1. Department of Mechanical Engineering, Columbia University, New York, NY, USA;
2. Department of Physical Therapy, Hunter College, City University of New York, New York, NY, USA;
3. Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium;
4. Department of Orthopedic Surgery, Weinberg Cerebral Palsy Center: Columbia Orthopedics, Columbia University Medical Center, New York, NY, USA;
5. Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY, USA;
6. Department of Human Physiology, University of Oregon, Eugene, OR, USA