why do younger people have more energy than older people? and thank you for answering my previous question :P

Question: why do younger people have more energy than older people? and thank you for answering my previous question :P
- Keywords:
  age,
  energy,
  older
Asked by KittyKat73 to Sara on 17 Nov 2015.
- Sara Falcone answered on 17 Nov 2015:
  
  You are very welcome! Ask me everything you want (but don’t be too meany :P).
  As for your question, older people have less energy because of the changes in their body, especially in their muscles. The reduction of muscle mass reduces the strength. The muscle tissue is replaced more slowly and it could be even replaced by a tissue that is tougher (called fibrous tissue) hence harder to contract. All these changes (and more) make it hard for an old people to move quickly and for long periods.

Question: why do younger people have more energy than older people? and thank you for answering my previous question :P