The effect of leg flexion angle on the mechanomyographic responses to isometric muscle actions

• Published in: European journal of applied physiology 1998-08, Vol.78 (3), p.264-269
• Main Authors: EBERSOLE, K. T, HOUSH, T. J, JOHNSON, G. O, EVETOVICH, T. K, SMITH, D. B, PERRY, S. R
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Biomechanical Phenomena; Fundamental and applied biological sciences. Psychology; Humans; Isometric Contraction - physiology; Joints - physiology; Leg - anatomy & histology; Leg - physiology; Male; Myography; Striated muscle. Tendons; Torque; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0301-5548; 1439-6319; 1432-1025; 1439-6327
• DOI: 10.1007/s004210050418

The purpose of this investigation was to examine the effect of leg flexion angle on the relationship between mechanomyographic (MMG) amplitude and isometric torque production. Adult males (n = 9) performed isometric muscle actions of the leg extensors at 25, 50, 75, and 100 percent maximal voluntary contraction (%MVC) on a calibrated CYBEX 6000 dynamometer at 25, 50, and 75 degrees below full extension. A piezoelectric MMG recording device was placed over the mid-portion of the rectus femoris. At 25 degrees of leg flexion, the MMG amplitude increased to 100%MVC. At 50 and 75 degrees of leg flexion, however, MMG amplitude increased to 75%MVC, and then did not change significantly (P > 0.05) between 75 and 100%MVC. These findings indicate that the MMG amplitude-isometric torque relationship is joint angle specific and may be the result of leg flexion angle differences in: (1) muscle stiffness, or (2) motor unit activation strategies.