Reyes was born in Viladecans, near Barcelona. Her father was a founding member of the local athletics club – Club Atletismo Viladecans – and this was where she picked up the sport. She began her international career in 1985, making her global debut at the 1985 IAAF World Race Walking Cup, then winning the gold medal at the 1985 European Athletics Junior Championships. Her best finish at a major outdoor tournament followed at the 1986 European Athletics Championships, where she was fifth, and her first senior medal came a year later at the 1987 IAAF World Race Walking Cup, sharing in the women's team silver alongside Teresa Palacio, Mari Cruz Díaz and Emilia Cano. She placed ninth at the 1987 World Championships in Athletics, which was the first ever women's world championship race walk.