The essential first thing to check for in the wheelchair athlete is whether anything cause be causing a situation of Wikipedia reference-linkAutonomic dysreflexia.

Strangely enough self inducing a level of this can lead to performance increases in spinally injured athletes and I have seen people at world championship events take it to far and ending up collapsed. Things like a distal 'pain-provoking' stimulus or a kink in something as simple at a catheter bag could bring this on.

You can read more about it here: Autonomic Dysreflexia and Hyperreflexia