SYMPOSIA PAPER Published: 01 January 1985

Torsion of the Lower Extremity and Surface Electromyogram Measurements


The relationship between mean rectified electromyogram signals (MREMG) from lower extremity medial and lateral rotator muscle groups and the torsional moment about the longitudinal axis of the lower leg was investigated in the laboratory and in snow skiing experiments. The MREMG was measured by six surface probes positioned over the gluteus maximus, gluteus medius, semitendinosus, biceps femoris, tibialis posterior, and peroneus longus muscles. In the laboratory, torsion was self-induced by each subject. During snow skiing, torsion of the lower extremity resulted from the normal skiing process. Analyses of the laboratory tests data showed excellent correlation between torsion at the foot and MREMG from some rotator muscle groups. Linear regressions of the MREMG from the gluteus medius and peroneus longus with the measured torsion predicted the torsion with correlation coefficients as high as 0.98 and standard deviations as small as 3.3 N ∙ m. A similar correspondence between MREMG from the rotator muscles and the measured torsion at the foot during normal skiing does not exist. In the field measurements, large MREMG were recorded simultaneously from the medial and lateral rotator muscle groups during falling, binding release, and other events associated with large external force. Posture and body position control during skiing dominate the observed MREMG, thus masking contributions to MREMG from lower extremity torsion.

Author Information

Louie, James, K.
University of California, Berkeley, CA
Kuo, Chen, Y.
University of California, Berkeley, CA
Gutierrez, Maria, D.
University of California, Berkeley, CA
Mote, C., D.
University of California, Berkeley, CA
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Developed by Committee: F27
Pages: 55–75
DOI: 10.1520/STP46627S
ISBN-EB: 978-0-8031-6832-9
ISBN-13: 978-0-8031-6833-6