Sum of phase-shifted sinusoids stimulation prolongs paralyzed muscle output.
Kristen Gelenitis, Max Freeberg, Ronald Triolo
PMID 32276627WHAT IT FOUND
In one person with spinal cord injury, phase-shifted electrical stimulation to knee extensors maintained knee extension force longer than constant stimulation, and closed-loop control made the force steadier.
This was seated isometric knee extension testing, not standing.
Key findings
01Both open-loop and closed-loop phase-shifted stimulation increased time to fatigue and total work compared with constant stimulation.
02Closed-loop phase-shifted stimulation delayed the point at which knee moment fell below the target level compared with open-loop or constant stimulation.
03Closed-loop control reduced moment fluctuations seen with open-loop phase-shifted stimulation to a level not significantly different from constant stimulation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only one participant was tested, and only two legs, so the result is a single-person demonstration, not a pattern across patients. The task was seated isometric knee extension, not standing, walking, or transfers, so it does not show functional benefit. Closed-loop control depended on a laboratory load cell; portable sensors for real tasks have not been tested. Trials lasted at least 10 minutes over three consecutive days, so longer or repeated daily use is unknown. The conditions were tested in a fixed order. The participant had a specific implanted electrode system and selected contacts, so generalisation to other stimulation systems is limited.
Declared interests
The paper names the Foundation for the National Institutes of Health as funder.
The easy way to misread this
Do not conclude that this stimulation prolongs standing. It was tested in one person during seated isometric knee extension, not in standing or walking.