Hi Liping,
I am going to revise this question a bit to be more clear. The question specifically pertains to the Behrman and Harkema article and treadmill training. Walking at faster speeds taps into our central pattern generators to facilitate a more normal and reflexive walking pattern.
For functional overground walking, bracing is necessary and effective for many individuals post-SCI. In the right circumstances and with adequate manual assistance, some of these patients may benefit from treadmill training without bracing.