Martínez has stated that he initially did not like athletics, but after doing a test with the said coach he was told he had the potential to enter the provincial sports school.

He began specialising in the jumps under the supervision of coach Manuel Guilarte, whom he credits for instilling in him the love of athletics.

[1] At the 2013 World Youth Championships in Donetsk, Martínez equalled the World Youth Championship record set by compatriot Héctor Dairo Fuentes in 2005 with an attempt of 16.63 m in the fourth round, earning him his first major gold medal.

Martínez's record-breaking continued into 2014, as he jumped a world youth best of 17.24 m in front of a home crowd in the Cuban capital Havana.

He became the fourth Cuban world junior champion in the triple jump after Yoelbi Quesada in 1992, René Hernández in 1996, Arnie David Giralt in 2002 and Pedro Pablo Pichardo in 2012.