Vibration-induced extra torque during electrically-evoked contractions of the human calf muscles

<p>Abstract</p> <p>Background</p> <p>High-frequency trains of electrical stimulation applied over the lower limb muscles can generate forces higher than would be expected from a peripheral mechanism (i.e. by direct activation of motor axons). This phenomenon is presumably originated within the central nervous system by synaptic input from Ia afferents to motoneurons and is consistent with the development of plateau potentials. The first objective of this work was to investigate if vibration (sinusoidal or random) applied to the Achilles tendon is also able to generate large magnitude extra torques in the triceps surae muscle group. The second objective was to verify if the extra torques that were found were accompanied by increases in motoneuron excitability.</p> <p>Methods</p> <p>Subjects (n = 6) were seated on a chair and the right foot was strapped to a pedal attached to a torque meter. The isometric ankle torque was measured in response to different patterns of coupled electrical (20-Hz, rectangular 1-ms pulses) and mechanical stimuli (either 100-Hz sinusoid or gaussian white noise) applied to the triceps surae muscle group. In an additional investigation, M_maxand F-waves were elicited at different times before or after the vibratory stimulation.</p> <p>Results</p> <p>The vibratory bursts could generate substantial self-sustained extra torques, either with or without the background 20-Hz electrical stimulation applied simultaneously with the vibration. The extra torque generation was accompanied by increased motoneuron excitability, since an increase in the peak-to-peak amplitude of soleus F waves was observed. The delivery of electrical stimulation following the vibration was essential to keep the maintained extra torques and increased F-waves.</p> <p>Conclusions</p> <p>These results show that vibratory stimuli applied with a background electrical stimulation generate considerable force levels (up to about 50% MVC) due to the spinal recruitment of motoneurons. The association of vibration and electrical stimulation could be beneficial for many therapeutic interventions and vibration-based exercise programs. The command for the vibration-induced extra torques presumably activates spinal motoneurons following the size principle, which is a desirable feature for stimulation paradigms.</p

Placemaking from Interstitial Spaces: Participatory planning and collaborative community design as strategies to revitalize a service alleyway in Montreal (Bishop/Mackay)

This project explores participatory planning and community design methodologies (i.e. pattern language design, placemaking, community planning charrettes, planning-in-situ, open planning and peer to peer urbanism) to revitalize a service alleyway in downtown Montreal. The objective of this project is to democratize planning and urban design practices and to engage ordinary citizens in the planning of their own spaces. After a series of visioning workshops, brainstorming sessions and a community planning charrette, this project incorporates inputs from stakeholders, students and ordinary citizens into a collaborative urban design project. The project proposes interventions such as a woonerf, a planning committee, a cubic/fractal scaffolding structure, art murals and wall projections (among others). With the objective of encouraging future adaptations and transformations, this project is published under a Creative Commons license. Adopt and adapt these ideas (but cite and acknowledge accordingly)