Kevin Varley  asked the Naked Scientists:
   
Hello Dr. Chris
 
As we get older we can not achieve the level of 'fitness' that we could when we were younger. Example professional footballers typically retire before 40 years of age. Can you explain......
 
1. What is fitness?

2. Why does the level of (potential) fitness decrease with age?
 
3. How do we know wether our fitness is decreasing because we are not exercising sufficiently, or because of incresing age?
 
Regards
 
Kevin Varley
Malaysia

What do you think?