A biker is racing to keep up with the runners
A person is outdoors.
Biker is a person. Racing with the runners implies he is outdoors.
exists e1 p1 x1 x2.(n_runner(x2) & Topic(e1,p1) & Actor(e1,x1) & v_race(e1) & exists e2 s1.(a_up(s1) & Manner(e2,s1) & with(e2,x2) & Actor(e2,x1) & v_keep(e2)) & n_biker(x1))
exists p1 x1.(exists x2.((x1 = x2) & n_outdoors(x2)) & n_person(x1))