Along with a reduction in physiological properties, the natural history of aging may include a mechanical plasticity emphasizing proximal muscles as a compensatory mechanism for reduced distal muscle function in locomotion. Pilot data show that while walking at the same speed, healthy old vs. young adults produced more torque and power with proximal hip muscles and less with distal knee and ankle muscles. Since old adults may have larger physiological deficits in distal vs. proximal muscles this mechanical plasticity in torques and powers may enable old adults to perform gait tasks with a motor control strategy favoring their physiological characteristics. We hypothesize that healthy human aging involves mechanical plasticity in locomotion that produces a distal to proximal shift in muscle function. Hypothesis will be tested with 4 specific aims: 1) demonstrate the existence of mechanical plasticity with age and test the effect of gait speed on mechanical plasticity in level walking; 2) determine the relationship between age and mechanical plasticity; 3) determine the generalizability of mechanical plasticity by comparing gait in young and old adults on stairs and an inclined walkway; and 4) assess the effect of strength on mechanical plasticity in locomotion. 140 adults approximately evenly distributed through the ages of 18-85 yrs will be screened for health and mobility status and measured with video, force plates, and EMG in level, stair, and incline walking. Lower extremity strength will be measured isokinetically. Inverse dynamics will calculate lower extremity joint torques and powers. Factorial ANOVAs and regression analyses will be used to analyze joint kinematics, torques and powers and their relationships with age. We expect greater hip and less knee and ankle torque and power in old vs. young. We expect curvilinear relationships between age and measures of mechanical plasticity (torques & powers). We expect that strength will have no effect on mechanical plasticity with all strong and weak old adults exhibiting the altered motor strategy. Our long term goal is to establish a theoretical framework of biomechanical adaptations with age in locomotion. This framework provides a basis for designing exercise and rehabilitation programs for aged individuals with mobility impairments. ? ?
| Hortobágyi, Tibor; Rider, Patrick; Gruber, Allison H et al. (2016) Age and muscle strength mediate the age-related biomechanical plasticity of gait. Eur J Appl Physiol 116:805-14 |
| Hortobagyi, Tibor; Finch, Adria; Solnik, Stanislaw et al. (2011) Association between muscle activation and metabolic cost of walking in young and old adults. J Gerontol A Biol Sci Med Sci 66:541-7 |
| Howatson, Glyn; Taylor, Mathew B; Rider, Patrick et al. (2011) Ipsilateral motor cortical responses to TMS during lengthening and shortening of the contralateral wrist flexors. Eur J Neurosci 33:978-90 |
| Hortobagyi, Tibor; Herring, Cortney; Pories, Walter J et al. (2011) Massive weight loss-induced mechanical plasticity in obese gait. J Appl Physiol 111:1391-9 |
| Solnik, Stanislaw; Rider, Patrick; Steinweg, Ken et al. (2010) Teager-Kaiser energy operator signal conditioning improves EMG onset detection. Eur J Appl Physiol 110:489-98 |
| Hortobagyi, Tibor; Solnik, Stanislaw; Gruber, Allison et al. (2009) Interaction between age and gait velocity in the amplitude and timing of antagonist muscle coactivation. Gait Posture 29:558-64 |
| Devita, Paul; Janshen, Lars; Rider, Patrick et al. (2008) Muscle work is biased toward energy generation over dissipation in non-level running. J Biomech 41:3354-9 |
| Solnik, Stanislaw; DeVita, Paul; Rider, Patrick et al. (2008) Teager-Kaiser Operator improves the accuracy of EMG onset detection independent of signal-to-noise ratio. Acta Bioeng Biomech 10:65-8 |
| Helseth, Joseph; Hortobagyi, Tibor; Devita, Paul (2008) How do low horizontal forces produce disproportionately high torques in human locomotion? J Biomech 41:1747-53 |
| DeVita, Paul; Helseth, Joseph; Hortobagyi, Tibor (2007) Muscles do more positive than negative work in human locomotion. J Exp Biol 210:3361-73 |
