Grossfeld represented the United States as a gymnast for 15 consecutive years in 35 countries as a member of 26 international United States men's national artistic gymnastics teams including the Olympic Games, World Championships, and Pan American Games.

[citation needed] Grossfeld joined the West Side YMCA in New York City at the age of 16, initially to swim.

[citation needed] Additionally, he helped the team as a diver, and also swam and competed unattached in the NYC Boys’ Swimming Championships, winning gold in the 100 and silver in diving in 1949.

[citation needed] He was awarded the “New York Maritime Benevolent Association Medal” in 1951 for saving a human life in peril.

[citation needed] When he was 16 years old, he dove into an ice-filled river in New York to save a drowning five-year-old.

[1] Grossfeld finished 2nd in the individual all-around at the 1957 NCAA Championships (he attended the University of Illinois, class of 1960).

Grossfeld received the Dike Eddleman Athlete of the Year Award in 1959 as an Illinois Fighting Illini men's gymnastics team member.

A two-time Olympian for the United States' men's gymnastics team, Grossfeld first competed at the 1956 Melbourne Games.

During this time, he also became a professor of physical education and head gymnastics coach at Southern Connecticut State University, helping the program become one of the best in the country.

He coached four Nissen Award winners (akin to football's Heisman Trophy), three NCAA Div.