Kinesiological study of the push-up motion in spinal cord injury patients: involving measurement of hand pressure applied to a force plate.

We studied the pressure exerted by hands during push-ups in 21 paraplegic and 2 tetraplegic patients employing 4 different hand positions. In the fingers-spread position, the initial force exerted was a vertical force (Fz), followed by a medio-lateral force (Fy) and then an antero-posterior force (Fx). In the other 3 positions, the order of force type exertion was Fz, Fx, and then Fy. All subjects with neurological injury levels above T4 and subjects between T5 and T10 without spinal instrumentation could not push themselves up in the fingers-spread position. The fact that Fy is initiated before Fx in the fingers-spread position indicates that lateral balancing of the trunk is critical in this position, thus explaining why subjects without spinal instrumentation with neurological injury at a level higher than T10 could not control their spinal columns while performing push-ups. In contrast, antero-posterior balancing takes priority in the other hand positions. We believe that spinal instrumentation helps balance the trunk in the lateral direction, converting the thoracic spine into a rigid body in subjects with neurological injury at levels above T10.