Van Dyk, a record 10-time winner of the men’s wheelchair title at the world’s oldest marathon, pushed the early pace but lost ground to Hug, the world champion, who stormed clear to win by more than six minutes in 1:29:53.
While the 42-year-old South African was caught by the chasers, he held on to outsprint Masazumi Soejima of Japan for the silver medal in 1:36:27.
April, meanwhile, did well to hang on to the lead group in the first half, with the pace gradually slowing in cold, wet conditions after a fast start.
The pack charged through the 10km mark in 29:43 but reached halfway in 1:04:01.
