Can somatosensory enhancement amplify rhythmic human arm and leg movement?

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My prior work reveals strong neuronal linkages between arms and legs that are sculpted and adapted to motor behaviour by somatosensory feedback. The current proposal tests the efficacy of pathways formerly used to assess interlimb coordination to now amplify that coordination to harness performance in a targeted way. Now, I am testing the efficacy of enhanced sensory stimulation applied coincidentally with rhythmic motor behavior. Using fatigue and spinal cord reflex modulation as proxy performance criteria, this proposal will assess the potential for enhanced cutaneous input from the hands or feet to amplify neural excitability and motor performance during rhythmic arm and leg cycling. Non-local neuromuscular fatigue, that is typically thought of in association with athletic and exercise performance as used within this proposal, is defined as alteration in neurophysiological and/or performance outcomes of a remote or contralateral non-exercised limb. This type of fatigue is prominent in many forms of exercise involving rhythmic activation of the arms and legs. Thus, fatigue is operationally defined here as a persistent change in interneuronal excitability produced by a bout of rhythmic motor activity that produces short term (e.g. minutes after cessation of movement) changes in reflex amplitudes. Projects proposed in this grant constellate within 2 themes related to the timing of sensory enhancement: A) during; or, B) prior to rhythmic activity. These projects assess the potential for enhanced somatosensory stimulation to: 1) prolong motor output (e.g. mitigate against fatigue, Theme A) during arm or leg cycling (Projects 1-3); 2) prime for enhanced performance (Theme B, Projects 4-7); 3) be amplified by the number of active limbs (arm, leg, and arm Project 8). Enhanced cutaneous input will be delivered to the hands, feet, and hands and feet during rhythmic arm, leg, and combined arm and leg cycling across projects of cycling and sensation.  My long-term objective is to establish the extent to which enhanced somatosensory feedback interacting with CPG mechanisms amplifies motor output during human locomotion. To achieve my long-term objective, a detailed investigation of the extent to which the human somatosensory system may be artificially enhanced by sensory traffic is a requisite next step. Hence the objective for this research is to systematically characterize efficacy of amplifying CPG elements regulating arm and leg movement during motor behaviour using enhanced sensory stimulation via electrical activation of cutaneous nerves innervating the skin of the hands and feet. The working hypothesis for this next phase of my research program is that the application of enhanced sensory input will amplify excitability between the arms and legs during rhythmic activity of both arms and legs.