Background To gain insight into the role of plantar intrinsic foot muscles in fall-related gait parameters in older adults, it is fundamental to assess foot muscles separately. Ultrasonography is considered a promising instrument to quantify the strength capacity of individual muscles by assessing their morphology. The main goal of this study was to investigate the intra-assessor reliability and measurement error for ultrasound measures for the morphology of selected foot muscles and the plantar fascia in older adults using a tablet-based device. The secondary aim was to compare the measurement error between older and younger adults and between two different ultrasound machines. Methods Ultrasound images of selected foot muscles and the plantar fascia were collected in younger and older adults by a single operator, intensively trained in scanning the foot muscles, on two occasions, 1–8 days apart, using a tablet-based and a mainframe system. The intra-assessor reliability and standard error of measurement for the cross-sectional area and/or thickness were assessed by analysis of variance. The error variance was statistically compared across age groups and machines. Results Eighteen physically active older adults (mean age 73.8 (SD: 4.9) years) and ten younger adults (mean age 21.9 (SD: 1.8) years) participated in the study. In older adults, the standard error of measurement ranged from 2.8 to 11.9%. The ICC ranged from 0.57 to 0.97, but was excellent in most cases. The error variance for six morphology measures was statistically smaller in younger adults, but was small in older adults as well. When different error variances were observed across machines, overall, the tablet-based device showed superior repeatability. Conclusions This intra-assessor reliability study showed that a tablet-based ultrasound machine can be reliably used to assess the morphology of selected foot muscles in older adults, with the exception of plantar fascia thickness. Although the measurement errors were sometimes smaller in younger adults, they seem adequate in older adults to detect group mean hypertrophy as a response to training. A tablet-based ultrasound device seems to be a reliable alternative to a mainframe system. This advocates its use when foot muscle morphology in older adults is of interest.
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A wheelchair undergoes vibrations while traveling over obstacles and uneven surfaces, resulting in whole body vibration of the person sitting in the wheelchair. According to clinicians, people with spinal cord injury (SCI) report that vibration evokes spasticity. The relatively new Spinergy wheelchair wheels (Spinergy, Inc; San Diego, California) are claimed to absorb more road shock then conventional steel-spoked wheelchair wheels. If this claim is true, this wheel might also reduce spasticity in people with SCI. We hypothesized that Spinergy wheels would absorb vibration, reduce perceived spasticity, and improve comfort in individuals with SCI more than standard steel-spoked wheels. To test this hypothesis, 22 nondisabled subjects performed a passive ramp test so that we could more closely examine the dampening characteristics of the Spinergy versus traditional wheels. Furthermore, 13 subjects with SCI performed an obstacle test with both wheel types. Vibrations were measured with accelerometers, and spasticity and comfort were assessed with subject-reported visual analog scales. The results of the study showed that, within the current experimental setup, the Spinergy wheels neither reduced vibration or perceived spasticity nor improved comfort in people with SCI more than the conventional steel-spoked wheels.
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