The rise of professional athletics--with competitors who earn a living participating in sports--has also elevated the notion of professionalism, or the proper behavior of a sportsman. Ethics in athletic competition are of paramount importance because of the intense pressure to perform, the staggering amounts of money involved, and society's willingness to treat professional athletes as special or extraordinary people (and thus exempt from many of the rules that govern the rest of us).
Preparation
Preparation forms a basic tenet of professionalism in sports, often overlooked amid more overtly ethical concerns. It means putting in the work required to perform on the field: showing up for every practice, studying the playbook, staying in shape during the off-season and even watching footage of opponents to get an idea of how they play. Preparation is key to performance, and without putting in those long hours beforehand, the athlete won't be able to do his best on the field.
Opponents
Sports professionals need to treat their opponents with honor and respect. This becomes blurry sometimes, since trash talking and "head games" have become viable strategies on the field. But opponents are not the same as enemies, no matter how heated the rivalry. Treating them with respect means adhering to rules of sportsmanship and fair play, as well as offering a handshake and a "well done" after the game no matter who came out on top.
Losses
No one is perfect, not even the 1972 Dolphins (anyone who saw their sloppy Super Bowl victory can attest to this). Sooner or later, every athlete is going to lose a game, blow a big play or fail to perform when he needs to. Professionalism dictates that the athlete take such setbacks in stride: accept responsibility for the failure with grace and dignity and understand that it's part of the game. At the same time, it behooves the professional to examine what went wrong and work harder to ensure that he doesn't repeat the mistake in the future.
Competition
The purpose of any sporting match is to evaluate the participants as fairly as possible, which means adhering to principles of fair play. Some athletes believe that they should get away with as much as they can--that it's the referee's job to "catch" them and that unless they are called on their behavior, they can use cheap tactics, surreptitious fouls and doctored equipment to get ahead. The most egregious examples of this type of behavior involve doping or sabotage. True professionals adhere to the notions of fair play, relying on their skill and preparation to prevail, rather than bending or breaking the rules.
Team Effort
Some sports rely solely on individuals: tennis, for example, or golf. Most, however, field entire teams, and even athletes for individual sports rely on coaches, trainers and other "team" members to win matches. In that dynamic, the professional understands that the team matters more than the individual. It means performing one's duties within the team's strategies and not emphasizing personal glory over the group's accomplishments.