Final answer:
The Isthmian Games in ancient Greece likely involved young adult and mature men as competitors, with no specific age groups mentioned. Women were forbidden from watching the games. The societal structure of the time would have prevented women, non-citizens, and slaves from participating in the competitions.
Step-by-step explanation:
The Isthmian Games, like other ancient Greek athletic festivals, did not have specific age restrictions for competitors as modern games do. However, the societal norms and physical requirements of the sports typically limited participation to young adult and mature men with proven abilities. It was over time that professional athletes, no longer just locals, came to dominate these events. Their victories and prowess were often celebrated by poets like Pindar of the early fifth century BCE. Nevertheless, it's important to note that these games and the associated political life of ancient Greece were highly exclusive. Women were forbidden from watching the games and could face severe punishment if they disobeyed this rule. The right to participate in the political process of Athens, which was contemporary with the games, was limited to male citizens over the age of 20, leaving a large portion of the population, including women, non-citizen residents, and slaves, without political rights. Therefore, while there was no explicit age group stated for the Isthmian Games, the societal structure implied that competitors were mainly mature men.