Akio Tsubahara, MD, DMSc, Masanori Kamiue, PT, MS, Tomotaka Ito, PT, PhD, Tomoya Kishimoto, PT, PhD, Chiharu Kurozumi, OT, PhD
Jpn J Compr Rehabil Sci 12: 27-31, 2021
Purpose: To identify the optimal stimulation site and
technique for inducing strong muscle contraction
using a high-frequency magnetic stimulator.
Methods: High-frequency magnetic stimulation was
administered to the right vastus lateralis (VL) of eight
healthy adults at maximal intensity within the range of
tolerable pain. The stimulation sites were as follows:
section A, the area between the lateral edge of the base
of the patella (LEBP) and the distal one-third of the
thigh (point D); section B, the area between point D
and the proximal one-third of the thigh (point P).
Isometric maximal muscle contraction forces induced
by magnetic stimulation (Stim-MCF) were compared
between the two sections.
Results: The Stim-MCF was significantly higher in
section B than in section A. Additionally, the sites
susceptible to stimulation were confined to a narrow
area near point D in section A and the central part
between points D and P in section B. The degree of
pain was very low in both sections.
Conclusion: The optimal site for magnetic stimulation
of the VL was limited to the central part of the thigh.
In addition to the superficial proximal sub-branch, the
deep proximal sub-branch and/or deeply clustered
motor nerve endings may have been stimulated. Our
results suggested that moving the probe was a useful
way to identify the site that elicited the strongest
muscle contraction force.
Key words: high-frequency magnetic stimulation, muscle contraction force, strengthening, quadriceps femoris, motor points