Valutazione degli effetti dell'allenamento controlaterale sulla performance dei muscoli dorsiflessori della caviglia in soggetti sani

Purpose:to investigate the Cross-Training effect, induced on ankle dorsiflexors (AD) by unilateral strength-training of the contralateral muscles, as transfer of peak torque (PT) and muscle work (MW) and their relative contributions to muscle performance.Methods:30 healthy volunteers were randomly assigned to a training or control group. The trained group sustained a 4-week maximal isokinetic training of the weaker AD at 90 and 45°/s. At both angular velocities, PT, MW and MW/PT ratio were measured from both legs at baseline and after intervention (trained group) or no-intervention (controls). The learning-effect was calculated and subtracted by PT and MW measures to obtain their net changes.Results:Net PT and MW increased in both the untrained and trained legs. PT and MW gains were larger in the untrained than trained AD (p<0.0005), with MW increasing more than PT at 45°/s (p=0.04). The MW/PT ratio improved bilaterally only in the trained group (p<0.05), depending on the angular velocity.Conclusions:The Cross-training effect occurred in AD muscles in terms of both PT and MW, with MW adding valuable information to PT-analysis in describing muscle performance. Moreover, the MW/PT ratio allowed estimating the contributions of these parameters to muscle capability and may represent a novel index in isokinetic testing. The greater improvements in the untrained than trained limb raises interesting clinical implications in asymmetric conditions.