Effects of the Use of Cross-education to the Affected Side through Various Resistive Exercises of the Sound Side and Settings of the Length of the Affected Muscles

The purpose of this study was to determine what kind of resistive exercise of the sound limb causes the most effective cross-education, which is defined as the muscle activity of the unexercised limb during contralateral exercise, by analyzing the force and electrical activity of the affected muscle. Six orthopedic patients with unilateral lower extremity impairment that resulted in unexercised quadriceps muscles through treatment by immobilization were the subjects of this investigation. The effect of cross-education was determined by observing the maximal torque of the unexercised quadriceps (MT) and the integrated electromyograms of the unexercised rectus femoris at the time of the maximal response of the torque (IE). A double-blind experiment was conducted with eighteen randomly applied combinations, consisting of six different exercises and three different knee angles. The various resistive exercises on the sound side consisted of proprioceptive neuromuscular facilitation (PNF) movements, PNF positions, straight movements and straight positions in the sagittal plane. Both the mean percentage of the IE and MT were above 23% in the PNF movement, while a mean above 13% was not found in any of the other exercises. PNF movement combined with hip internal rotation was found to be significantly effective for inducing cross-education.