Publications by authors named "J R Franz"

Introduction: Individuals with anterior cruciate ligament reconstruction (ACLR) often walk with a less dynamic vertical ground reaction force (vGRF), exemplified by a reduced first peak vGRF and elevated midstance vGRF compared to uninjured controls. However, the mechanism by which altered limb loading affects actual tibial plateau contact forces during walking remains unclear.

Methods: Our purpose was to use musculoskeletal simulation to evaluate the effects of first peak vertical ground reaction force (vGRF) biofeedback on bilateral tibiofemoral contact forces relevant to the development of post-traumatic osteoarthritis (OA) in 20 individuals with ACLR.

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Shoes or insoles embedded with carbon fiber materials to increase longitudinal stiffness have been shown to enhance running and walking performance in elite runners, and younger adults, respectively. It is unclear, however, if such stiffness modifications can translate to enhanced mobility in older adults who typically walk with greater metabolic cost of transport compared to younger adults. Here, we sought to test whether adding footwear stiffness via carbon fiber insoles could improve walking outcomes (eg, distance traveled and metabolic cost of transport) in older adults during the 6-minute walk test.

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Background: Structural malalignments, such as talar malalignments and hindfoot varus, are hypothesized to contribute to early ankle joint degeneration by altering joint contact force (JCF). These malalignments, common in individuals with chronic ankle instability (CAI), can modify the articular geometry of the ankle joint, potentially leading to abnormal joint loading patterns. This study leverages musculoskeletal modeling and simulation to conceptualize the effects of increasing severity of these malalignments on ankle JCF during walking.

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Background: Older adults walk with a diminished foot and ankle push-off compared to younger adults and this difference may be a target for assistive devices. Dynamic mean ankle moment arm (DMAMA) is an aggregate measure of foot and ankle control that varies in younger adults across walking speeds and inclines.

Research Question: Does age affect DMAMA across a range of walking tasks designed to challenge power output from the ankle and foot?

Methods: We enrolled 12 healthy younger adults and 10 healthy older adults.

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Rehabilitation to prevent falls should not only directly address intrinsic and extrinsic factors, but also the neuropsychology of falls to promote safe and independent mobility in our aging population. The purpose of this study was to determine the relation between falls self-efficacy and objective responses to a series of walking balance perturbations. 29 healthy younger adults and 28 older adults completed four experimental trials, including unperturbed walking and walking while responding to three perturbations: mediolateral optical flow, treadmill-induced slips, and lateral waist-pulls; and three self-reported questionnaires: Activity-specific Balance Confidence, Falls Efficacy Scale, and the Fear of Falling Questionnaire-Revised.

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