My Friend Is Approximately 58 Years Old. He Has Cerebral

my friend is approximately 58 years old. He has cerebral palsy and is confined to a wheelchair most of the day. He is being treated for mild to moderate hypertension. His pulse ox is 92. He is slightly cold to the touch- periodically he get cold chills. I am trying to help him be more active to increase his metabolism slowly**** and prudently. However I am wondering about the cold chills- is this common with this condition - is it circulation? I would appreciate your help and insight please.