Limits to Improvement as you age

What are the limitations to improving speed-strength attributes as you age?
Specifically, vertical leap, sprint times and reactive ability: how long can you continue to improve?

Merlene Ottey age 43 Olympic sprinter
Jud Logan, Olympic thrower age 44
Barry Bonds age 39
Roger Clemens age 41

We are seeing more and more athletes improve as they get older, is there an explanation?

I’m sure genetics “may” play a role with some older athletes. However, as more research is conducted, better approaches in education and training strategies will help athletes and coaches deal with the aging athlete population.

I guess my question is which motor qualities decline first and what can be done to prevent it. I know for men, testosterone levels begin to decline. What are other hormonal changes will affect performance?

Merlene Ottey and Jud Logan still elite athletes in their mid 40’s??!!

I believe that testosterone levels begin to decline slightly from the age of about 30. Growth hormone levels begin to decline very slowly from the age of about 20. As long as one continues to train for the development of maximum strength, it is possible to make continued improvements until late 40s or beyond. Empirically, however, one’s rate of force development begins to decline slowly from around 25. This is why it is very rare to see sprinters at the top of their game in their mid 30s.
How many people think we will ever see a 40yr old male Olympic 100m champion?