In the 22 Paralympic sports in which athletes compete alongside a guide or assistant, successful collaborations are often marked by their quiet.

“During the race we try not to speak so much, just as strictly necessary,” Jerusa Geber dos Santos of Brazil said of her relationship with her guide, Gabriel Garcia. Geber dos Santos, 42, who became blind in her teens, holds the women’s world record in the 100-metre dash (11.83 seconds) in a classification of athletes (T11) who are blind or nearly so.