RESEARCH

CURRENT PROJECTS

Integration of Biomechanics-based Informatics for Prevention of Stress Fractures

We were recently awarded a 3-year grant from the Pac-12 to study stress fracture risk in
student-athlete distance runners. Our goal is to develop a system to identify individuals at
highest risk of developing stress fractures. The project will supplement what is typically known
about a student-athlete (training volume/intensity, overall health) with new insights from
biomechanical measures, and integrate the data into a collaborative system for analysis and
knowledge discovery. Outcomes will provide novel and effective tools to guide sports medicine
and coaching decisions that can be incorporated at other Pac-12 schools. In coordination with
current best practices, we will monitor stress fracture risk factors among distance runners at four
Pac-12 Universities (Oregon, Colorado, Stanford and USC) over a three-year period. Foot-
contact forces, accelerations and motion patterns will be monitored throughout the year. With
these data, we will develop an integrated and accessible informatics system that identifies
individuals at risk so that existing program resources can be more effectively utilized, bringing
the Pac-12 to the frontier of informatics-based training and injury prevention. This development
project will result in an integrated, multifactorial approach that leverages existing expertise and
resources to prospectively identify risk factors associated with overuse injuries. Additionally, the
measurement system and analysis approach will be designed to ease implementation in other
collegiate sports, particularly those which involve running for conditioning.

Increasing Forefoot Function to Improve Performance in Distance Runners

Evan Day, M.S.                                                                                                  IIIIIII     

The forefoot serves as the base of support and as a contributor to forward propulsion once the heel lifts off the ground during stance phase. Changes in foot-shoe complex stiffness can alter the ground reaction force lever arm, affecting the mechanics and energetics of the lower extremity. The purpose of this project is to investigate and optimize how modulating MTP joint stiffness via intrinsic (strength training of the toe-flexor musculature) and extrinsic (footwear midsole modifications) factors affects mechanics and energetics of the foot, spatiotemporal parameters, and metabolic cost while running at different speeds. The end goal of this project is to have a better understanding of how to optimize forefoot function to help distance runners improve performance.

A Simulation Based Framework for Informing Prosthetic Foot Design

Mike McGeehan, M.S.

Passive foot-ankle prostheses are designed to replace the energy absorption and propulsion functions of a lost limb. Traditionally, these devices are prescribed based on the anthropometrics and activity level of the wearer. This prescription process may lead to a mismatch between the mechanical properties of the prosthetic device and the biomechanical gait characteristics of the wearer. This dissertation aims to explore the utility of OpenSim biomechanical gait simulations for informing prescription and design of foot-ankle prostheses. The goals of this project include developing a limb loss-specific gait model, using optimal control simulations to determine the ideal stiffness of a foot-ankle prosthesis for improving kinematic and kinetic gait symmetry, and ultimately to deploy these methods in laboratory and clinical testing.

Development of Flexible Control Systems for Assistive Devices

Seth Donahue, M.S.

Seth is interested in the fusion of different machine learning methodologies to implement into the control systems of assistive devices.  Current work includes the use of the beta process autoregressive-hidden Markov model to estimate gait events and locomotion transitions from minimal sensor data in ecological environments.  He is also interested in how to deal with missing sensor data with artificial neural networks, and non-linear dynamical systems and their measures of variability, specifically to explore the connections between non-linear variability measures and predictions from machine learning algorithms.

Projects in Development

Ola Adeniji, M.S.

O’s interest encompasses athletic training assessment, athletic performance analysis, and injury prevention during high level athletic movements in sports such as track. A focus with respect to training approaches, training components, and the implementation of components that lend themselves to proper neuromuscular responses and adaptations will be considered. By doing so, the mechanisms with which aspects such as strength, power, and velocity are generated and applied will be analyzed biomechanically in order to foster optimal performance results.

PAST DISSERTATION PROJECTS

Lower Extremity Joint Stiffness, Energy Generation, and Transfer in Walking and Running Gait

Li Jin, Ph.D.                                                                                               

Jin L & Hahn ME. Modulation of lower extremity joint stiffness, work and power at different walking and running speeds. Human Movement Science. 58:1-9. 2018.

Variability of Practice and its Application to Locomotor Adaptation

Jake Hinkel-Lipsker, Ph.D.

Hinkel-Lipsker JW & Hahn ME. Coordinative structuring of gait kinematics during adaptation to variable and asymmetric split-belt treadmill walking – A principal component analysis approach. Human Movement Science. 59, 178-192. 2018

Hinkel-Lipsker JW & Hahn ME. Contextual interference during adaptation to asymmetric split-belt treadmill walking results in transfer of unique gait mechanics. Biology Open. bio.028241. 2017.

Hinkel-Lipsker JW & Hahn ME. The effects of variable practice on locomotor adaptation to a novel asymmetric gait. Experimental Brain Research 235(9), 2829-2841, 2017.

Hinkel-Lipsker JW & Hahn ME. Novel kinetic strategies adopted in asymmetrical split-belt treadmill walking. Journal of Motor Behavior 48(3), 209-217, 2016.

Hinkel-Lipsker JW & Hahn ME. A method for automated control of belt velocity changes with an instrumented treadmill. Journal of Biomechanics 49(1), 132-134, 2015.

Analysis of Unique Myoelectric Characteristics in Lower-Extremity Musculature during Locomotive State Transitions

Bryson Nakamura, Ph.D.

Nakamura BH & Hahn ME. Myoelectric Activation Pattern Changes in the Involved Limb of Individuals With Transtibial Amputation During Locomotor State Transitions. Archives of Physical Medicine and Rehabilitation 98(6), 1180-1186, 2017.

Nakamura BH & Hahn ME. Myoelectric Activation Differences in Transfemoral Amputees During Locomotor State Transitions. Biomedical Engineering: Applications, Basis and Communications. 28, 1650041, 2016.

Other Publications:

Jin L, Adamczyk PG, Roland M, Hahn ME. The effect of high and low-damping prosthetic foot structures on knee loading in the uninvolved limb across different walking speeds. Journal of Applied Biomechanics, 32, 233-240, 2016.

Ohm K, Hahn ME. The Effect of Stimulus Timing on Unplanned Gait Termination. Journal of Applied Biomechanics, 32(4), 388-393, 2016.

Resseguie SC, Jin L, Hahn ME. Analysis of Dynamic Balance Control in Transtibial Amputees with use of a Powered Prosthetic Foot. Biomedical Engineering: Applications, Basis and Communications. 28, 1650011, 2016.

Joshi D, Hahn ME. Terrain and Direction Classification of Locomotion Transitions Using Neuromuscular and Mechanical Input. Annals of Biomedical Engineering. 44(4), 1275-1284, 2016.

Joshi D, Nakamura BH, Hahn ME. High energy spectrogram with integrated prior knowledge for EMG-based locomotion classification. Medical Engineering & Physics. 37(5), 518-524, 2015.

Joshi D, Nakamura BH, Hahn ME. A Novel Approach for Toe off Estimation During Locomotion and Transitions on Ramps and Level Ground. IEEE Journal of Biomedical and Health Informatics. 20(1), 153-157, 2014.