I wanna add onto to OPs question. How did the media portray the black athletes during the time?
I don't have anything for 1930, but Jesse Owens from 1936 might be good to look into if you don't mind the 6 year gap.
Jesse Owens was something of a Micheal Phelps for the 1936 Olympics in Germany, taking home 4 gold medals and breaking two records. He participated in track and field sports in the US starting in high school, so I can't really answer anything about the first half of your question. I'm not sure if sports weren't actually segregated, or if it ended before 1936.
His tale does say something about the white American response. For one, unlike other Olympic athletes (especially gold medal winners), Owens never received scholarship money from his college. He had to work his way through college using a variety of small jobs, on top of his training.
As a second bit, the president normally personally meets with gold medal winning Olympians, but FDR never met with Owens. Owen's quote on the topic is somewhat famous:
"Hitler didn't snub me—it was [FDR] who snubbed me. The president didn't even send me a telegram."
If you're really interested in the subject, I'd recommend reading his online biographies. http://www.jesseowens.com/about/ http://www.biography.com/people/jesse-owens-9431142
I recall that there was some story about how Owens had to ride the service elevators at various hotels instead of the normal elevator, but I may be thinking about the wrong person.
In all I've read it seems the general american didn't like the fact that African-Americans competed in the Olympics and that the African-American competitors were not as publicized by the media as the others were.
Here are two quotes from Jesse Owens an African-American who competed in the '36 Games held in Berlin under the rule of Hitler. "When I came back to my native country, after all the stories about Hitler, I couldn't ride in the front of the bus;" "I wasn't invited to shake hands with Hitler, but I wasn't invited to the White House to shake hands with the President, either." Source
Here is a good article about the '36 Games from The Holocaust museum in DC but it seems to talk more about how those fighting for civil rights saw the games and not so much about the average american.
I'm sorry if these sources aren't good enough or anything else that's wrong about my post. If I broke the rules and this gets deleted I'd appreciate a PM explaining why because I wanna learn and be active in this sub. Also I'd love to find more info on this but I must get to bed. If for some reason still doesn't have a good response tomorrow I'll do more research and make another post.
It seems like Jesse Owens has gotten a lot of attention, but another good example of the public's lack of interest in it's black Olympians is Mack Robinson. Mack Robinson was the older brother of Jackie Robinson and he was only able to afford the trip to Berlin in 1936 with the help of local buisnessmen. Unfortunatly, he was still unable to afford new shoes. The shoes he used during every meet in college and the Olympic trials were falling apart and the spikes were worn down. He still only lost to Owens by .4 seconds. Despite being a silver medalist, no one was there to greet him when he came home to passedena. The only job he could get was street cleaning and he often wore his Team USA sweater, unable to afford new clothes. He was eventually fired along with all black city employees after a court decision forced Pasadena to integrate it's public pools.
African American athletes have pretty much always competed in the Olympics due to its international nature; however, they still had to deal with Jim Crow laws, segregation and difficulty capitalizing on their Olympic success due to their race.
African Americans aren't as well represented in the early Olympics largely due to a lack of access to the institutions and facilities afforded white athletes and their inability to fund their participation, but George Poage competed and medaled in the 1904 St. Louis games despite calls from some African American leaders to boycott due to the segregated facilities utilized. African Americans would continue to compete in the Olympics to varying degrees from this point on.
Louise Stokes and Tidye Pickett were the first female African American athletes to qualify for the Olympic team, but experienced segregated conditions on the trip to Los Angeles and were replaced on the team by two white athletes before they could compete. However, they did compete in the Games in 1936.
I think others have covered the 1936 Games and Jesse Owens fairly well. Another interesting story is that of Alice Coachman who won bronze at the 1948 games and had a segregated parade thrown in her honor when she returned to her hometown.
The biographies and autobiographies of these athletes are pretty frank about the struggle that these athletes went through. Most received little or no media coverage compared to their white counterparts; often, they would have to use back doors and service entrances at hotels where they were being honored. Like Jesse Owens, these athletes struggled to capitalize on their Olympic success and often faded into obscurity.
I hope this meets the standards of this subreddit. If it needs more sources or elaboration or doesn't meet the requirements of the community please let me know. I studied the history and philosophy of sport in some depth in pursuing my Master's degree in Athletic Administration and it is also a personal interest of mine, so I'd like to see and answer more questions in this area if they arise.
Additional sources: A History and Philosophy of Sport and Physical Education, Robert Mechikoff
Minority Black Olympic Athletes in the 20th and Early 21st Centuries