@article{HagoortVuillermeHortobagyietal.2022,
  author    = {Hagoort, Iris and Vuillerme, Nicolas and Hortob{\´a}gyi, Tibor and Lamoth, Claudine J. C.},
  title     = {Outcome-dependent effects of walking speed and age on quantitative and qualitative gait measures},
  series = {Gait \& posture},
  volume    = {93},
  journal   = {Gait \& posture},
  publisher = {Elsevier},
  address   = {Clare},
  issn      = {0966-6362},
  doi       = {10.1016/j.gaitpost.2022.01.001},
  pages     = {39 -- 46},
  year      = {2022},
  abstract  = {Background: Walking speed predicts many clinical outcomes in old age. However, a comprehensive assessment of how walking speed affects accelerometer based quantitative and qualitative gait measures in younger and older adults is lacking. Research question: What is the relationship between walking speed and quantitative and qualitative gait outcomes in younger and older adults? Methods: Younger (n = 27, age: 21.6) and older participants (n = 27, age: 69.5) completed 340 steps on a treadmill at speeds of 0.70 to a maximum of 1.75 m.s(-1). We used generalized additive mixed models to determine the relationship between walking speed and quantitative (stride length, stride time, stride frequency and their variability) and qualitative (stride regularity, stability, smoothness, symmetry, synchronization, predictability) gait measures extracted from trunk accelerations. Results: The type of relationship between walking speed and the majority of gait measures (quantitative and qualitative) was characterized as logarithmic, with more prominent speed-effects at speeds below 1.20 m.s(-1). Changes in quantitative measures included shorter strides, longer stride times, and a lower stride frequency, with more variability at lower speeds independent of age. For qualitative measures, we found a decrease in gait symmetry, stability and regularity in all directions with decreasing speeds, a decrease in gait predictability (Vertical, V, anterior-posterior, AP) and stronger gait synchronization (AP-mediolateral, ML, AP-V), and direction dependent effects of gait smoothness, which decreased in V direction, but increased in AP and ML directions with decreasing speeds. We found outcome-dependent effects of age on the quantitative and qualitative gait measures, with either no differences between age-groups, age-related differences that existed regardless of speed, and age-related differences in the type of relationship with walking speed. Significance: The relationship between walking speed and quantitative and qualitative gait measures, and the effects of age on this relationship, depends on the type of gait measure studied.},
  language  = {en}
}
@article{HeroldTheobaldGronwaldetal.2022,
  author    = {Herold, Fabian and Theobald, Paula and Gronwald, Thomas and Rapp, Michael A. and M{\"u}ller, Notger Germar},
  title     = {Going digital - a commentary on the terminology used at the intersection of physical activity and digital health},
  series = {European review of aging and physical activity},
  volume    = {19},
  journal   = {European review of aging and physical activity},
  publisher = {Springer},
  address   = {Berlin ; Heidelberg},
  issn      = {1861-6909},
  doi       = {10.1186/s11556-022-00296-y},
  pages     = {7},
  year      = {2022},
  abstract  = {In recent years digital technologies have become a major means for providing health-related services and this trend was strongly reinforced by the current Coronavirus disease 2019 (COVID-19) pandemic. As it is well-known that regular physical activity has positive effects on individual physical and mental health and thus is an important prerequisite for healthy aging, digital technologies are also increasingly used to promote unstructured and structured forms of physical activity. However, in the course of this development, several terms (e.g., Digital Health, Electronic Health, Mobile Health, Telehealth, Telemedicine, and Telerehabilitation) have been introduced to refer to the application of digital technologies to provide health-related services such as physical interventions. Unfortunately, the above-mentioned terms are often used in several different ways, but also relatively interchangeably. Given that ambiguous terminology is a major source of difficulty in scientific communication which can impede the progress of theoretical and empirical research, this article aims to make the reader aware of the subtle differences between the relevant terms which are applied at the intersection of physical activity and Digital Health and to provide state-of-art definitions for them.},
  language  = {en}
}
@article{HortobagyiUematsuSandersetal.2018,
  author    = {Hortobagyi, Tibor and Uematsu, Azusa and Sanders, Lianne and Kliegl, Reinhold and Tollar, Jozsef and Moraes, Renato and Granacher, Urs},
  title     = {Beam Walking to Assess Dynamic Balance in Health and Disease},
  series = {Gerontology},
  volume    = {65},
  journal   = {Gerontology},
  number    = {4},
  publisher = {Karger},
  address   = {Basel},
  issn      = {0304-324X},
  doi       = {10.1159/000493360},
  pages     = {332 -- 339},
  year      = {2018},
  abstract  = {Background: Dynamic balance keeps the vertical projection of the center of mass within the base of support while walking. Dynamic balance tests are used to predict the risks of falls and eventual falls. The psychometric properties of most dynamic balance tests are unsatisfactory and do not comprise an actual loss of balance while walking. Objectives: Using beam walking distance as a measure of dynamic balance, the BEAM consortium will determine the psychometric properties, lifespan and patient reference values, the relationship with selected "dynamic balance tests," and the accuracy of beam walking distance to predict falls. Methods: This cross-sectional observational study will examine healthy adults in 7 decades (n = 432) at 4 centers. Center 5 will examine patients (n = 100) diagnosed with Parkinson's disease, multiple sclerosis, stroke, and balance disorders. In test 1, all participants will be measured for demographics, medical history, muscle strength, gait, static balance, dynamic balance using beam walking under single (beam walking only) and dual task conditions (beam walking while concurrently performing an arithmetic task), and several cognitive functions. Patients and healthy participants age 50 years or older will be additionally measured for fear of falling, history of falls, miniBESTest, functional reach on a force platform, timed up and go, and reactive balance. All participants age 50 years or older will be recalled to report fear of falling and fall history 6 and 12 months after test 1. In test 2, seven to ten days after test 1, healthy young adults and age 50 years or older (n = 40) will be retested for reliability of beam walking performance. Conclusion: We expect to find that beam walking performance vis-{\`a}-vis the traditionally used balance outcomes predicts more accurately fall risks and falls. Clinical Trial Registration Number: NCT03532984.},
  language  = {en}
}
@article{BeurskensHelmichReinetal.2014,
  author    = {Beurskens, Rainer and Helmich, Ingo and Rein, Robert and Bock, Otmar L.},
  title     = {Age-related changes in prefrontal activity during walking in dual-task situations: A fNIRS study},
  series = {International journal of psychophysiology},
  volume    = {92},
  journal   = {International journal of psychophysiology},
  number    = {3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0167-8760},
  doi       = {10.1016/j.ijpsycho.2014.03.005},
  pages     = {122 -- 128},
  year      = {2014},
  abstract  = {Background: Previous studies suggest that the human gait is under control of higher-order cognitive processes, located in the frontal lobes, such that an age-related degradation of cognitive capabilities has a negative impact on gait. Results: Our behavioral data partly confirm previous accounts on higher dual-task costs in stepping parameters (i.e., decreased step duration) in old age, particularly with a visual task and negative dual-task cost (i.e., improved performance) during the verbal task in young adults. Functional imaging data revealed little change of prefrontal activation from single- to dual-task walking in young individuals. In the elderly, however, prefrontal activation substantially decreased during dual-task walking with a complex visual task. Conclusion: We interpret these findings as evidence for a shift of processing resources from the prefrontal cortex to other brain regions when seniors face the challenge of walking and concurrently executing a visually demanding task. (C) 2014 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@misc{BeijersbergenGranacherVandervoortetal.2013,
  author    = {Beijersbergen, Chantal M. I. and Granacher, Urs and Vandervoort, A. A. and DeVita, P. and Hortobagyi, Tibor},
  title     = {The biomechanical mechanism of how strength and power training improves walking speed in old adults remains unknown},
  series = {Ageing research reviews : ARR},
  volume    = {12},
  journal   = {Ageing research reviews : ARR},
  number    = {2},
  publisher = {Elsevier},
  address   = {Clare},
  issn      = {1568-1637},
  doi       = {10.1016/j.arr.2013.03.001},
  pages     = {618 -- 627},
  year      = {2013},
  abstract  = {Maintaining and increasing walking speed in old age is clinically important because this activity of daily living predicts functional and clinical state. We reviewed evidence for the biomechanical mechanisms of how strength and power training increase gait speed in old adults. A systematic search yielded only four studies that reported changes in selected gait biomechanical variables after an intervention. A secondary analysis of 20 studies revealed an association of r(2) = 0.21 between the 22\% and 12\% increase, respectively, in quadriceps strength and gait velocity in 815 individuals age 72. In 6 studies, there was a correlation of r(2) = 0.16 between the 19\% and 9\% gains in plantarflexion strength and gait speed in 240 old volunteers age 75. In 8 studies, there was zero association between the 35\% and 13\% gains in leg mechanical power and gait speed in 150 old adults age 73. To increase the efficacy of intervention studies designed to improve gait speed and other critical mobility functions in old adults, there is a need for a paradigm shift from conventional (clinical) outcome assessments to more sophisticated biomechanical analyses that examine joint kinematics, kinetics, energetics, muscle-tendon function, and musculoskeletal modeling before and after interventions.},
  language  = {en}
}