The effect of eccentric training at different velocities on cross-education

The purpose of this study was to determine whether cross-education, defined as the increase in strength of an untrained limb after training of the contralateral homologous limb, is specific to low and high velocity eccentric training. Twenty-six subjects were randomized into two groups (n=13 each) that performed unilateral eccentric training of the elbow flexors on an isokinetic dynamometer at velocities of either 30° s^-1 (0.52 rad s^-1) or 180° s^-1 (3.14 rad s^-1 ). Subjects trained three times per week for 8 weeks. Ten subjects served as controls and did not train. Subjects were tested before and after training for peak torque of the elbow flexors during eccentric and concentric contractions at 30° s^-1 and 180° s^-1 . Eccentric peak torque at the velocity of 180° s^-1 in the untrained arm increased only for the group that trained at that velocity (P<0.05). There were no other changes in untrained arms for any of the groups at velocities of 30° s^-1 or 180° s^-1. For the trained arm, the increase in eccentric torque (pooled over velocities) was greatest for the group training at 180° s^-1, whereas the increase in concentric torque was similar for the groups training at 30° s^-1 and 180° s^-1. For the trained arm, there was no specificity for velocity or contraction type. We conclude that cross-education was specific to contraction type and velocity when fast (but not slow) eccentric contractions were used during training; whereas there was no specificity of training in the trained arm.