In the cell treated group muscle tension development was significantly higher than in the vehicle group at both time points and recovery to control muscle tension values was observed 28 days after cell injection ( Fig 1 ). This demonstrates that local injection of bone marrow mesenchymal cells (BMMC) significantly improves functional capacity of soleus muscle 14 and 28 days after re-injuries in comparison to vehicle-treated group. It is possible that longer observation times would result in complete recovery of tension development even in the vehicle group; this remains to be investigated and will allow distinction between an accelerated repair mechanism after cell therapy and a gain of function improvement induced by the cells.