[1] Columbia Univ, Dept Mech Engn, 220 SW Mudd Bldg,500 West 120th St, New York, NY 10027 USA
[2] CUNY, Hunter Coll, Dept Phys Therapy, New York, NY 10021 USA
[3] Catholic Univ Louvain, Inst Neurosci, Louvain La Neuve, Belgium
[4] Columbia Univ, Weinberg Cerebral Palsy Ctr, Dept Orthoped Surg, Columbia Orthoped,Med Ctr, New York, NY USA
[5] Columbia Univ, Dept Biobehav Sci, Teachers Coll, New York, NY USA
[6] Univ Oregon, Dept Human Physiol, Eugene, OR 97403 USA