Marín competed in three events at the 1988 Summer Paralympics: the men's 800m, 1500m, and 5000m, winning gold in all three events and setting new world records in the 1500m and 5000m. Unfortunately at the 1992 Summer Paralympics in his home country, he did not do as well. He finished sixth in the 800m, fifth in the 1500m, and third in the 5000m, he also won a silver in the 10,000m. All four of these races were won by compatriot Javier Conde, who broke the world record in the 1500m, 5000m, and 10,000m.