1894 revisited: Cross-education of skilled muscular control in women and the importance of representation.

Abstract

In 1894 foundational work showed that training one limb for "muscular power" (i.e. strength) or "muscular control" (i.e. skill) improves performance in both limbs. Despite that the original data were exclusively from two female participants ("Miss Smith" and "Miss Brown"), in the decades that followed, such "cross-education" training interventions have focused predominantly on improving strength in men. Here, in a female cohort, we revisit that early research to underscore that training a task that requires precise movements in a timely fashion (i.e. "muscular control") on one side of the body is transferred to the contralateral untrained limb. With unilateral practice, women reduced time to completion and the number of errors committed during the commercially available game of Operation® Iron Man 2 with both limbs. Modest reductions in bilateral Hoffmann (H-) reflex excitability evoked in the wrist flexors suggest that alterations in the spinal cord circuitry may be related to improvements in performance of a fine motor task. These findings provide a long overdue follow-up to the efforts of Miss Theodate L. Smith from more than 125 years ago, highlight the need to focus on female participants, and advocate more study of cross-education of skilled tasks.