Pitt | Swanson Engineering

Current Research

Adaptive Postural Strategies - Impact of Aging

National Institutes of Health / NIH-NIA 1 F31 AG025684

Adaptive Postural StrategiesPI: Brooke Coley
One critical requirement to avoid falling is to maintain balance in the face of unexpected and anticipated environmental hazards that perturb walking such as slipping and tripping hazards. This study is interested in understanding more about the association between aging and the ability to maintain or recover balance after a slip or a trip. We also want to explore this relationship while performing both familiar and unfamiliar tasks, e.g. walking forward and walking backward. In this study, we will repeatedly expose subjects to slipping and tripping hazards. The results of this research study may reveal differences in strategies adopted by young and older adults in efforts to maintain balance. These differences may be used to better identify those at risk of falling and to develop specific interventions improving recovery strategies and fall prevention programs among older adults to minimize fall incidence.

Biomechanics of Slips in Older Adults

National Institute for Occupational Safety and Health / R01 OH007592

Biomechanics Slips in AdultsPI: Dr. Rakié Cham
Slip and fall accidents are among the leading generators of injuries in older adults. The long-term goal of this research is to prevent slip and fall accidents among older adults. The causes of slipping are numerous and complex. In this study, we focus on human factors: the way humans walk, that is, gait biomechanics. More specifically, we will look at the differences in the way humans walk to compare individuals that slip and are able to recover balance and those that fall, the impact of strength and balance on the risk of slipping and the ability of recovering from a slip and whether slippery floor warnings affect the risk of slipping and the ability of recovering from a slip. The results of this research study will provide a better understanding of the reasons for the high incidence of slip/fall accidents among older adults. The use of this knowledge might improve fall prevention and training programs among older adults.

Medication Effects on Balance and Gait in the Normal Old

PI: Dr. Robert Nebes
The primary goal of this study is to examine whether some of the balance and gait decrements common in elderly individuals may be due to anticholinergic medications they are taking for their various medical conditions. We will give subjects several tests of attentional abilities known to be impaired by anticholinergic drugs and which are thought to contribute to balance and gait problems in the elderly. This will be followed by tasks evaluating the subjects? standing balance and gait both when performed alone and when performed concurrently with a simple cognitive task which will impose an additional demand on attentional capacity during performance of the balance/gait measures. Blood samples will be obtained to determine the participants? serum anticholinergic activity. We will examine the degree to which anticholinergic medications are associated with performance on two relevant aspects of attention.

Balance During Walking in Moving Visual Environments

PI: Dr. Rakié Cham
The goal of the proposed study is to investigate the impact of moving visual environments on balance during walking in young and older adults. Vision is one of three sensory inputs used in postural control. Our group has significant expertise in studying processes involved in the integration of visual cues to maintain balance during standing. In this pilot study, we would like to collect similar data during walking. Of particular interest are responses to visual perturbations. Postural responses of healthy young and older adults will be measured while participants view different optic flows during walking.

Modeling shoe-floor interface properties to predict slips and falls

Shoe Slip TesterPI: Dr. Mark Redfern
Slip and falls continue to be one of the leading causes of work-related injuries. The reduction of these injuries is dependent upon improved identification of slippery conditions and the design of proper shoes and floors for various environments. The long-term goal of this research project is to reduce injuries due to slips and falls in the workplace through the development of a computational model that predicts the coefficient of friction of the shoe-floor-contaminant interface. The model will be based upon: micro-level properties of the shoe-floor- contaminant interface and macrolevel designs of the shoe and floor. The micro-level model will include measurements of properties of shoes, floors and contaminants that will be combined in a computational model based upon fundamental tribological relationships. The macro-level model will incorporate the micro-level model into a finite element representation of the shoe-floor interface. Micro-level model predictions will be compared to current tribological coefficient of friction testing and macro-level model predictions will be compared to currently used shoe-floor interface slip resistance testing devices. The model predictions will also be compared to actual human slips and falls during gait to determine the efficacy in predicting slips and/or falls. If successful, this model will be able to be used in the evaluation and, more importantly, the design of shoes and floors for various environments.

Comparing microprocessor controlled prosthetic knees to conventional technologies

PI: Dr. April Chambers
The goal of the proposed research is to compare falls risk between microprocessor controlled prosthetic knee joints and non-microprocessor controlled prosthetic knee joints in older adults with unilateral transfemoral amputations. Microprocessor controlled prosthetic knee joints have been shown to improve certain aspects of gait in young adults, such as side to side symmetry, loading patterns, energy consumption, and risk of falling. However, no studies have examined older adults with unilateral transfemoral amputations to determine if the benefits of microprocessor controlled prosthetic knee joints apply to this high fall risk group. This knowledge is needed for health-care organizations to pay for these devices. A fall risk biomechanical analysis will be performed using whole-body motion capture and ground reaction forces to compare non-microprocessor controlled and microprocessor controlled prosthetic knee joints while walking on a level surface, stairs, ramps, uneven terrain and during stumbling. Clinical information and self-reported risk of falls and near falls will also be considered.

Flooring and long term walking/standing fatigue

Shoe Slip Tester PI: Dr. April Chambers
This is a pilot study to explore the feasibility of using Near Infrared Spectroscopy as an objective physiological measure of long-term muscle fatigue due to standing. Near Infrared Spectroscopy will allow us to quantify oxygenation and blood flow in lower extremity muscles over time. If Near Infrared Spectroscopy proves to be a reliable and sensitive tool, we will then use this technology to quantify the impact of flooring on long term standing muscle fatigue, to understand the underlying mechanisms of this problem in occupational settings and to relate oxygenation and blood flow measures to subjective measures of discomfort. The long term goal of this line of research is to quantify and understand the impact of flooring on the physiological, biomechanical and psychological constructs of long term lower extremity fatigue in occupational settings.

Effect of vibrotactile feedback on gait

PI: Dr. Rakié Cham
The goal of this study is to minimize the risk of falls triggered by slipping in young and older adults through the use of a wearable vibrotactile feedback device that detects onset of slip and provides cues to the wearer to generate a compensatory postural response that we have shown to maximize the chance of recovering balance after such external perturbation. Initially, we will focus on using the vibrotactile feedback device to train adults how to walk 'safely' by minimizing slip risk. In particular, as a starting point, we will focus on a fast and coordinated swing phase interruption of the trailing leg in an attempt to arrest the body’s downward descent. This will be validated in young and older healthy subjects while walking on dry floors. The influence of vibrotactile feedback on slip severity will be investigated in young adults only.

Lower extremity muscle contributions to rapid voluntary stepping in the elderly

PI: Dr. Arash Mahboobin
The primary objective of this study is to use musculoskeletal computational modeling techniques to investigate the influence of aging on lower extremity muscle contributions and coordination during anticipatory postural adjustments. Subjects will perform a stepping task that includes simple step reaction time trials where subjects will be asked to step as quickly as possible to a location forward with their left foot, in response to an auditory cue. Subjects will have knowledge of the step location prior to each auditory cue. Our modeling approach will be to conduct muscle-driven forward dynamics simulations based upon optimum tracking techniques common in musculoskeletal modeling using captured experimental data.

Effects of visual fields on standing balance and gait

PI: Dr. Rakié Cham
Age-related vision impairments are a well-acknowledged risk factor for geriatric falls. The goal of this proposed research is to determine the importance of central and peripheral vision loss on postural control during standing, walking and upper body coordination tasks in older adults. Specifically, a contact lens model with variable opacity that we have recently developed will be utilized to occlude either central or peripheral vision. This model will allow us to mimic diseases which selectively impair central (macular degeneration) or peripheral (glaucoma) visual fields. Little is known about the specific underlying mechanisms by which common age-associated vision impairments such as Age-Related Macular Degeneration and glaucoma impact postural control. The scarce literature on this topic has focused on the differences in balance/gait performance between patients and controls, or on descriptive studies of functional improvement during rehabilitation processes. This cross-sectional approach, while valuable, makes it difficult to disentangle the effects of deteriorating visual fields from secondary confounding factors associated with other sensory and balance disorders, or ocular pathologies. This gap in knowledge hinders clinical interventions and rehabilitation strategies. In this application, we propose a novel approach based on a within-subject experimental design to focus on the specific impact of deteriorating visual fields alone on balance/gait in older subjects, and also the ability to accurately and quickly manipulate small objects.

Biomechanics of slips and falls in the elderly

PI: Dr. Rakié Cham
Falls initiated by external perturbations such as slips, trips and stumbles are a serious health hazard to older workers. Experimental studies have provided a general description of postural responses to perturbations. However, causes of failed recovery attempts are challenging to disentangle through experiments alone due to the complexity of the postural control system and the significant degree of correlation among key gait variables. In summary, through experiments and simulations of slipping, this project will systematically identify aging-related biomechanical limitations that predispose older workers to slip and fall. These biomechanical limitations may be the result of underlying deficits in neuromuscular control and sensory integration but they are the ultimate cause of failed recoveries from external perturbations. This fundamental knowledge is required to plan, to develop and to implement effective deficits-targeted interventions focused on minimizing the risk of falling in the workplace.

Past Research

Anthropometrics of Aging

Pittsburgh Claude D. Pepper Older Americans Independence Center

Anthropometrics of AgingPI: Dr. Rakié Cham
Anthropometric data are needed in aging-related biomechanical investigations of postural control and gait to estimate net muscular joint torques and location of the whole body center of mass. Such information is typically estimated using anthropometric data sets based on cadaveric studies and/or proportional models using regression equations developed with body segment parameters sampled in younger adults and assuming constant body density. Estimates of body segment parameters derived using non-age specific predictive methods can be associated with significant errors in older adults. The objective of this proposed project is two-fold: to report on the magnitude of these errors and to develop preliminary regression equations providing accurate estimates of body segment parameters in older adults.

Balance and Instability: A Multidisciplinary Approach

Pittsburgh Claude D. Pepper Older Americans Independence Center/National Institutes of Health / NIH-NIAMS P30 AG024827

PI: Dr. Stephanie Studenski
This multidisciplinary project is an effort to understand causes/contributors and consequences of balance disorders in older adults, and to develop effective interventions for these disorders.

Biomechanical Stability of Pregnant Women

National Institute for Occupational Safety and Health / K01 OH008548-01

PI: Dr. Jean McCrory
Pregnant women fall at a rate similar to that of women over the age of 70. The factors that contribute to this increased risk of falling are unknown, as little research has been performed to study gait and postural stability biomechanics during pregnancy. The purpose of the proposed research study is to investigate the changes to dynamic stability during level walking, stair ascent and descent, and perturbed stance in pregnant women.

Biomechanics of Human Reactions to Slip Events

National Institute for Occupational Safety and Health / NIOSH 1 R03 OH007533

PI: Dr. Rakié Cham
The long-term goal of this research is to reduce slip and fall accidents, particularly in older adults. The causes of slipping accidents are numerous and complex. In this study, we focus on a human factor: the way humans walk, that is, gait biomechanics. More specifically, we will look at the impact of gait biomechanics on the risk of slipping and the ability of recovering from the slip. Those findings are compared between men and women, and young and older subjects. The results of this study will provide a better understanding of the reasons for the high incidence of slip/fall accidents among older adults. The use of this knowledge might improve fall prevention and training programs among older adults.

Biomechanics of slips and trips while wearing firefighting protective equipment

Firefighting Slips Study PI: Dr. Pui Kong
Falls, often induced by slips or trips, are common among firefighters. These falls not only negatively influence the quality of life among firefighters but are also costly to the society. The proposed study aims to investigate the biomechanics of slips and trips in order to pursue the long-term goal of reducing occupational falls among firefighters. Subjects will perform several balance and gait tests before and after a 20-minute fatigue protocol consisting of simulated firefighting tasks. Various kinetic and kinematic gait variables will be derived from the ground reaction forces and 3D body motion data. In summary, this proposed study will provide a better understanding of how fatigue influences slip-initiated falls among firefighters.

Computer Model of Knee

National Institute for Occupational Safety and Health

Computer Model of KneePI: Dr. Mark Redfern & Dr. Richard Debski
The goal of this work is to help reduce knee injuries during kneeling and squatting work. Knee injuries are believed to be a significant problem in mining. This is particularly true when the work is preformed in a kneeling posture. The development of a knee model for evaluation of injury potential in kneeling postures is important to reducing injuries. The specific aim of this work is to validate a computerized biomechanical model of the knee that is being developed to prevent knee injury and to determine the internal stresses in the knee from externally applied forces and moments similar to those found during the postures analyzed in kneeling and squatting work environments. The combined experimental and computational validation methodology will enable study of the stresses in the soft tissue at the knee in response to various loading conditions.

Determining the Biomechanical Characteristics of Falls

Bosch, Inc.

PI: Dr. Mark Redfern
Human balance is challenged during every day activities and for some people this task can be more difficult than others. This problem is particularly true as we age, resulting in increased falls in older adults. This aspect raises the question about the practicality of detecting a fall or even of predicting a fall before it happens to potentially avoid the consequences associated with falls. The specific aim of this small study is to gather sensor data during perturbations to locomotion. An internally induced sensory perturbation using galvanic vestibular stimulation will be used to induce sensation of loss of balance, and the postural response will be recorded using a set of miniaturized sensors placed on the body and motion capture. Such a study is very valuable for the community because it is a step forward toward a better understanding of characteristics of instability and lead towards a system that could reduce injuries and discomfort associated with falls, such as fear of falling.

Developing an Instrument to Measure Personal Keyboarding Style

National Institute for Occupational Safety and Health / K01 OH007826-01

Developing Keyboard InstrumentPI: Dr. Nancy Baker
This project is focused on developing an observational instrument (the Personal Computer Keyboard Style (PeCKS)) that can be used to identify and evaluate parameters of personal keyboarding styles that may be related to MSD-UE's. The PeCKS would provide a way to measure and identify personal work style risk factors. Development of the instrument required us to develop a method of objectively measuring personal typing style using motion measurement instruments in order to compare ratings on the PeCKS to these objective measurements. While subjects typed on a keyboard, motion and force data will be recorded. This data was used to derive various hand posture variables distance of the hands from the keyboard, and force. The findings will be compared to the ratings on the PeCKS. Researchers have commented that personal style is an important factor in MSD and yet personal style for work tasks has rarely been examined in the context of the work environment.

Development of a Balance Measure for Use Across the Lifespan

ENH Research Institute (Northwestern University)

Balance Measure for use across LifespanPI: Susan L. Whitney
Measuring how much a person sways while standing is an indicator of how easily that person might fall. There are platform machines used in balance clinics to measure this sway. Because of the size and expense, it is not practical for all clinics to have this machine. The investigators of this research study are developing a system that will be similar to the clinical balance machine but will be much smaller and easier to move. This research study will help the investigators decide what materials to use for this new system. The results from this setup will be compared to the results of the clinical balance machine.

Development of a Measure of Smoothness of Walking

Pittsburgh Claude D. Pepper Older Americans Independence Center

Dr. Jennifer Brach
The primary aim of the project is to develop a measure of smoothness of walking. Both biomechanical and neurological factors contribute to the smoothness of gait. A measure of smoothness of walking could be used to identify older persons with walking difficulty and to assess the outcomes of interventions focused on improving balance and mobility.

Development of an Ergonomic Program at the University of Pittsburgh

Environmental Health and Safety, University of Pittsburgh

PI: Dr. Rakié Cham
The purpose of this project is to assess the incidence of work-related injuries in employees of the University of Pittsburgh. Also, potential solutions to reduce the high risk of such injuries are proposed.

Ergonomics of Flooring. The Influence of Flooring on Standing Comfort and Fatigue

3M Company

Ergonomics of FlooringPI: Dr. Mark Redfern
The objective of this study is to investigate the influence of varying floor mat parameters on standing fatigue and comfort. Subjective questionnaires and physiological measures are used to evaluate these effects in the laboratory.

Evaluation of Ergonomic Keyboards

Evaulation of KeyboardsPI: Dr. Nancy Baker
The aim of this research project is to determine if using an ergonomic keyboard changes the motor performance of the wrist, hands, fingers, and thumbs during typing. Experienced keyboard users will be randomly assigned to a sequence of keyboard use on a standard keyboard or a split-angle ergonomic keyboard. After acclimating to the key, their motor performance will be captured using a Vicon motion measurement system, a Bertec force plate, and three video cameras mounted on the right, left, and overhead. Various hand posture variables, distance of the hands from the keyboard, and keying forces will be derived. In addition, the visual data will be evaluated using the previously developed PeCKS, an observational instrument that examines personal computer keyboarding style, by raters blinded to the hypothesis of the study. The changes in performance between keyboard conditions will be evaluated. The findings of this study will be used to describe the kinematics of typing and assess the effectiveness of the ergonomic keyboard.

Fear of Falling: Integrating Psychological and Gait Constructs

Pittsburgh Claude D. Pepper Older Americans Independence Center

PI: Dr. Nancy Baker
Fear of falling is common in the elderly, especially in populations with mobility impairments. Fear of falling is associated with a spiral of serious physical and psychological problems. The long term goal of this research is the development of multidisciplinary interventions centered on the integrative management of fear of falling, its psychological correlations and associated gait/mobility impairments. The purpose of this portion of the study is to understand more about how anxiety affects the way people walk and maintain their balance. We also want to understand what sort of symptoms people who report fear of falling have, with respect to anxiety and depression. In this study, we will look at anxiety symptoms and how they impair walking. The results of this research study will provide a better understanding of the causes of gait disorders including the contribution of anxiety to balance problems. This knowledge might improve fall prevention programs among older adults.

Functional Biomechanics and Obesity

PI: Dr. Jean McCrory
This study examined the relationship between function and adiposity across the spectrum of body types from normal to obese individuals. The associations between BMI and function, as well as between biomechanical movement parameters and function were examined.

Knee Stability Training in Individuals with Knee Osteoarthritis

National Institutes of Health / NIH-NIAMS 1 R01 AR048760

Knee StabilityPI: Dr. Kelly Fitzgerald
The overall aim of this project is to test the effectiveness of supplementing traditional exercise therapy with knee stability training techniques, specifically tailored for individuals with knee OA, for improving pain, physical function, and lower extremity biomechanics in individuals with knee OA. A randomized clinical trial is being conducted to compare individuals with knee OA who receive a standard exercise therapy program to those who receive the same standard program, supplemented with knee stability training techniques.

Modeling of Trips

Quality of Life Technology (QoLT) Engineering Research Center (ERC)

PI: Dr. Rakié Cham
The major goal of this project is to simulate trips in young adults using physiologically relevant controllers in an attempt to understand underlying mechanisms of failed recoveries from trips.

Trip Modeling

Neurobiological and Postural Control Mechanisms Underlying Risk of Falling

Veterans Administration / VA P01 E2869R

Neurobiological and Postural Control Mechs of FallingPI: Dr. Nicolaas Bohnen
Parkinson's disease (PD) is caused by nigrostriatal dopaminergic denervation which can be detected by neurochemical in-vivo imaging using positron emission tomography (PET). A significant role of dopamine in postural control can be implicated as PD-related falls most frequently occur during hypodopaminergic "off" states. Normal aging (no PD) is also associated with loss of dopaminergic neurons. The extent of this loss is less striking than in PD but quite variable. The purpose of this study is to look for possible reasons why some elderly persons and patients with nerve slowing or mini-strokes may be falling. The study uses a series of clinical tests to detect mild balance problems in normal elderly and in patients with neuropathy or brain white matter disease that is often seen in patients with high blood pressure. The study tests balance using a specific electronic platform device. A gait and slipping analysis is also performed. PET is used to measure dopamine activity in the brain. Finally, a diary study is completed where any near-falls or falls are documented.

Quantifying Accelerometry Based Physical Activity in Community Dwelling Older Adults: What is the Clinical Meaning Behind the Measurements?

Pittsburgh Claude D. Pepper Older Americans Independence Center

PI: Dr. Jamie Talkowski
The goal of this pilot project is to provide a further understanding of the activity counts data provided by accelerometer units used to assess physical activity. This goal will be achieved by collecting both activity counts measurements and raw acceleration data during walking and while performing activities of daily living.

Restoring Skill in Walking: A Motor Re-Learning Approach to Intervention for Older Adults with Mobility Disability

Pittsburgh Claude D. Pepper Older Americans Independence Center

PI: Dr. Jessie VanSwearingen
The purpose of this research study is to compare two different exercise treatments for walking problems in older adults. We want to determine if participation in the exercise programs for three months will improve balance, walking abilities, and confidence in walking. Adults aged 65 years or older participate in the treatment program and undergo gait evaluation and MRI.

Summer Research Training in Aging for Medical Students

National Institutes of Health / NIH-NIA 1 T35 AG026778

PI: Dr. Stephanie Studenski
The purpose of this training summer program is to engage medical students in aging research and to promote careers in aging research. The summer program is an 8-12 week intensive experience that includes an individualized research experience under a sponsoring mentor, a structured didactic experience that is directly linked to student research projects, opportunities to interact with potential role models and peers and efforts to build a sense of identity and membership for participants.