Man is crosscountry cycling in the forest.
A man training for a bicycle marathon.
A man riding a bicycle could just be getting some exercise. It does not have to mean training for a marathon.
exists p1 x1 x2.(n_forest(x2) & in(p1,x2) & exists s1 x3.((x1 = x3) & n_cycling(x3) & a_crosscountry(s1) & Theme(s1,x3)) & n_man(x1))
exists x1 x2 x3 x4.(a_topic(x1) & for(x1,x3) & n_marathon(x3) & of(x3,x4) & n_bicycle(x4) & n_training(x1) & of(x1,x2) & n_man(x2))