She set Finnish age group records as a middle-distance runner and was national champion in the women's 800 metres in 2013, but injuries and stagnating results led her to concentrate on skiing.

[6] She represented Finland in cross-country skiing at the 2013 European Youth Olympic Winter Festival in Brașov, placing eighth in the 5 km classical race.

[4] The move paid off, as she had a good 2016–17 season; at the 2017 World Junior Championships in Park City she won silver in the under-23 women's skiathlon despite skiing with an injured ankle.

[5] Matintalo had a breakthrough race, placing an unexpectedly good 12th in the 10 km classical; she was the second-best Finn behind Krista Pärmäkoski, defeating national team mainstays Kerttu Niskanen, Aino-Kaisa Saarinen, Laura Mononen and Anne Kyllönen.

Kerttu Niskanen won the race in Falun rewriting history together with Johanna: it had been 16 since two Finnish skiers last received gold and silver medals in the World Cup.