction (p=0.71). We believe the similarity in peak forces between groups is due to dancers’ training and technique, as dancers are expected to control and soften their landings. GRF provides information about the load placed on the body, but lacks details related to landing technique. Further research describing 3D landing kinematics, joint moments, and muscle activation is required to determine if different landing techniques exist between dancers with and without GJL.

Listed In: Biomechanics
Name: DKingston

When performing high knee flexion movements (>120º), thigh-calf (TC) and heel-gluteal (HG) structures come into contact and transmit force between segments. Previous work has only assessed the effect of these forces on net external knee joint forces and moments in the sagittal plane. Therefore, the purpose of this study was to quantify the effect of incorporating the 3D location and orientation of TC and HG force vectors on external forces and moments acting on the knee. Sixteen participants (8 M/F) completed five repetitions of six high-flexion movements. Kinematics, kinetics, and pressure distribution (of TC and HG contact) were measured from the right lower limb. Inverse dynamics were calculated with and without TC and HG force, to determine the change in magnitude. During high knee flexion movements, there was a significant reduction in AP forces (~50%) and F/E moments (~27%) as a result of considering contact between lower limb segments. Novel to this study was the ability to account for the 3D force vector and CoF location of TC and HG by tracking the motion of the pressure mat allowing the effect on frontal plane moments to be determined. There was a significant increase in the Ab/Ad moment (~60% in two movements) which is a known risk factor for knee osteoarthritis development. These results will improve the biofidelity of future high flexion musculoskeletal models of the knee. Future work is required to determine if findings from this young and healthy population translates to occupational or individuals that habitually kneel.

Listed In: Biomechanics
Name: brunobedo

Fatigue is a case of interaction between different factors and is characterized by the increase in the perceived effort to exercise and produce force. However, the effect on balancing tasks are not completely understood, especially the time course of the postural sway parameters during the recovery phase. Twenty female handball athletes participated in this study. They stood upright in a one-leg posture supported by the non-dominant limb on a force plate. The center of pressure (COP) and the maximum propulsion force (FMAX) were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase. For the postural-sway measures, participants stood on the force plate for 30 s with eyes opened looking to a target. Based on the COP displacement, the ellipse area containing 95% of the COP data points (Area) was computed. The FMAX was measured during a countermovement jump. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. The force decreased ~9.5% after the fatigue protocol (p = 0.01) and returned to baseline values during the recovery phase at the fifth minute. For the postural sway, the Area decreased during the recovery phase until the fourth minute (p = 0.007). The fatigue protocol affected postural sway and force variables, which returned to baseline values after four minutes of the protocol. Therefore, we suggest that future fatigue analyses should be tested during this time window.

Name: Gina DiGiacomo

When evaluation cognition, there is a certain complexity surrounding electroencephalographic (EEG) recordings, which would greatly benefit from being supplemented by secondary recordings, such as those from a force platform. Currently, there is also a lack of evidence supporting the need to implement creative exercise on analytical coursework, specifically in STEM degrees where there is gaining momentum to incorporate the arts [3]. This pilot study aims to correlate electroencephalography (EEG, Brain Vision) and postural sway (AMTI AccuSway) data to verify cognitive changes. This study hypothesizes that participants will have 1) increased EEG alpha activity and 2) increased postural sway when participating in iterations of a problem-solving tasks administered after the participant engages in creative activities. The study will use human-subject data gathered from electroencephalography (Brain Vision) and postural sway (AMTI AccuSway) to quantify the cognitive engagement of participants during the learning of new concepts in a unique manner that allows the participants to think about them visually. The hypothesis is that the teaching methods introduced will encourage participants to have increased cognitive attention. Two participants were evaluated on their postural sway and EEG activity during the answering of Raven’s Progressive Matrices tests before and after artistic viewing and drawing activities. The data generated by this study by these means will show that increased cognition is apparent when concepts are presented in a visual manner, fortifying a philosophy that engineering curricula would benefit from artistic additions.

Name: nlaw098

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.