He played college football for the Dartmouth Big Green, earning consensus All-American honors in 1919.

Outside of the NFL, Youngstrom played pro football for the Millville Big Blue and the Haven-Villa of Winter Haven.

However, when a local paper included some highlights involving Swede's on-field performance the secret was revealed.

After graduating, Swede was operating a candy store in Hanover, New Hampshire, with Dartmouth teammate Ed Healey when he was approached by representatives from Buffalo with an offer to play for their 1920 team in the new American Professional Football Association (renamed the National Football League in 1922).

In 1923 the All-Americans went 5–4–3, but Youngstrom's stellar play earned him a spot on the Green Bay Press-Gazette All-Pro team.

He spent two seasons with the Jackets, and played a major role in helping the team win the 1926 NFL title.

He also played for the Haven-Villa of Winter Haven, a barnstorming team, made up of several Big Blue members.