Effect of Anodal Transcranial Direct Current Stimulation of the Motor Cortex on Elbow Flexor Muscle Strength in the Very Old.
Kentaro Oki, Leatha A Clark, Shinichi Amano and 1 others
PMID 28906348WHAT IT FOUND
A single 20-minute session of anodal tDCS over the motor cortex did not improve elbow flexor strength or biceps electrical activity in 11 adults aged 80 and older.
Their elbow flexors were already near fully activated. There was little room for strength gain.
Key findings
01Anodal tDCS did not significantly improve average or peak elbow flexor strength, or average or peak EMG amplitude, compared with sham.
02Voluntary activation averaged 99.3 (1.8)%, and only 1 participant was below 99%.
03The study was stopped early because the effect size was negligible.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 11 participants were studied, and the experiment was stopped early because the effect size was negligible. The elbow flexors showed near-full voluntary activation (99.3 (1.8)%), so a ceiling effect may have prevented detection of a strength change. Motor cortical excitability was not measured, so the study cannot confirm how much excitability changed after tDCS. Participants were community-dwelling adults aged 80 years and older who were excluded for ADL disability, neurological disorder, severe cardiac disease, or cognitive impairment. The trial tested a single 20-minute session and only the non-dominant elbow flexors, so it does not address repeated stimulation or other muscle groups.
Declared interests
No author conflicts are reported in the supplied text. The article is listed as supported by NIH extramural research funding.
The easy way to misread this
Do not conclude that tDCS cannot help very old adults. This trial tested a single 20-minute session on elbow flexors in 11 people, and their voluntary activation was already near full (99.3 (1.8)%). A null result here does not settle whether tDCS could affect other muscles or people with activation deficits.