General:
* Field: This is a good general term for a group of competitors.
* Contenders: This implies they are all strong and likely to win.
* Rivals: This emphasizes a strong competition between them.
Specific to sports:
* Team: If the competitors are on a team, this is the most common term.
* Squad: Similar to team, but sometimes used for smaller groups or more specialized teams.
* Lineup: This refers to the specific competitors participating in a particular event or race.
* Opposition: This is used to refer to the team or group of competitors that your team is playing against.
Other options:
* Cohort: This is a more formal term for a group of people with a shared characteristic, such as being competitors in a particular industry.
* Contingent: This can be used for a group of competitors from a particular company or organization.
Ultimately, the best collective noun to use will depend on the specific context and what you want to emphasize.