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The effect of a unilateral isometric strength training program on joint angle specificity and cross-training
Abstract
The purpose of this study was to examine the effects of unilateral isometric leg extension strength training on the strength and integrated electromyogram (IEMG) of both the trained and untrained limbs at multiple joint angles. A training (TRN) group (nine females; mean age +/$-$ SD = 20.1 +/$-$ 1.2 yrs.) exercised for six weeks with isometric leg extensions at 80% of maximal isometric torque. A control (CTL) group (eight females; mean age +/$-$ SD = 21.0 +/$-$ 1.2 yrs.) did not exercise. The training was performed three times per week on a Cybex II isokinetic dynamometer at a joint angle where the lever arm was 0.79 rad. below the horizontal plane. The subjects were tested pre- and post-training for maximal unilateral isometric torque in both limbs at joint angles of zero, 0.26, 0.79, 1.31, and 1.57 rad. below the horizontal plane. Bipolar surface electrodes were used to record the IEMG of the vastus lateralis and vastus medialis during the isometric tests. Three univariate (torque, IEMG-lateralis, and IEMG-medialis) four-way (group x time x limb x angle) mixed factorial ANOVA's were used to analyze the data. The results indicated a joint angle specificity effect for isometric torque in the TRN group only, with significant increases in torque at 0.79 (p = 0.0004) and 1.31 (p = 0.0039) rad. No significant (p $>$ 0.05) increases in torque were found in the untrained limb or in the CTL group. Similarly, there were no significant (p $>$ 0.05) changes in IEMG for the vastus lateralis or vastus medialis that were meaningful to the research questions of interest. The angle specific strength increases without concomitant increases in IEMG were hypothesized to result from angle specific decreases in antagonistic co-contraction and/or preferential hypertrophy of the quadriceps femoris group at specific levels of the muscle group.
Subject Area
Anatomy & physiology|Animals
Recommended Citation
Weir, Joseph Paul, "The effect of a unilateral isometric strength training program on joint angle specificity and cross-training" (1993). ETD collection for University of Nebraska-Lincoln. AAI9331432.
https://digitalcommons.unl.edu/dissertations/AAI9331432