Generally, most enter their athletic prime somewhere between 20 and 30, before undergoing an "irreversible" decline.

What age is your peak fitness?

Strength peaks at age 25.

Your muscles are at their strongest when you're 25, although for the next 10 or 15 years they stay almost as hefty — and this is one of the traits that can be most easily improved, thanks to resistance exercise.

At what age does a female reach their peak athletically?

The age at which peak performance is achieved is different depending upon sports disciplines and is typically in the range of 20–30 years old (Schulz and Curnow 1988; Allen et al.