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1: J Electromyogr Kinesiol. 1999 Jun;9(3):219-27.Click here to read Links

MMG and EMG responses of the superficial quadriceps femoris muscles.

Ebersole KT, Housh TJ, Johnson GO, Evetovich TK, Smith DB, Perry SR.

Center for Youth Fitness and Sports Research, University of Nebraska-Lincoln, 68588-0229, USA. ket1@unlgrad1.unl.edu

Eighteen adults performed isometric muscle actions of the leg extensors at 25, 50, 75, and 100% maximal voluntary contraction (%MVC) at leg flexion angles of 25, 50, and 75 degrees. The results indicated that isometric torque production increased as leg flexion angle increased (75 degrees > 50 degrees > 25 degrees). For each muscle tested (rectus femoris, vastus lateralis, and vastus medialis), the EMG amplitude increased up to 100%MVC at each leg flexion angle (25, 50, and 75 degrees). The MMG amplitude for each muscle, however, increased up to 100%MVC at 25 and 50 degrees of leg flexion, but plateaued from 75 to 100%MVC at 75 degrees of leg flexion. We hypothesize that the varied patterns for the MMG amplitude-isometric torque relationships were due to leg flexion angle differences in: (1) muscle stiffness, (2) intramuscular fluid pressure, or (3) motor unit firing frequency.

PMID: 10328417 [PubMed - indexed for MEDLINE]