Takayuki Yoshikawa, MD, Yoichi Shimada MD, PhD, Naohisa Miyakoshi, MD, PhD,
Toshiki Matsunaga, MD, PhD, Kazutoshi Hatakeyama, RPT, PhD, Takehiro Iwami, PhD
Jpn J Compr Rehabil Sci 4: 17-21, 2013
Purpose: We developed a three-dimensional
musculoskeletal model and used this model for motion
analysis of the change in posture from standing upright
to maximum anterior inclination of the trunk.
Methods: A new three-dimensional musculoskeletal
model combining the trunk and lower limbs was
constructed from a healthy volunteer. For motion
analysis using this model, five healthy volunteers
participated in this study. A three-dimensional motion
analysis system was used to analyze the flexion phase
from standing upright to maximum anterior inclination
of the trunk, and the return phase from maximum
anterior inclination of the trunk to standing upright.
The muscle activities of the erector spinae, the rectus
abdominis and the gluteus maximus were calculated
from the motion analysis. The ratio of muscle activity
at standing upright phase to the peak muscle activity
was analyzed statistically for each muscle.
Result: The mean ratios of muscle activity at standing
upright phase to peak muscle activity were 1: 3.94 ±
0.65 (mean ± SD) for the erector spinae, 1:1.75 ± 0.22
for the erector spinae, and 1: 4.07 ± 0.68 for the gluteus
maximus. The muscle activity at standing upright
phase and the peak muscle activity were significantly
different in all muscles (paired t-test ; p < 0.0001).
Conclusion: A new three-dimensional musculoskeletal
model combining the trunk and lower limbs is useful
for simultaneous analysis of muscle activities of the
trunk and lower extremities.
Key words: three-dimensional musculoskeletal model, motion analysis, muscle activity