Bergamotte said: "Hypothetically, even a paraplegic PWP could achieve the necessary speed, by using equipment that assists."
There has been at least one study done with passive leg cycling [1] but, from memory, the effect was fairly mild.
Acute effects of passive leg cycling on upper extremity tremor and bradykinesia in Parkinson's disease. - PubMed - NCBI
[1] Ridgel AL, Muller MD, Kim CH, Fickes EJ, Mera TO. Acute effects of passive leg cycling on upper extremity tremor and bradykinesia in Parkinson's disease. Phys Sportsmed 2011 Sep;39(3):83-93. doi: 10.3810/psm.2011.09.1924.