Effect of high-frequency alternating current transcutaneous stimulation over muscle strength: a controlled pilot study.
Diego Serrano-Muñoz, Juan Avendaño-Coy, Cristina Simón-Martínez and 2 others
PMID 30419966WHAT IT FOUND
High-frequency alternating current at 10 kHz applied over ulnar and median nerves reduced handgrip strength during and just after stimulation in 11 healthy volunteers; 5 kHz and sham did not.
Key findings
0110 kHz high-frequency alternating current applied over ulnar and median nerves reduced maximal handgrip strength during stimulation, from 32.6 N at baseline to 28.1 N at 15 min; 10 min after stimulation it was 31.4 N.
025 kHz high-frequency alternating current and sham stimulation did not show any statistical change in maximal handgrip strength from baseline.
0310 kHz produced lower handgrip strength than 5 kHz and sham during stimulation (28.1 N vs 31.1 N and 33.7 N) and immediately after (29.9 N vs 32.1 N and 32.2 N).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was a pilot study in 11 healthy volunteers, not a clinical trial in patients with pain, hypertonia, spasms, or tremors. Handgrip strength was used as an indirect indicator of motor nerve block, and direct neurophysiological confirmation was not done. The effect was seen only with 10 kHz; 5 kHz and sham did not change handgrip strength from baseline. Blinding was limited: the study was single-blinded, and participants were blinded to the hypothesis rather than fully blinded to active current.
Declared interests
The work was supported by Instituto de Salud Carlos III. No other conflicts of interest are stated in the supplied text.
The easy way to misread this
Do not conclude that 10 kHz transcutaneous high-frequency alternating current is a proven nerve block or treatment for spasms or tremors. It was a pilot in 11 healthy volunteers, handgrip strength was an indirect measure, and the reduction was seen only during and immediately after 10 kHz stimulation.